GE Industrial Solutions Entellisys System Test Kit - Manual (Page 21)

System Test Kit 22
1.6.1 Overcurrent Protection Test
1.6.1.1 Functions
Tests various Overcurrent Protection functions. The functions must be optioned and enabled in
the system to perform the respective tests.
Long Time (LT) Overcurrent Protection
Verifies the long time overcurrent protection function for a circuit breaker in the system. It can
be performed as either a trip or no trip test. To test LT, the test kit injects a sum-of-squares
current value for any phase above the LT pickup setting. The result of the test is a trip time with
an accuracy of 10% of the expected trip time.
Short Time (ST) Overcurrent Protection
Verifies the short time overcurrent protection function for a circuit breaker in the system. The
test can be performed as either a trip or no trip test. To test ST, the test kit injects a
sum-of-squares current value for any phase above the ST pickup setting. The result of the test is
a trip time with an accuracy of 10% of the expected trip time.
Instantaneous (IOC) Overcurrent Protection
Verifies the instantaneous overcurrent protection function for a circuit breaker in the system.
The test can be performed as either a trip or no trip test. To test IOC, the test kit provides an
input current that exceeds the programmed IOC threshold. The result of the test is a trip time
with an accuracy of 10% of the expected trip time.
Ground Fault (GF) Protection
Verifies Ground Fault protection function for a circuit breaker in the system. The test can be
performed as either a trip or no trip test.
In a three-wire system, the test kit will provide three phase currents with vector sum greater
than the pickup threshold.
In a four-wire, WYE-system, the test kit will provide three phase currents and a neutral with
vector sum greater than the pickup threshold.
In either case, the result is a trip time with an accuracy of 10% of the expected trip time.