DC shunt motor

Hi Guys

come across an oldish dc shunt motor. Noticed it has 4 wires , 2 red two white. I have a speed controller for this but i dont know which wires are the armature and which are the field.

does anyone have an idea. i was thinking red is armature and white is field but it could also be red +ve side armature white -ve side???

any idea guys??/

cheers

Andy

The armature wires should go to the bushes. So use an Ohm meter to discover which ones are connected to the bushes. Also, if you measure the resistance between the wires and slowly turn the shaft, the resistance should vary as the bushes cross the segments.

The field will normally have higher resistance than the armature, if you can measure that low.

If I remember right, then reducing current through the field should make the motor run faster, if it helps you. Also there should be no connection between field and armature, so you should be able to find the pairs with ohm meter.