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GBT 1029-2005

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  • ICS 29.160.01

    K 21

    NATIONAL STANDARD

    OF THE PEOPLE'S REPUBLIC OF CHINA

    GB/T 1029-2005

    Replace GB/T 1029-1993

    Test Procedures for Three-phase Synchronous Machines

    Issued on August 26, 2005 Implemented on April 01, 2006 Jointly issued by the General Administration of Quality Supervision,

    Inspection and Quarantine (AQSIQ) and the Standardization Administration (SAC) of the People's Republic of China

    GB

  • I

    Contents

    Foreword ............................................................................................................................ IV 1 Scope ..............................................................................................................................1 2 Normative References .....................................................................................................1 3 Test Preparation...............................................................................................................2 4 General Test Items ...........................................................................................................2 4.1 Determination of Insulation Resistance .........................................................................2 4.2 Determination of DC Resistance of the Winding at Actual Cold State............................4 4.3 Determination of Shaft Voltage .....................................................................................6 4.4 Determination of No-load Characteristics .....................................................................6 4.5 Determination of Steadystate Shortcircuit Characteristics..............................................8 4.6 Test of Exciter ..............................................................................................................9 4.7 Overspeed Test .............................................................................................................9 4.8 Interturn Short-circuit Test of Non-salient Pole Generator Rotor ...................................9 4.9 Determination of Vibration ...........................................................................................9 4.10 Inspection on Sealing State and Determination of Hydrogen Leakage .........................9 4.11 Interturn Impulse Withstand Voltage Test ....................................................................9 4.12 Short Time Voltage Rising Test ...................................................................................9 4.13 Power-frequency Withstand Voltage Test .................................................................. 10 4.14 DC Leakage Current Test and DC Withstand Voltage Test of the Insulation of Armature Winding .............................................................................................................................. 12 4.15 Determination of Voltage Waveform Sinusoidal Distortion Factor ............................. 14 4.16 Noise Determination................................................................................................. 14 4.17 Determination of Telephone Harmonic Form Factor (THF)....................................... 14 5 Efficiency Determination............................................................................................... 14 5.1 Direct Determination Method of Efficiency ................................................................ 15 5.2 Indirect Determination Method of Efficiency .............................................................. 17 5.3 Calorimetric Method................................................................................................... 18 5.4 Determination of Losses Corresponding to the Rated Load ......................................... 18 5.5 Retardation Test.......................................................................................................... 22 5.6 Calculation of Efficiency under other Loads ............................................................... 23 6 Temperature Rise Test ................................................................................................... 24 6.1 Measurement Method of Temperature......................................................................... 24 6.2 Determination of Cooling Medium Temperature in Temperature Rise Test .................. 25 6.3 Determination of Temperature at Different Parts of the Machine in Temperature Rise Test ..................................................................................................................................... 25 6.4 Correction of the Measured Temperature at Different Parts of the Machine after Cutting off the Supply...................................................................................................................... 26 6.5 Short-circuit Insulation and Brake Method.................................................................. 26 6.6 Method of Temperature Rise Test................................................................................ 26 7 Determination of Voltage Regulation Performance at Self-excited Constant Voltage....... 31 7.1 Determination of Steady-state Voltage Regulation Rate............................................... 31

  • II

    7.2 Determination of Voltage Deviation Degree of Generator Operating under Asymmetric Loads .................................................................................................................................. 32 7.3 Determination of Transient Voltage Variation Rate ...................................................... 33 8 Determination of Torque and Rotational Inertia ............................................................. 33 8.1 Determination of Locked-rotor Current and Locked-rotor Torque................................ 33 8.2 Determination of Nominal Pull-in Torque ................................................................... 35 8.3 Determination of Pull-out Torque of Synchronous Motor ............................................ 37 8.4 Short-time Overtorque Test of Motor .......................................................................... 39 8.5 Determination of Rotational Inertia............................................................................. 39 9 Overcurrent Test and Mechanical Strength Test.............................................................. 39 9.1 Occasional Overcurrent Test ....................................................................................... 39 9.2 Overload Test ............................................................................................................. 40 9.3 Short-circuit Mechanical Strength Test........................................................................ 40 10 Negative Sequence Current Affordability Test.............................................................. 40 11 Determination of the Terminal Dynamic Characteristics of Stator Winding................... 40 12 Parameter Determination (This Chapter is identical to IEC 60034-4) ........................... 41 12.1 Description ............................................................................................................... 41 12.2 Determination of Parameters from No-load Saturation Characteristic and Three-phase Steadystate Shortcircuit Characteristic................................................................................. 42 12.3 Over-excitation Test at Zero Power-factor ................................................................. 43 12.4 Determination of the Excitation Current Corresponding to the Rated Voltage and Rated Armature Current at Zero Power Factor (Overexcitation)..................................................... 43 12.5 Determination of Potier Reactance from the No-load and Three-phase Steadystate Shortcircuit Characteristics and the Excitation Current Corresponding to the Rated Voltage and Rated Armature Current at Zero Power Factor (over-excitated) ..................................... 44 12.6 Determination of the Rated Excitation Current by the Potier's Diagram..................... 44 12.7 Determination of the Rated Excitation Current by the ASA Diagram......................... 46 12.8 Determination of the Rated Excitation Current by the Swedish Diagram ................... 46 12.9 Negative Excitation Test ........................................................................................... 48 12.10 Determination of Xq by Negative Excitation Test..................................................... 48 12.11 Low Slip Test.......................................................................................................... 49 12.12 Determination of Xq from the Low Slip Test ............................................................ 49 12.13 Determination of the Load Angle by On-load Test ................................................ 50 12.14 Determination of Xq from On-load Test Measuring the Load Angle ......................... 50 12.15 Sudden Three-phase Short-circuit Test .................................................................... 50 12.16 Determination of Parameters from the Sudden Three-phase Short-circuit Test ......... 53 12.17 Voltage Recovery Test............................................................................................. 54 12.18 Determination of Parameters from the Voltage Recovery Test ................................. 55 12.19 Applied Voltage Test with the Rotor in Direct and Quadrature Axis Positions with Respect to the Armature Winding Field Axis ....................................................................... 56 12.20 Determination of Parameters from the Applied Voltage Test with the Rotor in Direct and Quadrature Axis Positions with Respect to the Armature Winding Field Axis ................ 56 12.21 Applied Voltage Test with the Rotor in any Arbitrary Position ................................. 57 12.22 Determination of Parameters from the Applied Voltage Test with the Rotor in any

  • III

    Arbitrary Position................................................................................................................ 57 12.23 Line-to-line Steadystate Short-circuit Test ............................................................... 57 12.24 Determination of Parameters from the Line-to-line Steadystate Short-circuit Test.... 58 12.25 Negative Phase Sequence Test ................................................................................ 59 12.26 Determination of Parameters from the Negative Phase Sequence Test ..................... 59 12.27 Single-phase Voltage Application to the Three-phase Test ....................................... 59 12.28 Determination of Parameters from Single-phase Voltage to Three-phase Test .......... 59 12.29 Line-to-line and to Neutral Steadystate Short-circuit Test ........................................ 60 12.30 Determination of Parameters from the Line-to-line and to the Neutral Steadystate Short-circuit Test................................................................................................................. 60 12.31 Field Current Decay Test with the Armature Winding Open Circuited ..................... 61 12.32 Determination of T'd0 from Field Current Decay Test with the Armature Winding Open Circuited.................................................................................................................... 61 12.33 Field Current Decay Test with the Armature Winding Short Circuited ..................... 61 12.34 Determination of T'd from Field Current Decay Test with the Armature Winding Short-circuit ........................................................................................................................ 61 12.35 Suspended Rotor Oscillation Test............................................................................ 62 12.36 Determination of TJ and H from Suspended Rotor Oscillation Test .......................... 62 12.37 Auxiliary Pendulum Swing Test .............................................................................. 62 12.38 Determination of TJ and H from Auxiliary Pendulum Swing Test ............................ 63 12.39 No-Load Retardation Test ....................................................................................... 63 12.40 Determination of Tj and H from the No-load Retardation Test ................................. 63 12.41 On-load Retardation Test of Mechanically Coupled Machines with the Synchronous Machine Operating as a Motor ............................................................................................ 64 12.42 Determination of Tj and H from the On-load Retardation Test with the Synchronous Machine Operating as a Motor ............................................................................................ 64 12.43 Acceleration after a Load Drop Test with the Machine Operating as a Generator ..... 64 12.44 Determination of Tj and H from the Acceleration after a Load Drop Test with the Machine Operating as a Generator....................................................................................... 64 12.45 Rated Voltage Regulation Factor UN ..................................................................... 65 12.46 Determination of Parameters by Calculations Using Known Test Parameters........... 65 Appendix A (Normative) The Value While Determining Excitation Winding Temperature Rise by No-load Short-circuit Method ................................................................................. 69 Appendix B (Informative) Symbols and Units .................................................................. 70

  • IV

    Foreword

    This standard specifies the test methods for the products of three-phase synchronous machines and is the reference for the tests of three-phase synchronous machines.

