22
Record the results obtained in Table 2 and compare with the
nominal values in Table 1.
Repeat the test for the other phases.
b.) Output relays
1.Trip – 1 N/O contacts (13 & 14, 15 & 16)
This contact to be used whiles testing the Bias characteristic and
Highset of the relay.
2. Biased Differential - 1 N/O Contact (17 & 19)
This contact to be used whiles testing the Bias characteristic and
of the relay.
3. Differential Highset – 1 N/O contact (17 & 20)
This contact to be used while testing the highset characteristic.
4. Protection Unhealthy - 1 N/C contact (17 & 18)
5.3 PRIMARY INJECTION
Primary injection is needed however to verify the secondary connection
of a neutral CT relative to the phase CT's and the relay. In these
circumstances primary current must be injected through the associated
power transformer winding. It may be necessary to short-circuit another
winding in order to allow current to flow. Refer Fig. 2
During these primary injection tests the injected current is likely to be
small due to the impedance of the transformer. Measure the phase
current and neutral spill current
5.3.1 CT Ratio and Polarity Tests
These tests check the ratio and polarity of the star connected CT's with
or without a neutral CT and also their connections to the correct
terminals of the MIB202 input modules.
5.4 PUTTING INTO SERVICE
After completing all tests satisfactorily, the relay should be put
back into service as follows:
