How Do You Calculate Primary Current in a Step-Up Transformer?

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To calculate the primary current in a step-up transformer with a 5kVA rating and a primary voltage of 1000V, the formula for current is applied. Given the transformer's ideal nature, the primary current at full load can be determined directly by dividing the power rating by the primary voltage, resulting in 5A. The turns ratio of 200:1700 indicates that the secondary voltage is 8500V, with a corresponding secondary current of approximately 0.588A. This confirms that both primary and secondary calculations align with the 5kVA rating. Thus, the primary current at full load is indeed 5A.
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Homework Statement


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.

Homework Equations


Vs/Vp = Ns=Np = Ip/Is

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
 
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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
 
RRTF said:

Homework Statement


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.

Homework Equations


Vs/Vp = Ns=Np = Ip/Is

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
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.
 

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