CT Sizing PS Class

[sasalu]

Dear All,

While calculating EMF developed across the CT secondary during fault for a through fault current , we have to consider CT internal resistance along with the connected burden or only R lead and Relay coil to be considered.

 

[Kiribanda]

What is your question please?

 

[scottf]

Yes, you should include the Rct (internal resistance). Normally, there is a limit established as part of the PS class spec.

 

[sasalu]

Sir my question is To calculate EMF developed across a Line protection PS core CT for Zone-01 faults, Normally in the case of 5P20 we will calculate EMF developed is ALF X Burden/Rated Secondary current but here we are not using Rct or burden mentioned in the CT is inclusive of internal CT resistance.