Transformer efficiency/primary current (help )

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SUMMARY

The discussion focuses on calculating the primary current of a step-down transformer with an efficiency of 92.5%, which converts 125 V to 23.0 V while supplying a secondary current of 27.0 A. The efficiency formula used is e = (100%) Ps/Pp, where Ps represents the power output and Pp the power input. The user seeks assistance in determining the primary current based on the given efficiency and secondary current values.

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Transformer efficiency/primary current (help!)

Real transformers are not 100% efficient. That is, the efficiency, in percent, is represented by e = (100%) Ps/Pp. A step-down transformer has an efficiency of 92.5% is used to obtain 23.0 V from the 125 V household voltage. The current in the secondary circuit is 27.0 A. What is the current in the primary circuit?

I have tried basically everything but I cannot seem to figure it out. Help?
 
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If it was 100% efficient what current would need to be supplied?

That means the power in is the power out.

So what is the power out?

Once you know the power in then you know that it needed to be more by how much? .92 of actual Power = Power you calculated as required to meet the statement of the problem.
 

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