Need help on my small project

[ykho21]

Hi,

I am a new member on this forum which I found during my search for electrical project.
I would like to ask all the expert here some simple question but a bit difficult to me due to my electrical knowledge is limited.

From the picture attached (1), the circuit is for 250v, 3-phase induction motor.
I have a project in my mind to set-up a testbox which used to load test the motor controller (electronic cartridge).
Without install a motor inside my testbox, can replace the motor with 500ohm wirewound resistor just to simulate the motor load?
From my calculation from the basic ohm's law, V=I.R and puting the load of 500mAmp, I'll get R value is 500ohm.

Any idea this will successful or can give an idea on this.

 

[Knobhead]

A motor can be connected two ways, star or delta. In star as shown in your drawing the voltage across each leg has to be divided by √3.
Hope this drawing helps.
View attachment 9614

 

[Inteificio]

Motors are very inductive, and can have a large back EMF.

Your motor started might be able to 'start' the resistor, but blow when you connect a motor.

In addition motors normally have a start up current that is significant. Can't remember the exact bodge rule on that one, but once I finish my morning coffee I may come back and revise, something like x5 or x3 current until the motor is spun up.

Sorry, but this is quite a big topic unless you are using a VERY small motor.

You could use your fancy starting circuit to start a secondary motor starter circuit?

 

[ykho21]

Thanks a lot for replying me. Forgot to mention that this motor use 250v each phase. Mean using 440v 3-phase supply.

 

[Marvo]

You can't use resistors to simulate the load of a motor for test purposes. The load presented by a motor firstly isn't constant, the start current is high for example compared to the run current. Secondly a large part of the load presented by a motor is inductive impedance not linear resistance so resistors wouldn't represent this type of load to a supply.