3-Phase Squrrel Cage Well Pump Motors
3-Phase Squrrel Cage Well Pump Motors
(OP)
I'm a recent graduate and I specify well pump motors in new water plants along with replacements after they fail. My company in past few years is having numerous problems with the well motors failing within 5 years, while in the past the motors could last up to 25 years. The motors are used are in the Greater Houston, Texas Area, so the coastal environment is harsh along with Houston's pollution. I'm looking for the best quality at the best price in motors. I'm looking for information on motor manufacturers, heat rise, insulations, enclosures, monitors, heaters, starters, and cost. Any info will be helpful.
Greg
Greg





RE: 3-Phase Squrrel Cage Well Pump Motors
RE: 3-Phase Squrrel Cage Well Pump Motors
I would say if you want a reliable motor in general you will that you will find some very good off-the-shelf options among the IEEE841 "severe-duty" motors.
Other parts of the reliability picture are of course careful review of application requirements, consideration of preventive maintenance, condition monitoring, post-mortem examinations. Part of condition monitoring is the process of verifying your assumed application parameters during actual operation. (loading, voltage, starting duty).
RE: 3-Phase Squrrel Cage Well Pump Motors
are you looking for vertical or horizontal motors?
also what type of failures do you have?
RE: 3-Phase Squrrel Cage Well Pump Motors
We use vertical motors. The motors usually fail from insulation breakdown. We used to spec WP1 enclosures and Insulife 2000 insulation with US Motors (two dips and bakes). For the past few motors I have been going to TEFC thinking that will help. I'm also wondering if I should go to a the Insulife VPI 2000 (two cycles of vacuum pressure impregnation). Any thoughts on that?
RE: 3-Phase Squrrel Cage Well Pump Motors
RE: 3-Phase Squrrel Cage Well Pump Motors
Are you using hollow shaft motors?
RE: 3-Phase Squrrel Cage Well Pump Motors
A good EASA motor repair shop should be giving you more information than you have given us. What do they say about your failurers?
RE: 3-Phase Squrrel Cage Well Pump Motors
Concerning the motor shafts, I don't know what we've used in the past. Our specs dont say anything about shaft types. I did look at a recent installation and it was a hollow shaft motor.
RE: 3-Phase Squrrel Cage Well Pump Motors
If the pump electrical system is ungrounded/“floating” in the 240-600V range, some small transformers and a resistor to permit high-resistance grounding may be more effective than non-linear “TVSS” devices like MOVs or SADs for limiting insulation-damaging phase-to-ground transient overvoltages.
Search this site for “high-resistance grounding”.
RE: 3-Phase Squrrel Cage Well Pump Motors
For the moisture issue in the motor, do you install winding space heaters in the motors? What is your duty cycle, run time/off time? Are the motors in direct sun light? What are the running loads of the motors that have failed?
If you decide that heat is the issue, I would suggest you intall motor winding RTDs in the next motor purchased or rewound. Connect them to the Multilin and monitor.
Would you circumstances be something like:
The well pump is started in the morning to meet peak demand, which is at or near full load (or better yet in the service factor because the mechanical side of the house wants to save capital costs), operated all day on a hot day (typical of Houston 100+) and the motor is in full direct sun light(adds 20 degrees to operating temp). Runs through the evening peak and is shutdown for the night, motor cools down to ambient and sucks in the moisture (lots of that in Houston). Add to all this the lightning strike related power problems (seen that in Houston), five years seems about right!
RE: 3-Phase Squrrel Cage Well Pump Motors
IHMO there is no doubt that global vpi is superior for outdoor applications. Also I have a preference for epoxy over polyester I know some will disagree with that based on recent advances.
"Insulife" sounds vendor specific.... not sure what it means. A lot of the OEM's can provide info on their systems. Some will brag that their insulations systems have passed immersion tests and are used in hermitically-sealed motors immersed in refrigerant. I would look for this as well as an insulation system that has been around for awhile (time-proven).
As mentioned space heaters are an important acccessory. Should be set up to come on automaticlly when motor is switched off.