    The previous edition GB/T 1029-1993 "Test Procedures for Three-phase Synchronous Machines" of this standard was developed referring to such international and foreign standards as IEC 60034-2: 1972, IEC 60034-4: 1985, IEEE115: 1983, OCT 10169: 1977 and OCT 11828: 1986.

    This standard is a revision of GB/T 1029-1993 "Test Procedures for Three-phase Synchronous Machines" and there have been some main revisions as follows:

    1. In consideration of actual national conditions of China, Chapter 12 "Parameter Determination" is modified in relation to IEC 60034-4: 1985 "Rotating Electrical Machines-Part 4: Methods for Determining Synchronous Machine Quantities from Tests" of the International Electrotechnical Commission, and Annex A of IEC 60034-4 provides the test methods that are not finally authorized, as its contents are immature in practical application so that it is deleted in this standard.

    2. Foreword was added; Negative-sequence performance test was added; Determination of the terminal dynamic characteristics of stator winding was added; Contents on determination of transient voltage variation were added.

    3. Relevant contents on total current method and superposition method were deleted; The specified synchronous feedback method that may be adopted for two similar or suitable machines was deleted; Contents on the short-circuit current test were deleted.

    4. The determination of excitation current and voltage regulation factor and the determination of rotational inertia were adjusted into the "Parameter Determination".

    5. The mistakes in GB/T 1029-1993 were corrected. The main corrections are as follows:

    In 6.6.3.4 of the former standard: ( cffN RI q75,732 ) was changed into

    ( cffN RI q-75,752 );

    In Formula (52) of the former standard: The second "=" was changed into "";

    In Formula (60) of the former standard: N

    fwsNpin Ps

    PPUUUUt

    )1(''

    -+

    --

    = was changed

    into N

    fwsNpin Ps

    PPUUUUt

    )1('' 2

    -

    +

    --

    =

    Several errors in printed characters (superscripts and subscripts). 6. Appendixes A, B and C of the former standard were deleted. This standard shall replace GB/T 1029-1993 from the implementation data hereof. Appendix A of this standard is normative and Appendix B is informative. This tandard was proposed by China Machinery Industry Federation.

  • V

    This standard is under the jurisdiction of Subcommittee on Generator of National Technical Committee on Electric Rotating Machinery of Standardization Administration of China.

    This standard was drafted by Harbin Institute of Large Electrical Machinery with the participation of Dongfang Electric Machinery Co., Ltd., Shanghai Turbine Generator Co., Ltd., North China Electric Power Research Institute, Huazhong University of Science and Technology, Power Equipment National Engineering Research Center, Harbin Institute of Technology and Shanghai Electrical Apparatus Research Institute, etc.

    . Chief drafting staffs of this standard: Fu Lixin, Gou Zhide, Zhu Changqian, Shen Rongzhou, Bai Yamin, Ning Yuquan, Zhao Yijun, Sun Li, Kang Erliang and Ni Lixin.

    All previously repalced editions hereof are as: GB 1029-1967 (issued for the first time), GB 1029-1980 (revised for the first time) and

    GB/T 1029-1993 (revised for the second time). This edition is a revision for the third time.

    NOTE: The English version hereof has been translated directly from the openly-published Chinese standard GB/T 1029-2005 . In the event of any discrepancy in the process of implementation, the Chinese version shall prevail.

  • 1

    Test Procedures for Three-phase Synchronous Machines

    1 Scope

    This standard specifies the test methods for three-phase synchronous machines. This standard is applicable to the synchronous motors, generators and synchronous

    compensators with rated power of 1kW (kvA) and above. It is not applicable to the synchronous machines without DC exciting winding, but the tests on the synchronous motors powered by static variable frequency power supply may be made reference to it.

    2 Normative References The following standards contain provisions which, through reference in this text,

    constitute provisions of this standard. For dated reference, subsequent correctionments to (excluding correction to), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document is applicable to this standard.

    GB 755-2000 "Rotating Electrical Machines-Rating and Performance" (idt IEC 60034-1: 1996)

    GB/T 5321 "Measurement of Loss and Efficiency for Large AC Electrical Machines by the Calorimetric Method" (GB/T 5321-1985, neq IEC 60034-2A: 1974)

    GB/T 7409.3 "Excitation System for Synchronous Electrical Machines-Technical Requirements of Excitation System for Large and Medium Synchronous Generators"

    GB 10068 "Mechanical Vibration of Certain Machines with Shaft Heights 56 mm and Higher-measurement Evaluation and Limits of Vibration Severity" (GB 10068-2000, idt IEC: 60034-14: 1996)

    GB/T 10069.1 "Measurement of Airborne Noise Emitted by Rotating Electrical Machinery and the Noise Limits-Engineering Method for the Measurement of Airborne Noise"

    GB/T 10069.2 "Measurement of Airborne Noise Emitted by Rotating Electrical Machinery and the Noise Limits-Survey Method for the Measurement of Airborne Noise"

    GB/T 10585 "Fundamental Requirements of Excitation Systems Medium and Small Synchronous Machines"

    GB/T 15548 "General Specification for Three-phase Synchronous Generators Driven by Reciprocating Internal Combustion Engine"

    JB/T 6227 "Checking Methods and Evaluation of Sealing of Hydrogen-cooled Electrical Machines"

    JB/T 7836.1 "Electric Heater for Electrical Machine Part 1: General Technique

  • 2

    Specifications" JB/T 8445 "Test Methods for Negative Sequence Current Affordability of Three-phase

    Synchronous Generator" JB/T 8446 "Methods for the Determination of Interturn Short-circuit in the Rotor

    Winding of Cylindrical Synchronous Generators" JB/T 8990 "Modal Test Analyses and Natural Frequency Measurement Methods of

    Large Turbo-generators on Stator End Windings and Evaluation Criteria" JB/T 9615.1 "Test Methods of the Interturn Insulation on Random Wound Winding for

    AC Low-voltage Machines" JB/T 9615.2 "Test Limits of the Interturn Insulation on Random Wound Winding for

    AC Low-voltage Machines" JB/T 10098 "Impulse Voltage Withstand Levels of Rotating a.c. Machines with

    Form-wound Stator Coils" (JB/T 10098-2000, idt IEC 60034-15: 1995) JB/T 10500.1 "Embedded Thermometer Resistance for Electrical Machines Part1:

    General Specification, Measuring Methods and Examine Rule" IEC 60034-2 "Rotating electrical machines-Part 2: Methods for Determining Losses

    and Efficiency from Tests" IEC 60034-4 "Rotating electrical machines-Part 4: Methods of Determining

    Synchronous Machine Quantities from Tests"

    3 Test Preparation The electric testing instruments and meters used during the tests shall have an accuracy

    class no less than 0.5 (tramegger excluded), the measurements of the three-phase power may be conducted by using three-phase wattmeter in accuracy class of 1.0 and the measurements of temperature may be conducted by using the thermometer with error of 1 .

    Before the test, the to-be-tested machine shall be at its normal state and be correctly wired, all the equipments and conductors shall meet the test requirements.

    4 General Test Items 4.1 Determination of Insulation Resistance 4.1.1 Determination of insulation resistance of the winding with the enclosure and between the windings 4.1.1.1 State of the machine during the measurement

    The measurements of the insulation resistance of machine winding shall be conducted respectively at the actual cold state and hot state of the machine (or after the temperature rise test).

    During the inspection test, unless otherwise specified, the measurements of the insulation resistance of the winding with the enclosure and between the windings shall be conducted only at the cold state.

    When measuring the insulation resistance, the winding temperature shall be measured,

  • 3

    however, at the actual cold state, the environmental temperature may be measured as the winding temperature. 4.1.1.2 Selection of tramegger

    To measure the insulation resistance of the winding with the enclosure and between windings, the tramegger shall be selected according to Table based on the rated voltage of the tested winding.

    Table 1

    Rated voltage of the tested winding UN/V Specification of tramegger /V

    UN

  • 4

    the method specified in JB/T 7836.1. 4.2 Determination of DC Resistance of the Winding at Actual Cold State 4.2.1 Determination of winding temperature at actual cold state

    After keeping the machine indoors for some time, the temperature of the machine winding and iron core as well as the ambient temperature shall be measured by using thermometers (or embedded temperature detectors), the difference between the measured temperature and the cooling medium temperature shall not exceed 2K; as for the large and medium machines, the thermometers shall have the thermal insulating measures with the outside, and the time for keeping the thermometer shall not be less than 15min.

