question

This is called Current Injection Test.

Normally this is done on Switch boards, relay and control panels, to check the performance of protective relays,instruments.

There are two type Current Injection tests.One is called Secondary Injection Test and other one is called the Primary Injection Test.

In a switch Board /Relay and control panel the relays .instruments will be provided and these will have either 5 amps or 1 Amp as for their current coil.In this instance Current of 5 Amps / 1 amp will be injected into the circuit and relays /instrumentswill be tested for proper functioning.But the CTs are not connected to the system.

In the primary injection test, Primary current will be injected to the switch board and tested.In this case CTs are also put into the circuit and tested.

hi

thanks for your reply, i understand about the secondary test now, but about the primart test: how do u inject current in to the switch room?

many thanks

Please register yourself and identify to give some more clarifications.

Hi,

For any CT there Primary Injection Test is conducted. It is nothing but injecting a High Cuurent using Loading Transformer and checking out the current in the secondary terminals.(2000/1 A, 800/1A, 400/1A). This is nothing Ratio Test for the CTs.

N.Suresh