start capcitor

[ageer]

Hi this is my first time so please excuse me for any errors. My scenario is
I am working with a compressor for a ice maker which has FLA 27amps and
the start capacitor has gone out twice in less than 6 months the voltage
is 208/230 single phase. the compressor is only 6months old. I checked the
incoming voltage it reads 210 volts phase to phase and 122volts to ground.
the compressor has built in overload protection and is fed with a 40amp
inverse time breaker which is also tripping. I megged the wires back to the panel
they were fine. we have A on sight HVAC tech he checked refrigeration it checked out fine. the relay also has gone out twice and the contactors look
a little burnt which leads me to believe that there has been high current. we have put an amp meter on during start up which reads about 23amps. so what would cause the start capacitor to go out? Capcitors are sized correctly we double checked.

 

[kwired]

Hi this is my first time so please excuse me for any errors. My scenario is
I am working with a compressor for a ice maker which has FLA 27amps and
the start capacitor has gone out twice in less than 6 months the voltage
is 208/230 single phase. the compressor is only 6months old. I checked the
incoming voltage it reads 210 volts phase to phase and 122volts to ground.
the compressor has built in overload protection and is fed with a 40amp
inverse time breaker which is also tripping. I megged the wires back to the panel
they were fine. we have A on sight HVAC tech he checked refrigeration it checked out fine. the relay also has gone out twice and the contactors look
a little burnt which leads me to believe that there has been high current. we have put an amp meter on during start up which reads about 23amps. so what would cause the start capacitor to go out? Capcitors are sized correctly we double checked.

is the relay you are talking about the motor control contactor or a potential relay for switching the start capacitor out of circuit?

if the latter the start capacitor is probably being held in the circuit too long and your challenge is to find out why?

have you checked voltage with no load, running load and starting load conditions, voltage drop causing long hard starts?

 

[mcclary's electrical]

You need a buck boost xfmr.

 

[cschmid]

what brand is the ice maker? be nice to look at prints because kwire is correct.

 

[kwired]

Another possibility is the operating control is allowing too short of an 'off' cycle. and the compressor is trying to start with too much head pressure making starting difficult.

 

[qcroanoke]

Another possibility is the operating control is allowing too short of an 'off' cycle. and the compressor is trying to start with too much head pressure making starting difficult.

A definite possibility! Easily fixed with an adjustable time delay. There may be one in the circuit that has gone bad. Check that out.

 

[mcclary's electrical]

Another possibility is the operating control is allowing too short of an 'off' cycle. and the compressor is trying to start with too much head pressure making starting difficult.

So the compresor's got no unloading valve?,,,

 

[cschmid]

I would bet it does, but the unloading valve does not disengage the start capacitor. without the brand and model we will not know what causes the capacitor to be removed from the circuit.

 

[kwired]

So the compresor's got no unloading valve?,,,

OP mentioned compressor for ice machine - probably a hermatic refrigerant compressor. I have not seen one with unloading valve, the refrigerant will usually unload itself just takes a minute or two most of the time, if compressor were to try to start again during this time it will usually not have enough torque to overcome the head pressure. delay timer could be a possible solution but on an ice maker if there is an off cycle that is repeatedly this short there is some other problem causing the short cycle.

 

[kwired]

if there is an unloading valve perhaps it is not working

 

[hardworkingstiff]

I checked the
incoming voltage it reads 210 volts phase to phase and 122volts to ground.

Is this with the compressor running or with it off? Did you get to watch the voltage when the compressor started, if so, what happens?

the compressor has built in overload protection and is fed with a 40amp
inverse time breaker which is also tripping.

also in addition to the start capacitor problems or in addition to something else?

I megged the wires back to the panel
they were fine. we have A on sight HVAC tech he checked refrigeration it checked out fine. the relay also has gone out twice and the contactors look
a little burnt which leads me to believe that there has been high current. we have put an amp meter on during start up which reads about 23amps. so what would cause the start capacitor to go out? Capcitors are sized correctly we double checked.

Your starting voltage is on the low end of the motor rating. If you have the PoCo going into brown outs, or if there is a heavy load in the building at times that causes voltage drop, you could be trying to operate this equipment below the rated specs and that would in turn cause higher amperage which would aggravate the voltage problem.

You might need to have a recorder installed for a few days.