Perplexing Pump Problem - intermittent elevated loads on main

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MichaelSK

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This electrical problem has me perplexed. I thought Valveman, from another forum/thread, solved the problem with a simple straight forward explanation - the Klixon-type breakers become weaker with subsequent "breaks."

Background: 3 y/o Shakti 3/4 hp 3-wire submersible pump - the control box has two breakers (start and main/run). I have checked amps on several occasions, and they have been nominal - well within specs. (e.g. The Y-line amps ~ 5.4 [6.7/7.37]; B-main amps ~ 5.1 [5.8/6.38]; R-start amps ~ 2.0 [2.6/2.86]) note: the numbers in [ ] are full load/max load specs.

Based on what Valveman said (makes good sense, appreciated his explanation), I removed the Klixon breaker and installed a 7.5 amp slow-blow fuse. Went through a couple of fuses, apparently there are intermittent load spikes on the "main circuit," which I have not been able to isolate and describe.

Does anyone have any suggestions how to problem solve this one? I am in the process of accessing two junction boxes to assess the line connections (?condensation, oxidation, intermittent shorting?). Short of purchasing an entire new length of wire to run from the control box, which is located in the main house mechanical room, down to the well head - any other suggestions?

At this point, I am reluctant to merely short the breaker if indeed there is an unidentified problem.
 

Reach4

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Have you checked the resistance to ground after opening the breaker? I think a 500 volt ohmmeter is usually suggested for this, but you could see if your regular ohmmeter tells you something.
 

MichaelSK

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Thanks for the quick reply/suggestion Reach4. I have not checked that yet. My Klein CL450 has a resistance range of 600 ohms with a resolution of 0.1 ohms and a claimed accuracy of +- 1.2% + 5 digits.

I will check this resistance to ground. What is perplexing is that it's intermittent. (!@#$%^!!!)
 

Valveman

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It would be extremely rare to have an intermittent overload. Overload usually happens on high pressure if the thrust bearing is bad. Or happens after the pump has run dry for a few minutes. Low voltage will also make for high amperage.
 

MichaelSK

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Valveman, we have been having lots of thunderstorms with resulting fluctuations in delivered power quality. However, I cannot say that the problem only presents itself when we are experiencing electrical storms/power quality issues. I don't have a recording volt meter to reliably assess that issue. However, we have had numerous brown-outs when my computer UPS would take over and power the computer. It may be that I have not been attuned to whether the pump was running when the brown-outs occurred.

It is very unlikely that the pump runs dry - it's been very wet here, static water level is about 25 feet/120' well. What is "high pressure" range you are talking about? Relay clicks off about 62 lbs.
 

MichaelSK

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Valveman, am I correct in understanding that I could meter the amps from the pump start to pump off and make (you could assess the data) and determine if the thrust bearing was problematic?
 

MichaelSK

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Valveman: Moreover, am I understanding that I could reduce the parameters of the pressure switch in such a way that it would decrease the probability that the overload would trip?
 

Reach4

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I removed the Klixon breaker and installed a 7.5 amp slow-blow fuse. Went through a couple of fuses, apparently there are intermittent load spikes on the "main circuit," which I have not been able to isolate and describe.
10 amps would be the normal slow blow fuse for a 3-wire 3/4 HP pump.

Do you know how many seconds it took to blow the fuse usually?
 

MichaelSK

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Reach4: Oh, 10 amps. Interesting. Supposedly, according to Shakti the "full load is 6.7 amps/110 watts", "Max load is 7.37 amps/1310 watts". I don't have the documentation in front of me now, but I am reasonably certain that I checked to make sure it was for 60 Hz and not 50 Hz. Is there any risk of damaging the motor, if the thrust bearing, or some other hydrostatic/dynamic problem is loading the motor if I used the 10 amp slow-blow fuse?

Unfortunately, I have not had the control box, pressure gauges, and pressure relay under direct observation when the fuse or resets blow.
 

