Compressor fault

[D-300tdi]

Hi all,

Hoping someone might be able to help, got a issue with my air compressor on start up if the tank is left with air in it will set off the thermal switch if tanks drained and started up it runs with no issues?

I had the motor checked and the shop said it wasn’t the motor and most likely the cut of switch fitted a new one and it’s still doing it?

Cheers

 

[voipio]

Faulty unloading valve, or a leaky non return valve.

 

[dave h 2]

No Pssst when you switch it off, but small psst on empty startup - non return valve . The tank will slowly leakdown through the cylinder.
Some unloaders on the cylinder head have a little button you can press with a screwdriver to test them.

 

[D-300tdi]

Faulty unloading valve, or a leaky non return valve.

No Pssst when you switch it off, but small psst on empty startup - non return valve . The tank will slowly leakdown through the cylinder.
Some unloaders on the cylinder head have a little button you can press with a screwdriver to test them.

Thanks guys will check those, it works fine as long as when it turned on it has a empty tank then it will works all day and when pressure drops the pump kicks in to build up pressure again just won’t fire up if it’s been left overnight with a air in it!

 

[brightspark]

Thanks guys will check those, it works fine as long as when it turned on it has a empty tank then it will works all day and when pressure drops the pump kicks in to build up pressure again just won’t fire up if it’s been left overnight with a air in it!

empty it off after use then . its probably that the oil is cold and taking a bit more power to start

 

[not done it yet]

Does the compressor reach full speed when this problem occurs? Guessing, here, it is a single phase machine?

If the compressor slows and speeds up, but does never reaches full speed it would indicate a motor overload.

Usually the speed would drop until the start windings are re-energised, giving it a kick. Likely, if warm enough, the motor would eventually reach normal speed before the trip becomes overheated.

 

[D-300tdi]

With air in the tank when left over night it doesn’t it struggles turns slowly then trips then thermal cut off pretty much straight away

 

[D-300tdi]

Sorry yes 240v machine

 

[not done it yet]

It’s over-loaded. Remember, a motor is an inductive load - designed for running at 50Hz. Maximum current is at start-up (up to about six times normal full load current) when it is presents a virtually resistive load to the power supply. Not surprising it trips if only running very slowly.

Does it have start and run capacitors? Does it get past the start-winding switch-off? You would hear the switch re-engaging as the speed reduces at switch-off or trip.

Compressors should not be expected to start under full load - they have some form of venting the high pressure side at the point of starting. Back to post #2, I expect, if the capacitor(s) is(are) OK.

 

[D-300tdi]

Thanks I thought it might more helpful if I filmed it but typically it didn’t do it today! I’ve left the tank pressured overnight and will try again tomorrow!