High Amp Pump Draw

[Riddler]

My not-so-old (2-3 years) 1 HP 230V submersible well pump is suddenly drawing 30 amps (start and run). Will install a new control box because the start cap is visibly cooked and the relay may be as well. Until the circuit breaker trips, motor/pump still runs long enough and strong enough to almost pressurize the system to cut-off (60 psi).

Can a bad control box that only has a start cap and relay (no run cap) cause an amp draw increase from a spec of around 8 amps to the 30 amps I'm seeing? For example, can the elevated amp draw be attributable to a voltage drop to the motor caused by the damaged control box? Or it is far more likely that a malfunction in the motor or pump is responsible for the elevated amp draw, and that in turn cooked the control box?

 

[Valveman]

A 1HP doesn't need a run capacitor. Because the start cap and relay were bad, I am sure the pump cycled itself to death. All the start cap and relay does is start the pump, and if they go bad you have started the pump too many times.

Check your voltage. But if the voltage is still 230 and a new control box doesn't fix it, the motor is most likely toast. When you get the old pump out study it. If the motor shaft doesn't stick up 1.5" the thrust bearing got hot and a flow inducer sleeve is needed. But if the motor shaft stick up is still 1.5" then it is probably locked up from cycling damage. Cycling on and off is what destroys most pumps. Eliminate the cycling with a Cycle Stop Valve and the pump will last 20-30 years instead of 2-3.

 

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[Riddler]

A 1HP doesn't need a run capacitor. Because the start cap and relay were bad, I am sure the pump cycled itself to death. All the start cap and relay does is start the pump, and if they go bad you have started the pump too many times.

Check your voltage. But if the voltage is still 230 and a new control box doesn't fix it, the motor is most likely toast. When you get the old pump out study it. If the motor shaft doesn't stick up 1.5" the thrust bearing got hot and a flow inducer sleeve is needed. But if the motor shaft stick up is still 1.5" then it is probably locked up from cycling damage. Cycling on and off is what destroys most pumps. Eliminate the cycling with a Cycle Stop Valve and the pump will last 20-30 years instead of 2-3.

Curious how a bad start cap can lead to short cycling? Wouldn't a bad start cap just prevent the pump from starting? The pressure tank (Hydropro V250D) and pressure switch still work fine (i.e., 40 psi cut-on/60 psi cut-off), so how could there have been excessive cycling? Even now, when I reset the breaker, the pump
runs for the same (or almost the same) length as a normal cycle. It just pulls 30 amps for the duration so the breaker pops intermittently just before the 60 psi cut off is reached.

Before I was able to test the amp draw, I toyed with the idea of lowering the 60 psi cut-off to shorten the amount of time the pump needed to cycle, but I figured I should first try to get to the bottom of why the pump was suddenly not cycling long enough to get to 60 psi every cycle.

BTW, the motor has a flow inducer sleeve because it sits in a 2000 gallon tank.

 

[Valveman]

Curious how a bad start cap can lead to short cycling?

BTW, the motor has a flow inducer sleeve because it sits in a 2000 gallon tank.

It is the other way around. Cycling is what causes the start cap to go bad. Start caps are only in the circuit for a fraction of a second on each start. That is the only time it is used. So, when a start cap goes bad it is a sign of too much cycling on/off. That 83 gallon size tank may look huge, but only holds 20 gallons of water. Using water for long period of time or a leak in the system will cause the pump to cycle on/off for every 20 gallons used. Plus, that brand of tank is not known for having a long lasting diaphragm anyway.

The 2000 gallon tank is not a flow sleeve. It is no different than having a pump in a lake or a large diameter well. The water can still get hot around the motor while pumping cold water out the pipes if there is no 4" or 5" flow sleeve to make the flow go past the motor.

 

[Riddler]

It is the other way around. Cycling is what causes the start cap to go bad. Start caps are only in the circuit for a fraction of a second on each start. That is the only time it is used. So, when a start cap goes bad it is a sign of too much cycling on/off. That 83 gallon size tank may look huge, but only holds 20 gallons of water. Using water for long period of time or a leak in the system will cause the pump to cycle on/off for every 20 gallons used. Plus, that brand of tank is not known for having a long lasting diaphragm anyway.

The 2000 gallon tank is not a flow sleeve. It is no different than having a pump in a lake or a large diameter well. The water can still get hot around the motor while pumping cold water out the pipes if there is no 4" or 5" flow sleeve to make the flow go past the motor.

View attachment 96694

It is the other way around. Cycling is what causes the start cap to go bad. Start caps are only in the circuit for a fraction of a second on each start. That is the only time it is used. So, when a start cap goes bad it is a sign of too much cycling on/off. That 83 gallon size tank may look huge, but only holds 20 gallons of water. Using water for long period of time or a leak in the system will cause the pump to cycle on/off for every 20 gallons used. Plus, that brand of tank is not known for having a long lasting diaphragm anyway.

The 2000 gallon tank is not a flow sleeve. It is no different than having a pump in a lake or a large diameter well. The water can still get hot around the motor while pumping cold water out the pipes if there is no 4" or 5" flow sleeve to make the flow go past the motor.

View attachment 96694

It is the other way around. Cycling is what causes the start cap to go bad. Start caps are only in the circuit for a fraction of a second on each start. That is the only time it is used. So, when a start cap goes bad it is a sign of too much cycling on/off. That 83 gallon size tank may look huge, but only holds 20 gallons of water. Using water for long period of time or a leak in the system will cause the pump to cycle on/off for every 20 gallons used. Plus, that brand of tank is not known for having a long lasting diaphragm anyway.

The 2000 gallon tank is not a flow sleeve. It is no different than having a pump in a lake or a large diameter well. The water can still get hot around the motor while pumping cold water out the pipes if there is no 4" or 5" flow sleeve to make the flow go past the motor.

View attachment 96694

Perhaps the sentence could have been worded better, but the motor has a flow inducer installed because that is what I do whenever I put a submersible well pump in a tank. I'm aware that a 2000 gallon tank is not a flow sleeve.

As my post mentioned, I never observed short-cycling, even when with the breaker was tripping, but maybe the start cap and relay just weren't good enough quality to handle whatever cycling the pump generates.

Anyway, turns out there is nothing wrong with the pump whatsoever. I just swapped out the blown control box for a new, better quality one and my amp draw went from 30 down to 10. So it looks like a blown control box can still allow a pump to run, but only at a highly elevated amp
draw. Must be because the damage in box reduces voltage to the pump, which in turn requires a high amp draw when the pump struggles to run. Interesting.

 

[Valveman]

Sorry for confusion about the flow inducer. 30 amps was because the start relay was not opening up. Either the start relay was bad and couldn't work, the capacitor was bad and the relay knew it wasn't up to speed, or both. It could have been a weak relay, capacitor, or both. But it doesn't have to be "short cycling" for the start mechanisms to fail. They are designed to fail after a certain amount of so called "normal" cycling. They just fail even quicker after the tank fails and the pump is rapid cycling.