What size capacitor do I need for extractor fan?

[Bobchip]

Hi all,
I was called out to a business as their kitchen extractor fan isn't working. It has 230v but only rotates after you physically give it a flick rotation. I believe that I need a new capacitor? It has a variable speed controller. The capacitor looks very old and the tech info has completely worn off. Neither controller or the fan has any make, model labels so I have nothing to work with. Can anyone help me determine the size of the capacitor required and point me in the right direction to where I could pick on up.? Not sure if it helps but I've added a photo of the capacitor
Thanks in advance.
Rob

 

[Pete999]

Take the motor to a motor repair outfit, and charge the customer, simples

 

[Besoeker]

Throw it away and get a new replacement.

 

[Marvo]

Did you actually test the capacitor? Is it showing signs of heat damage or bulging/distortion? More often than not it's one of the motor windings that's at fault, not the cap so start by testing the windings before buying capacitors.

 

[Lucien Nunes]

A few decades ago I would have agreed with you Marvo, but failure of motor-run caps seems to be ever more prevalent in my neck of the woods. Especially the self-healing types gradually losing value until they are effectively open-circuit, although they don't smoke the motor as viciously as a traditional solid short-circuit on a PIO cap.

Re the OP's fan, if you don't have any motor data, you can't spec the cap. If you know voltage, frequency, power and speed you can take a reasonable guess, as most manufacturers arrive at the same optimum values for a particular rating of motor although they are not all exactly equal. Incorrect value can result in poor torque, overheating and eventual winding failure. I probably wouldn't bother in this case though, unless it's really tricky to replace the fan outright.