## Protection CT's ANSI/IEE Standard Burden Calculation

## Protection CT's ANSI/IEE Standard Burden Calculation

(OP)

When you calculate CT's ANSI/IEEE standard burden, do you have to include CT's internal registance?

This is to calculate Per Unit CT burden (Zb)for the final calculation of CT's performance in terms of saturation at the time if there is a (severe) fault.

For instance, for a CT C400 the ANSI standard burden is 2 ohms. And you may want to calculate CT remanence (20-80%)and this further downgrades your C400 CT to, say, C350 (depends on your % used).

But I'm not sure whether I still have to add CT's internal registance in order to calculat the final standard burden. Note that this internal registance has already been taken into consideration when CT's normal burden (i.e., internal registance + CT lead registnace + relay burden)is calculated.

Thanks for any comments.

This is to calculate Per Unit CT burden (Zb)for the final calculation of CT's performance in terms of saturation at the time if there is a (severe) fault.

For instance, for a CT C400 the ANSI standard burden is 2 ohms. And you may want to calculate CT remanence (20-80%)and this further downgrades your C400 CT to, say, C350 (depends on your % used).

But I'm not sure whether I still have to add CT's internal registance in order to calculat the final standard burden. Note that this internal registance has already been taken into consideration when CT's normal burden (i.e., internal registance + CT lead registnace + relay burden)is calculated.

Thanks for any comments.

## RE: Protection CT's ANSI/IEE Standard Burden Calculation

1. CTs secondary windings resistance

2. Resistance of the wires from CTs to the relays

3. Burden of the relays

The sum of all above you will be using to calculate the knee point voltage at a given fault current to check the CT for saturation.

## RE: Protection CT's ANSI/IEE Standard Burden Calculation