7PG2113/4/5/6 Commissioning & Maintenance
©2012 Siemens Protection Devices Limited
Chapter 6 Page 14 of 77
1.4.1 Stability
Tests
The purpose of these tests is to ensure that the pilots are correctly connected and that the current transformers at
each end are starred correctly relative to one another in order to permit stabilisation of the protection under
through fault conditions.
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E
Figure 1.4-2 -Connections for Stability Tests on Load without Isolating Transformers
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Figure 1.4-3 -Connections for Stability Tests on Load with Isolating Transformers
The test should be made with the load current in the feeder equal to at least 10 -15% of the rating of the feeder
current-Transformers. Since in these tests all three phases of the primary circuits are energised, take care that
the current-transformer secondary leads are not open circuited.
Remove the trip-links at both ends of the feeder but check that the remainder of the equipment, including the
pilots, is connected for normal operation.