RE: 3-Phase Squrrel Cage Well Pump Motors
There also heater gizmos that use low-level off-cycle DC current applied to stator windings, like: www.motortronics.com/products/otpr.html
www.ab.com/manuals/pd/1410-2.2.pdf
www.benshaw.com/literature/applications/AN0009.pdf {part of a SS starter}
www.emersonct.com/pdProducts/downloads/appNotesPDF/CTAN194.pdf {VF drive software implementation}
www.usmotors.com/Products/ProFacts/1-109.htm {electromechanical method}
www.friesenelectric.com/brochures/pdf/Motor_Control/S_Motor_Winding_Heater_1pg.pdf
www.dnhindustries.com/
RE: 3-Phase Squrrel Cage Well Pump Motors
the stuff the crew have pointed out sounds like the go. But as a back up find out what changes where made at the time the first of these failures was installed or about the time of the failures. As I read your post I am starting to feel there is a root cause here. And the techinical may fix it but finding the root may be suprising.
(with lots of repect to the prior posts)
Regards
Don
RE: 3-Phase Squrrel Cage Well Pump Motors
re lightning strikes,
I dare say Houston has been getting lightning strikes for many years, Has the power co changed the way they work or the regs around that area changed ?
Do all the failed units have rust in WP1 enclosure? (what is WP1 enclosure?)
Are these at various sites around the region or one plant site?
Don
RE: 3-Phase Squrrel Cage Well Pump Motors
Interesting that someone told you that the old motors lasted 25 years and the newer motors only last 5 years.
Something very drastic had to happen to the systems to account for the 500 % reduction in durability.
You might have to ask yourself what really changed either on the new motors or on the electrical systems(protections).
The previous advice to make sure your Anti-cond heaters are working is a must.Loads of water can accumulate in the windings if you don't have heaters.Houston polution and all.If your motors are randonm wound ,the VPI may not make much difference.
Lets assume this scenario.Years ago the demands were probably lower so the motors ran at low loads,low winding heat.In the last few years the demand increased and motors are now running at full tilt or more, and pretty hot as well.For every 10Deg increase in operating temperature
you reduce the life of your motor by a half.
Next time ,when a motor fails,follow it to the repair shop and look at what the windings look like.Ask the shop to give you their opinion on the failure.
If the windings are toasted ,you could bet you have overloads and consequent overheating.If it burns on aturn to turn short it can be poor winding or poor impregnation.
If it shorted to ground,the water accumulation could be the culprit.
Make sure you have Anti-cond heaters, also for a few dollars more install winding RTDs.
Good luck
heatThere is one possibility. previous adv lchange for this
GusD
RE: 3-Phase Squrrel Cage Well Pump Motors
Maybe instead of specifying the materials/technique etc I should have suggested to specify the performance requirements. NEMA MG-1 has provisions for a sealed winding conformance test which includes complete immersion in liquid, followed by an overpotential test. You can either ask for the test or just ask the OEM to provide documentation that his insulation system has passed the test on comparable motors. Talk to some good distributors and I'm sure they can pitch you some good product lines for your application.
RE: 3-Phase Squrrel Cage Well Pump Motors
If the end turns are taped as you mention ,than VPI may be of some value.AgEng02 mentions that this motors operate on an environment that is near the sea and subject to possible excess polution.This is not a Tropical climate but conditions could be similar and subject windings to the same problems.The windings could be treated with a Fungicidal Treatment.This coumpound can be added to air dry varnish to discourage the growth of fungus.
Like many other problems,one cannot find the right soulutions unless you know what the problem is.
My suggestion for AnEng02 to follow that motor to the repair shop and find out what failed and how,may give you surprising results.
GusD
RE: 3-Phase Squrrel Cage Well Pump Motors
RE: 3-Phase Squrrel Cage Well Pump Motors
RE: 3-Phase Squrrel Cage Well Pump Motors
If you want long life in the Gulf Coast region, make sure you specify heaters and a totally enclosed design with copper bars.