    To measure the temperature of armature winding and auxiliary winding (such as the harmonic winding of self-excited constant voltage generator), the temperature at the winding head and winding slot shall be measured at different positions based on the size of the machine (if it is difficult, the surface temperature at the iron core tooth and iron core yoke may be measured), the average value shall be taken as the temperature of winding at the actual cold state.

    To measure the temperature of excitation winding of salient pole machine, temperature may be measured directly at several points on the winding surface. The average value of the measured values shall be taken as the temperature of winding at the actual cold state.

    To measure the temperature of the excitation winding of non-salient pole machine, the surface temperature of winding shall be measured, if it is difficult to measure, it may be replaced by the surface temperature of rotor; as for the large and medium machines, at least three measuring points shall be set, and the average value of the measured values shall be taken as the temperature of winding at the actual cold state.

    To measure the temperature of the winding in excitation device of self-excited constant voltage generator (such as the windings of transformer and reactor, etc), the surface temperature of iron core or winding shall be measured by using thermometer as the temperature of winding at the actual cold state.

    As for the liquid directly cooled winding with liquid supplied, the average value of the liquid temperatures at the inlet and outlet of winding when the difference in the inlet and outlet liquid temperature does not exceed 1K and the difference in the core temperature and ambient temperature does not exceed 2K may be taken as the temperature of winding at the actual cold state. 4.2.2 Determination of the DC resistance of winding

    The DC resistance of winding may be measured by bridge method, microhmmeter method, voltmeter-amperemeter method or other measurement methods. 4.2.2.1 When measuring the DC resistance of winding by using such instruments as automatic checkout equipment and digital microhmmeter, the test current passing through the tested winding shall not exceed 10% of the rated current, and the power on time shall not exceed 1min. 4.2.2.2 When measuring by bridge method, each resistance shall be measured for three times, each measurement shall be done again after the bridge balance is destroyed, the difference between the reading every time and the average value of the readings of these three times shall be within 0.5% of the average value, and the average value shall be taken as the actual measured value of resistance. If the DC resistance of winding is less than 1, the

  • 5

    double bridge with at least four significant digits shall be used for the measurement. 4.2.2.3 When measuring by the voltmeter-amperemeter method, the wiring principle is as shown in Figure 1. In the diagram, Rb is the adjustable current-limiting resistance, R is the winding of the machine under test, V is the voltmeter and A is the amperemeter. The wiring shown in Figure 1(a) is applicable to the measurement of the resistance of such winding that the ratio between the internal resistance of voltmeter and the measured resistance is larger than 200, and the wiring shown in Figure 1(b) is applicable to the measurement of the resistance of such winding that the ratio between the internal resistance of voltmeter and the measured resistance is less than 200.

    During the test, the applied current shall not exceed 10% of the rated current of winding, the power on time shall not exceed 1min, the current and voltage values shall be read simultaneously, each resistance shall be measured under at least three different kinds of current values, the difference between each measured value and the average value shall be within 0.5%, and the average value shall be taken as the actual measured value of resistance.

    Figure 1

    4.2.2.4 To measure the armature winding, the rotor of the machine shall be stay still. Where both the start and tail ends of each phase and each branch circuit of the winding are led out, the DC resistance of each phase and each branch circuit shall be measured respectively.

    Where the windings of different phases are connected in the machine, the resistance shall be measured between each outlet terminals, and the phase resistance values shall be calculated according to the following formulae:

    For the star-connected winding, as shown in Figure 2(a) Ru=Rmed-Rvw (1) Rv=Rmed-Rwu (2) Rw=Rmed-Ruv (3)

    For the delta-connected winding, as shown in Figure 2(b)

    meduvuvdm

    wuvwu RRRR

    RRR -+-

    =e

    (4)

    medvwvwmed

    uvwuv RRRR

    RRR -+-

    = (5)

    medwuwumed

    vwuvw RRRR

    RRR -+-

    = (6)

  • 6

    Where: Rmed=(Ruv+Rvw+Rwu)/2, Ruv, Rvw and Rwu respectively are the resistance values () measured between the outlet terminal u and v, v and w, and wand u;

    Ru, Rv and Rw respectively are the phase resistance of each phase ().

    Figure 2

    4.2.2.5 The DC resistance of the excitation winding shall be measured at the terminal from which the winding is led to the slip ring or on the surface of slip ring, and the DC resistance the winding in the excitation device of self-excited constant voltage generator shall be measured on the outlet terminal of winding separately. 4.3 Determination of Shaft Voltage

    The machine under test shall operate under no load at its rated voltage and speed. The typical measurement diagram is shown as Figure 3, the shaft voltage U1 shall be measured firstly with high internal resistance AC voltmeter, then the end without insulation of the rotating shaft shall be short-circuited with its bearing seat (the rotating shaft insulated on both sides shall be short-circuited on any side), the voltage U2 on the other side to the bearing seat (namely the voltage of oil layer) shall be measured, and then the voltage U3 of this bearing seat to the ground shall be measured. The surface of the measuring point shall contact well with the lead wire of voltmeter. Before the test, the insulation resistance between the bearing seat and metallic gasket and between the metallic gasket and metal base shall be inspected respectively. 4.4 Determination of No-load Characteristics 4.4.1 Generator method

    The machine under test shall be dragged to its rated speed with the armature winding open-circuited, and the test shall be conducted by separate excitation mode.

    The excitation current is adjusted. If there is no other requirement, the no-load armature voltage shall be adjusted to 1.3 times of the rated value or the voltage corresponding to the rated excitation current shall be taken as the starting point of no-load characteristic. Later, the excitation current will be reduced to zero in one single direction, generally 7~9 points shall be laid off (more points shall be measured near to the rated voltage value), the three-wire voltage, excitation current and frequency (or rotation speed) shall be read at each point. Finally, the residual voltage shall be read when the excitation current is equal to zero.

    If the three-wire voltage is symmetrical, besides reading the three-wire voltage at the rated voltage, the one-wire voltage value of any wire may be measured at other points.

  • 7

    1Bearing seat;

    2Insulation gasket;

    3Metallic gasket;

    4Insulation gasket;

    5Rotor.

    Figure 3

    Where the frequency f differs from the rated frequency fN during the test, the non-load voltage of armature shall be converted according to the following formula:

    Uff

    U N=0 (7)

    Where: Uthe no-load voltage (three-phase average value) measured from test, V; U0the no-load voltage converted to the state at rated frequency, V. The relation curve U0=f(If) is the calculated no-load curve. If the residual voltage is high

    in the no-load characteristic test, then the no-load curve shall be corrected. The correction method is to extend the straight line portion of the curve to intersect with the abscissa axis,

    the absolute value If of the intersection point with abscissa is the corrected value, and all the measured excitation current value from tests shall be added by this value (If) to obtain the corrected curve. The straight line portion of no-load curve and its extension line generally are named as the air-gap line, See Figure 4.

    Figure 4

    4.4.2 Motor method

  • 8

    The machine under test is connected to a actually symmetrical, stabilized supply with rated frequency and adjustable voltage so that the machine will operate under no load at separate excitation mode.

    The supply voltage is adjusted and the excitation current of the machine under test is adjusted correspondingly to make the armature current reach the minimum value (here, the power factor of machine is 1.0, the readings of two wattmeters as connected by two-voltmeter method are equal and are in the same direction), the corresponding excitation current at this time is the excitation current at this voltage.

    If there is no other requirement, the test shall be started from 1.3 times of the rated voltage of armature, the terminal voltage and excitation current shall be adjusted till the minimum voltage of the machine just before pull-out, 7~9 points shall be measured during the whole process, and the applied voltage, excitation current and frequency (or rotation speed) shall be read at each point.

    If the three-wire voltage is symmetrical, besides reading the three-wire voltage at the rated voltage, the one-wire voltage value of any wire may be measured at other points.

    If the frequency during the test differs from the rated frequency, the no-load armature voltage shall be corrected according to Formula (7). 4.4.3 As for the synchronous machines bellow 1000kVA, the excitation current at the rated voltage shall be measured possibly during the tests. 4.5 Determination of Steadystate Shortcircuit Characteristics 4.5.1 To determine the three-phase steadystate shortcircuit characteristic, the low impedance conductor shall be used to short circuit the terminals by approaching to the outlet terminal of armature winding as much as possible. During the test, the machine shall operate at separate excitation mode. 4.5.2 Generator method

    In the test, the machine under test shall be dragged to its rated speed and the excitation current shall be adjusted to make the armature current be about 1.2 times of the rated current, meanwhile, the armature current and excitation current shall be read. The excitation current will be reduced gradually down to zero, totally 5~7 points shall be read, and then the shortcircuit characteristic curve IK=f(If) shall be plotted. If the three-phase current is symmetrical, besides reading the three-wire current at the rated current, the one-wire current value of any wire may be measured at other points. 4.5.3 Motor method (retardation test)

    The motor under test shall operate under no load, the excitation current will be reduced to zero immediately after cutting off the power, and the excitation source also shall be cut off, then the three phases of the armature winding shall be short circuited simultaneously with switches that have been prepared in advance.

