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Electric Motor Configurations

AdrianWint

So I have a (new) 1.5kW motor.

The motor rating plate declares the machine as being 380V 60Hz 3 phase, 3.96A and then ' WIRED IN STAR'.

The rating plate only gives details about the star configuration - it doesn't mention delta.

Looking inside the terminal box, all 6 wire ends are brought out - three being linked to form the star point.

Removing the star point reveals that all three coils are indeed electrically separate & the opposite ends are all displaced by one position as they would need to be if one was to reconfigure this machine into delta by turning the three links through 90 deg.

My question for the learned forum - why hasn't the manufacturer given any details about the delta configuration on the plate? Indeed he has even specified 'WIRED IN STAR'.

Why would he wish to rule out the use of the delta configuration? What badness might result from me re-configuring into delta & running from 220/3/60? The windings don't care whether they are in star or delta - if I apply 380/3/60 in star or 220/3/60 in delta the winding still has the same voltage across it.

What am I missing?

Parents
  • 0

    Perhaps "wired in star" means "wired in star when supplied" and not "must remain in star"  It should be fine if connected in delta on a three phase supply with 220 volts between phases. 

    If for some odd reason this motor must not be wired in delta, then provision of a terminal box that facilitates changing to a delta connection seems unlikely.

    If use in the UK is contemplated then the frequency difference is more important. Running a 220/380 volt motor and our supply which is still 240/415 volts in practice is a bit marginal. Running a 60 cycle motor on 50 cycles is also marginal. Running a 220 volt 60 cycle motor on 240 volts 50 cycles may end badly.

Reply
  • 0

    Perhaps "wired in star" means "wired in star when supplied" and not "must remain in star"  It should be fine if connected in delta on a three phase supply with 220 volts between phases. 

    If for some odd reason this motor must not be wired in delta, then provision of a terminal box that facilitates changing to a delta connection seems unlikely.

    If use in the UK is contemplated then the frequency difference is more important. Running a 220/380 volt motor and our supply which is still 240/415 volts in practice is a bit marginal. Running a 60 cycle motor on 50 cycles is also marginal. Running a 220 volt 60 cycle motor on 240 volts 50 cycles may end badly.

Children
  • 0 in reply to broadgage

    Thanks Broadgate.

    The motor will be used in the UK... but hiding behind a single to three phase inverter drive. I want a final speed of 0 - 3600 rpm hence using a 2 pole 60Hz motor. Obviously the inverter, being supplied from 230V single phase can only give 230 phase to phase out, so my plan was to flip the motor into delta & power it from the inverter.

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