# What exactly is primary rated voltage of transformer?

For example, we have a 2200/220 V non-ideal transformer.

Is primary rated voltage defined as the supply voltage to get 220 V across the load in this case? Or it is just the 2200 V as mentioned in rating?

More generally, is primary rated voltage defined as the supply voltage we need to have so that the secondary rated voltage is appeared across the load? Or is it just equal to primary induced EMF RMS value?

Model of transformer:

Source: Electrical4U.com.

• When writing, please add a space after ,. and section it into paragraphs, I cant read this... Sep 2, 2017 at 9:36
• It's not clear what your edit was for or what exactly your question is. Sep 2, 2017 at 10:56
• Tried to make it clear. Sep 2, 2017 at 12:47
• Still not clear but see my answer and ask for clarification. Sep 2, 2017 at 13:08
• I fixed the link (yours didn't work and wasn't formatted properly) and embedded an image so that readers don't have to follow the link. (The link may die in future and then your question becomes useless to anybody else so always put enough information into your question.) Sep 2, 2017 at 13:52

For example, we have a 2200/220 V non-ideal transformer.

OK.

• This transformer is designed to take 2,200 V on primary side.
• It is designed to give out 220 V on the secondary side when the primary is excited by 2,200 V.
• Therefore it is a 10:1 transformer.

Is primary rated voltage defined as the supply voltage to get 220V across the load in this case? Or it is just the 2200 V as mentioned in rating?

The primary rated voltage is that at which the transformer can pass maximum power.

• If the primary voltage is reduced then you will no longer be able to get the same VA out of the secondary. Power output will be reduced. Remember that the windings will have a certain current rating so you can't draw higher current from the secondary just because you have reduced the voltage.
• If primary rated voltage is exceeded the transformer will saturate and overheat.

More generally, is primary rated voltage defined as the supply voltage we need to have so that the secondary rated voltage is appeared across the load?

Answered above, but yes, you are correct.

Or is it just equal to primary induced emf rms value?

This doesn't make sense. Induced where and by what?

• You say that the transformer takes 2200 on primary side and supplies 220 on secondary side.I do not get this.The rating means that the induced emf in primary coil due to AC exciting voltage is 2200V .It will be equal to supply voltage (i.e 2200 here)only when losses 0 (ideal transformer.)Similarly for the secondary side. Sep 2, 2017 at 13:12
• If you connect the primary to 2,200 V then the primary voltage will be 2,200 V no matter what the losses are. If you are talking about some model using an ideal transformer and series resistance on the primary and secondary windings then you need to edit your question, insert a diagram showing your transformer model (you can use the built-in schematic tool) and explain what the problem is. Sep 2, 2017 at 13:18
• "If primary rated voltage is exceeded the transformer will saturate and overheat." --- Not necessarily. It depends on the magnitude of the magnetizing current and how much power is lost due to copper losses. The main problem is with the isolation. If the transformer is designed to work with 2200V, applying a higher voltage may damage the isolation between the wires in the winding. Mar 24, 2020 at 9:57

Yes a transformer have two coils (in your example) and the windings ration is determine the Vin ratio to Vout.

Vin = 2200 volt

Vout = 220 volt

= ratio of 10:1