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326 Practical Power System and Protective Relays Commissioning
20.1.2.1 Secondary Injection Tests
These tests confirm the relay characteristic and check the relay pick-up
accuracy.
20.1.2.2 Protection Scheme Function Test
This test confirms the operation of the relay with other relays, auxiliary
relays, and other scheme components of protection. This test is done not
only in the relay panel itself but is also done between the relay panel and
other relays panels, for example, the busbar protection panel and the feeder
main-1 protection panels.
20.1.2.3 Primary Injection Tests
In these tests the complete system of protection is tested. The operation of
current transformer (CT), voltage transformer (VT) and protection relays
also will be tested, for example, checking the stability of the transformer
differential and restricted earth fault protection by injection 380 V and also
busbar protection sensitivity and stability tests. These tests are explained in
the following chapters of this book in detail.
20.1.2.4 End-to-End Test
To be done on transmission lines differential protection and distance
relay telecommunications tripping schemes. These tests need two
engineers at each end of the line to simulate normal and fault conditions
and to check the relay response at both ends of the line and also to check
the decision for tripping the circuit breakers (CBs) at the two ends of
the line.
20.1.2.5 On-Load Tests
These tests are performed after energization of a new circuit and can
include a directionality test to check that the relay (directional over current
(OC) relays or distance relays) works in the line direction and not in the
busbar direction, whilst also checking the operation of line differential
relays on the load. These load tests are done after opening the tripping links
of the relay but keeping the circuit protected by another protection on the
same circuit which the relay under test protects. These tests are explained
in the following chapters.
