type sa-1generator differential relay - abb ltd 2 type sa-1 generator differential relay 2.1....

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Type SA-1Generator Differential Relay

2.1. RESTRAINT CIRCUIT

The restraint circuit of each phase consists of a cen-ter-tapped transformer, a resistor, and a full waverectifier bridge. The outputs of all the rectifiers areconnected in parallel. The parallel connection of rec-tifiers is a maximum voltage network. Hence, thevoltage applied to the filter circuit is proportional tothe phase current with the largest magnitude.

2.2. OPERATING CIRCUIT

The operating circuit consists of a transformer, aresistor, and a full wave rectifier bridge. The outputsof all the rectifiers are connected in parallel. This par-allel connection of rectifiers is a maximum voltagenetwork. Hence, the voltage applied to the filter cir-cuit is proportional to the phase current with the larg-est magnitude.

2.3. SENSING CIRCUIT

The sensing circuit is connected to the output of therestraint filter circuit, the operating filter circuit andthe input to the amplifier circuit.

2.4. AMPLIFIER CIRCUIT

The amplifier circuit consists of a two-transistoramplifier which controls the operation of a relaxationoscillator.

The amplifier circuit is connected to the sensing cir-cuit such that it receives the difference in output ofthe restraint filter and the operating filter. Thus, thepolarity of the input voltage to the amplifier dependsupon the relative magnitude of the voltages appear-ing on the restraint and operating filters. When thevoltage output of the operating filter is greater thanthe output voltage of the restraint filter, a voltage of acertain polarity appears across the input of the ampli-fier. To trigger the amplifier requires that the outputvoltage of the operating filter be greater than the out-put voltage of the restraint filter.

2.5. TRIP CIRCUIT

The trip circuit consists of a thyristor which has ananode, cathode, and a gate. The anode of the thyris-tor is connected to the positive side of the dc supplyand the cathode of the thyristor is connected to thenegative side of the dc supply through the trip coil ofa breaker. The gate of the thyristor is connected tothe output of the amplifier circuit through a pulsetransformer.

With no gate current flowing, the thyristor acts as anopen circuit to the breaker trip coil. When a gate cur-rent is applied tot he thyristor the thyristor connectsthe breaker trip coil to the dc supply.

2.6. INDICATING CIRCUIT

The indicating circuit is triggered by a signal from theamplifier of the relay. Under normal or non-fault con-ditions, the indicating circuit is turned off. When afault is applied to the relay, the amplifier will conductto cause a signal to flow into the indicator circuit.When the indicator circuit is triggered, the lamp willturn on. This lamp will remain lit until the indicator cir-cuit is interrupted by resetting the micro-switch.

2.7. SURGE PROTECTION CIRCUIT

The surge protection circuit consists of two capaci-tors (C10 and C11) and a R-C network which is con-nected across the anode and cathode of the trippingthyristor to prevent the SCR from firing by a surge ofvoltage.

2.8. EXTERNAL REACTORS

Three reactors are mounted on a metal plate with aseparate terminal strip. The reactors are of the satu-rable type.

3. OPERATION

The Type SA-1 relay is connected to the protectedapparatus as shown in Figure 9. On external faults,current flows through the primary winding of therestraint transformers to induce a voltage on therestraint side of the sensing circuit. If the two sets ofmain current transformers have different perfor-mances, some current will flow out of the mid-tap ofthe restraint transformers to the operating transform-ers. This will produce a voltage on the operating sideof the sensing circuit. With the relay correctly applied,sufficient restraint voltages will exist to prevent theoperating voltage from triggering the amplifier.

The percentage slope characteristic of the relay lim-its the operating voltage on heavy external faultswhere the performance of the two sets of currenttransformers may be quite different.

On internal faults, the operating coil current is thesum of the current flowing in each of the windings ofthe restraint transformer and sufficient operating volt-age is available to overcome the restraint voltage.

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4. CHARACTERISTICS

The percentage slope curves are shown in Figures12 and 13. It will be observed that the relay operatesat 5% unbalance at 5 amperes restraint (Figure 12)to provide high sensitivity for internal faults up to fullload conditions. At 60 amperes restraint, the operat-ing current required to trip the relay is 30 amperes or50% unbalance (Figure 13). Thus, when 60amperes through-fault current is flowing, the outputof the main current transformers may vary consider-ably without causing incorrect operation.

