Reverse osmosis machine motor overheating

[waterguy]

Hello,
I have been struggeling with an electrical problem for over a year that is driving me crazy. I have a water purification machine it runs a 208/240 pump motor to move the city water through the system. A year ago a local blackout happened and when power came back my control panel ignited and burned. I have replaced it bypassed had several people look at it had the local electric company test my voltage coming in to my building bypassed the control panel everthing under the sun but the the motor for the pump continues to run hot, I can only run it for 10 min at a time and then have to shut if off to cool for a half hour it has burned up three pumps two of them new, the pumps say 208-240 but i am getting 210 when measured with volt meter at the pump. The local power is Y three phase. The pumps are labeled 208-240 but they keep burning up. The amp range is max 9.0 but when measured at the pump with an amp meter is drawing 9.2 amps. There are no restrictions in the system as i have three pressure gauges at various points in the process. The machine ran fine for 10 years prior to the power interuption. No one can figure out why the pumps are overheating nothing in the system was changed.
Peter

 

[don_resqcapt19]

I approved this as it does not appear to be a DIY post. It is just looking for possible reasons for the failure.

 

[ptonsparky]

Pump. Centrifugal? Restrict the flow.

 

[kwired]

Pump. Centrifugal? Restrict the flow.

I agree. Centrifugal pump is loaded by flow not pressure.

If it is a positive pump then there must be too much pressure.

Other problem may be imbalanced voltages? A motor that is running near full load won't handle imbalance as well as one that isn't all that loaded.

 

[topgone]

If there was no problem before, then something must have changed in your system. The short-term solution is to adjust/ perhaps, a 90% opening or so on your pump discharge valve to lessen the amps drawn. Check the amps if it is displaying the rated current of your pump motor else, ryen down some more. Then, do a walkaround of your lines to see if there are no system leaks. Pumps are chosen to operate at a specific point in their pump curve. Any increase in the flow will result in a rise in motor current draw.

 

[don_resqcapt19]

Rated current of 9 amps with actual current of 9.2 amps is only a bit over a 2% overload. That should not result in a motor burning up.

 

[hbiss]

Has anybody measured the voltage between all phases- A to B, B to C, A to C? Has anybody checked the rotation?

-Hal

 

[petersonra]

It is very hard to diagnose this kind of thing without adequate information.

You posted the original control panel ignited. That suggests maybe some kind of surge came thru.

You mention the motor runs hot but also that pumps are failing. A motor running at full load will be quite warm to the touch but that does not mean it is overheating. How hot does it actually get?

Is the motor on a vfd?

Among other things I design control panels and software for reverse osmosis systems. Done a bunch of them. Just shipped a real pretty one made of 316 SS.

There are a lot of things it could be but if you replaced the motor, the control panel, and the pump, you have replaced just about everything it is likely to be.

Who did you get this system from? What do they say about your problems?

 

[waterguy]

If there was no problem before, then something must have changed in your system. The short-term solution is to adjust/ perhaps, a 90% opening or so on your pump discharge valve to lessen the amps drawn. Check the amps if it is displaying the rated current of your pump motor else, ryen down some more. Then, do a walkaround of your lines to see if there are no system leaks. Pumps are chosen to operate at a specific point in their pump curve. Any increase in the flow will result in a rise in motor current draw.

thank you we increased the discharge to full open and the amp draw went up from 9.2 to 9.4

 

[kwired]

Rated current of 9 amps with actual current of 9.2 amps is only a bit over a 2% overload. That should not result in a motor burning up.

A motor running at full load will get pretty hot to the touch but is still within it's rated temperature.

 

[waterguy]

It is very hard to diagnose this kind of thing without adequate information.

You posted the original control panel ignited. That suggests maybe some kind of surge came thru.

You mention the motor runs hot but also that pumps are failing. A motor running at full load will be quite warm to the touch but that does not mean it is overheating. How hot does it actually get?

Is the motor on a vfd?

Among other things I design control panels and software for reverse osmosis systems. Done a bunch of them. Just shipped a real pretty one made of 316 SS.

