Submersible pump

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yetiman

Member
I have a customer with a 3hp well pump that is approx. 300' down. The control box with the capacitor is about 100 to 150' away from the well house. I get a call that the circuit breaker from the service panel has begun to trip on a regular basis (after quite a few years after install). He has run #10 copper uf feeder to the well house and down to the pump. The readings on the 3hp pump read OK at around 14.5a on 1 leg and around 16 on the other. 4.5 on the start leg. The contacts on the starter are worn and slightly burnt . I am wondering if the voltage drop on the line could be contributing to the wear on the contacter and the wear on the 30a breaker feeding this circuit . Any comments out there?
 

One-eyed Jack

Senior Member
I have a customer with a 3hp well pump that is approx. 300' down. The control box with the capacitor is about 100 to 150' away from the well house. I get a call that the circuit breaker from the service panel has begun to trip on a regular basis (after quite a few years after install). He has run #10 copper uf feeder to the well house and down to the pump. The readings on the 3hp pump read OK at around 14.5a on 1 leg and around 16 on the other. 4.5 on the start leg. The contacts on the starter are worn and slightly burnt . I am wondering if the voltage drop on the line could be contributing to the wear on the contacter and the wear on the 30a breaker feeding this circuit . Any comments out there?

The start capacitor could have lost some capacity over time and no longer has the capacitance to rotate the motor on startup. Pump could be short cycling do to bad bladder in water tank. Easy check on tank is to press the valve on top of tank. Just a short burst. If you get water the bladder is bad. Replace tank or tanks,some applications use multiple smaller tanks due to cost and space concerns.
 

cadpoint

Senior Member
Location
Durham, NC
... Pump could be short cycling do to bad bladder in water tank. Easy check on tank is to press the valve on top of tank. Just a short burst. If you get water the bladder is bad. ....


Are you saying to test the pressure releif valve?

If you are; some caution should be taken before this application:

PPE - Eye Protection and note spray direction should be noted!

Note any available pressure gauges before a release!

Realize that one is releasing a pressurized vessel! (not a lot of people are use to dealing with pressurized vessels)

Cycling water into the tank stirs up tank and things that might be in the water.

Note that all valving that might be closed when it should be open to the tank! (due to tinkering, by owner or other third parties, before ones arrival)
One might have to close some valves to isolate the tank!

Note that the relief valve closes, if you do test - lease it. Rust and other minerals, even bladder parts might well get trapped between the valve seat and the throat outlet below. If the valve is connected to a directional drain line, it might have to be removed, if a slow drain remains after a test.

Bottom Line if you test a pressure relief valve, just be ready to replace it as well. Same goes for a water heater pressure relief valve.
 

hockeyoligist2

Senior Member
Are you saying to test the pressure releif valve?

If you are; some caution should be taken before this application:

PPE - Eye Protection and note spray direction should be noted!

Note any available pressure gauges before a release!

Realize that one is releasing a pressurized vessel! (not a lot of people are use to dealing with pressurized vessels)

Cycling water into the tank stirs up tank and things that might be in the water.

Note that all valving that might be closed when it should be open to the tank! (due to tinkering, by owner or other third parties, before ones arrival)
One might have to close some valves to isolate the tank!

Note that the relief valve closes, if you do test - lease it. Rust and other minerals, even bladder parts might well get trapped between the valve seat and the throat outlet below. If the valve is connected to a directional drain line, it might have to be removed, if a slow drain remains after a test.

Bottom Line if you test a pressure relief valve, just be ready to replace it as well. Same goes for a water heater pressure relief valve.

I think Jack is thinking about the valve where you check or add pressure. It's kind of like a tire valve.
 

mtfallsmikey

Senior Member
I think Jack is thinking about the valve where you check or add pressure. It's kind of like a tire valve.

That is correct. Air charge in tank = cut-in pressure on pressure switch, most residential switches factory set to cut in @ 30lb., cut out @50lb. Haven't messed around with well pumps for awhile, but most pumps under 1 hp. have start cap. built into the motor, larger pumps probably could not have them built in due to size.
 
