NG CH 09 PDF

PURPOSE

 The purpose of this procedure is to provide a model process for primary injection testing of feeder protection. The tests are intended to establish the integrity of the associated current transformers and their secondary connections. These tests are required to prove:

• The CTs have not been damaged during transport or erection.
• The ratio of each CT, or that a CT ratio change has been correctly carried out.
• The relative polarity of the three phase group of CTs.
• The secondary connections from the CT, up to and including the relay.

In some instances it may only be possible to carry out this test from the CT to a defined terminal connection point, with the connections from this point onward to the relay, including an overlap, being proved by secondary injection.