GE Multilin 489 User Manual

CHAPTER 7: TESTING
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL 7–5
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.
Z In the
S2 SYSTEM SETUP Z CURRENT SENSING menu, set:
GROUND CT: “1A Secondary”
GROUND CT RATIO: “1000:1”
PHASE CT PRIMARY: “1000 A”
Z In the S5 CURRENT ELEMENTS ZV PHASE DIFFERENTIAL menu, set:
PHASE DIFFERENTIAL TRIP: “Unlatched”
DIFFERENTIAL TRIP MIN. PICKUP: “0.1xCT”
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.
Measured values should be ±10 A.
Z Inject (I
A
only) the values shown in the table below into one phase only
and verify accuracy of the measured values.
Z View the measured values in the
A2 METERING DATA Z CURRENT
METERING menu or press the NEXT key to view the current values when
differential trip element is active.
200 V 2000 V
Applied Line-
Neutral Voltage
Expected Voltage
Reading
Measured Voltage
A-N B-N C-N
Table 7–1: Neutral and Ground Current Test Results
Injected
Current
1 A Unit
Expected
Current
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
Differential
Phase A
Differential
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
Courtesy of NationalSwitchgear.com

GE Multilin 489 Specifications

General

Brand	GE
Model	Multilin 489
Category	Relays
Language	English