CT Sautration & Pickup

[ukgraduate]

Hi,

I have an application where the prospective fault level is 10kA. The CT ration is 200/1 5P20. So the max current before CT saturates and larger inaccuracies start is around 4kA.

My settings are such that the pickup will occur at 2kA.

Will this CT pose a problem with the high fault level and saturation?
Or is this not an issue because the pickup is below the saturation level?

Regards

UkGrad

 

[RBlais13]

Saturation occurs when the Primary CT current is so High (or above the accuracy rating) that it can not put out a secondary current in a linear fashion. Since your pickup is well below the "Knee" of the saturation curve, You will be fine.

This could cause an issue if say, you have a breaker with C800 CTs and a breaker with C400 CTs and each of these breakers are associated with line and bus protection. If there was a line fault, the C400 CTs could saturate before the C800 cts. The result would be differing secondary currents going to the bus relaying which could cause a false Bus differential trip.