There are a lot of things it could be but if you replaced the motor, the control panel, and the pump, you have replaced just about everything it is likely to be.

Who did you get this system from? What do they say about your problems?

the system was custom made 15 years ago and has been running great the problem of overheating only surfaced after the control panel burned up we replaced it with a new one from the company that made the original one.

 

[kwired]

I agree. Centrifugal pump is loaded by flow not pressure.

If it is a positive pump then there must be too much pressure.

Other problem may be imbalanced voltages? A motor that is running near full load won't handle imbalance as well as one that isn't all that loaded.

Too much pressure could be the filtering media is plugged and needs cleaned or replaced?

My understanding of RO systems is pressure forces water through the filtering media and sometimes you do need some sort of booster pump as ambient pressure isn't enough to get the desired volume through the system.

 

[waterguy]

it is not on a vfd, the surge may have come when power was restored after a blackout in our area. the motor is 209-240 and we are only getting 210v at the pump the supply is from DTE (Detroit Edison) and my friend who is an engineer there says they tell him it is 3 phase Y supply

 

[kwired]

it is not on a vfd, the surge may have come when power was restored after a blackout in our area. the motor is 209-240 and we are only getting 210v at the pump the supply is from DTE (Detroit Edison) and my friend who is an engineer there says they tell him it is 3 phase Y supply

Have you looked into whether there is problems with driven load?

If not the pump itself maybe the water flow circuit has had something change in it which has changed the loading on the pump?

Many times motor overcurrent issues are not the motor but the driven load.

 

[synchro]

Has anybody measured the voltage between all phases- A to B, B to C, A to C? Has anybody checked the rotation?

-Hal

I agree. Also, under the circumstances given I think the L-L voltages to the motor should be measured both when it's running and not running for a comparison. A 3-phase service from DTE is mentioned, but it would be helpful if you would confirm that the motor itself is 3-phase since that wasn't explicitly mentioned.

 

[don_resqcapt19]

Have you looked into whether there is problems with driven load?

If not the pump itself maybe the water flow circuit has had something change in it which has changed the loading on the pump?

Many times motor overcurrent issues are not the motor but the driven load.

Still can't see this as a motor load issue with an actual current of 9.2 amps on a motor with a rated full load current of 9 amps.

 

[don_resqcapt19]

it is not on a vfd, the surge may have come when power was restored after a blackout in our area. the motor is 209-240 and we are only getting 210v at the pump the supply is from DTE (Detroit Edison) and my friend who is an engineer there says they tell him it is 3 phase Y supply

The nominal system voltage for a 3 phase wye system is 208/120. The recommended utilization equipment voltage rating for this system would be 200 volts.

 

[petersonra]

Too much pressure could be the filtering media is plugged and needs cleaned or replaced?

My understanding of RO systems is pressure forces water through the filtering media and sometimes you do need some sort of booster pump as ambient pressure isn't enough to get the desired volume through the system.

That is not how a ro system works. Usually there is some kind of particle filtration upstream, but that is just normal bag filters mostly.

Filtration is a mechanical function. Water flows thru the holes in the filter media while participate matter larger than the holes is retained. Ions such as calcium or sodium pass thru the media.

The pump pressurizes water against a membrane that keeps ions on the high pressure side while allowing pure water to pass thru the membrane. It is called reverse osmosis because it is the opposite of the process of osmosis which is the process by which ions pass thru your cells in your body. In both cases ionsvendvuo on the higher pressure side.

 

[ptonsparky]

Something changed or is changing while unobserved. Pure and simple.
Put some PQ recording on it. Hire it out, if need to. Minor cost compared to three motors and down time.

 

[petersonra]

the system was custom made 15 years ago and has been running great the problem of overheating only surfaced after the control panel burned up we replaced it with a new one from the company that made the original one.

Are the people that made it still in business?

The problem is there is some piece of information we are missing that would probably make what is going on pretty obvious.

I don't know quite what you mean by a pump burning up either. They don't typically catch on fire. The motor might but not the pump. When the pump failed what went wrong with it?

This seems like a case of the motor single phasing but that would not cause the pump itself to fail.