A capacitor on my well pump control box blew up. What's wrong?

Question

2 hp sta-rite. Pump short cycles, pumps water, shuts down after three seconds. Have new pressure switch. 30 to 50 psi system. 50 foot submersable pump.

Answer 1

Are you implying that in normal operation the pump shuts down after 3 seconds? How long between starts? if the cap is a starting cap and the interval between starts is too short then the cap will not have time to dissipate any heat leading to premature failure. In any case contact starite

Answer 2

this is correct about the capacitor blowing up sometimes they dry out and blow up .

but if as it happens again it could mean that you are overloading your motor

check your amps on your motor feed and compare it to your nameplate rating of amps in full load (FLA)

it should never be higher than that over an extended period of time.

now if you are overloading your motor

you have to go bigger on your motor rating HP

or you can change your belt ratio any electro supply house will help you to figure out what size of belt you will need

(grainger)

will cost you maybe $30

a motor will cost you $300

Answer 3

Capacitors *do* wear out and blowing up is actually one of the failure mechanisms, so there may very well be nothing 'wrong'.  Replace the capacitor with an identical model and if the next one blows out within a few days, then your problem is the starting torque requirement.  The starting torque has changed somehow (higher psi pressure switch, now, higher head to pull from deeper water?).   Higher starting torque will cause more current to flow through the capacitor and will cause it to blow.

If the new capacitor blows after a few days, then you need to look into getting a bigger motor.

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