Phase Current Accuracy - GE 239 Instruction Manual

CHAPTER 7: TESTING
7.3

Phase Current Accuracy

INJECTED EXPECTED READING IN
CURRENT
0.5 A
1.0 A
3.5 A
5.0 A
10.0 A
† displayed current
=
INJECTED EXPECTED READING IN
CURRENT
0.1 A
0.3 A
0.6 A
1.0 A
2.0 A
† displayed current
=
239 MOTOR PROTECTION RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
Any phase current protection is based on the ability of the 239 to read phase input
currents accurately to ±2% of full scale. Perform the steps below to test the phase
current accuracy.
1. Alter the following setpoint.
S2: SYSTEM SETUP\CT INPUTS\PHASE CT PRIMARY: 100A
2. To determine if the relay is reading the proper input current values, inject phase
currents shown in the table below, view the readings in
verify with the expected readings stated in the table.
Table 7–1: Phase Current Accuracy Test, 5 A Input
ACTUAL PHASE A
EACH PHASE † READING (A)
10 A
20 A
70 A
100 A
200 A
PHASE CT PRIMARY
⎛
injected current × ----------------------------------------------- -
⎝
5 A
3. Alter the setup to inject current into the 1 A input of each phase and repeat the above
step with current settings shown in the table below.
Table 7–2: Phase Current Accuracy Test, 1 A Input
ACTUAL PHASE A
EACH PHASE † READING (A)
10 A
30 A
60 A
100 A
200 A
injected current × PHASE CT PRIMARY
A2: METERING\CURRENT
ACTUAL PHASE B
READING (A)
⎞
⎠
ACTUAL PHASE B
READING (A)
, and
ACTUAL PHASE C
READING (A)
ACTUAL PHASE C
READING (A)
7–97