CT, High and Impedance Electrical System


Thread Starter


Dear sir,

1. How you can say tht my sytem is high impedance system or Low impedance system. While testing micom P632 [Differenrial and REF protn. Relay], i saw in REF protection it was high impedance what does that mean?

And can you differentiate between both? Is it depended on grounding system.

2. We usually says Saturated CT should be replaced immediately. Why? How does it respond during fault and normal condition?

3. What is the difference between IDMT E/F chara 51N and thermal chara 49?

4. Why earth fault protection should be kept OFF if i am using contactor breaker.

Testing engineer