Ainsley Whyte
Senior Member
- Location
- Jamaica
- Occupation
- Senior Electrical Engineer
This 50hp, 440 VAC submersible well pump was recently damage. Any one familiar with this pump?. I am doing a root cause analysis and would like to know how it works.
50 Hp submersible pump
- Thread starter Ainsley Whyte
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
440 volts is not a standard voltage please confirm
Looks like overheating
Need to know the following
Motor amperage
RPM
Need you to calculate voltage drop from the controller, what was the measured running voltage?
The motor hangs below the pump, please take the well diameter, look in the manual to see if it met minium flow requirements to keep motor cool.
Was the motor on a VFD?
Is it possible the motor single phased. Pleade verify the settings of the overload.
Looks like overheating
Need to know the following
Motor amperage
RPM
Need you to calculate voltage drop from the controller, what was the measured running voltage?
The motor hangs below the pump, please take the well diameter, look in the manual to see if it met minium flow requirements to keep motor cool.
Was the motor on a VFD?
Is it possible the motor single phased. Pleade verify the settings of the overload.
Ainsley Whyte
Senior Member
- Location
- Jamaica
- Occupation
- Senior Electrical Engineer
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
OK, keep workkng on the rest of the questions.
Ainsley Whyte
Senior Member
- Location
- Jamaica
- Occupation
- Senior Electrical Engineer
I know its on a 150A circuit breaker via a contactor and heater
Did you look at the attachment there is a hole near the the bottom of the motor could this be the cause
Ainsley Whyte
Senior Member
- Location
- Jamaica
- Occupation
- Senior Electrical Engineer
Attachments
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
What was rhe megger reading from maintenance checks and after failure?
What was the pumped liquid?
What was the pumped liquid?
Ainsley Whyte
Senior Member
- Location
- Jamaica
- Occupation
- Senior Electrical Engineer
the pump liquid is water its a well pump
not sure of the meg readings but the motor is burnt
Hard to tell cause looking at the outside only.
Burned up has multiple causes especially in this case. Not sure why Megger readings matter. It will be 0 (shorted).
Well pump motors are water cooled. If it plugs up, it burns up. There should be openings...ports for water. There is supposed to be a thermal switch internally. An overload relay is utterly useless on these. You wire the switch up instead of the overload relay. So far sounds like installation error right there. Unlike air cooled motors you simply cannot rely on an overload relay (“heater”) to protect submersible motors.
Remove rotor and look inside. Based on appearance of the stator and rotor you can immediately identify single phasing, manufacturer defect, overload, surged, etc., although so far it looks like overload. Some faults such as broken rotor bars or eccentric air gap or bad bearing also look like overload. Check bearings (should be obvious). Check core loss/growler test. Check for full of mud/sand which is sort of unavoidable in a new well (expect failures) and indicates the screen on the well point failed in old ones. But don’t bother doing it yourself...
Or...most motor shops charge very little for disassembly/diagnosis. This motor is big enough that rewinding will be cheaper than new. All shops are going to send it to usually Texas for rewinding. The stator is very long and narrow on these. It requires a special winding machine very few shops have. So I’d encourage you to just take it to a reputable motor shop for diagnosis and rewinding.
Also there is often a moisture probe. It is just two contacts located between the inner and outer seals. It typically ohms around 100k. It should trigger an alarm/shutdown at under 10-30k. At that point the motor is fine, just needs new desks installed. The moisture relays also monitor and trigger on thermal switches. On some motors they series these together so “open” (megaohms) is overload, under 10k is moisture alarm/shutdown, everything else is good. Macromatic makes a good inexpensive moisture/overload relay.
As to which shops look for third party inspection. The shop should be either EASA or ISO 9000. UL stamps would be a definite second inspection. Also look at the voltages and sizes. Walk away from shops that don’t do over 500 HP themselves and don’t do 4160 themselves. It doesn’t matter if you have equipment in those ranges or not. It takes extra quality to handle large and higher voltage motors that a local shop just does not have. A clean room winding shop is necessary above 10 kV but that’s pretty rare so don’t get concerned about that. Also they need to test run EVERY motor. Look for a test stand and reports.
