# Ideal Step-up transformer

1. Apr 18, 2015

### RRTF

1. The problem statement, all variables and given/known data
An 5kVA ideal step-up transformer having a turns ratio of 200:1700 and is connected to a primary voltage of 1000V. Determine the primary current at full load.

2. Relevant equations
Vs/Vp = Ns=Np = Ip/Is

3. The attempt at a solution
I think it is 1700/200=Vs/1000=8500V
But, I do not know how to calculate the current,
I think it is 5kVA/8500 is Secondary current
then when I have Secondary current is 10/17 (0.58823)
((10/17) x 8500) / 1000 = 5A

I think the primary current at full load is 5A????

Thank you

2. Apr 19, 2015

### Merlin3189

All sounds good to me.
Since it is ideal, 5 kVA can be used on primary or secondary:
primary 1000V x 5A or secondary 8500V x 0.588A both = 5 kVA

3. Apr 19, 2015

### rude man

Since the transformer has capability of 5000 VA and 1000V is connected to the primary, the input current is at "full load" is 5000/1000 = 5A, a quick way to your answer.