The minimum pickup of the relay is 0.14 ampere or0.5 ampere for the desensitized version.

The operating characteristic of the desensitized SA-1 is shown in Figure 14.

The time curve of the relay is shown in Figure 15.

The frequency response characteristic of the SA-1relay is shown in Figure 16.

5. ENERGY REQUIREMENTS

Each Restraint Circuit

Burden at 5 amperes is 0.25 VAContinuous rating 20 amperes1 second rating 300 amperes

Operating Circuit

The burden imposed by the operating circuit oneach circuit transformer is variable because of thesaturating transformer and reactors. At 0.5 amperes,it is 0.37 VA, and at 60 amperes it is 170 VA.

Continuous rating 10 amperes1 second rating 200 amperes

Amplifier

The dc burden on the station battery is:

6. SETTINGS

There are no taps on either transformer and, conse-quently, there are no settings to be made except forthe choice of battery voltage level.

The 48/125 Vdc relays are normally shipped for 125volts. For 48 Vdc applications use the mid-tap on theresistor mounted at the top of the relay. The red doton the resistor is the common point – DO NOTREMOVE.

7. INSTALLATION

The relay should be mounted on switchboard panelsor their equivalent in a location free from moisture.Mount the relay vertically by means of the fourmounting holes on the flange for semi-flush mount-ing.

Either a mounting stud or the mounting screws maybe utilized for grounding the relay. The electricalconnections may be made directly to the terminalsby means of screws.

The external reactor assembly should be mountedand wired per “interwiring Connection Drawing”, Fig-ure 11.

For detailed FT case information, refer to I.L. 41-076.

8. ADJUSTMENTS AND MAINTENANCE

The proper adjustments to insure correct operationof this relay have been made at the factory andshould not be disturbed after receipt by the cus-tomer.

8.1. ROUTINE TEST

The following check is recommended to insure thatthe relay is in proper working order. All checks canbest be performed by connecting the relay per thetest circuit of Figure 17. Due to high impedance of theexternal reactor, prior to saturation, the test circuit ofFigure 17 should be used to test the relay only. Thereactors can be checked by applying 0.2 amperes 60hertz and reading the voltage drop across the reactorwith a high impedance True RMS reading voltmeter.The voltage drop will be between 20 and 26 voltsTrue RMS. For 0.4 amperes input, the readingshould be between 29 and 31 volts True RMS.

Volts Milliamperes Watts

125 dc48 dc

5560

6.92.9

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1. Minimum Trip Current with IR set at zeroamperes, apply 0.14 ±5% (0.5 ±5% got desensi-tized SA-1) amperes operating current to eachoperating circuit of the relay. The relay shouldoperate and the indicator lamp should light.

2. Differential Characteristic

a) Apply IR of 5 amperes and adjust the operat-ing current until the relay operates. The relayshould operate and the indicator lamp shouldlight with an operating current of 0.25 ±5%amperes (0.71 5% for desensitized SA-1).Repeat for each phase of the relay.

b) Apply IR of 60 amperes and adjust the oper-ating current until the relay operates. Therelay should operate and the indicator lampshould light with an operating current of30 ±10% amperes. Repeat for each phase ofthe relay. (IR = 40 amperes and IO =24 ±10% for desensitized SA-1).

8.2. MAINTENANCE

All relays should be checked once a year to detectany failures which may have occurred. The tantalumcapacitors C1, C2, C3, C4 and C13 may have a com-mon mode failure characteristic and should bechecked visually for symptoms of electrolyte leakageevery year and replaced if necessary.

8.3. CALIBRATION

Use the following procedure for calibrating the relay ifthe relay adjustments have been disturbed. This pro-cedure should not be used until it is apparent therelay is not in proper working order.

1. Minimum Trip Current – Connect the relay pertest circuit of Figure 17 with switch K open.Adjust the operating resistor in the rear of therelay until the relay operates with IO equal to0.14 ampere, 0.5 ampere for desensitized SA-1.DO NOT make adjustments to the resistorunless the dc is disconnected .

The indicator lamp should light when the relayoperates.

Repeat for each phase of the relay.

