Start of 4kW DC motor

Hello,

I have a DC motor wit below specs. We need to test run it but. We have a transformer and a recitifier that can provide the DC voltage and current. However we have no start resistance. Is it possible to start anyway? If not how to calculate start current?

kW 4.0
Rev/min 1500
Arm Volts 110
Armature Amps 41.6
Field Volts 110
Field Amps 0.55
Wound Compound

NOTE:
Resistance start required. Starter not of our supply

I would use either 2 transformers & rectifiers or a transformer/rectifier for the field and a lower voltage for the armature to start and test, or even a car battery for the armature to test...

The Locked Rotor Amps (starting current ) of the armature will blow up a power supply rated too low with a full-voltage start. The armature resistance is likely < .25 ohms, so figure 110v/.25ohm= 440A!

I wouldn't dream of touching it without a 4kw dc drive to control it.

41.5 amps ate a lot for a 110 volt motor
the other odd thing is that most DC motors are rated at 90VDC the rectified 110 vac
that beaing the motor start inrush of that motor could be 10 X the full load rating
more than likley it would exceed 200 amps you power supply would need to supply at least that.
A resistive start means you need to put a resister in series on start up to limit the inrush
current
what you really need is a DC drive sizes correctly I would think you client could be able to supply you with the one they are using so you test the project.

Ronnie Sullivan said:

I wouldn't dream of touching it without a 4kw dc drive to control it.

Click to expand...

Amen Ronnie
Why take a chance and damage the motor