    The excitation source shall be switched on, the excitation current will be adjusted to make the armature current be about 1.2 times of the armature current, meanwhile, the armature current and excitation current shall be read. Later, the excitation current will be reduced gradually, 5~7 points shall be read within the allowable range of the precision of instruments and meters; if the read test data are insufficient from one retardation test, the above-mentioned steps may be repeated till obtaining sufficient test data. Finally, the shortcircuit characteristic curve Ik=f(If) shall be plotted.

  • 9

    4.5.4 As for the synchronous machines bellow 1000kVA, only the excitation current at the rated armature current may be read possiblly during the tests. 4.6 Test of Exciter

    The tests of exciter shall be conducted in accordance with GB/T 7409.3, GB/T 10585 and the method specified for this type of machine. 4.7 Overspeed Test

    If there is no other requirement, the overspeed test may be conducted at cold state. Before the overspeed test, the assembling quality of the machine, especially the

    assembling quality of the rotating parts, shall be inspected carefully so as to prevent sundries parts from flying out when the rotation speed is increased.

    During the overspeed test, corresponding safety protection measures shall be taken, the measurements of such parameters as the control of machine under test, vibration, rotation speed and bearing temperature shall adopt the remote measurement method.

    The overspeed test may adopt motor method (improving the supply frequency) or prime mover dragging method according to specific conditions.

    During the process of raising the speed, the working condition of the machine shall be observed when its reaches its rated speed in order to confirm the machine is free from abnormal phenomena, and then its speed shall be increased by a appropriate accelerated speed till the specified rotation speed. The overspeed value and the duration time shall be carried out according to the method specified in 8.5 of GB 755-2000 or the method specified in the standard on this type of machine.

    After the overspeed test, the machine shall be checked carefully whether its rotating parts have damages or harmful deformation, whether its fasteners are loose or whether other unallowable phenomena appear. After the test, the rotor winding must meet the requirements of withstand voltage test. 4.8 Interturn Short-circuit Test of Non-salient Pole Generator Rotor

    The interturn short-circuit test of the non-salient pole generator rotor shall be conducted according to the method specified JB/T 8446. 4.9 Determination of Vibration

    The determination of vibration shall be conducted according to the method specified GB 10068. 4.10 Inspection on Sealing State and Determination of Hydrogen Leakage

    The test methods shall be carried out in accordance with the method specified JB/T 6227. 4.11 Interturn Impulse Withstand Voltage Test

    The interturn impulse withstand voltage test shall be conduced according to the methods specified in JB/T 10098, JB/T 9615.1 and JB/T 9615.2. 4.12 Short Time Voltage Rising Test

    The test shall be done when the machine bear no load, except for the following requirements, the applied voltage (motor) or induction voltage (generator) in the test shall be 130% of the rated voltage.

    As for the machine of which the non-load voltage is above 130% of the rated voltage at the rated excitation current, the test voltage shall be equal to the non-load voltage at rated excitation current.

  • 10

    Where no other relevant standards or technical documents are available, the test duration shall be 3min, but the following requirements are excluded.

    At the voltage of 130% of the rated voltage, the test duration for the machine of which the no-load current exceeds its rated current may be shortened to 1min. As for the exciter of forced excitation, if the voltage during forced excitation exceeds 130% of the rated voltage, then the test shall be conducted at the limit voltage for forced excitation, and the test duration shall be 1min.

    Where the test voltage is increased to 130% of the rated voltage, it is allowed to increase the frequency or rotation speed simultaneously, however, the rotation speed shall not exceed 115% of the rated speed or the rotation speed specified in the overspeed test. The allowable speed increasing value shall be specified in the standards on different types of machines.

    As for the generator with relatively saturated magnetic circuit, when the rotation speed is increased to 115% of the rated speed and the excitation current also has been increased to the allowable limit, if the induction voltage value can not reach the specified test voltage, then it is allowed to do the test at the achievable maximum voltage. 4.13 Power-frequency Withstand Voltage Test

    The frequency of test voltage is the power frequency and the voltage waveform shall be approximate to the sinusoidal waveform as much as possible. During the whole process of withstand voltage test, necessary safety protection measures shall be taken. Specific personnel shall be arranged around the machine under test for monitoring. 4.13.1 Test Requirements 4.13.1.1 Unless otherwise specified, the power-frequency withstand voltage test shall be conducted when the machine is at stationary state. 4.13.1.2 The insulation resistance of the winding shall be measured before the test; if the machine needs to pass the overspeed test, occasional overcurrent test, short-time overtorque test and short-circuit mechanical strength test, the power-frequency withstand voltage test shall be conducted after those tests. During the type test, the power-frequency withstand voltage test shall be conducted immediately the temperature rise test. 4.13.1.3 Where the starting and tail ends of each phase or each branch circuit of the armature winding or auxiliary winding are led out separately, the armature winding and auxiliary winding shall be tested respectively. 4.13.1.4 During the test, both ends of the tested winding shall be applied with voltage simultaneously (as for the small machines, the winding may be applied with voltage at one end), here, the other windings and embedded thermometric elements not included in the test all shall have electrical connection with the iron core or the enclosure, and the enclosure shall be grounded. Where the neutral points of three-phase winding are uneasy to separate, the three-phase winding shall be applied with voltage simultaneously. 4.13.1.5 As for the water-cooled armature winding, if the test is conducted when the winding is supplied with water, the water header shall be grounded. If the test is conducted when water is not supplied, the insulating hose must be blown to dry inside. 4.13.1.6 The testing transformer shall have adequate capacity, if the capacitance C of the winding of the machine under test is large, the rated capacity SN(kVA) of this transformer shall be larger than the value obtained by the following formula:

    SN=2pifCUUNT10-3 (8)

  • 11

    Where: fthe supply frequency, Hz; Uthe test voltage value, V; UNTthe rated voltage at high-voltage side of testing transformer, V; Cthe capacitance of the tested winding of machine, F.

    4.13.2 Method of power-frequency withstand voltage test The wiring diagram of the test is given in Figure 5 (the wiring diagram of the withstand

    voltage test of rotor is given in diagram). In this diagram, T1 is the regulating transformer, T2 is the high-voltage test device, PT is the potential transformer, R is the current-limiting protective resistance and its value generally is 0.2~1/V, R0 is the sphere gap protective resistance (not for low-voltage machine) and its value generally may adopt 1 /V, QX is the overvoltage protective sphere gap (not for low-voltage machine), V is the voltmeter, TM is the machine under test, therein, the sphere gap and sphere diameter shall be selected according to the insulation test voltage of high-voltage electrical apparatus and the requirements of the test method, the discharge voltage of sphere gap shall be set to 1.1~1.5 times of the test voltage. If the capacitance current needs to be measured, the amperemeter and the short-circuit protection switch parallel to the amperemeter may be connected at the high-voltage side of the test device. If the amperemeter is connected at the low-voltage side, the influence of stray current on the readings shall be taken into account.

    In the test, the applied voltage shall be started from a value not exceeding a half of the full test voltage and shall be increased to the full value by a rate no larger than 5% of the full value uniformly or by stages, and the time for the voltage increasing from half of the full value to the full value shall not be less than 10s. The voltage in the test adopting full value shall be in accordance with those specified in Table 14 of GB 755-2000 and shall be maintained for 1min.

    Figure 5

    When conducting routine tests on the 5kW (or kVA) or below machines that are produced in batches, the 1mm test may be replaced by about 5s test, and the test voltage shall adopt the normal value specified in Table 14 of GB 755-2000. Or the test may also be replaced by 1s test, but the test voltage shall be 120% of those specified in Table 14 of GB 755-2000, and the test voltage shall be applied by using test bar. At the end of the test, the voltage also shall be reduced uniformly, the supply source can be cut off only after the voltage drops to one third of the full value, and the tested winding shall discharge.

