Compressor motor start capacitor is blowing

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by Kipp
(Catskill , NY)

It’s a 5hp GE 1phase/220v compresses motor mounted on an 80gal vertical tank with single stage v-twin pump.

Pump is recently new as is control switch/head bleed valve.

After 3yrs no problems , one of the capacitors blew, motor would not start.

Air compressor motor capacitor
Air compressor motor capacitor

Replaced with same and blew immediately. had motor serviced at electric motor shop. replaced capacitor and switch plate assbly. Ran great bfor two days, the n armature fried completely( says same shop) sold me replacement motor, Marathon 21.0amp 220v .

Installed after checking bleed valve operation and pump operation. Ran fine for one week with part time use. motor will not start again , will hum but will not start under load, as did when cap went.

take belt off motor starts but draws 42 amps at start. pump turns over easily too.

with belt on, no start just hum and blow 20amp breaker.

Landlord has done some major construction and elecrical work on this building and next door facility too. but to my knowledge nothing to my electrical box, everything in same place.

hard to believe its another motor oriented issue with brand new motor from very reputable shop, could some elecrical mis hap or such issue be the contributing cause to this repeated motor failure?

how do I check? what do I look for? Landlords electrician checked box said its fine but hinted may be some problem with the way landlord had service split recently, electrician mum about what was done.


Possible electrical issue
by: doug

They may have spit your 220 from different phases. Some devices care, others don’t, so other stuff working doesn’t mean it is right.

Happened at One Wilshire in Los Angeles once while I was there.
Thanks for the advice on this one, Doug. Appreciate it.

If how to size a motor pulley, we have a guide with a worked example on our site! Visit our Air Compressor Capacitor Guide for more information on capacitors.

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COMPRESSOR MOTOR START CAPACITOR IS BLOWING I have a Kobalt 80 gallon air compressor and it and it keeps blowing the capacitor today will be the third time I’ve changed the capacitor and it still blow up but only on one side it blows up the other capacitor works I need some help