This test checks out all the protection system, including the current transformers.
The principal aims of this test are to verify the CT transformation ratios and all the
secondary circuit wiring of both the protection and the measurement CTs so that the
operations of the tripping, signalling and alarm circuits are confirmed.
Figure 14.4 shows the schematic diagram of a typical equipment used for carrying
out primary injection tests. The test current is usually between 100 and 400 A. The two
high current terminals of the primary injection equipment marked and
should be temporarily connected to the terminals of the CT that is being tested