    During the test, if it is discovered that the voltmeter pointer beats greatly, the indication of amperemeter increases suddenly and the insulation has such abnormal phenomena as smoke or noise, the voltage shall be reduced immediately and the supply source shall be

  • 12

    disconnected, and the tested winding shall be checked after discharging. 4.14 DC Leakage Current Test and DC Withstand Voltage Test of the Insulation of Armature Winding

    Where the starting and tail ends of each phase or each branch circuit of the three-phase winding are led out separately, their leakage current test to the ground shall be conduced respectively. Before testing one phase or one branch circuit of the winding, the other two phases of windings or other branch circuits shall be grounded; if the neutral points of three-phase winding are linked together and uneasy to separate, then the test may be conducted on these three phases of windings. In the test, the armature winding temperature and the ambient temperature and humidity shall be recorded.

    The maximum voltage for the DC leakage current test is the value from DC withstand voltage test and this value is specified in the relevant technical documents. 4.14.1 Test methods 4.14.1.1 Air-cooled or hydrogen-cooled armature winding

    The wiring for test is as shown in Figure 6. In the Figure, T1 is the voltage regulator; T2 is the high-voltage test device; R is the current-limiting protective resistance and its value is (0.1~1); D is the high-voltage rectifying silicon stack; V is the high-voltage measurement device; A is microammeter; K is knife switch; TM is the machine under test; and C is the high-voltage filter capacitor.

    Figure 6

    In the test, the voltage of voltage regulator shall be set at the minimum position, the voltage regulator will be adjusted after being energized and the voltage will be increased uniformly. The voltage shall be increased step by step during the test. For example, increasing from 0.5UN, 1.0UN and 1.5UN to the specified value. The test shall stay at each voltage stage and the current value (the leakage current value) of microammeter at the starting and at the 1 min of this stage shall be recorded. At the end of the test, the voltage regulator shall be reset, the supply source shall be cut off, and the winding shall be grounded after discharging. After discharging, another winding can be tested.

    During the test, if it is discovered that the leakage current increases rapidly with time or abnormal discharge phenomenon exists, the test shall be stopped immediately and the supply source shall be disconnected, the winding shall be grounded after discharging for testing again.

    The relation curve of leakage current with test voltage shall be plotted based on the test data.

    The amperemeter and the short-circuit protection switch parallel to it shall be connected at the high-voltage side, and the personnel safety shall be guaranteed when measuring. If the

  • 13

    amperemeter is connected at the low-voltage side, the influence of stray current on the readings shall be taken into account. 4.14.1.2 Internal water-cooled armature winding

    The wiring for test is as shown in Figure 7. In the Figure, T1 is the regulating transformer, T2 is the high-voltage test device; R is the current-limiting protective resistance and its value is (0.1~1)/V; D is the high-voltage rectifying silicon stack; A is microammeter; K is knife switch; TM is the machine under test; C is high-voltage filter capacitor; V is high-voltage measurement device; C1 is low-voltage filter capacitor; L1 is inductive choke coil; E is 1.5V battery; Rb is 100k carbon film resistor; Ra is 500k potentiometer; and mA is milliammeter for monitoring. The selection of the capacitive C(F) of high-voltage filter capacitor shall make the time constant meet the following conditions:

    TCRy0.3s Where: Rythe insulation resistance between tested winding and water header, . If the armature winding is tested with water supply, the water electrical conductivity

    shall not be larger than 1.5s/cm; before each test, the potentiometer R shall be adjusted to obtain one compensatory potential that has opposite polarity but equal value with polarization potential, and the microammeter indicates zero. Then the no-load DC leakage current of the tested equipment shall be measured (the reading of microammeter with no test object connected).

    The operating method after connecting the test object is given in 4.13.1.1. The actual DC leakage current I(A) shall be calculated according to the following formula:

    Figure 7

    02

    11 1 IR

    RII -

    += (9)

    Where: I1the reading of microammeter, A; R1the series resistance value of the resistance of choke coil with the internal

    resistance of microammeter, ; R2the resistance value to ground of the water header measured when the armature

    winding is wire at test state, ; I0the no-load DC leakage current of the test equipment, A. If the armature winding is tested after blowing, the test method is basical same as that

    Water header

  • 14

    for the armature winding with water supply, and the compensatory potential will be unnecessary.

    If required, the hydraulic test shall be conducted after this test. 4.15 Determination of Voltage Waveform Sinusoidal Distortion Factor 4.15.1 The machine shall operate at the state of no-load generator, its rotational speed and voltage shall be adjusted to their rated values before the determination. 4.15.2 Based on the test conditions, any one method listed bellow may be adopted for the determination. 4.15.2.1 Determination by using waveform distortion tester. 4.15.2.2 The values of the fundamental voltage and harmonic voltages shall be measured by using harmonic analyzer and the distortion factor shall be calculated according to Formula (10).

    %1001

    224

    23

    22

    ++++=

    UUUUU

    K nu (10)

    4.15.2.3 The instantaneous value of voltage waveform shall be recorded with recorder, and the values of fundamental voltage and harmonic voltages shall be obtained through decomposing, and the distortion factor shall be calculated. 4.15.3 The measured armature voltage may be measured after reducing the voltage with voltage divider or potential transformer, the waveform shall be kept undistorted when using a voltage divider or potential transformer. 4.16 Noise Determination

    The noise test shall be conducted according to the method specified in GB/T 10069.1 and GB/T 10069.2. 4.17 Determination of Telephone Harmonic Form Factor (THF)

    The determination of THF shall be conducted when the machine is at the no-load rated voltage and rated frequency, the values of the fundamental voltage and harmonic voltages shall be measured by using special instruments or harmonic analyzer, and the frequency range shall include all the harmonics from the rated value to 5000Hz. THF shall be calculated according to the following formula:

    2

    1)(100(%)

    -

    =n

    iiiEU

    THF l (11)

    Where: Uthe effective value of line voltage, V; Eithe effective value of the ith harmonic voltage, V; ithe weighting coefficient corresponding to the ith harmonic frequency, the

    weighting coefficients for different frequencies may be inquired from the weighting coefficient table or the weighting curve, see Table 16and Figure 13 in GB 755-2000.

    The telephone harmonic form factor of the machine shall adopt the maximum value among the THF values obtained from three line voltages.

    5 Efficiency Determination

  • 15

    5.1 Direct Determination Method of Efficiency

    Output and input power of machine under test is measured so as to determine the efficiency. 5.1.1 During the test, the measurement shall be carried out where the machine under test is operated till thermal-stable at the rated power, voltage, speed and power factor.

    Where the input and output power of machine under test is measured, the armature current, excitation current and cooling medium temperature of the machine shall be measured at the same time.

    Where the cooling medium temperature is not at 25 , every winding temperature rise and DC resistance shall also be measured at the same time (it may be measured just after test, however, shall be corrected to the disconnection instant). 5.1.2 Any of the following methods may be adopted where the machine efficiency is determined with direct method. 5.1.2.1 Brake method

    Where the machine under test operates as a motor, it shall be connected with the brake or dynamometer in order to measure the rotation moment of machine; at the same time, its rotation speed is determined to determine the output power of machine; the input power of machine is measured with electrical instruments. Where the machine under test operates as a motor, dynamometer shall be adopted to trail the machine under test and measure the input power of the machine; electrical instrument is used to measure the output power of machine.

    Rotation speed of the machine shall be paid much attention to due to its direct influence on power calculation.

    The test shall be conducted at the temperature which is obtained at the end of the specified time of quota and it is not necessary to take temperature conversion for winding resistance. 5.1.2.2 Machine calibration method

    Machine under test is mechanically coupled with the calibrated machine; input (for generator) or output (for motor) power of machine under test is measured with the calibrated machine and the output (for generator) or input (for motor) of the machine under test is measured with electrical instrument.

    The test shall be conducted at the temperature which is obtained at the end of the specified time of quota and it is not necessary to take temperature conversion for winding resistance. 5.1.2.3 Towards-tow method

    Two identical machines are mechanically coupled, with one as motor and another as generator. Motor input power and generator output power are measured with electrical instruments; where the operation conditions of two machines are almost the same and it is assumed that the loss is shared, the motor output power is the difference between halves of the input power and the total loss; while the generator input power is the sum of halves of the output power and the total loss.

    The test shall be conducted at the temperature which is obtained at the end of the specified time of quota and it is not necessary to take temperature conversion for winding resistance.

  • 16

    5.1.3 Total loss determination 5.1.3.1 Feedback method

    Two identical machine machineries are coupled with electricity, with one as the motor and the other as the generator; the losses of both machines are provided by the power grids connected to them, by the dynamometer of mechanical coupling or by calibrated machines.

    Where the operation conditions of both machines are almost the same and the loss is assumed to be shared, the input/output power of the machine under test may be determined according to the methods in 5.1.2.3.

    The test shall be conducted at the temperature which is obtained at the end of the specified time of quota and it is not necessary to take temperature conversion for winding resistance.

