Motor "run" capacitors. - UK Vintage Radio Repair and Restoration Discussion Forum

Andrew B · 21st Jan 2018, 11:34 am

I had the fortune to be called to take a look at an "industrial/catering" expresso coffee machine that had stopped working. To cut to the "meat", I found the water pump motor, (a fractional HP affair) was stalled. After checking the motor, I found the 6mF 450V "start" capacitor to be split open and it being a Saturday lunchtime, no chance of getting one. I did have a 4mF 450v in my junkbox, which I fitted. The machine sprung back to life and functions OK. In the expert opinion here, will it be OK to leave the 4mF in place or should I obtain and fit a 6mF capacitor?

Andrew

barrymagrec · 21st Jan 2018, 11:53 am

Fit the proper part when you can source one. The motor torque will be reduced with a smaller cap, I assume that the 450 volt rating is AC?, 450 volt DC is somewhat marginal for mains motors.

Andrew B · 21st Jan 2018, 11:30 pm

Thank you Barrymagrec, going to get one and fit it. It is rated at 450VAC, so will look around for one, at least it's got the machine running.
The Motor turns a high pressure, low volume pump to raise mains water pressure from 3 bar up to 12 bar and "injects" it into the pressure vessel to maintain a constant 4.2 bar of liquid water at 110C for the liquor extraction, hot steam is taken off from a tap on the boiler/ pressure vessel to heat / froth the milk.

21st Jan 2018, 11:34 am	#1
Andrew B Heptode Join Date: May 2015 Location: Bradford, West Yorkshire, UK. Posts: 512	Motor "run" capacitors. I had the fortune to be called to take a look at an "industrial/catering" expresso coffee machine that had stopped working. To cut to the "meat", I found the water pump motor, (a fractional HP affair) was stalled. After checking the motor, I found the 6mF 450V "start" capacitor to be split open and it being a Saturday lunchtime, no chance of getting one. I did have a 4mF 450v in my junkbox, which I fitted. The machine sprung back to life and functions OK. In the expert opinion here, will it be OK to leave the 4mF in place or should I obtain and fit a 6mF capacitor? Andrew __________________ worried about the electrons entering the circuit and the smoke leaving Andrew

21st Jan 2018, 11:53 am	#2
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,561	Re: Motor "run" capacitors. Fit the proper part when you can source one. The motor torque will be reduced with a smaller cap, I assume that the 450 volt rating is AC?, 450 volt DC is somewhat marginal for mains motors.

21st Jan 2018, 11:30 pm	#3
Andrew B Heptode Join Date: May 2015 Location: Bradford, West Yorkshire, UK. Posts: 512	Re: Motor "run" capacitors. Thank you Barrymagrec, going to get one and fit it. It is rated at 450VAC, so will look around for one, at least it's got the machine running. The Motor turns a high pressure, low volume pump to raise mains water pressure from 3 bar up to 12 bar and "injects" it into the pressure vessel to maintain a constant 4.2 bar of liquid water at 110C for the liquor extraction, hot steam is taken off from a tap on the boiler/ pressure vessel to heat / froth the milk. __________________ worried about the electrons entering the circuit and the smoke leaving Andrew