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Fuse Rating

=

=

=

Name Plate Details of Induction Motor

Rated Power =

Rated Current =

Rated Voltage =

Rated Speed =

CIRCUIT DIAGRAM FOR NEGATIVE AND ZERO SEQUENCE IMPEDANCE OF

ALTERNATORS

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EXP. NO:

DATE

:

AIM:To determine zero and negative phase sequence reactance of an alternator.

APPARATUS REQUIRED:

FORMULA:

1. DETERMINATION OF NEGATIVE SEQUENCE IMPEDANCE (Z2):

1. Z2=

Where,

Z2 is negative sequence impedance

Mean current I mean= (Imax + Imin)/2

Mean voltage Vmean= (Vmax + Vmin)/2

2. DETERMINATION OF ZERO SEQUENCE REACTANCE (Z0):

Z0=3.V/I

Where, V is zero sequence voltage

Iis zero sequence current

S.NO Name of the apparatus Range Type Quantity

1. Voltmeter (0-300V) MI 1

2. Ammeter (0-2A) MC 1

3. Ammeter (0-5A) MI 1

4. Wattmeter 300V,10A UPF 1

5. Tachometer (0-3000 RPM) Digital 1

6. Connecting wires As required

MEASUREMENTS OF NEGATIVE SEQUENCE AND ZERO SEQUENCE IMPEDANCE OF

ALTERNATORS

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TABULATION :

NEGATIVE SEQUENCE IMPEDANCE:

ZERO SEQUENCE IMPEDANCE:

S.NO

MAXIMUMVOLTAGE

Vmax(VOLTS)

MINIMUMVOLTAGE

Vmin(VOLTS)

MAXIMUMCURRENT

Imax(AMPS)

MINIMUMCURRENT

Imin(AMPS)

MEANVOLTAGE

Vmean(VOLTS)

MEANCURRENT

Imean(AMPS)

Z2()

S.No

ZEROSEQUENCE

Voltage(Volts)

ZEROSEQUENCE

Current(Amps)

Z0()

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PROCEDURE:

1. DETERMINATION OF NEGATIVE SEQUENCE REACTANCE (X2):

1. Connections are given as per the circuit diagram.

2. The autotransformer is kept at minimum position.

3. The field rheostat of the DC motor is kept at minimum resistance position.The field winding of

the alternator is opened.

4. The DC motor is started with the help of three point starter.

5. The DC motor is adjusted to run at the synchronous speed of the Alternator with the help of

field rheostat.

6. Reduced voltage is applied to the armature of the alternator with the help of autotransformer

such that some current flows in the armature.

7. Ammeter and voltmeter needles start to oscillate.

8. The minimum and maximum deflections on the meters for various values of voltage are noted

down.

2. DETERMINATION OF ZERO SEQUENCE REACTANCE (X0):

1. Connections are given as per the circuit diagram.

2. The field winding of the armature is kept open.

3. Alternator must be at standstill position.

4. The autotransformer is kept at minimum position.

5. With the help of autotransformer reduced voltage is applied and the meter readings are noted

for various values of voltage.

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MODEL CALCULATION:

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RESULT:

Thus the negative and zero sequence impedance of the alternator were determined.