Tripping compressor

[dobbslc]

There will probably be two circuits for the motor windings, the run and start circuits, you should have continuity on both of those (fairly low ohms reading)
You should NOT have continuity from those windings to earth.
From your description of the breaker blowing instantly it could be a dead short to earth or live neutral.

 

[WorkshopChris]

I disconnect the wiring from the motor and capacitor side and i check the continuity between L and N of the wires going into the motor and there is continuity, correct me if i am wrong, but i always thought they should be continuity as it is one circuit. There is no continuity between either L or N and the earth.

Can you measure the resistance?

If your going to fit a new motor you only need to check continuity in the other direction ie:- from the wires that fed the motor back towards the plug (via the switch) to make sure your problem is not within the switch. You should not get a reading between L & N.

 

[luccass_j]

I will check the resistance once im back from work and i will also doudle check the continuity between L and N of tge wires leading to the swich .

Thank you for all the help so far.

 

[luccass_j]

So there are three wires coming out of the switch/socket side. Yellow and green earth one which is connected to the motor case. Next Ive got blue (neutral) one and brown (load) one. N wire joins a yellow wire using female/male connectors and the yellow wire disappears into the motor case. The L wire is connected to a 15amp reset switch. on the other side of the switch there is a black wire connecting it to the capacitor responsible for running the motor. I believe this wire energises this capacitor. There are two more wires coming from this capacitor and passing through the case. one of them is black and the other is brown.
There is continuity between those two wires and they show 0.52 Ohm resistance.

Next I have two wires coming from the case and connecting the motor starting capacitor. One of them is N(blue) and the other is L(brown). There is also connectivity between them the resistance shows 0.51 Ohm.

There is no continuity between any of those wires and earth wire and there is no continuity between any of the wires at the switch/plug side of the wires.

one of the capacitors is mark starting capacitor that's why I know which one is which.

 

[WorkshopChris]

Does the motor have any data plate info on it, might be able to find a datasheet online if it has to confirm exactly how the windings are configured.

 

[luccass_j]

It doesnt have any data plate on it but on the box with capacitors there is a sticker satating that it is 3hp motor, class F, RPM, S1, the sizes of the capacitors and the date of the production.

 

[luccass_j]

I think most if those motors are made by the same conpany no mater what make your comressor is.

 

[luccass_j]

So whats my best bet? I need my compressor to finish the work im doing inn the garage.

 

[dobbslc]

https://www.machinemart.co.uk/p/motor/
Try this link but check the motor speed and shaft size. They've gone up in price since I bough one!

 

[luccass_j]

Thanks i bought some staff from them before so im hoping for vat free halloween weekend. Why do i need shaft size? Im gonna change the pulley anyway as the one i removed got bended when i was removing it. Before applying heat.

 

[luccass_j]

By the way what if i replace the motor with 4hp one?

 

[WorkshopChris]

By the way what if i replace the motor with 4hp one?

You might have to make a adapter plate if the foot mountain holes are a wider pitch. As long as the speed is the same, can't remember if you are running of s 13a or 16a plug. 4 hp is pushing it for a 13a fuse.

 

[dobbslc]

By the way what if i replace the motor with 4hp one?

Not worth the bother and will possibly start blowing fuses and breakers.

 

[luccass_j]

13a plug

 

[WorkshopChris]

13a plug

Not much chance of a 4hp running off 13a plug without problems, 3hp is right on the limit.

 

[luccass_j]

Thanks i thought it was 2hp actually do you think its time to buy new motor?

 

[luccass_j]

Update first of all thanks for all the help and suggestions.

I did change the motor and it did the same thing do i returned it. I check the voltage at the breaker and it is healthy 248v i also dragged my compressor home to plug it in a different socket and it tripped different breaker. I think it is time to call proffessional so does anybody knows anybody in south east london area i could call?

 

[daleyd]

Update first of all thanks for all the help and suggestions.

I did change the motor and it did the same thing do i returned it. I check the voltage at the breaker and it is healthy 248v i also dragged my compressor home to plug it in a different socket and it tripped different breaker. I think it is time to call proffessional so does anybody knows anybody in south east london area i could call?

Is this with the motor running with no belts on? If it won’t run with no belts off 2 different power supplies then I find that very strange, barring a fault on the cable. (Presumably you also tried a new cable to the motor, wired directly to a plug by passing all other components internal to the compressor)

Start simple and get the motor spinning directly from a plug first....

 

[Memmeddu]

Sometimes motor internal wirings that go from the box to the windings, blows up they can also catch fire whitout damage the windings.
Last month i had to work on a Keys douplicator where the motor internal wirings was crappy and they were touching the housing, so differential switch cut off the power.
first i insulate the ground, than i started on the motor.
The wirings got hot very quickly and got red heat.
When i saw this i cut off the power.
So i replaced the wirings, melted the copper to have a good conduction, insulated all.
And start the motor
It started working as new

 

[John Hale]

If you google Kingsdown Compressed Air, they service our compressors at work and we're in Charlton