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Induction Motors

Posted: 29 Sep 2009
by Bx Bandit
Anyone know shit about these? Apart from no brushes and the like.....

As in the one in my dishwasher don't work. AFAIK there are no open/closed circuits (vague I know) where you wouldn't expect them
It has a thermal device that i think is working ok. This thing changes it's resistance as it heats up. It's purpose is to help get the motor spinning (by providing out of phase mag field to main coils) and then keep it going (thermal thing changes resistance to (I'm guessing) reduce the phase lead)). Also there is a capacitor connected to the motor windings.
Other facts:
The motor is getting a feed.
The thermal device seems to operate as expected
The windings and associated contacts have resistances of 11.6 ohms, 68.3 ohms and 80 ohms
I have no idea if the capacitor is working correctly. It's not short or open circuit. What actual function does this thing do? I have managed to dent the aluminium casing a bit - would this fuck it up?
Even with the voltage applied to the motor, a manual kick start does nowt!

Re: Induction Motors

Posted: 30 Sep 2009
by docchevron132
Erm, fuck knows mate!
Tried a bigger hammer?

Re: Induction Motors

Posted: 30 Sep 2009
by Way2go
[quote="Bx Bandit"]I have managed to dent the aluminium casing a bit - would this fuck it up?/quote]

If this caused an internal short - yes, but you probably haven't.

Check it with your meter it should read open circuit or alternatively give a kick and then get increasingly higher resistance over a short period. Reverse your meter connections and it will kick again and descend if all is well with it.
("kick" is really on an analogue meter, for a digital read starts LR going HR. :wink: )

For the rest, very difficult to analyse remotely.

Re: Induction Motors

Posted: 30 Sep 2009
by Philhod
Is that what they call a squirrel cage motor? Takes all it's power at start then runs on very little. They also produce no sparks so were used down't pit.

Re: Induction Motors

Posted: 30 Sep 2009
by Bx Bandit
/\ Don't think it is a squirrel cage mate, think they tend to have much more powerful applications. This is just a water pump to swirl the arms round.

w2g, the meter exhibits exactly what you say - rising resistance with -ve polarity upon switching the leads.

Hmph.......that means it ain't the capacitor then....or the windings....or the thermal thingy......bigger hammer it is - thanks Doc!

Fuck............... :x

Re: Induction Motors

Posted: 30 Sep 2009
by Philhod
I pay the gas board a few pounds a month extra on my 3* tarriff and they cover all my kitchen appliances, as well as my CH system, parts and labour.

Re: Induction Motors

Posted: 01 Oct 2009
by Way2go
Philhod wrote:I pay the gas board a few pounds a month extra on my 3* tarriff and they cover all my kitchen appliances, as well as my CH system, parts and labour.
The alligator parable needs to be quoted in response to that bit of retrospective advice! :roll: