3 phase induction motor & transformer

Well, a motor pulls about 5 times the full load current on starting.

What happens to the transformer depends upon the size of both the motor and of the transformer, which haven't been stated yet.

What about the wiring? Not interested?

Classic inrush current occurs when the motor is connected directly to the power line using a simple three phase switch or relay. Generally the capacity of the transformer group (three transformers) is much greater than the motor.

If the transformers were not capable of providing up to 5 times the rated current then the transformers would simply saturate and thereby limit the current flow during the inrush. But you are still talking about a very brief event so chances are small that you would even notice.

Once the magnetic fields are formed (energized), the reverse EMF forces the current to drop and the rotor begins to turn. If the rotor is locked, you will get a higher current than normal full load current. But if that happens, you have other problems.

"what is the effect of starting current or inrush current of a 3 phase induction motor on a transformer feeding electricity to the motor?"

The answer to the question AS ASKED is, nothing.

Hey J,

I always enjoy your perspective. But this time I'm a bit lost. Perhaps I'm intpreting the question a little differently. Are you suggesting that a motor could never overload a transformer?

NYOJ

No, I actually understand what he was asking and I think you answered the question he MEANT to ask just fine. I'm just being a curmudgeon about his phrasing of the question.

I deserve to be chastized I guess...