Motor capacitor tripping advice

[Sheptonphil]

Hi All

I have a hot tub that trips the breaker when pump 2 is started. Pumps 1 and 3 run fine. I have removed the terminal cover and the capacitor is shot, as in half of it melted away. it is a 1.27.6caz.mkp 30uf two wire going to motor terminals.

I have removed the capacitor from the motor. Whilst I do not expect the motor to either start or run, would running a motor without its capacitor connected cause breaker to trip if the motor was good. Pumps 1 and 3 are identical to each other, but different to pump 2, so I can't borrow the capacitor as a swap to check.

I think I am going to have to buy a capacitor to try it, but my reckoning was that if it was the motor was OK it would not now trip the breaker with the burnt capacitor removed. Is this logic sound, in which case I need a £300 motor replacement.

Thanks for advice

Phil

 

[Myfordman]

Yes running without a capacitor could easily draw more current and trip an MCB (but not an RCD!)

 

[Monkey Mark]

Yes, as above. Without the capacitor the motor will effectively stall on start up and current draw will shoot up. As will heat in the coils potentially damaging it.
If there are only two wires to it then it's likely to be a start cap only and not a run cap. (another clue to this is if its a dry cap as run ones are often oil filled).

It is much more likely to be the capacitor than the motor at fault. Any 220v capacitor of similar value, they don't have to be exact, will do.
They are only a few quid to buy.

Whatever you do don't keep trying to run it without a start cap as it will kill the motor.

One way to test is put power to it then give the shaft a spin by hand to get it going. If it continues to run after the help, it's just the capacitor.

 

[Sheptonphil]

Thanks for the helpful advice.

It is the MCB that trips, not the rcd.

I attach a couple of pics of the blown one, not an ideal sight, but better than a blown motor.

Will try to source a replacement, this one looks as though it will fit the bill, http://www.conrad-electronic.co.uk/ce/e ... s?ref=list Same specs as far as I can tell.

Phil

 

[Myfordman]

It will be cheaper on ebay. search Motor run capacitor 30mfd and look of one with wire leads rather than tags

 

[Sheptonphil]

It will be cheaper on ebay. search Motor run capacitor 30mfd and look of one with wire leads rather than tags

Thanks again for the help

http://www.ebay.co.uk/itm/Pre-Wired-Cab ... YSxlcVNMlw
£6.25 inc delivery

or http://www.ebay.co.uk/itm/Universal-30U ... SwjVVVlTzR £3.99 inc delivery

would either be OK

Phil

 

[sunnybob]

How old is the tub? Capacitors should last for several years.
If the 30 micro farad blew. it wouldnt hurt to replace it with the 31.5 listed on your first link.
as monkey mark says, if you can safely spin the end of the motor by hand, it will keep running if the motor is ok. if that trips, then electrical fault finding is needed.

 

[Monkey Mark]

It will be cheaper on ebay. search Motor run capacitor 30mfd and look of one with wire leads rather than tags

Thanks again for the help

http://www.ebay.co.uk/itm/Pre-Wired-Cab ... YSxlcVNMlw
£6.25 inc delivery

or http://www.ebay.co.uk/itm/Universal-30U ... SwjVVVlTzR £3.99 inc delivery

would either be OK

Phil

Either of those will do the job nicely. I come across plenty of failures in high bay lights usually caused by heat.

Just check water ingress hasn't been the cause.

 

[Sheptonphil]

How old is the tub? Capacitors should last for several years.
If the 30 micro farad blew. it wouldnt hurt to replace it with the 31.5 listed on your first link.
as monkey mark says, if you can safely spin the end of the motor by hand, it will keep running if the motor is ok. if that trips, then electrical fault finding is needed.

Motors have been in use for 10 years on the hot tub, so not constant but regular use.

I can't spin the spindle end as it is in an enclosed water pump, but I can spin the cooling fan fins freely through the grill, so I at least know the rotor spins freely but can't safely rotate it to start running. As it is now out of circuit, the tub can be used almost as usual. Will buy one of the eBay ones and pop it on in the week and hopefully get it all running. If this didn't cure it I will replace the motor as I have swapped motors 2 and 3 on the control board and the board works and controls motor 3 on number 2's switch. So definitely capacitor and might be motor as well.

Cheers all

Phil

 

[Sheptonphil]

Either of those will do the job nicely. I come across plenty of failures in high bay lights usually caused by heat.

Just check water ingress hasn't been the cause.

The motor is sited under the tub and it can certainly get damp there, although there is a good rubber seal on the cable box cover.

Cheers

Phil