CT transformer Burden formula transposition?

Thread Starter


Joined Apr 7, 2011
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..
Is this correct?? If so could an one please help with explaining the process?

Thx in advance..


Joined Mar 6, 2009
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.