Installation and Commissioning
284
7SS52 V4 Manual
C53000-G1176-C182-3
7.4.3.2
Check Zone
To test the check zone, the check zone must be set more selective than the busbar-
selective protection so that the supervision of the check zone picks up earlier.
Example
You want to test the supervision of the check zone with the parameters for the differ-
ential current threshold
(
6309/CU
) =
0,2
I/I
no
and the delay time
/
CU
) =
2,0
s. For the busbar-selective protection the param-
/
CU
) is assumed to be set to
0,8
I/I
no
.
Test setup
Arrange the test setup as in Chapter 7.4.2, page 279.
Test steps
Check of the pickup threshold and the delay time:
Increase the current in feeder 1 slowly until the check zone supervision picks up.
The measured current must correspond to the set current
(6309/CU
).
Carry out a time measuring as in Chapter 7.4.3.3, page 284
Checking the blocking:
The reaction of the protection when the differential current supervision of the check
zone picks up can be set with the parameter
(
) to
blocking
or to only
indicate
(without protective blocking).
Connect the bays 1 and 2 to the same bus zone.
Increase the current in feeder 1 slowly until the supervision of the check zone picks
up.
Apply to feeder 2 a current 4 times as high as the rated current I
N
. If the parameter
is set
CU
) to
blocking
, no TRIP commands follow.
7.4.3.3
Time Delay
Time measuring is possible with the standard test equipment for protection devices.
To measure the delay time for the differential current supervision, apply to feeder 1
through the testing device twice the current set in the parameter differential current
threshold
(
).
As soon as the differential current supervision picks up, the test current source is
switched off. The measured time corresponds to the set delay time in parameter
(
).
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