Phase Current Accuracy - GE 239 Instruction Manual

8 TESTING
Any phase current protection is based on the ability of the 239 to read phase input currents accu-
rately to ±2% of full scale. Perform the steps below to test the phase current accuracy.
1. Alter the following setpoint.
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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 $ 0(7(5,1*?&855(17 , and verify with the expected read-
ings stated in the table.
Table 8–1: PHASE CURRENT ACCURACY TEST, 5 A INPUT
INJECTED
CURRENT READING IN EACH
0.5 A
1.0 A
3.5 A
5.0 A
10.0 A
† displayed current
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 8–2: PHASE CURRENT ACCURACY TEST, 1 A INPUT
INJECTED
CURRENT READING IN EACH
0.1 A
0.3 A
0.6 A
8
1.0 A
2.0 A
† displayed current
8-2
Courtesy of NationalSwitchgear.com
EXPECTED ACTUAL PHASE
A READING (A)
PHASE †
10 A
20 A
70 A
100 A
200 A

PHASE CT PRIMARY
×
---------------------------------------------------------- -
= injected current

EXPECTED ACTUAL PHASE
A READING (A)
PHASE †
10 A
30 A
60 A
100 A
200 A
×
= injected current PHASE CT PRIMARY
239 Motor Protection Relay

8.3 PHASE CURRENT ACCURACY

ACTUAL PHASE
B READING (A)


5 A
ACTUAL PHASE
B READING (A)
8 TESTING
ACTUAL PHASE
C READING (A)
ACTUAL PHASE
C READING (A)
GE Multilin