Can a three-phase motor work not at full capacity if the voltage is slightly more than 220 V on all phases?

  • Mar 15, 2021
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This question, already 65 in a row, with just such a title, was asked by the reader Roman. If you have your own answer to the question, then write it in the comments below. I and other readers will be happy to read it.

The text of the question itself read literally as follows:

Hello. Can a three-phase motor work not at full strength if the voltage is slightly more than 220v on all phases? The main thing for me is to cut off the problem in the electrical.
The photo is illustrative.
The photo is illustrative.

I reviewed the issue and advised Roman within the framework of my knowledge and qualifications as follows:

Good day!

In an amicable way, it cannot, an AC electric machine consists of three windings with a radial displacement and the same resistance. Thus, provided that the windings are correctly connected to the electrical circuit, in them, according to Ohm's law, the current strength will increase in proportion to the increase in voltage over 220V:

I = U / R

As you can see from the expression, the current in the windings of a three-phase AC motor will increase, and, accordingly, the torque of forces acting on the motor shaft will also increase. Therefore, the force on the shaft will only increase if the operating voltage is exceeded, albeit within the permissible limits.

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At the same time, I dare to assume that the engine may have a wrong wiring diagram. So, on the nameplate of an AC electric machine, where there are three windings, it is possible to connect them according to a star or delta scheme.

Depending on the type of connection chosen, the value of the rated voltage of 220V or 380V will also depend, for some models, 220V or 127V, etc. If you connected the wrong one connection diagram of windings for 220 V, instead of the required 380 V for the existing type of connection, then it is likely that the electric motor will not give out the power for which you counted. If you did not take into account this particular moment, I recommend that you familiarize yourself in detail with the corresponding article on the website: https://www.asutpp.ru/podklyuchenie-trexfaznogo-dvigatelya.html .