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Thread: electric motors

  1. #1
    New Member Frikkiemieny's Avatar
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    Mar 2018
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    electric motors

    I have a 3 phase motor and want to use it, the problem my house supply is single phase some one said it can be done but not sure, can someone give me advice please

  2. #2
    Gold Member
    Join Date
    Jun 2017
    Port Elizabeth
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    You can use a single phase in , 3 phase out Variable Speed drive ( or soft start ) depending on the size of motor you re referring to - They are available up to around 2Kw - The majority will put 3 phase 220v output - Again going to depend on your winding configuration of the motor that can be seen on the rating plate.

    The other way is to insert a run cap across the last phase to give the 120 degree shift in the phase - Is a struggle to find the correct size capacitor as I am not aware of any calculations and you tend to lose torque.
    Better option is to fit the VSD

  3. #3
    Bronze Member mikilianis's Avatar
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    Dec 2008
    Cape Town South Africa
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    Running 3-phase motors on 1-phase Three-phase motors will run on single phase as readily as single phase motors. The only problem for either motor is starting. Sometimes 3-phase motors are purchased for use on single phase if three-phase power is anticipated. The power rating needs to be 50% larger than for a comparable single phase motor to make up for one unused winding. Single phase is applied to a pair of windings simultanous with a start capacitor in series with the third winding. The start switch is opened in Figure below upon motor start. Sometimes a smaller capacitor than the start capacitor is retained while running. Starting a three-phase motor on single phase. The circuit for running a three-phase motor on single phase is known as “ add a phase ” or various other brand names. “ Add a phase ” supplies a phase approximately midway ∠ 90 o between the ∠ 180 o single phase power source

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