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6 comments
Anonymous Poster

Three Phase Induction Motors

08/03/2010 12:17 PM

HI everyone here,.....

I know that the three phase induction motors are usually six –leads coming out of the motor,, why there are some ones are described as motors of 9 leads, or even 12 leads? How come do we get the 9,12 leads if we just need 6 leads to achieve the external connections?

please further explanation!

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Guru
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#1

Re: three phase induction motors

08/03/2010 12:29 PM

Different types of motors.

NEMA, IEC, 2 speed, dual voltage, part winding, Y start/delta run and/or any combination of the above makes for various winding connection points requiring more or less leads.

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Guru

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#2
In reply to #1

Re: three phase induction motors

08/03/2010 7:10 PM

For additional help, see these links:

http://hollandindustrial.com/PDF%20Files/European%20and%20American%20Motor%20Connections.pdf

(see details of the tables "Single Speed Motors, 3 Phase, 3, 6 and 9 Leads", "Single Speed Motors, 3 Phase, 12 Leads", "Two Speed Motors, 3 Phase")

http://www.electricmotorwarehouse.com/motor_connection_diagrams.htm

- MS

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Power-User
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#4
In reply to #2

Re: three phase induction motors

08/04/2010 6:41 AM

Nice overview of all the possible motor connections

Thanks a lot and GA from me

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Power-User

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#3

Re: Three Phase Induction Motors

08/04/2010 4:15 AM

These are normally used for different speeds and/or torque connections. Those motors will typically have a diagram in the terminal cover showing the available connections and which leads are to be connected together or to which other terminal. If the diagram "ran away" you will have to isolate the winding pairs and do various tests to determine what you may get.

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Commentator

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#5

Re: Three Phase Induction Motors

08/04/2010 12:42 PM

Hi Guest,

I agree with JRaef, but What I can add is that the 3-phase Ind motors are connected in several ways to get particular operating conditions like a change of speed, constant torque,….. I think it's not necessarily that such motors are 6 leads brought out of a motor as some motors(particularly those of low power rating) are internally-connected either Star or Delta, and in this case you find just 3 leads out of the motor, and such these motors usually work on particular voltage according to its internal connection. However, the load conditions will surely determine the way you pick in order to connect a motor.

I'll try finding any illustration at my desk!

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#6

Re: Three Phase Induction Motors

08/04/2010 3:19 PM

I have seen 6 leads in commonwealth countries and 9 leads in american motors.But in Saudi Arabia I have seen two standard voltages (220V 3ph and 400V or 480V 3ph).So we used 12 lead motors from GEC coupled to water pumps as we do not know what will be the supply voltage at site.The two parts of each phase winding of the 12 lead motor can be connected in series for higher voltage or in parallel for lower voltage.The name plate of these motors give two current ratings one for lower voltage and another for higher voltage. But the speed and output will be same.

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