This motor is rebuildable if not damaged beyond repair. It will not just save you money. Motor shops use better wiring than factory original. They tend to use higher quality construction techniques because the techniques are different (one at a time, hand built, not assembly line). The same shoo can/should rebuild the well pump too. Often pumps destroy motors when they have bad bearings, worn out impellers, casing holes, etc.
Burned up has multiple causes especially in this case. Not sure why Megger readings matter. It will be 0 (shorted).
Well pump motors are water cooled. If it plugs up, it burns up. There should be openings...ports for water. There is supposed to be a thermal switch internally. An overload relay is utterly useless on these. You wire the switch up instead of the overload relay. So far sounds like installation error right there. Unlike air cooled motors you simply cannot rely on an overload relay (“heater”) to protect submersible motors.
Remove rotor and look inside. Based on appearance of the stator and rotor you can immediately identify single phasing, manufacturer defect, overload, surged, etc., although so far it looks like overload. Some faults such as broken rotor bars or eccentric air gap or bad bearing also look like overload. Check bearings (should be obvious). Check core loss/growler test. Check for full of mud/sand which is sort of unavoidable in a new well (expect failures) and indicates the screen on the well point failed in old ones. But don’t bother doing it yourself...
Or...most motor shops charge very little for disassembly/diagnosis. This motor is big enough that rewinding will be cheaper than new. All shops are going to send it to usually Texas for rewinding. The stator is very long and narrow on these. It requires a special winding machine very few shops have. So I’d encourage you to just take it to a reputable motor shop for diagnosis and rewinding.
Also there is often a moisture probe. It is just two contacts located between the inner and outer seals. It typically ohms around 100k. It should trigger an alarm/shutdown at under 10-30k. At that point the motor is fine, just needs new desks installed. The moisture relays also monitor and trigger on thermal switches. On some motors they series these together so “open” (megaohms) is overload, under 10k is moisture alarm/shutdown, everything else is good. Macromatic makes a good inexpensive moisture/overload relay.
As to which shops look for third party inspection. The shop should be either EASA or ISO 9000. UL stamps would be a definite second inspection. Also look at the voltages and sizes. Walk away from shops that don’t do over 500 HP themselves and don’t do 4160 themselves. It doesn’t matter if you have equipment in those ranges or not. It takes extra quality to handle large and higher voltage motors that a local shop just does not have. A clean room winding shop is necessary above 10 kV but that’s pretty rare so don’t get concerned about that. Also they need to test run EVERY motor. Look for a test stand and reports.
This motor is rebuildable if not damaged beyond repair. It will not just save you money. Motor shops use better wiring than factory original. They tend to use higher quality construction techniques because the techniques are different (one at a time, hand built, not assembly line). The same shoo can/should rebuild the well pump too. Often pumps destroy motors when they have bad bearings, worn out impellers, casing holes, etc.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
I would say lightning damage caused the holes, probably started as pin holes, then a arcing fault enlarged them. I pulled a small single phase pump many years ago that had pin holes on the side, right where the sticker said “lightning protected” LOL!
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
I'd call Franklin. My experience with their tech support has been great in the past. The guy I talked to is probably gone by now, he was up in his 60's 10 years ago.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Lightning protectors typically only work once. It doesn’t have to hit the panel, it just has to hit the wires anywhere nearby.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Yeah, I know, it was just ironic it blew out at the label! LOL!
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Murphy’s Law...
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
To Paulengr:
I've wired a lot of submersibles...have not seen one with a moisture probe and overload, for water pumps, common on sewer pumps. For the water wells rhat requires a seperate cable for the ol and moisture?
And its probably lightning damage, we see very little lighting in the Seattle area.
I've wired a lot of submersibles...have not seen one with a moisture probe and overload, for water pumps, common on sewer pumps. For the water wells rhat requires a seperate cable for the ol and moisture?
And its probably lightning damage, we see very little lighting in the Seattle area.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
It is common to include a "dry running" detector (pump protector) for the case where the pump rate can exceed the recharge rate of the well. Instead of detecting over current it detects under current or low power factor indicating that the motor is running unloaded. A thermal switch inside the pump assembly may not work fast enough.
- Status