# CT transformer Burden formula transposition?

Discussion in 'Homework Help' started by stinky111, Dec 4, 2011.

1. ### stinky111 Thread Starter Member

Apr 7, 2011
39
1
Hi guys,

stuck on one final question revising for a transformers final..

A CT has a 25VA Burden rating. The connected ammeter requires 4A for full scale deflection. What is the maximum allowable impediance??

The only burden formula I have in my notes is: Burden = I2Z (VA)

Im very average on formula transposition, obviously I must need to transpose above formula to allow me to find maximum allowable impediance..

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
That formula

Burden=I^2Z [VA]

will do just fine.

So make Z the subject of the equation and you will hopefully have the correct solution.

3. ### stinky111 Thread Starter Member

Apr 7, 2011
39
1
Would it be Z=I^2/VA???
Thx

4. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
Try

Z=burden[VA]/I^2

....

5. ### stinky111 Thread Starter Member

Apr 7, 2011
39
1
Thx very much yet again for your time

Last edited: Dec 5, 2011