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•
With 1.1 times the pick up current the relay should trip instantaneously in between 10 to 50 ms.
•
With 4 times the pick up current the relay should trip instantaneously in between 10 to 40 ms.
•
The test should be carried out for phases A, B and C.
6.14. INSTANTANEOUS GROUND OVERCURRENT UNIT, HIGH LEVEL (50NH)
•
Enable only 50NH function and the related trip.
•
Set its time delay and pick up to the minimum possible.
•
With 0.9 times the pick up current the relay should not trip.
•
With 1.1 times the pick up current the relay should trip instantaneously in between 10 to 50 ms.
•
With 4 times the pick up current the relay should trip instantaneously in between 10 to 40 ms.
6.15. INSTANTANEOUS GROUND OVERCURRENT UNIT, LOW LEVEL (50NL)
•
Enable only 50NL function and the related trip.
•
Set its time delay and pick up to the minimum possible.
•
With 0.9 times the pick up current the relay should not trip.
•
With 1.1 times the pick up current the relay should trip instantaneously in between 10 to 50 ms.
•
With 4 times the pick up current the relay should trip instantaneously in between 10 to 40 ms.
•
The test should be carried out for phases A, B and C.
6.16. PHASE TIME OVERCURRENT UNIT (51PT)
The 4 curves (Inverse, Very Inverse, Extremely inverse and Definite time) are tested with three points for
each curve (one not-to-trip and two to trip). This gives us a total of 12 points for each protection unit. The
tests are carried out for different phases. Each point is tested with a different pick up and dial in order to test
the whole range of the relay.
Enable only 51PT function and its related trip, and set the pick up to the minimum possible.
INVERSE CURVE
• Set the relay as follows:
51PT Settings Group
Curve
Time Dial
•
Apply 0.9 times the pick up current into phase A and the relay should not trip.
•
Apply 1.5 times the pick up current and the relay should trip in 15.96 sec. Acceptable time range
between 14.24 and 18.28 sec.
•
Apply 5 times the pick up current and the relay should trip in 3.97 sec. Acceptable time range between
3.85 and 4.10 sec.
VERY INVERSE CURVE
• Set the relay as follows:
51PT Settings Group
Curve
Time Dial
•
Apply 0.9 times the pick up current into phase B and the relay should not trip.
•
Apply 1.5 times the pick up current and the relay should trip in 16 sec. Acceptable time range between
13.91 and 18.82 sec.
GEK-105593C
INVERSE
1
VERY INVERSE
0.5
54
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