Motor Class 1 Specifications

Motor inrush current (ic) and the magnitude of the current is not dependant on the type of motor, ie Eff1 or Eff 2, 2 or 4 pole.

Inrush current is an electrical phenomona which occurs in most electrical equipment.

When the starter contactor closes to start the motor an inrush current of between 15 and 25 times motor full load current flows for approxiamately 20m seconds.

The moment the contactor close the full voltage is supplied to the motor terminal. This voltage is basically applied to a "short circuit" and hence the inrush current.The same as taking 2 of the lines and short them out (large current will flow). At this stage only the resistance of the winding will limit the current drawn from the supply.

Once the motor starts rotating and the impedance is also effective the inrush current falls away and the current will change to the motor start up current (normally 5 to 7 times Fla).

The major motor manufacturers will quote an inrush current of between 15 and 25 times.

Thanks for the explanation Aldego. and that makes sense. i am trying to contact the manufacturer of the pump to get that info.

Does anyone have more inputs?

Thanks!