Induction Motor Question

V=IR or the current form E=IR is a form of Ohm's Law and applies to "pure" DC only, the "R" representing ohmic resistance. The reason you cannot use it for an induction motor (generally taken to mean an AC motor) is that another "resistance" occurs in an inductive circuit when you have a time varying voltage (typically AC) and that is called impedance or in this case inductive reactance. An equivalent formula for a circuit containing an induction motor would take the general form of E=IZ, where Z consists of a combination of the ohmic resistance R and the inductive (and capacitive) reactances. Beware that in most cases this is an oversimplification for real world measurements but it is conceptually useful to understand the differences and with the right equipment will be accurate for the purpose intended. A significant difference in applying an analog to Ohm's Law on an inductive (and/or capacitive) circuit is that the current and voltage will be out of phase with each other. Temperature has nothing to do with the reason you can't use V=IR.

As to the Hopkinson Test yes it is certainly possible but you offer no details or specifics.

Has no one who asks questions here heard of Google or other search engines ????????

Guest,

I suggest you should study more about Lesson in Electric Circuit, The type of Electrical Loads, Power Triangle, Power Factor. Don't say that you don't have enough time.....or try a short-cut.

When you have learnt then you find some difficulties of understanding, then you may expose your question in a forum.

And I think everbody here is willing to help.