# Homework Help: Transformer Primary and secondary currents

1. Jan 6, 2012

### jitznerd

1. The problem statement, all variables and given/known data

A single phase transformer has the following rating : 120kVA. 2000v/100v, 60 Hz with
1000 primary turns.

Determine:

a.Secondary turns
b.The rated primary and secondary currents

2. Relevant equations

Vp/Vs = Np/Ns

3. The attempt at a solution

a. I have used the Vp/Vs = Np/Ns to work out secondary turns
1000 x 100/2000 which gave me 50 secondary turns.

b. I arent sure if I have gone about this the right way and just wanted to check.

I divided the 120000VA by the primary voltage of 2000 to give me 60A. Is this correct to do this.
Then with my 60A I put that into the Vp/Vs = Ip/Is which gave me 3A as secondary current.

Could someone please tell me if this is correct thanks

2. Jan 6, 2012

### technician

Vp/Vs = Ip/Is is not the correct equation.... have another look at it.
If the transformer is 100% efficient then power supplied = power delivered.