Contactor Heater Packs

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goldstar

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I had a service call at a day camp that has a lake with a 240V aerator-sprayer. The control unit for the aerator as well as the aerator have been in existence for (I don't know how) many years. There's a 2-P, 30A breaker inside the control panel, a HOA switch on the front and a 3-pole contactor with a CH heater pack like these on the load side of the heaters :

http://www.newark.com/eaton-cutler-hammer/h2011b-3/heater-pack/dp/48K1141

This aerator has been running steady since the camp opened in May. Suddenly the aerator runs for about 20 minutes and then the heater pack trips out. When I got there I clipped an amp-probe on and the unit is drawing 15.5 amps steady on each leg. The heater pack ranges from 9A to 14A (adjustable). I have no idea what the unit was initially intended to draw but I guessed the heaters were getting too hot. So, I changed them out for the next size up which ranges from about 14.5A to 20A. I set the dial for 15.5A and the unit is running.

My questions are :
  1. Did I do the right thing by increasing the heater pack amperage ?
  2. What is the proper way to size these heaters ?
  3. What is the exact purpose of these heaters ?
  4. Why can't a fuse or breaker do the same thing ?
  5. Could I possibly damage the unit or the control by increasing the size of the heater packs ?
  6. Could there be something wrong with the aerator ?

Thanks in advance.:thumbsup:
 
Heaters are typically sized at 115% of the motor nameplate current. I would guess that the original installation had the correct size heaters. What does the nameplate say regarding the motor current?
 
infinity said:
Heaters are typically sized at 115% of the motor nameplate current. I would guess that the original installation had the correct size heaters. What does the nameplate say regarding the motor current?
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I would have to get in a boat and row out there to find out. If they continue to have problems I'll have the maintenance crew pull it out and see if I can get that info. Until then I'll have to pray that I don't burn the pump out. I'm guessing that if they continue to have problems it's a sure bet that something is wrong with the aerator.

The heaters that I pulled out were definitely hot but they didn't look burnt. Have you ever seen these heaters go bad ? Unless they are severely damaged I can't see any visible reason that they wouldn't last forever.
 
You did your customer a disservice.

I'm not sure why someone would pay for an electrician to come out and troubleshoot a problem, but instead the electrician simply changes parts without verifying any motor data or doing any troubleshooting. Heaters tripping/getting warm may only by a symtom, not the problem.

On top of that, the pump stands a higher probability of burning up now with larger heaters installed.

You need to know the motor FLA and SF. Without that, you're just guessing. Which isn't the same as troubleshooting.
 
Cow said:
You did your customer a disservice.
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You may be 100% correct.
I'm not sure why someone would pay for an electrician to come out and troubleshoot a problem, but instead the electrician simply changes parts without verifying any motor data or doing any troubleshooting. Heaters tripping/getting warm may only by a symtom, not the problem.
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That's why I posted the questions that I did. If I were familiar with the product and if had that info I wouldn't have posted the questions here in the Forum. If I had that info for you do you have any recommendations or things that I should be looking for ?
On top of that, the pump stands a higher probability of burning up now with larger heaters installed.
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The pump is in submersed in the water. I only increased the amperage setting by 1 amp. Unless the pump was on its way out anyway what possible damage could I cause ?
You need to know the motor FLA and SF. Without that, you're just guessing. Which isn't the same as troubleshooting.
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I would say that could be construed as a "guess". Wish I had you here to help me but I'm not flying you in from Oregon :p
 
With the high temps. of late seaweed, or some other blockage.
Pump wearing out.
Overloads could be worn out, who knows how many times they were reset.
The overloads must have been working, as an old system so no to the increase of amps.
 
OL heater elements are there for one purpose; to protect the motor from the damaging effects of excess heat due to excess current flow. By putting in larger heaters, you are now allowing that motor to pull more current than it is rated for. The old rule of thumb on replaceable heaters is that for each “next size up” you put in, you cut the motor life in half. And what if you are the SECOND guy to do this, ie the motor is rated for 10A and the LAST guy to look at it bumped the heater size by one? So is that a disservice to the customer? I happen to think so.

Yes, we have all been under that pressure to “get ‘er done” and users often ask if you can just make the “problem” go away, which for them the “problem” is seen as the tripping. But that’s the SYMPTOM, not the problem. As a responsible electrician, you have to explain this situation to them and help them find the REAL problem. It could be a low voltage situation (did you check the voltage when running?) and or a mechanical problem like those mentioned above. In similar situations where a machine must be pulled just to get the nameplate data, that’s usually how the mechanical issue is discovered. But if ANYONE has records of what brand and model of aerator they have, you can probably find out the motor data on line. You may STILL end up pulling the motor (after eliminating the electrical issues), but it would confirm whether the right heaters were in there to start with.
 
