Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 11 replies
  • Subscribers 34 subscribers
  • Views 1616 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Fixing a small motor

Chris Pearson

I want to fix an ancient 1/8 hp motor (Carter Electrical Co Ltd). As far as I can tell, the centrifugal switch has worn out, so that will be fun making a new one.

My question is what resistance seems reasonable for the coils. IR is good (well into the tens of megaohms) but they are a little dark and I would like to be confident that there has been no internal shorting.

The main coil is about 18 ohms and the starting coil 33 ohms. My maths tells me that the running current should be around 0.4 A. I cannot remember a lot about motors, but I realise that the impedance of the coils will be higher at 50 Hz than the (DC) resistance and that back EMF reduces the current. I hope therefore that the resistance values are about right.

Grateful for any reassurance!

Parents
  • 0

    mapj1: 
    Looks as if you could file a touch off the back of the weighted pawl to allow it to swing in a bit further and with a bit of brasso and old sock rubbing perhaps  get another 50 years out of it (!)

    There'd be no fun in that and I am under doctor's orders to take it easy this week.

    The curved lip to the fixed contact allows the pawls to slip over it.

    What is bizarre is that there seems to be no way of disassembling the motor without damaging the paxolin plate because the force required to pull off the tail bearing is greater than it can withstand. By contrast assembly will be no problem - the bearing will be fitted to the case, the switch will go over that, and then the armature may be fitted.

    Better get it right first time!

Reply
  • 0

    mapj1: 
    Looks as if you could file a touch off the back of the weighted pawl to allow it to swing in a bit further and with a bit of brasso and old sock rubbing perhaps  get another 50 years out of it (!)

    There'd be no fun in that and I am under doctor's orders to take it easy this week.

    The curved lip to the fixed contact allows the pawls to slip over it.

    What is bizarre is that there seems to be no way of disassembling the motor without damaging the paxolin plate because the force required to pull off the tail bearing is greater than it can withstand. By contrast assembly will be no problem - the bearing will be fitted to the case, the switch will go over that, and then the armature may be fitted.

    Better get it right first time!

Children
No Data

Community Rules & Guidelines