Checks With Secondary Values
285
7SS52 V4 Manual
C53000-G1176-C182-3
7.4.4
Overcurrent Threshold Tripping
Example
For two feeders the overcurrent limit shall be checked which is set in parameter
XX13/CU
).
Test setup
Arrange the test setup as in Chapter 7.4.2, page 279.
Test steps
To prevent the differential current supervision from blocking the protection during
the test switch it off with the parameter
).
Set the differential current thresholds for the busbar-selective measuring system
and for the check zone with the parameters
) and
(
) to
1,0
I/I
no
.
Set the overcurrent threshold with the parameter
(
XX13/CU
) for feeder 1
to
2,0
I/I
n
and for the feeder 2 to
0,0
I/I
n
.
Set the isolators so that bay 1 and 2 are connected to the same bus zone
Increase the current in feeder 1 slowly with the test equipment. At 1 I
no
bay unit 2
must output a TRIP command, because the overcurrent threshold for this feeder is
set to
0,0
I/I
n
. Bay unit 1 must output a TRIP command at 2 I
N
.
7.4.5
Breaker Failure Protection
7.4.5.1
Trip Characteristic for Operating Mode “Unbalancing”
Example
The trip characteristic is assumed to be characterized by the parameters
(
XX18/CU
) =
0,5
I
/
I
N
for the differential current threshold
(
CU
) =
0,5
for the stabilizing factor.
Test setup
The test setup is shown in Figure 7-14, page 285.
Figure 7-14 Test setup for the trip characteristic of the breaker failure protection
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