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    why don't we use neutral in 3 phase motors ?

    why don't we use neutral in 3 phase motors ?

    whether motors are connected in star or in delta .........

    Can we use neutral of the system as the earthing for these 3 phase motors ? (connect a wire to the neutral of the system & then to the body of the motor so that the motors is grounded)

    thanks

    •   Alt22nd January 2012, 16:33

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    Re: why don't we use neutral in 3 phase motors ?

    Why is a neutral not required? At three phase, the phases conduct through one another and a dedicated load like a motor uses all three phases and ONLY all three phases. Only in single phase need neutral.


    Additional Info :
    Three-Phase


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    •   Alt22nd January 2012, 16:54

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    Re: why don't we use neutral in 3 phase motors ?

    Neutral and earth are not the same thing. Neutral sends the return current down the line back to the transformer or power station. Earth is a safety conductor and ensures that under fault conditions the metalwork of machines can not become live. It never carries any current other then under fault conditions.
    Frank


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    •   Alt22nd January 2012, 20:36

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    Re: why don't we use neutral in 3 phase motors ?

    The voltage between phases are more (delta load ) than the phase-neutral voltage (star load)



  5. #5
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    Re: why don't we use neutral in 3 phase motors ?

    you can use neutral if you need and phase to null line voltage will be 220V,but usually 3phase loads doesn't need neutral line for operation, because the zero potential is created at the joint point of delta or star connection at the load side.
    also i must say that the equality of neutral and earth depends on the selection of earthing system of network(tn-s, tn-c ,tt,...), i recommend you take a look at this address:
    Earthing system - Wikipedia, the free encyclopedia


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