Baldor Motor Problems

[loewem]

I have a 3 HP 3 Phase motor that I am having problems with. The motor drives a cat 310 pump that i have been using too wash down bays. The motor can be switched on in the pump room via a toggle switch. When the toggle switch is in the off position the motor can be turned on via the meter box in the wash bay. The bay hasn't been used for the past three years, but will be used again in the near future. Long story, but I thoght i should mention the toggle switch in case it might be part of the problem.

About a month ago I flipped the switch and heard a pop. The motor contactor would not engage to turn the motor on. I thought that the contactor was bad so I took out. The plastic around one of the poles that connects the overload relay to the contactor (L1) had melted a little. I tried a new contactor and that didn't work. I found out that the 24 volt transformer was bad. Put in a new transformer and the motor would start and run, but it would get hot and trip the relay overload. Took the motor to a motor shop and it tested fine. Put the motor back in place and ran it without the pump and it ran fine for a while without getting hot and/or tripping the relay overload. Had a technician come and do everything that I did as well as test the current/amps the motor was drawing for each leg/phase. He said it was okay. He suggested a new motor. Before i tried a new motor i tried a different pump. Sme thing. Put on a new regulator, same thing. Put a new seal kit in the original pump and put a new pully and belt on, same thing. Bought a new motor and a new pully, same thing.

I've checked every connection from the motor to the wall and all look okay. Only other things I can think to try are a knew plug and a new circuit breaker.

Thoughts, ideas, suggestions?

Thanks

Mike

 

[mjwalsh]

Mike,

Since it sounds like the toggle switch could be suspect, I would bypass the toggle switch & just turn it on & off via the its dedicated circuit breaker.

Let us know how you come out on this.

 

[wash4me]

I would say you have a load issue. Something is loading the motor or rather overloading the motor. Maybe while you are washing it's over loading but not while you were checking it. put an ammeter on while you're washing. If you want to get serious check volts and amps at the motor peckerhead while running and washing and not washing. Look at your pressure and your gpm and use the formula on cats website to calculate horspeower required. You may need a new overload. It could have been damaged from the heating of the original bad connection. Is the overload set at fla on the nameplate? 3 phase motors almost never intermittently have problems.

 

[loewem]

Thanks for the responses. I forgot to mention that I bought a new contactor and overload since the others were melted together. The old ones still work, but figure that whatever happened couldn't have been good for the components. I will try the ammeter and direct to the breaker.

I think that fla is set correctly, but I will check to make sure.

Thanks

Mike

 

[MEP001]

Mike,

Since it sounds like the toggle switch could be suspect, I would bypass the toggle switch & just turn it on & off via the its dedicated circuit breaker.

Let us know how you come out on this.

How did you come to this decision? The toggle switch only controls voltage to the contactor coil. How could that cause the motor's thermal overload to trip?

 

[MEP001]

Thanks for the responses. I forgot to mention that I bought a new contactor and overload since the others were melted together. The old ones still work, but figure that whatever happened couldn't have been good for the components. I will try the ammeter and direct to the breaker.

I think that fla is set correctly, but I will check to make sure.

Thanks

Mike

When it's working properly, the thermal overload trips because of heat caused by excessive amperage draw after the contactor. The only things you haven't replaced that can cause this is the wiring to the motor and the thermal overload itself. If you can't access an amp meter, the quickest, cheapest thing to try would be be new wire to the motor.

 

[Greg]

Hi loewem,
To assist with checking the load/HP requirement, keep in touch about the pulley diameters being used and pressure setting.
Were the pulley diameters changed when you put new ones on ?

Good luck today - Happy to help !
Greg Thoennes
Arimitsu Pumps

 

[soapy]

If it is a 3 phase motor check to see that you have all 3 legs of the power to the motor.

 

[Rudy]

If I'm not mistaken, dropping a phase usually causes the motor to run backwards???

 

[loewem]

Thanks for all of the thoughts and suggestions. I will be able to work on this on thursday and friday. Will let you know how it goes.

 

[mjwalsh]

Mike,

I have seen where the strength of the internal contact-make of a toggle switch caused problems. I am not saying it is the problem but it seems like one of the easier things to verify. It might be even easier to jumper the toggle switch wires with jumper wires while the breaker is off & then test.

mike walsh www.kingkoin.com

 

[Greg Pack]

If I'm not mistaken, dropping a phase usually causes the motor to run backwards???

It won't run with a dropped leg

 

[Greg Pack]

As mentioned already , I would take a second look at each wire amps and voltage while the motor is under load. They should all be running very close to the same amperage. A bad breaker, connection, or wire might show full voltage at rest, but could decrease under load as the connection is strained.

You didn't mention whether this was 208 or 230 volt 3ph system. Although it would still probably run, make sure your motor is wired correctly for the appropriate voltage and that all wire connections have been properly made.

Oh, and what flow and pressure are you trying to discharge?

just grasping at straws.

 

[MEP001]

FWIW, to reverse a 3-phase motor you swap two legs of the voltage. It won't run with one dropped, it will just hum until it trips something or burns up.

208 to 240 volts will wire the same, it will just use more amperage at 208.

 

[loewem]

Thanks for all the responses. I can't get after this until tomorrow, but at least now I've got someplace to start that makes sense.

To try and answer some of the questions that I haven't:

- I matched the specs on the new motor and old motor when I purchased the new motor. Double checked the tags, so it is all the same.
- Purchased the same size pulley (as the old and other set ups) for the pump and for the motor.
- I've run the pump at a couple of different PSI seetings. 1200 and 1500. I've used a couple of different tip sizes too. 1508 and 2505. Currently trying at 2505 at 1200 PSI.
- I don't know if my three phase is 208 or 230. That is beyond me at this point, but I will find out.

Can anyone suggest a good ammeter for me to buy? I've looked at a few and would rather spend some extra $$ and get a good one that will last.

I'm not very knowledgeable about electricity, but I'm learning with each opportunity. Thanks for the help and education.

Mike

 

[wash4me]

T5-600 fluke is easy to use

 

[WikiWash]

You may want to check your phase configuration at the motor's peckerhead, for example Wye phase or Delta phase. I am also a Fluke fan I use a Fluke 324 and a Fluke 1587.

 

[mjwalsh]

Mike,

http://www.harborfreight.com/digital-clamp-meter-96308.html

For $13 ... I am thinking based on reviews it would be better than nothing.

We have a Fluke 325 mainly because of the true RMS & the ability to also clamp on for tiny fractions of an amp & dc amps etc. was something that we needed for our specific projects ... albeit more investment & more worry if it gets broken or lost.

 

[wash4me]

If these lead numbers are all present in the motor peckerhead and not any other numbers this is how the leads should be connected.

6,7,1
4,8,2
5,9,3

 

[MEP001]

If these lead numbers are all present in the motor peckerhead and not any other numbers this is how the leads should be connected.

6,7,1
4,8,2
5,9,3

Not sure what that's supposed to mean, but 1 & 7 connect to one line, 2 & 8 to one, 3 & 9 to the third, 4-5-6 connect together and to nothing else.