CT and PT

[dwijaya]

can anybody help me?
I have some questions:
1. How long we can use a current transformer (CT) and a Potensial Transformer (PT)? CT and PT are in medium voltage (20Kv) and connected to kWhmeter.
2. what the effect if the CT and PT are used in their rating and over their rating in long periode? Are there any temperature effect?
3. If I use re-condition kWhmeter, what the effect for the measurement of energy?
I would appriciate if someone could help me a.s.a.p.

Best regard
dwi

 

[charlie tuna]

transformers have no moving parts and as long as their insulation remains in good condition they can last forever. current transformer and potential transformers produce very little heat and since heat is what usually causes insulation failures -- they should last a very long time.
any new meter should match the existing meters specs to remain accurate.

 

[newt]

If ct,s become overloaded for a long period of time the core can become magnetized making them inaccurate.