Electrical Gurus: Motor run capacitor (induction)
#1
Electrical Gurus: Motor run capacitor (induction)
Got a 0.45hp bench grinder thats stopped working (was running, then just lost torque, slowed to a halt and now just hums).
Its a induction motor rated at 2.4amps, 0.45hp, single phase, 2950rpm, cos 0.96
I reckon the run capactor has gone (it only has one capacitor; no switch start or start cap etc). So I figured to try out a new one.
BUT
On the can it says "8MF" Now what the hell is MF? (capital M )
Microfarads(uF)?
Millifards( mF)?
Megafarads (probably not as it'd be the size of a house )?
I'm sure there is a way to work out the run cap rating based on horsepower to confirm the correct size, but I'm too rusty to work it out.
Any help would be appreciated.
Its a induction motor rated at 2.4amps, 0.45hp, single phase, 2950rpm, cos 0.96
I reckon the run capactor has gone (it only has one capacitor; no switch start or start cap etc). So I figured to try out a new one.
BUT
On the can it says "8MF" Now what the hell is MF? (capital M )
Microfarads(uF)?
Millifards( mF)?
Megafarads (probably not as it'd be the size of a house )?
I'm sure there is a way to work out the run cap rating based on horsepower to confirm the correct size, but I'm too rusty to work it out.
Any help would be appreciated.
#2
TBH,
factor in :-
Costs of
Searching for part
Finding & procuring part
dismantling item
fitting part
rebuilding
Testing
And then price up new grinder,
It may well be cheaper to buy a new grinder, given there low price these days...
It could also be one of the windings has gone open circuit, and no end of cap replacement would fix that puppy
Sounds like its stuck in the transition point from one winding to the next, hence the humming
Mart
factor in :-
Costs of
Searching for part
Finding & procuring part
dismantling item
fitting part
rebuilding
Testing
And then price up new grinder,
It may well be cheaper to buy a new grinder, given there low price these days...
It could also be one of the windings has gone open circuit, and no end of cap replacement would fix that puppy
Sounds like its stuck in the transition point from one winding to the next, hence the humming
Mart
Last edited by mart360; 07 June 2012 at 12:49 PM.
#3
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http://uk.farnell.com/multicomp/8mf-...tud/dp/1692738
Looks like 8MF is a designator, not a rating. As you say, 8 megafarads would be a hefty item!
Looks like 8MF is a designator, not a rating. As you say, 8 megafarads would be a hefty item!
#6
TBH,
factor in :-
Costs of
Searching for part
Finding & procuring part
dismantling item
fitting part
rebuilding
Testing
And then price up new grinder,
It may well be cheaper to buy a new grinder, given there low price these days...
It could also be one of the windings has gone open circuit, and no end of cap replacement would fix that puppy
Sounds like its stuck in the transition point from one winding to the next, hence the humming
Mart
factor in :-
Costs of
Searching for part
Finding & procuring part
dismantling item
fitting part
rebuilding
Testing
And then price up new grinder,
It may well be cheaper to buy a new grinder, given there low price these days...
It could also be one of the windings has gone open circuit, and no end of cap replacement would fix that puppy
Sounds like its stuck in the transition point from one winding to the next, hence the humming
Mart
That's my issue as my learning from A-levels was milli farads was mF spelt with a lower case m not upper case as I see on the casing of the cap. IYSWIM.
Aren't tumble dryer motors typically brushed motors, not pure induction (brushless)?
Sorry to be pedantic, but if I'm ordering a cap to try, I just want to make sure it's the right one ( milli or micro)
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#8
"...Aren't tumble dryer motors typically brushed motors, not pure induction (brushless)?..."
No - they use start/run cap. when i go to a machine that is just 'buzzing', i just give the drum a push - if the machine then starts running, I know that the problem is the cap
No - they use start/run cap. when i go to a machine that is just 'buzzing', i just give the drum a push - if the machine then starts running, I know that the problem is the cap
#12
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