2. Percentage Slope Characteristic (Low Cur-rent) . Close switch K and set IR equal to 5amperes and adjust the restraint resistor in therear of the relay until the relay operates with Io =0.25 ±.010 amperes. DO NOT adjust resistorwith dc applied to relay .

The indicator lamp should light when the relayoperates.

Repeat for each phase of the relay.

Percentage Slope Characteristic (High Cur-rent) – Set IR equal to 60 amperes for the oper-ating current of 30 amperes. Replace the resistorR17 if necessary. The value of R17 can bebetween 0 and 100 ohms. Repeat for the othertwo phases if necessary, replacing R18 and R19respectively.

3. Electrical Checkpoints – See Table 1.

9. RENEWAL PARTS

Repair work can be done most satisfactorily at thefactory. However, interchangeable parts can be fur-nished to customers who are equipped for doingrepair work. When ordering parts, always give thenameplate data.

10.ELECTRICAL CHECKPOINTS

Connect relay per test circuit of Figure 17. All voltagereadings should be made with a high resistance volt-meter. Refer to component location of checkpoints.Voltage readings are approximate. The voltage read-ings “Input to Amplifier” should not be taken withrelay in service.

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Table 1:(Values in Parenthesis Represent Desensitized SA-1)

CIRCUITPRIMARYCURRENT PHASE

CHECKPOINTS (Typical Value)

TERMINAL VALUE FUNCTION

Operating0.14A(0.5A)

123

2 - 73 - 64 - 5

2.5 ac2.5 ac2.5 ac

Input to operate rectifierInput to operate rectifierInput to operate rectifier

Sensing(Operating)

0.14A(0.5)

Anyphase

+ to -23 - 2624 - 2624 - 88 - 25

25 - 26

2.1 dc1.85 dc0.55 dc0.65 dc0.65 dc

Output to rectifiera. Output to operating sensing circuitb. Input to amplifierc.d. Output to restraint sensing circuit

Ref.: a = b + c + d

30.0AAny

phase+ to -

24 - 26 51.0 dc

Restraint5.0A 1

23

18 - 1317 - 1415 - 16

6.0 ac6.0 ac6.0 ac

Input to restraint rectifierInput to restraint rectifierInput to restraint rectifier

Sensing(Restraint)

5.0AAny

phase+ to -

25 - 2625 - 88 - 24

24 - 26

2.1 dc1.2 dc0.6 dc0.3 dc

a. Output of restraint sensing circuitb.c. Input to amplifierd. Output to operating sensing circuit

Ref.: a = b + c + d

60.0AAny

phase+ to -

25 - 26 42.0 dc

Amplifier

0+ to -27 - 812 - 810 - 8

0.7 dc24.0 dc24.0 dc

MinimumTrip

Current+5%

Anyphase

+ to -27 - 812 - 821 - 8

0.5 dc24.0 dc10.0 dc

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† NOTE: The values of R17, R18 and R19 are between 0 and 100 Ohms. They are determined in test.

Table 2:Electrical Part List

Circuit Symbol Reference Style

ResistorsResistorsResistorsZenerSCRReactor

UT, UM, UBLT, LM, LBR14Z2

L1

60 Ohms, 25W265 Ohms, 25W1.8K, 40 WIN2986B

18756761725542187A321H06629A798H03184A614H051478B98G01

SA Module Style Number 408C673G01 Sub 35

ResistorResistorResistorResistorResistorResistorResistorResistorResistorResistorResistorResistor†

CapacitorCapacitorCapacitorCapacitorCapacitorCapacitor

DiodeDiode

ZenerSCRTransistorTransistorTransformer

R1R2R3, R4 R5R6R7R8R9R10R11R12R13R17, R18, R19

C1, C2, C3, C13C4C5C6C7C8, C9

D1 to D24D25, D26

Z1

T1, T2T3TR-1

270 Ohms, 1W2K, 5%15K, 5%2.7K, 5%68K, 5%27K, 5%2.2K, 5%100 Ohms, 10%220 Ohms, 5%680 Ohms, 5%47K, 5%33 Ohms, 5%

25 MFD, 125V22 MFD, 35V0.5 MFD, 200V2.2 MFD, 35V2.0 MFD, 200V0.47 MFD, 50V

IN4821IN645A

IN752AK1149-132N34172N2647

184A635H06184A763H34184A763H55184A763H37184A763H71184A763H61184A763H35184A763H03184A763H11184A763H23184A763H67187A290H13

184A637H01184A661H16187A624H03837A241H16187A624H05762A680H04

188A342H16837A692H04

186A797H12184A640H13848A851H02629A435H01629A372H02

SPK Module Style Number 1584C21G01

ResistorCapacitorCapacitor

R15C10, C11C12

470 Ohms, 1W0.01 MFD, 1.5KV2.0 MFD, 200V

187A643H193516A36H033509A33H01

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Figure 1. Type SA-1 Generator Differential Relay without Case (Front View)

