Question: What happens when a 60 Hz transformer is operated on 50 Hz?
Answer: The peak flux and magnetization current of a 60 Hz transformer increase when operated on 50 Hz supply.
The flux in a transformer is defined as the ratio of voltage to frequency.
Ømax = [Vmax / f ] * k
Where k is a constant.
Let’s assume the applied voltage is 120 V and f = 60 Hz.
Ømax = [120 V / 60 Hz ] = 2 … 1
The decrease in frequency increases the flux:
Ømax = [120 V / 50 Hz ] = 2.4 … 2
A decrease of 10 Hz frequency increase the flux by 20%.
For keeping same flux the transformer should be operated at 20% lower voltage.