Protection Engineering Basics and Schemes Protection Engineering | Page 12
( VA ) in CTs , but always remember burden is always calculated in terms of ohm Let suppose we have 400 / 1A CT , with burden of 10VA , then we can say ,
VA Burden =
2
I Secondary
= 10
1 2 = 10
Now Take 400 / 5A CT , with 10VA rating , then
Burden = 10VA / 5 2 A = 0.4 Let see one more issue related to Current Transformer , what happened when CT Secondary kept open during energized state . Now calculate it mathematically , when secondary open then current in secondary become zero because circuit is incomplete
We have 200 / 1A , 10VA CT Burden = 10VA / 0^2 = ∞
V = Burden
I Secondary
V = ∞ 1 = ∞V
When Voltage is infinitely large , then it can harm any person in contact or any associated equipment with it , even it ionize the air in between CT , all the primary