1

I'm trying to repair a drill where the switch got broken. It's turning into something more difficult than I expected due to several issues. One of them is that the brush wires got peeled due to some unknown friction or wear somewhere in the path. The brushes themselves don't look worn enough to be replaced, so I simply replaced the wire.

enter image description here

Then I noticed something that puzzled me on the old wire. Instead of being a single, continuous one, directly attached to the switch, there was a split in the middle, covered with heat shrink tubing. Even the wire color was different on each part. By chance, I peeled the tube off as I discovered something "solid" on the inside. At first sight I thought it was some reservoir wire for attaching it to the other half of the wire, but looking carefully, with its ferrite in the axis, I came to the conclussion that it's a coil.

enter image description here

  • What's the purpose of these coils?
  • What would happen if I connected the brushes directly to the switch?

Bonus question: As I cut it too tight from the edge of the coil, could it have any harmful side effect if I unwind, lets say, a turn of the coil in order to use the copper wire to attach the coil to the wire?

Pere
  • 117
  • 4

1 Answers1

4

To suppress radiated emissions that occur due to the small sparks in the brushes. This noise may interfere with nearby radios, etc.

Mike McDermott
  • 133
  • 4
  • I'm confused. After getting to know that they are called "interpoles" thanks to a previous user comment, I googled for it and found a Quora question (https://www.quora.com/Electrical-Machines-What-do-interpoles-do-in-DC-motors) where, to my understanding, there's no reference to this explanation on any of the answers... – Pere Jan 06 '21 at 13:43
  • 1
    @Pere This is the internet...if you are not satisfied with an answer (here or on quora) your payment will be happily refunded. – Elliot Alderson Jan 06 '21 at 14:30