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7-4 489 Generator Management Relay GE Multilin
7.2 HARDWARE FUNCTIONAL TESTS 7 TESTING
7
7.2.3 GROUND (1 A), NEUTRAL, AND DIFFERENTIAL CURRENT ACCURACY
The specification for neutral, differential and 1 A ground current input accuracy is ±0.5% of 2 × CT. Perform the steps below
to verify accuracy.
1. Alter the following setpoints:
S2 SYSTEM SETUP Ö CURRENT SENSING ÖØ GROUND CT: "1A Secondary"
S2 SYSTEM SETUP Ö CURRENT SENSING ÖØ GROUND CT RATIO: "1000:1"
S2 SYSTEM SETUP ÖØ CURRENT SENSING Ö PHASE CT PRIMARY: "1000 A"
S5 CURRENT ELEMENTS ÖØ PHASE DIFFERENTIAL Ö PHASE DIFFERENTIAL TRIP: "Unlatched"
S5 CURRENT ELEMENTS ÖØ PHASE DIFFERENTIAL ÖØ DIFFERENTIAL TRIP MIN. PICKUP: "0.1 x CT"
2. Note: the last two setpoints are needed to view the neutral and the differential current. The trip element will operate
when differential current exceeds 100 A.
3. Measured values should be ±10 A. Inject (I
A
only) the values shown in the table below into one phase only and verify
accuracy of the measured values. View the measured values in:
A2 METERING DATA Ö CURRENT METERING
or press the key to view the current values when differential trip element is active.
7.2.4 NEUTRAL VOLTAGE (FUNDAMENTAL) ACCURACY
The specification for neutral voltage (fundamental) accuracy is ±0.5% of full scale (100 V). Perform the steps below to verify
accuracy.
1. Alter the following setpoints:
S2 SYSTEM SETUP ÖØ VOLTAGE SENSING ÖØ NEUTRAL VOLTAGE TRANSFORMER: "Yes"
S2 SYSTEM SETUP ÖØ VOLTAGE SENSING ÖØ NEUTRAL V.T. RATIO: "10.00:1"
S2 SYSTEM SETUP ÖØ GEN. PARAMETERS ÖØ GENERATOR NOMINAL FREQUENCY: "60 Hz"
2. Measured values should be ±5.0 V. Apply the voltage values shown in the table and verify accuracy of the measured
values. View the measured values in:
A2 METERING DATA ÖØ VOLTAGE METERING
Table 7–1: NEUTRAL AND GROUND CURRENT TEST RESULTS
INJECTED
CURRENT
1 A UNIT
EXPECTED
CURRENT
READING
MEASURED
GROUND
CURRENT
MEASURED NEUTRAL CURRENT
PHASE A PHASE B PHASE C
0.1 A 100 A
0.2 A 200 A
0.5 A 500 A
1 A 1000 A
Table 7–2: DIFFERENTIAL CURRENT TEST RESULTS
INJECTED
CURRENT
EXPECTED CURRENT READING MEASURED DIFFERENTIAL CURRENT
DIFF. PHASE A DIFF PHASE B,C PHASE A PHASE B PHASE C
0.1 A 200 A 100 A
0.2 A 400 A 200 A
0.5 A 1000 A 500 A
1 A 2000 A 1000 A
APPLIED NEUTRAL
VOLTAGE AT 60 HZ
EXPECTED NEUTRAL
VOLTAGE
MEASURED NEUTRAL
VOLTAGE
10 V 100 V
30 V 300 V
50 V 500 V
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