Compressor blowing it's fuse, possible run cap issue?

[Bornfree]

Is it a twin capacitor motor with start and run caps?

 

[Nomad]

@carbon - not sure if the question was for me but for info the pump on mine was connected direct into / onto the motor shaft, not belt drive so no way to isolate the pump from the motor.

 

[carbon]

The question was aimed at @indy4x, but the problem with capacitors is that they don't always fail to 0uf. For example a 60uf capacitor can cause problems for a motor when the capacitance value drops, if it drops to 40uf the motor still may start but the current that the motor draws will increase, more current means more heat and the windings may suffer as a result. For me I tend to replace capacitors when the measured value is outside of the tolerance that is stated on the capacitor.
When I encounter a single phase motor that has started blowing fuses or tripping an overload the things I check are the supply voltage and the capacitor. I've recently seen someone trying to run a 230v motor from a supply with only 195v, and another where the overload was repeatedly reset, rather than find out what was causing the faults both motors are now big paper weights.

 

[indy4x]

Haven't done anymore with it today but just to answer the questions

Yes it is a twin cap motor so has start and run capacitors

The 40uf capacitor is goosed so fitted a new 60uf capacitor I had on the shelf and it still blows the fuse

Yes belt was attached, no air in the tank and the pump turns freely by hand

When it doesn't blow fuses it will pump up to pressure with no issues although the motor does sound a bit 'off' but can't put it into words

 

[carbon]

If it has two capacitors check if it has a centrifugal switch. These can stick and keep the start capacitor in circuit and can give the same symptoms as you have, ‘blows the fuse just as the motor gets up to speed’

 

[indy4x]

@carbon it has a centrifugal switch, I can hear it click when the motor shuts off and spins down

 

[indy4x]

Quick update, no progress on making the motor work and I need the compressor running.

Quick call to my local Machine Mart and they had a 3kW/4HP single phase motor on the shelf but no 2.2kW/3HP jobbies.

Not a problem as it's the same foot and spindle size on the 4HP motor so it's now mine, fitted and have a working compressor



Will put the faulty motor to one side for now and get it sorted when I have some more time

Many thanks to everyone for your help and advice much appreciated

 

[brightspark]

well at least it wont be running on the borderline having an extra hp

 

[indy4x]

@brightspark absolutely but also if the pump ever let's go I can fit the larger pump and get a few more cfm