Wolf Dakota 100 anomaly…?

[The Z'eer]

Back in July I purchased another Dakota 100. Upon the purchase the electrician came out and installed two separate dedicated circuits, one for each compressor with 20 amp breakers. Both circuits have three pin plug sockets.

A month on and the new compressor develops a fault. Upon start up the motor cuts our after a couple of seconds and fails to restart. The 20 amp breaker does not trip but the 13 amp fuse in the plug has blown. I contact UKHS and it’s decided a new motor is required. New motor arrives, fitted, all works.

Two days back the fault reappears. UKHS are contacted, this time it’s decided the capacitors are at fault. New capacitors arrive today, I fit them. The compressor fires up fine but on repeated attempts it NOW trips the breaker on start up only. The 13 amp fuse in the plug remains intact. No other appliance in use on the compressors circuit.

This is baffling, and ideas?? Thanks

 

[500e]

Is the compressor at full pressure ? if so drain down & try again if it still does it ask them to replace whole unit, have you swapped over plugs, checked the working one in the other supply ?
Did it not have caps fitted to the new motor ?

 

[Ubique]

What is the tripping curve of the MCB?

 

[The Z'eer]

Is the compressor at full pressure ? if so drain down & try again if it still does it ask them to replace whole unit, have you swapped over plugs, checked the working one in the other supply ?
Did it not have caps fitted to the new motor ?

The faulty compressor wasn't at full pressure, its tank was empty. I have tried the faulty unit in the other dedicated circuit and so far there doesn't appear to be a problem, so maybe it lies with the breaker, then again the fault is intermittent.

What I do find odd is that when the electrician finished the job he showed me that you could power both compressors off one of the dedicated circuits without blowing any fuses or tripping a breaker.

I haven't swapped over the plugs, would this make a difference? What are caps that are fitted to the motor?

 

[The Z'eer]

What is the tripping curve of the MCB?

I couldn't tell you since I've no idea what a tripping curve is.

 

[500e]

You have swapped plugs /changed connections does the faulty one work on other socket.
The capacitors usually come as part of motor if they sent you a new motor they would normally be on it, why send you others? it sounds as if the mcb
has the wrong curve, keep running the presumed faulty one on the circuit it is working on for a day or so, does the good one run OK on the circuit that trips
When I said change plug I meant swap compressors from one circuit to the other, presuming they were plugged in not wired direct.

 

[The Z'eer]

You have swapped plugs /changed connections does the faulty one work on other socket.
The capacitors usually come as part of motor if they sent you a new motor they would normally be on it, why send you others? it sounds as if the mcb
has the wrong curve, keep running the presumed faulty one on the circuit it is working on for a day or so, does the good one run OK on the circuit that trips

The older Dakota purchased back in 2017 has never had any issues, I've used it via an extension cable, on circuits with appliances in usage and never has it blown a fuse or tripped a breaker, same applies for using it on both of the newer dedicated circuits, never an issue in either.

The motor that was sent out in August for the new Dakota did not come with capacitors. The capacitors sent out yesterday (slightly different to originals) arrived without a new motor, I wired them in.

I will say that the breakers look slightly different from one another in the board...

The breaker that trips when the newer compressor is started (black trip switch)...

...the other breaker that seems not to trip when newer compressor is started...

 

[dobbslc]

When it tripped "on repeated start ups" the beaker will have tripped as it has a 'thermal trip' that will get hotter, if you keep starting sometime like a motor it finally trips, if you repeatedly stop / started it the breaker was doing it's job.
A tripping curve is to do with how much surge a breaker will take before it trips, yours is a B type you can get C & D types also.
Why did you repeatedly start stop it?
A 13A fuse will take a much larger surge before it blows so is better at holding out than a beaker sometimes.
Does it now run ok if used normally? If so it was probably the capacitor.

 

[Blobber]

They are both B curve 20 amp breakers except the one with the black switch is the old style, they can get tired if they are used near the limit for periods so it may be worth changing it for the newer version

 

[The Z'eer]

When it tripped "on repeated start ups" the beaker will have tripped as it has a 'thermal trip' that will get hotter, if you keep starting sometime like a motor it finally trips, if you repeatedly stop / started it the breaker was doing it's job.
A tripping curve is to do with how much surge a breaker will take before it trips, yours is a B type you can get C & D types also.
Why did you repeatedly start stop it?
A 13A fuse will take a much larger surge before it blows so is better at holding out than a beaker sometimes.
Does it now run ok if used normally? If so it was probably the capacitor.

I only repeated the procedure of starting the compressor to see how frequently the breaker trips. Contrary to the comment I made previously about one of the circuits being more suseptible than the other, both circuits seem to be equally affected. I have noticed if I leave the compressor for a period of time (makes no difference how full the air tank is) the breaker will trip.

I'm guessing a more resilient breaker will be needed then? Also, just how easy are these breakers to change?

 

[dobbslc]

I'd say if it's still tripping is a **** compressor, I would send it back.

Mmm I don't think you've said what size this compressor is!
If it's a 3hp / 2.2kw motor then it's pretty hefty for a B20 mcb.

 

[The Z'eer]

I'd say if it's still tripping is a **** compressor, I would send it back.

Mmm I don't think you've said what size this compressor is!
If it's a 3hp / 2.2kw motor then it's pretty hefty for a B20 mcb.

Yeah, it is 3 horsepower compressor 2.2kW motor

 

[Ubique]

Should be a 'C' curve MCB really, its probably been stressed with all the fault current tripping, and as you say, its an older breaker. Replace it with a C20.

 

[skotl]

Should be a 'C' curve MCB really, its probably been stressed with all the fault current tripping, and as you say, its an older breaker. Replace it with a C20.

Seconded - mine lives on a C20 all day long in the garage. When I use it round the other side of the house on a standard household main protected by a B20 it will trip that breaker every 2-3 startups.

 

[rikrobson]

mines on a 32A C curve with the welders and plasma cutter. I've never had a problem. i suspect the problem is the B curve. one is slightly less tolerant that the other. the other issue could be voltage drop. Is ths cabling between the two MCBs and the Compressors the same size and length? A longer cable will have more voltage drop and a higher current. you will need to measure the voltage at the compressors under load to check.

 

[carbon]

Also cold weather will make a difference at initial starts. Cold single phase motors draw more current than warm single phase motors when starting in my experience

 

[The Z'eer]

Thanks for all the replies, much appreciated

looks like a more robust breaker is needed. I did contemplate replacing it myself but I wonder if it could make the home insurance void should an incident occur.