Thermal motor switch

[Vixerfixer123]

Evening all.since raising the pressure on my sealey 3hp compressor,the motor thermal switch trips at about 90psi.any ideas anyone?.also why do I have one capacitor rated at 60uf and the other is rated at 65uf?I was led to believe one of em should be rated around three times more than the other.

 

[tigdlo]

Does the motor plate have the capacitor specs?

 

[carbon]

Usually the start capacitor will be the higher value one, but depends on the motor manufacturer how they are specified. The start one should only be in circuit briefly so shouldn't make a difference to the motor full load current.
Depends on how much you increased the pressure by, increasing the shut off pressure will increase the full load current which will influence how hot the motor and thermal trip gets. Excessive heat will shorten the life of the motor windings.
What was pressure before?
What does sealey list for the operating pressure?

 

[Vixerfixer123]

Does the motor plate have the capacitor specs?

No specs on the plate

 

[Vixerfixer123]

Usually the start capacitor will be the higher value one, but depends on the motor manufacturer how they are specified. The start one should only be in circuit briefly so shouldn't make a difference to the motor full load current.
Depends on how much you increased the pressure by, increasing the shut off pressure will increase the full load current which will influence how hot the motor and thermal trip gets. Excessive heat will shorten the life of the motor windings.
What was pressure before?
What does sealey list for the operating pressure?

Cuts off now at 125psi,and before that it cut out at 115psi I think it was.

 

[Turbo]

The higher the pressure the harder and longer the motor has to work to achieve that pressure.
By raising the pressure you are working the motor harder and exceeding its duty cycle.
Drop the pressure back down before you damage the motor or capacitors if you haven't already!
There is no need to have a compressor set that high, most tools have a max pressure of 90 psi!

 

[Erie Fred]

You could hang a computer fan on the end of the motor, wired to run all the time.

 

[knighty]

if it was running to 115 psi find before and now trips at 90psi I don't think the pressure setting has anything to do with it tripping

unless... you're running it for a lot longer/harder now...

does it trip at 90psi ish if you start it from cold? or is it just when you've been using it a lot?


I think it'll probably be a separate issue and nothing to do with your new pressure setting

 

[Turbo]

Those thermal switches get more sensitive if they trip too often.