    As the power transfer size between two machines are different along the load angle size, an accurate load angle relation shall be provided where two machines are mechanically coupled. 5.1.3.2 Zero power factor test

    The machine under test operates as no-load motor at rated voltage and rated speed; power factor is at about zero and the excitation current is adjusted to ensure the primary winding current reaches the rated value. Its total losses are equal to the input power during test; thereinto, the excitation loss is corrected according to the difference between the actual excitation current loss and the excitation current loss at rated load.

    The machine shall be provided with the same core loss value at power supply voltage as at no-load operation of rated voltage. The power supply voltage is generally equal to the rated voltage unless the power supply voltage would make the core loss increase much more than it does at full load. In principle, reactive power shall be positive (overexcited). If this couldn't be achieved due to insufficient excitation voltage, the test may be conducted at the working condition of absorbing reactive power (under-excitation). 5.1.4 Efficiency calculation 5.1.4.1 Efficiency of machine under test conditions is calculated according to the following formula:

    %100=inP

    Ph (12)

    Where: POutput active power of the machine, kW; PinInput active power of machine, kW.

    5.1.4.2 Where the machine efficiency is determined using direct method, if the cooling medium temperature is not 25 , it shall be converted to 25 according to the following formula:

    %100)25(

    )25( =inPPh (13)

    Where: Pin(25)= Pin + Pcua + Pcuf(kW)

  • 17

    -

    ++D+

    =D 125

    3 2a

    aaacua k

    kRIP

    qq

    (kW)

    -

    +

    +D+=D 1

    252f

    fffcuf k

    kRIP

    qq

    (kW)

    IaArmature phase current during efficiency determination, A; IfExcitation current during efficiency determination, A; RaDC resistance value of armature winding single-phase during efficiency

    determination, ; RfDC resistance value of excitation winding during efficiency determination, ; aTemperature rise value of armature winding during efficiency determination,

    K; fTemperature rise value of excitation winding during efficiency

    determination .K; aArmature winding temperature during efficiency determination, ; fExcitation winding temperature during efficiency determination, ; kCopper winding is taken with 235, non-copper winding is taken according to those

    specified in 7.6.2.2 of GB 755-2000. 5.2 Indirect Determination Method of Efficiency

    5.2.1 Where the machine efficiency is obtained through loss analysis method, the following losses shall be respectively determined or calculated. 5.2.1.1 Constant loss is noted as Pa, including:

    a) Iron loss (including no-load stray loss), which is noted as PFe; b) Bearing friction loss; c) Air loss; d) Brush friction loss The sum of the above losses in b), c) and d) are called to as mechanical losses, which are

    noted as Pfw. 5.2.1.2 Load loss I2R loss in machine armature winding, which is noted as Pcua

    5.2.1.3 Excitation loss, which is noted as Pf, including: a) I2R losses in excitation winding, which is noted as Pcuf; b) Rheostat loss, which is noted as PR; c) Electric loss of electrical brush, which is noted as Prs; d) Exciter loss, which is noted as PE; e) Loss of self excitation device, which is noted as PZE; f) Loss of I2R of self auxiliary winding.

    5.2.1.4 Stray loss, which is noted as Pd, including: a) The stray loss in armature winding conductor; b) The stray loss in magnetic circuit and other metal parts (excluding conductor).

    5.2.2 Machine efficiency is determined according to the following formula:

    %1001

    +

    -=PP

    Ph (14)

  • 18

    Where: PTotal losses, namely, P= P0+Pcua+Pf+Pd(kW); POutput power, kW. In order to determine the I2R loss of each winding, the DC resistance of winding shall be

    converted to the value corresponding to the reference operating temperature of the insulation grade indicated on machine nameplate according to the following formula:

    11

    Rkk

    R jj qq

    +

    += (15)

    Where: RjWinding DC resistance at reference operating temperature () ; R1Winding DC resistance under actual cold state, , 1The winding temperature corresponding to R1 measurement, ; jReference operating temperature, reference operating temperature is detailed in

    Table 2; kSee Formula (13).

    Table 2 Heat grade of insulation structure Reference operating temperature /

    A,E 75

    B 95

    F 115

    H 130

    Note: If the rated temperature rise or rated temperature is specified according to the heat grade lower than that used in

    structure, the reference operating temperature shall be specified according to the lower heat grade.

    5.3 Calorimetric Method If the loss couldn't be determined through the methods as specified in 5.1 or 5.2,

    calorimetric method may be adopted and the test methods are detailed in GB/T 5321. 5.4 Determination of Losses Corresponding to the Rated Load 5.4.1 Determination of constant losses 5.4.1.1 For no-load generator method: the excitation current of machine under test is supplied by independent DC supply to operate as no-load generator; dragging machine shall be the motor which has been analyzed or other prime movers (such as dynamometer) which could accurately measure or calculate the output power. During the test, the rotation speed shall be the rated speed of machine under test; output power of prime mover under different voltages of generator shall be measured after the bearing friction loss and brush friction loss

    become stable and this output power is the constant loss ( '0P )under corresponding voltage.

    In order to separate the core loss from the mechanical loss, it shall plot the curve of voltage per unit value square corresponding to the measured constant loss at different voltages

    as shown in Figure8. Loss corresponding to 02

    0 =

    NUU

    is namely the mechanical loss of

    the machine under test and the loss corresponding to the rated voltage is namely the constant loss of the machine at rated voltage; difference of both values is the core loss (PFe) of the

  • 19

    machine at rated voltage, also as the core loss of the machine at rated load. 5.4.1.2 No-load motor method: Machine under test is connected to the adjustable, actual, symmetrical and stabilized supply as no-load motor operation. Excitation current is supplied by independent DC supply; the excitation current adjusting the machine under test makes the armature current be the minimum; after the bearing friction loss and brush friction loss become stable, input power Pin and armature current I0 are measured at different voltages and the DC resistance Ra of armature winding is measured (which may be conducted immediately after the test, however it shall be corrected to the disconnection instant); the constant losses

    '0P (kW) of machine under test at corresponding voltage:

    Figure 8

    320

    '0 103

    --= ain RIPP (16)

    Where: PinInput power of machine under test, kW; I0Armature phase current (average value of three phases), A; R4DC resistance of armature phase winding (average value of three phases), . It shall make the curve of the constant loss at corresponding voltage against the square of

    voltage per unit value shall be plotted like 5.4.1.1. Straight line part of the curve is extended to intersect with the longitudinal axis and the longitudinal coordinate of intersection point is

    the mechanical loss and the loss corresponding to 12

    0 =

    NUU

    is the constant loss at rated

    voltage; difference of the two values is the iron loss at rated voltage. 5.4.1.3 Retardation test is seen in 5.5 5.4.2 I2R loss (kW) of armature winding is calculated according to the following formula:

    32 103 -= ajNcua RIP (17)

    Where: INRated armature current, A; RajAverage value of armature winding DC resistance at reference operating

    temperature, . As for the self-excited constant voltage generator, if there is a difference between

  • 20

    armature current and rated load current due to excitation mode, the I2R loss (kW) of armature winding shall be calculated according to the following formula:

    3222 10)( -++= wvuajcua IIIRP (18)

    Where: Iu, Iv and Iw are the measured armature currents of each phase under rated working state,

    A. 5.4.3 Excitation loss calculation 5.4.3.1 I2R loss (kW) of excitation winding is calculated according to the following formula:

    32 10-= fjfNcuf RIP (19)

    Where: IfNRated excitation current, A; RfjExcitation winding DC resistance at referene operating temperature ()

    5.4.3.2 Rheostat loss PR (kW) is calculated according to the following formula: 310-= RfRR UIP (20)

    Where: IfRCurrent flowing across rheostat under rated conditions, A; URPressure drop at both ends of master rheostat corresponding to the

    above-mentioned current, V. Where other auxiliary devices are provided in main field circuit, treatment method shall

    be the same with that of master rheostat; if the excitation winding of the machine under test is directly connected to the DC exciter armature circuit, this loss is zero. 5.4.3.3 Electric loss of electrical brush Prs (kW) is calculated according to the following formula:

    Prs= 2IfN Us10-3 (21) Where: IfNRated excitation current, A; UsPressure drop on each grade of electrical brush, for carbon-blacklead and

    electrographitic brush Us = 1V; For metallic graphite brush Us= 0.3V. 5.4.3.4 Exciter loss

    If the exciter is not trailed by the machine under test itself and is the exciter special for the machine under test, this loss is zero.

    If the exciter may be removed from the shaft of the machine under test and could conduct the test independently, the loss of this exciter may be independently determined according to relevant test method standard.