Reach4

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Interesting. Supposedly, according to Shakti the "full load is 6.7 amps/110 watts", "Max load is 7.37 amps/1310 watts". I don't have the documentation in front of me now, but I am reasonably certain that I checked to make sure it was for 60 Hz and not 50 Hz. Is there any risk of damaging the motor, if the thrust bearing, or some other hydrostatic/dynamic problem is loading the motor if I used the 10 amp slow-blow fuse?
Any risk? I don't know. It seems to me that if it fails when it is on a 10 amp fuse it is bad, and not because it was on a 10 amp fuse.

110 watts must be a typo.

It is not normal to fuse things at just above the nameplate rating. They all take a lot more amps to get started.

The reason I asked how long after being turned on the fuse blows is because if the motor does not actually start, fuse blowing would be normal. You did not replace your control box or start capacitor, I don't think.

I got the 10 amp slow blow fuse number from the Franklin AIM manual. You would want a 15 amp circuit breaker or a 20 amp standard-blow fuse as alternatives.
 

MichaelSK

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Guys: I have some data for you. I took the current readings off the Yellow (Y) lead ("line amps"). btw the inrush current is 17.95 amps then immediately is 5.29 amps (34 psi) slowly increases to 5.31 amps (38 psi - 48 psi), then decreases to 5.25 amps as the pressure rises to 60 psi, then decreases further to 5.19 amps (62 psi). Interestingly, the line amps decreases as top pressure is reached. It never approaches Shakti's "full load" much less "max load."

Another interesting anecdote, today we have not had any electric storms, and the old Klixon breaker has not tripped.
 

MichaelSK

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I just got back from the gym. There was some kind of thunderstorm. The relay in the pump control box was broken (carbon dust coming from housing joints). It's toast.... No water.... (!@#$%^&!!!!!!!
 

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That is a starting relay. It is only in the circuit for a split second to start the pump. Cycling usually gets the relay, not lightning. Are you sure you don't have a leak somewhere and your pump is just cycling itself to death?
 

MichaelSK

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No leaks, however we are running a water-to-air heat pump. When the heat pump is running (~ 4x/hr for 5 minutes each time) the pump is off (bladder drains) in ~ 1 minute, the pump is on (bladder filling) takes ~ 3 1/2 minutes. Last night when the relay died, there were no occupants in the house, the outside temp was cooler (evening, rain-cooled), hence probably fewer heat pump cycling.

Valveman, I received a CSV1a from Lubbock less than two weeks ago. I have not installed it because I wanted to get the electrical working first. By the way, that relay is new. I just replaced a similarly burned out relay, which had lasted ~ 3 years. This second relay lasted less than 14 days.

I am inclined to think that there's an electrical issue (coupled with the blown fuses/breakers) not a cycling issue. Admittedly the cycling, as currently configured, is not optimal. However the 3/4 hp pump is running in its optimal efficiency curve and the captive air tank is suitably sized for a non CSV setup - I would not expect that suddenly breakers/fuses, and relays start failing on an acute basis given that the operational parameters have not changed over the three years the pump has been in place.
 

Valveman

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4 cycles and hour adds up to 100 cycles per day, 36,500 per year, and 110,000 times in three years. Think if you started your car 110,000 times how hard that would be on the starter motor and engine. The same thing happens with pumps. The bearings in the pump/motor are dry at each startup like a car engine before the oil pressure comes up, and the start relay is like a car starter, they can only take so many starts.
 

MichaelSK

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Valveman: Interesting numbers, won't nit pick the numbers - only use heat pump 6 mo/yr - but cycle specs from pump companies are not in disagreement with these nominal figures. It's worth mentioning that a 1hp Gould pump ran for 22 years with a heat pump and five-member household. Whereas now we have only a two-member household (more significantly, no teenagers) and most showering is done at the gym not at home, and I no longer irrigate the yard. Seems there is something more than just cycling involved here.

btw: Does your cycle sensor monitor and intercept low and high voltage line conditions?
 

MichaelSK

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I was wondering if pressure switch chatter could be a culprit? I have not directly observed this (neither have I seen any control box reset or failure condition in real time).
 

Valveman

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If you only use the heat pump 6 months of the year you can cut those numbers in half, but it is still a lot of cycling. They don't make pumps as good as they used to. The Cycle Sensor only looks for rapid cycling or a dry well. You will need a voltage monitor to check for brownouts, but I still don't think that is the problem.
 
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