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