    If the exciter couldn't be removed, the losses of the whole unit under two situations: exciter with the sum of equivalent loads as stated in 5.4.3 and the exciter without load shall be measured with analyzed machine method, no-load motor method or retardation test. Difference of the two losses is the input power of exciter. The exciting load is the output power. The difference between input power and output power of exciter is the exciter loss. If it is still necessary to separate the excitation loss from other losses, exciter shall be

  • 21

    independently excited by DC supply; at this time, the input power of exciter shall be equal to the measured loss difference of the above two situations and the plus the excitation loss of exciter.

    If the above-mentioned methods are not available, the exciter loss may be determined according to the loss analysis method of this type of machine; however, it shall not count in the mechanical loss which has been counted into the machine loss under test. 5.4.3.5 Loss of self excitation device of machine

    a) Electrical loss of rectifying element Pz (kW) is calculated according to the following formula

    Pz= UzI10-3 (22) Where: IOutput current of rectifying device , A; UzOperating pressure drop of rectifying element, V; if it couldn't be determined,

    it may take design value or 1.2 V. b) The I2R loss of each winding is obtained by multiplying the square of the current

    flowing across this winding in rated operation mode with the resistance of this winding at reference operating temperature.

    c) The core loss of each part of excitation device may be calculated according to the design value. 5.4.3.6 Loss of I2R of auxiliary winding.

    It is obtained by multiplying the square of the current flowing across this winding in rated operation mode with the resistance of this winding at reference operating temperature. 5.4.4 Stray loss may be determined using the following method. 5.4.4.1 Short-circuit method

    Armature winding of machine under test is short circuited and trailed to the rated speed by prime mover; the prime mover shall be the machine which has been analyzed or other prime mover (such as dynamometer) which may accurately measure or calculate the output power. Excitation current is adjusted to make the armature current be the rated value; DC resistance of armature winding R0 () is determined and the DC resistance is measured immediately after the test. The stray loss Pd (kW) at rated armature current is obtained by subducting mechanical loss PfN (kW), armature winding and I2R loss from the input power Pin (namely the output power of prime mover, kW ) of the machine under test;

    32 103 ---= aNfNind RIPPP (23)

    5.4.4.2 Over-and-under-excitation method Machine under test is operated as no-load motor and is excited by independent supply

    source; after the bearing and brush friction loss become stable, test on the rated voltage of actually symmetrical rated frequency applied on armature winding may be conducted; during the test, excitation current is adjusted under respectively over-and-under excitation mode of machine to make the armature current reach the rated value; armature voltage, armature current, input power, excitation current and rotation speed are read and the DC resistance of armature winding is measured (it may be immediately measured after the test).

    Stray losses of the machine under test during respectively the over-and-under excitation operation are obtained by subducting constant loss and armature winding I2R loss from the

  • 22

    input power of the machine under test; their average value is regarded as the stray loss of machine; if the armature current couldn't be adjusted to the rated value in under-excitation mode, stray loss measured in over-excitation mode is allowed to be regarded as the stray loss of the machine under test.

    Low power factor wattmeter shall be adopted to measure the input power; the reading on the two wattmeters shall be read at the same time when adopting two-wattmeter method to determine the input power. 5.4.4.3 Retardation test is detailed in 5.5. 5.5 Retardation Test

    This method is mainly applicable to the machine whose moment of inertia is relatively big and whose losses are difficult to determine with other methods.

    During the test, the machine under test is connected to the power supply, or trailed by power machines and then supplied or excited by independent DC supply. The machine under test is firstly been accelerated till its rotation speed is slightly greater than the rated speed and for the nonsalient pole machine, it shall not be less than 105 % nN. For salient pole machine, it shall not be less than 110%nN and then the power is cutoff; before the motor speed reaches the above-mentioned rotation speed, required working state shall be established to make the machine automatically decelerate. For non-salient pole machine, time required from 105nN to 95%nN is measured; for salient pole machine, time required from 110%nN to 90% is measured and the time measurement accuracy between two upper and lower speed points is required to be within 2%. To determine all kinds of losses, tests under the following working states shall be conducted.

    a) Armature winding is open-circuited and the machine is not excited, herein the measured retardation time during the test is t1.

    b) Armature winding is open-circuited, excitation current is adjusted till the armature voltage at rated speed is the rated value; herein, the retardation time t2 is

    measured during the test; armature voltage and excitation current shall be measured at the same time where the machine retardation reaches the rated speed.

    c) Armature winding is three-phase short circuited, excitation current is adjusted till the armature current at rated speed is the rated value; herein the retardation time t3 is

    measured during the test. Armature current and excitation current are measured during retardation and are calculated according to the measured data:

    Mechanical loss

    6

    1

    1097.10 -DD

    =tnJnP NfN (24)

    Constant loss

    6

    20 1097.10

    -DD

    =tnJnP N (25)

    Sum of load loss, stray loss and mechanical loss

    6

    3

    1097.10 -DD

    =++tnJnPPP NfNdcua (26)

  • 23

    Where: JMoment of inertia of machine, kgm2; nNRated speed, r/min; nFor nonsalient pole machine, it is 1.05nN-0.95nN=0.10nN, For salient pole

    machine, it is 1.10nN-0.90nN= 0.20nN. In order to obtain an accurate result, the above-mentioned retardation test shall be

    repeated for three times and the average value of the three times shall be regarded as the actual value.

    Where hydro generator test is conducted in the power station, if possible, hydro turbines shall be disconnected; otherwise, the water in runner chamber shall be discharged; mechanical loss of hydro turbines in the air determined through method of calculation is subducted from each measured loss.

    If the moment of inertia of machine is unknown, the following method may be adopted: the machine under test is connected to the load of the known loss P (such as the transformer with known no-load loss or short circuit loss), retardation test is then conducted to determine

    the retardation time t1. Where it is with no-load transformer:

    6

    24

    1097.10

    DD

    -DD

    =

    tn

    tnn

    PJ

    N

    (27)

    Where it is with short-circuit transformer:

    6

    34

    1097.10

    DD

    -DD

    =

    tn

    tnn

    PJ

    N

    (28)

    Constant loss may also be determined with no-load motor method in advance and then item b) test in the above-mentioned retardation test is conducted; J is obtained by the following formula:

    6

    2

    1097.10

    DD

    +=

    tnn

    PPJ

    N

    FefN (29)

    During retardation test, if velometer counting in definite time is adopted to record the rotation speed, relation curve between rotation speed and time may be plotted and then

    gradient

    dtdn

    corresponding to the rated speed is obtained on the curve to replace the tn

    DD

    in the above-mentioned method. 5.6 Calculation of Efficiency under other Loads

    If the efficiency under other loads is required, it may be calculated according to the following methods: Constant loss remains the same; load loss is converted according to the square of armature current; stray loss is determined according to the method in 5.4.4 or converted according to the square of armature current and the excitation loss is converted

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    based on the excitation current required under this load according to the corresponding formulae in 5.4.3.

    6 Temperature Rise Test 6.1 Measurement Method of Temperature

    The temperature of machine winding or other parts may be measured by the following three methods: resistance method, thermometer method and embedded temperature detector method; different methods shall not be used to check each other. 6.1.1 Resistance method

    The DC resistance of tested winding shall be measured and the average temperature of the winding shall be determined according to the relation between DC resistance and temperature variation. 6.1.1.1 Copper winding

    The temperature rise (K) of copper winding is determined according to the following formula:

    0111

    12 )235( qqqq -++-=DR

    RR (30)

    Where: R2Winding resistance at the end of the test (); R1Winding resistance at actual cold state (); 1Winding temperature while determining R1 at corresponding actual cold state

    ( ); 0Cooling medium temperature at the end of the test ( ).

    6.1.1.2 Non-copper winding As for materials other than copper, the 235 in the above formula shall be replaced by the

    reciprocal of temperature resistance coefficient of materials at 0 ; 225 shall be adopted for aluminium winding unless otherwise specified. 6.1.2 Thermometer method

    In this method, the temperature is measured by placing the thermometer close to the accessible surface of machine; the thermometer includes expansion thermometer (such as mercury and ethanol thermometer), semiconductor thermometer and non-embedded thermocouple or resistance thermometer. During the measurement, the thermometer shall be close to the surface of measuring points and the measured part of thermometer shall be covered with thermal insulation materials so as to avoid the influence of surrounding cooling medium. Mercury thermometer shall not be used where there is strong alternating magnetic field. 6.1.3 Embedded temperature detector method

    In this method, the temperature shall be measured with the temperature detector embedded in the machine (such as resistance temperature detector, thermocouple or semiconductor thermosensitive element); the temperature detector is embedded at the inaccessible part of finished machine during its manufacturing process.