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Figure 2. Type SA-1 Generator Differential Relay without Case (Rear View)

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Figure 3. Internal Schematic of Type SA-1 Relay 48/125 Vdc

629A406Sub 15

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Figure 4. Internal Schematic of Type SA-1 Relay 250 Vdc

876A613Sub 9

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Figure 5. Internal Schematic of Desensitized SA-1 Relay

877A847Sub 8

RE

LAY

TY

PE

SA

-1 H

IGH

SP

EE

D D

IFF

ER

EN

TIA

LF

OR

GE

NE

RAT

OR

PR

OT

EC

TIO

N IN

TY

PE

FT-

32 C

AS

E(D

ES

EN

SIT

IZE

D)

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Figure 6. Component Location for 48/125 Vdc

762A601Sub 9

23 +C1

R17

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Figure 7. Component Location for 250 Vdc

867A639* Sub 5

* Denotes Change

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Figure 8. Component Location of the SPK Module

3532A07Sub 2

C10

C11

C12R15

2

1 345

SPK 1584C01G01

C11 & C10 .01 uf 3516A36H03C12 2.0 uf 3509A33H01R15 470 Ohm 187A643H19

COMPONENT LOCATION48/125 V

C10

C11

C12R15

2

1 345

SPK 1584C01G01

C11 & C10 .01 uf 3516A36H03C12 2.0 uf 3509A33H01R15 470 Ohm 187A643H19

COMPONENT LOCATION48/125 V

C10

C11

R15

2

1 345

SPK 1584C01G02

C11 & C10 .01 uf 3516A36H03R15 470 Ohm 187A643H19

COMPONENT LOCATION250 V

6 7

Illustration

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Figure 9. External Schematic of Type SA-1 Relay for Generator Protection

775B965*Sub 4

Figure 10. Reactor Outline

775B982Sub 1

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Figure 11. Relay and Reactor Interconnection

775B981* Sub 5

NOTE: A - PLACE IT. 1 TO 3 IN IT. 5 FOR SHIPPING

LeadIT. L SCREW SIZE

A B

1 3.00 .164 - 32 .164 - 32

2 4.00 .164 - 32 .190 - 32

3 3.00 .164 - 32 .190 - 32

4 13.438 .164 - 32 .190 - 32

ITE

M

PARTNAME

STYLEDWG.

ITEMGR.

NOTECODE

ENG.REF. REQ

01 LEAD 57Z0301 616 A 63-D-653 2

02 LEAD 57Z0401 622 A 63-D-655 3

03 LEAD 57Z0301 622 A 63-D-655 1

05 BAG 836A618 H04 B 27-D-5478 1

AB

L±.156

* Denotes Change

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Figure 12. Percentage Slope characteristic at Low Value of Restraint Current

3537A44Sub 2

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Figure 13. Percentage Slope Characteristic at High Value of Restraint Current

878A742Sub 3

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Figure 14. Percentage Slope Characteristic of High Value Restraint Current for Desensitized SA-1 Relay

619406Sub 1

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Figure 15. Typical Operation Time Characteristic

477706Sub 1

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Figure 16. Typical Frequency Response Curve

3537A45Sub 2

Figure 17. Typical Frequency Response Curve

184A864Sub 4

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Figure 18. Outline and Drilling Plan for the Type SA-1 Relay in Type FT-32 Case

3519A69* Sub 4

* Denotes Change

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NOTES

ABB Inc.4300 Coral Ridge DriveCoral Springs, Florida 33065Telephone: +1 954-752-6700Fax: +1 954-345-5329www.abb.com/substation automation

IL 4

1-34

8.1

- Rev

isio

n H

ABB

type sa-1generator differential relay - abb ltd 2 type sa-1 generator differential relay 2.1....

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