I have a customer with a 3hp well pump that is approx. 300' down. The control box with the capacitor is about 100 to 150' away from the well house. I get a call that the circuit breaker from the service panel has begun to trip on a regular basis (after quite a few years after install). He has run #10 copper uf feeder to the well house and down to the pump. The readings on the 3hp pump read OK at around 14.5a on 1 leg and around 16 on the other. 4.5 on the start leg. The contacts on the starter are worn and slightly burnt . I am wondering if the voltage drop on the line could be contributing to the wear on the contacter and the wear on the 30a breaker feeding this circuit . Any comments out there?

Not knowing the operating voltage, nameplate amps, nor overload (if there is one) settings it is difficult to comment with certainty, so I just offer some thoughts. Is the trip occure after the motor has been running for a while or on startup?

As I commented on other places all polymers absorb water over time. This increases capacitance therfore producing an increased capacitive leakeage that is additive to the current.

Voltage drop is probably over the desired 3%, but more importantly My question would be what is the actual terminal voltage at the motor at startup or running. If the supply is continously on the high side you may have enough juice to start, but if not then your motor maybe stalling on start, or tripping after it warmed up, or tripping when the suply voltage changes. Most voltage drop calculations are based on ordinary conductors, but a soaked conductor may have parameters that cold be a problem wehn you're deling with a marginal situation.

In other words, you may have a 'perfect storm' and it is not a single problem, but a compilation of several.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Just sit there a few minutes count the number of times it turns on/off and the time it runs. It may be short cycling due to a water logged pressure tank or a broken bladder as described. Some submersibles have a system to inject a certain amount of air into the tank each time it starts. This device does fail resulting in the water logging. Could be the pump is oversized for winter operation, short cylcles again, but just right for summer lawn sprinkling. A 3% drop for submersibles is not a problem. Sometimes they actually prefer a system with a bit of voltage drop because it causes less torque on the drop pipe at startup. Search for Franklin Pumps.
 

kwired

Electron manager
Location
NE Nebraska
more common problem I have seen and possibly what you have is the potential relay is not dropping start capacitor out of circuit. If this happens tripping of breaker is likely.

I see you say it is 3 hp and 30 amp breaker. 30 amps is on the light side for 3hp. May hold while starting initially but after time may no longer hold because of either deteriorating conditions in the breaker or additional load(s) drawing voltage down and therefore increasing starting current or starting duration. A 3 hp motor can easily have a 45 amp breaker installed before one should start to question if it is too large.
 

One-eyed Jack

Senior Member
Are you saying to test the pressure releif valve?

If you are; some caution should be taken before this application:

PPE - Eye Protection and note spray direction should be noted!

Note any available pressure gauges before a release!

Realize that one is releasing a pressurized vessel! (not a lot of people are use to dealing with pressurized vessels)

Cycling water into the tank stirs up tank and things that might be in the water.

Note that all valving that might be closed when it should be open to the tank! (due to tinkering, by owner or other third parties, before ones arrival)
One might have to close some valves to isolate the tank!

Note that the relief valve closes, if you do test - lease it. Rust and other minerals, even bladder parts might well get trapped between the valve seat and the throat outlet below. If the valve is connected to a directional drain line, it might have to be removed, if a slow drain remains after a test.

Bottom Line if you test a pressure relief valve, just be ready to replace it as well. Same goes for a water heater pressure relief valve.

This is not a pressure relief valve. The valve on captive air tanks is used to adjust the pressure in the bladder. If the bladder is good the only thing you will get is air. If it is bad you will get water. Since you cannot compress a liquid you no longer have a means for a differential for cut-in,cut-out pressures. The pressure in the bladder should be set at 2-4 lbs below cut-in pressure of pressure switch.
 

One-eyed Jack

Senior Member
Just sit there a few minutes count the number of times it turns on/off and the time it runs. It may be short cycling due to a water logged pressure tank or a broken bladder as described. Some submersibles have a system to inject a certain amount of air into the tank each time it starts. This device does fail resulting in the water logging. Could be the pump is oversized for winter operation, short cylcles again, but just right for summer lawn sprinkling. A 3% drop for submersibles is not a problem. Sometimes they actually prefer a system with a bit of voltage drop because it causes less torque on the drop pipe at startup. Search for Franklin Pumps.

If it has this type of air injection it will most likely be in the drop pipe in the well. Also it will most likely have a standard tank. NO BLADDER OP must first determine if it is indeed short cycling. If not the problem is electrical not mechanical.
 
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