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    While measuring the resistance of embedded resistance thermometer, the measuring current and galvanization time shall be controlled so that there will be no obvious change on the resistance due to the heating of measuring current. 6.2 Determination of Cooling Medium Temperature in Temperature Rise Test 6.2.1 As for the machine (open type or closed type without cooler) cooled by the surrounding air or gas, the ambient air or gas temperature shall be measured by several thermometers; the thermometer shall be distributed at different locations around the machine and shall be (1~2)m from the machine. The sphere part shall be at 1/2 of the machine height and shall be prevented from the influence of all radiation and air flow.

    As for the machine with forced air circulation or closed circulation cooling system, the temperature of cooling medium shall be measured at the air inlet of machine.

    The machine with internal water cooling for winding shall take the water inlet temperature as the temperature of cooling medium winding.

    The iron core and other parts with non-water direct cooling shall take the air inlet temperature of cooling medium. 6.2.2 Determination of cooling medium temperature at the end of the test

    As for the cooling medium temperature at the end of the test, it shall take the average value of several thermometer readings measured at equal time interval within 1/4 of the whole test period. 6.3 Determination of Temperature at Different Parts of the Machine in Temperature Rise Test 6.3.1 Determination of winding temperature

    The temperature of machine winding may be measured by resistance method and embedded temperature detector method; however, where the resistance method is used, the resistance at cold &hot state must measured at the same outlet terminal. Where both embedded temperature detector method and resistance method can't be used, the thermometer method may be adopted, which is also applicable to the occasions specified in a), b), c) and d) of 7.6.1 in GB 755-2000. 6.3.2 Determination of excitation winding temperature

    Where the temperature of excitation winding is measured with resistance method, the voltage shall be measured on the slip ring. 6.3.3 Determination of the temperature of excitation device winding and auxiliary winding temperature

    Resistance method and thermometer method shall be used to measure it. 6.3.4 Determination of stator core temperature

    Where embedded temperature detector is in use, it shall be measured with temperature detector; otherwise, it shall be measured with thermometer (at least two for large and medium machines), taking the maximum value as core temperature. 6.3.5 Determination of the temperature of slip ring, pole shoe and damping winding

    Thermometer or digimite shall be used for measurement immediately after the machine shuts down. 6.3.6 Determination of the temperature of bearing and sealing pad

    It shall be determined by thermometer and embedded temperature detector and the determination method is detailed in 7.9 of GB 755-2000.

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    6.4 Correction of the Measured Temperature at Different Parts of the Machine after Cutting off the Supply 6.4.1 Where the temperature of shutdown machine is measured by resistance method, the machine shall be stopped immediately after the end of temperature rise test; after the machine is disconnected, the reading measured at the first point within the time specified in Table 3 shall be used to calculate the temperature rise of machine and no exterpolation is needed till the instantaneous disconnection.

    Table 3

    Machine rated power P

    kW(kVA)

    Interval time after disconnection

    s

    P50 30

    50

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    low-power factor load method and no-load shortcircuit method. 6.6.1 Direct load method 6.6.1.1 The machine under test shall be tested at rated operation mode according to its functions; during the test, the cooling medium temperature shall meet the requirements of 5.3, 5.4 and 5.5 primary equipment of GB 755-2000 and mutation shall be avoided; the readings at each point shall be recorded every 30min; where the temperature at all parts of the machine tends to keep stable, the readings shall be recorded every 15 or 30 minutes. Where the temperature variation at all parts of the machine is less than or equal to 2K within the last 1h, the machine heating is considered as stable. The average value of temperature at several time intervals within the stable stage shall be regarded as the temperature of the machine at rated load; if shutdown exterpolation method is used to determine the temperature at load, it shall refer to 6.4.2.

    Where the difference between the current at temperature rise test and the rated value is within 5%, the machine winding temperature rise N may be corrected according to the following formula:

    2

    D=D

    II N

    N qq (31)

    Where: IThe average of current readings at several equal time intervals within the last 1h

    (A); Winding temperature rise corresponding to test current I (K).

    6.6.1.2 Within the scope ranging from 0.6 rated power to the maximum allowable power under test conditions, temperature rise test shall be carried out at 3~ 4 different loads, and the power factor shall be close to rated value.

    Where the temperature rise test is carried out at each load, it shall determine the temperature rise of winding and core corresponding to the cooling medium temperature. The test results at different loads shall be used to draw the relation curve between the temperature rise at this part of the machine and the square of winding current or the losses corresponding to this part; the temperature rise corresponding to rated load shall be determined according to obtained curve exterpolation. 6.6.2 Low-power factor load method

    Where the direct load method can't be used for temperature rise test due to the limit of equipment condition, low-power factor load method may be adopted; the zero power factor load of swap camera is also the direct load.

    In this method, the machine under test may operate as a generator or motor, without active load or with partial active load.

    During the test, the machine is adjusted to rated frequency, rated excitation current and rated armature current; the requirements during the test shall be the same as that for direct load method. If the armature voltage at the moment is greater than or equal to 95% rated value, the armature winding temperature rise a and stator core temperature rise Fe will not be corrected; otherwise, they shall be corrected according to the following methods. 6.6.2.1 Twice no-load temperature rise test

    a) Where the machine is no-load and the armature voltage is equal to the voltage in the

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    above-mentioned test, the measured armature winding temperature rise and stator core temperature rise shall be a1 and Fe1 respectively.

    b) Where the machine is no-load and the armature voltage is equal to rated voltage, the measured armature winding temperature rise and stator core temperature rise shall be a2 and Fe2 respectively.

    The temperature rise at rated operation mode is calculated according to the following formula:

    Armature winding: aN = a + ( a2-a1) (32)

    Stator core: FeN = Fe + ( Fe2-Fe1) (33)

    6.6.2.2 Empirical formula Armature winding temperature rise:

    D+D=D

    cuaa

    FeaaN PK

    P1qq (34)

    Where: aArmature winding temperature rise during temperature rise test at low power

    factor load (K); PFeDifference between core losses PFe at rated voltage and core losses PFe

    corresponding to temperature rise test voltage at low power factor load (kW); PcuaI2R losses of armature winding during temperature rise test at low power factor

    load (kW); KaCoefficient, taking 6 for small machine and 3 for medium machine. Stator core temperature rise

    +

    D+D=D '1

    Fecua

    FeFeFeN PP

    Pqq (35)

    FeStator core temperature rise during temperature rise test at low power factor load (K); 6.6.3 No-load shortcircuit method 6.6.3.1 The machine under test operates as a generator and the following four temperature rise tests shall be conducted:

    a) The measured temperature rise is 0 for idling machine without excitation; b) The measured temperature ris e is U1 for no-load machine with armature voltage

    equal to 105 % rated value; c) The measured temperature rise is U2 for no-load machine with armature voltage

    close as much to 120% rated value where the core temperature rise is less than or equal to the specified value;

    d) The measured temperature rise is K for three-phase symmetrical short-circuit machine with armature voltage equal to the measured temperature rise.

    6.6.3.2 The armature winding temperature rise at rated operation mode is determined according to the following formula:

    Turbine generators

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    0101401 qq

    qqqqqqq D-D+

    D++

    D-D+-+D=D U

    Kc

    UcKaN k

    (36)

    Other machines

    01011 qq

    qqqqqq D-D+

    D++D-D

    +D=D UKc

    UKaN k

    (37)

    Where: cCooling medium temperature during temperature rise test at three-phase

    symmetrical shortcircuit ( ); kSee Formula (13).

    6.6.3.3 The stator-core temperature rise at rated operation mode is determined according to the following formula:

    FeN = k + U1-0 (38) 6.6.3.4 The excitation winding temperature rise at rated operation mode is determined by plotting method:

    a) Turbine generators: First, qqq D+D=D ff' (See Appendix A for )

    The excitation winding temperature rise during b), c) and d) temperature rise tests in 6.6.3.1 is converted to the temperature rise corresponding to 40 cooli ng medium temperature; then, the excitation winding ho-state DC resistance Rf measured according to during b), c) and d) tests is converted to the resistance at 40 cooling medium temperature according to the following formula.

    (39)

    Where: cCooling medium temperature during temperature rise test ( ).

    Calculate the value of and plot the relation curve of as curve

    (1) (shown in Figure 9); mark the values of and corresponding 40

    cooling medium temperature as well as 0K and 35K temperature rise (namely, with 40 and 75 winding temperature), and indicate Point A where straight line (2) intersects with the

    extended line of curve (1) through Point ( , 0) and Point ( , 35) in Figure 9; then,

    the temperature rise fN corresponding to Point A will refer to the temperature riseof excitation winding at rated operation mode.

    b) Other machines: The determination method of excita