2hp 1ph motor problem

[willyz]

I received 3 different motors from Surplus Center they all are 2hp 1ph 1725 rpm 2 capacitor 20/10amp motors. When I hook them up 115v, they run at a lower rpm then kick out the breaker. They are drawing 50-60 amp. I wired them according to the diagram for low voltage. I'm thinking they don't switch to the run capacitor. Anyone have any thoughts or insight? I'd appreciate any input.

 

[John T]

My initial "thoughgt" (not being there no ohm or volt or current measurements or inspection mind you) is (among other possibilities) possibly the motor isnt wired correctly for 120 volt operation.

It can take some time and knowledge to figure it all out uisng an ohm meter, but in a nutshell the motors run windings are connectied in SERIES for 240 volt operation but PARALELL for 120 volt operation.

You might look up standard wiring color code configurations (if such exist???) to trace out which wires are for start windings and which are run windings and capacitor wiring and ohm it all out.

Other possibilities of motor problems can be bad capacitors but I think Id double check the wiring for 120 volts first and if its allllllllllllll correct then check the capacitors maybe

Other possibilities of motor problems can be the centrifugal switch mechanism not functioning properly

Hard to tell not there armed with test equipment yet my initial "thoughts" shes not wired right or theres a capacitor or switch problem

John T

 

[buickanddeere]

Sounds like start windings has been connected to operate 100% of the time. Instead of switching out with the centrifugal switch.
Why operate a 2HP motor on 120V ? That is looking for trouble.

 

[Stuart]

Why is that asking for trouble?

 

[M-MAN]

That's too big a motor to run on 120v. It would require a 20 amp breaker, wire, and outlet if you're using one just for the running amps. Factor in starting amps or heavy load & you're way over the top so it's most likely gonna trip the breaker even if you can figure out how to wire it properly.

 

[John T]

Id also suggest running it at 240 volt. Just to add a couple things to your post. In the event the continuous load were say 20 amps actually a 30 amp breaker would be used as 80% of 30 amps is 24 amps which the 20 falls within and besides as you noted a 20 amp thermal magnetic breaker could trip out (thermals) if subjected to a long term full 20 amp load. As far as the ability to get the motor started and up n running as the starting current could be 5 times the running current, the code does allow an over sized breaker in case a 30 amp would trip out when she starts. The motor thermal overload protection is there to protect the motor while the breaker is there to protect the feeders in case of a short.

Take care

John T

 

[RayP(MI)]

My 2hp air compressor came wired for 110v.. All kinds of problems with starting, fuses, lights diming, switch contacts burning. Rewired it with a new pressure switch, as a 220v. Problems solved.

 

[willyz]

I'll wire it to 230v tomorrow and see if it solves the problem. Thanks guys.