A 1 kVA, 220/110 V, 400 Hz transformer is desired to be used at a frequency of 60 Hz. What will be the kVA rating of the transformer at reduced frequency?

Question

Accepted Answer

We know that [latex]E_{1}=V_{1}=4.44\: \phi _{m}\: N_{1}\, f=4.44\: B_{m}A_{i}N_{1}\, f[/latex]

Assuming flux density in the core remaining unchanged, we have

[latex]V_{1}\propto f[/latex]

or [latex]\frac{{V_{1}}'}{V_{1}}=\frac{{f}'}{f}[/latex]

or [latex]{V_{1}}'=V_{1}*\frac{{f}'}{f}=220*\frac{60}{400}=33\: volt[/latex]

As current rating of the transformer remains the same, the kVA rating is proportional to voltage,

[latex] herefore [/latex] kVA rating of the transformer at 60 Hz,

[latex]{kVA}'=\frac{{V}'}{V}*kVA=\frac{33}{220}*1=0.15\: kVA[/latex]

Question : A 1 kVA, 220/110 V, 400 Hz transformer is desired to be used...