[MapesMotors]

I have an issue with a ten horse single phase Baldor. I know Baldors run hot, but this one gets really hot. I checked the stationary switch and governor and both are fine. It pulls 28 amps no load and is rated 40 amps. That is high for no load amps. The start caps were replaced and one blew in seconds. There is a contactor as well as the switch. It pulls in and releases but i cleaned the contacts anyway. Anyone had this problem? I need to check that there is a wavy washer because the only thing I can think of is that the rotor isnt lining up with the stator. That could cause high amps.. No wires are bad, the bearings are fine.

 

[HARRY304E]

I have an issue with a ten horse single phase Baldor. I know Baldors run hot, but this one gets really hot. I checked the stationary switch and governor and both are fine. It pulls 28 amps no load and is rated 40 amps. That is high for no load amps. The start caps were replaced and one blew in seconds. There is a contactor as well as the switch. It pulls in and releases but i cleaned the contacts anyway. Anyone had this problem? I need to check that there is a wavy washer because the only thing I can think of is that the rotor isnt lining up with the stator. That could cause high amps.. No wires are bad, the bearings are fine.

How old is the motor?

Welcome to the forum.:thumbsup:

 

[JRaef]

"Really hot" means nothing. If it is a relatively new motor with Class F insulation, it can get to 155 degrees C and still be OK, which is 311F, that is WAY too hot to touch!

Motor No Load Amps means nothing either, there is no standard for what it is supposed to be, just relative values. So if it USED to be lower on THAT specific motor and it has gone higher, then you should be concerned. But if you did not know what it was, measuring it now means nothing. 28A on a motor that is 40 A FLC is higher than you might expect, but those are low power factor amps, so they are not real anyway. If you put a load on it and the amps increase above 40, THEN you know you have a problem.

 

[mbednarik]

Sounds like you need the meg the windings, may be a ground fault in the start winding.

 

[wendon]

Too bad they can't just get a good start switch! Baldor started doing that with some of their larger motors when they had trouble with the start switches. The old switches worked fine, the new ones were a nightmare. I'm guessing there isn't as much silver on the new start contacts. Did it blow the start cap before or after you measured the amp draw? Did all the run caps check out okay?

 

[ampman]

i can't recall ever seeing a single phase 10 hp

 

[bobelectric]

5hp is the biggest I've seen at 240 volts.

 

[mbednarik]

15hp is usually the larges i run into, but i have worked on a 20.

 

[electro916]

Are all your jumpers in the right place on the capacitors? Run and start cap leads crossed? It seems to me that that cap was left in the circuit causing it to overheat.


I was always told 10hp was the largest standard single phase motor.

 

[Service Call]

The NEC tells us to size a 10hp 220-240 volt single phase motor for 50 amps. I don't think 28 is a problem.

 

[Service Call]

Possibly replaced start capacitor with wrong size?

 

[347sparky]

i can't recall ever seeing a single phase 10 hp

I worked on a 13 hp single phase 240v Baldor farm duty motor the other day. Thought maybe it was mismarked but it was in the Baldor catalog.

 

[wendon]

I worked on a 13 hp single phase 240v Baldor farm duty motor the other day. Thought maybe it was mismarked but it was in the Baldor catalog.

Grain dryer?

 

[347sparky]

Grain dryer?

Yes, for a small bin. Basically a fan blowing into a heater then in the bin.

 

[MapesMotors]

I did meg the motor and no grounds. The jumpers are all in order and I replaced the blown run caps with the same size new ones. The customer said that it doesnt trip any breakers and there is no sign of the windings getting too hot, like the tie string melting or the insulation melting. But why would it blow a brand new cap in minutes? I dont want to rip the guy off by selling him a new contact and have it do the same thing. But it seems to me that it has to be something like the start is staying in the circuit and that could only be that contact, because the governor and the switch check out fine. Oh yeah this motor is not that old, maybe 5 years or so. I dont know the exact age.

 

[MapesMotors]

One more thing. I did measure the amps when it first came in and they were 42 then I checked the run caps and found they were blown. I replaced them and the amps went down to 28, but then blew a start cap. I replaced the cap and filed down the contacts and the amps stayed at 28 and the guy put it back up and it worked but he said it was very hot in the hour that he ran it.

 

[Bootss]

One more thing. I did measure the amps when it first came in and they were 42 then I checked the run caps and found they were blown. I replaced them and the amps went down to 28, but then blew a start cap. I replaced the cap and filed down the contacts and the amps stayed at 28 and the guy put it back up and it worked but he said it was very hot in the hour that he ran it.

has the load this motor turns increased? maybe the customers machinery is getting tighter. call Baldor see what they have to say.

are you operating your own motor shop there?

 

[MapesMotors]

yes I have my own shop

 

[Bootss]

yes I have my own shop

ah very nice, I wound motors back in the day. take some pictures of your winding projects and post them for us, should be interesting education for the forum.

 

[Big John]

All I know to check would be the centrifugal switch: If it's sticking, you'd overhead your starting capacitor and it'd blow, but I'm sure you know that.

Other than an internally shorted start winding I'm not sure what would do it.