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Jraef said:
OL heater elements are there for one purpose; to protect the motor from the damaging effects of excess heat due to excess current flow. By putting in larger heaters, you are now allowing that motor to pull more current than it is rated for. The old rule of thumb on replaceable heaters is that for each “next size up” you put in, you cut the motor life in half. And what if you are the SECOND guy to do this, ie the motor is rated for 10A and the LAST guy to look at it bumped the heater size by one? So is that a disservice to the customer? I happen to think so.

Yes, we have all been under that pressure to “get ‘er done” and users often ask if you can just make the “problem” go away, which for them the “problem” is seen as the tripping. But that’s the SYMPTOM, not the problem. As a responsible electrician, you have to explain this situation to them and help them find the REAL problem. It could be a low voltage situation (did you check the voltage when running?), it could be a severe current imbalance (if its 3 phase) caused by a voltage imbalance of a bad connection (did you clamp all wires and record the current in each phase?) and or a mechanical problem like those mentioned above. In similar situations where a machine must be pulled just to get the nameplate data, that’s usually how the mechanical issue is discovered. But if ANYONE has records of what brand and model of aerator they have, you can probably find out the motor data on line. You may STILL end up pulling the motor (after eliminating the electrical issues), but it would confirm whether the right heaters were in there to start with.
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Thanks. That's the best advice so far.:thumbsup:
 
If the intake screen on the pump were clogged wouldn't the current go down? Is it possible that the pump itself is clogged?
 
Likely is a centrifugal pump, blockage in the line will decrease load on the motor not increase it.

If something has changed and there now is more flow then there originally was that would increase the load on the motor.

You could have bearing going out (whether in the motor itself or any driven component) and increasing load on the motor.

Assuming overload selection was done correctly when first installed - as others mentioned you didn't fix the cause and only put a band aid on the symptoms.
 
Thank you all for your advice. I went to the camp yesterday and noticed that the aerator was off and the heater pack tripped. I pushed the reset and the aerator started up but I then physically shut it off. I'll have the grounds crew pull it out and check for any blockages. If I find anything out of the ordinary I'll post my findings.
 
Submersibles used in that application are not running against much head pressure and most likely have been pumping well into or above the SFA since day one. We have a customer that replaces theirs every few years. I'm guessing throttling it back with a valve is to much trouble or they like to see the stream.
 
goldstar said:
Thank you all for your advice. I went to the camp yesterday and noticed that the aerator was off and the heater pack tripped. I pushed the reset and the aerator started up but I then physically shut it off. I'll have the grounds crew pull it out and check for any blockages. If I find anything out of the ordinary I'll post my findings.
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Often true. The OEM needs 4 HP but instead of providing a 5HP motor and having it run forever, they sell it with a 3HP 1.25SF motor and run it into the SF continuously, knowing full well that the shortened motor life will still be outside of the warranty period...
 
Well Said

Well Said

Jraef said:
OL heater elements are there for one purpose; to protect the motor from the damaging effects of excess heat due to excess current flow. By putting in larger heaters, you are now allowing that motor to pull more current than it is rated for. The old rule of thumb on replaceable heaters is that for each “next size up” you put in, you cut the motor life in half. And what if you are the SECOND guy to do this, ie the motor is rated for 10A and the LAST guy to look at it bumped the heater size by one? So is that a disservice to the customer? I happen to think so.

Yes, we have all been under that pressure to “get ‘er done” and users often ask if you can just make the “problem” go away, which for them the “problem” is seen as the tripping. But that’s the SYMPTOM, not the problem. As a responsible electrician, you have to explain this situation to them and help them find the REAL problem. It could be a low voltage situation (did you check the voltage when running?) and or a mechanical problem like those mentioned above. In similar situations where a machine must be pulled just to get the nameplate data, that’s usually how the mechanical issue is discovered. But if ANYONE has records of what brand and model of aerator they have, you can probably find out the motor data on line. You may STILL end up pulling the motor (after eliminating the electrical issues), but it would confirm whether the right heaters were in there to start with.
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Very well stated Jraef.
What I can say is going back to when I was in a Service Truck for the 2nd largest shop in Dallas, TX......
It is often times possible to get painted into some severe no win corners, where both the customer and then your boss will go for blood.
I have been in such situations where the Techs' that had gone before me were able to skirt around the real issues and somehow butter the customer up with what in retrospect must have been all manner of sweet lies before I had to show up on the jobsite and be the one to go telling the very blunt truth of the matter to a customer who had been living in illusion for years. I can think of 2 incidents where my honesty and the magnitude of the impossible to win scenario got me in major trouble for speaking the truth of the matter that both the customer and the boss did not want to hear. Its very bad when you have an employer who is making a judgement on things from a remote position and also not listening to what you are telling him with regards to the potential pitfalls of what you are seeing, and is not supporting your position on the matter in the least.
Its a tough call to have to run " worst case scenarios " all the way out mentally and then verbally in order to arrive at what needs to be done.
The Folly of what we all have going on can become transparent and your job can be on the line if you choose to stand your ground.
There is nothing easy about those kinds of calls.
ON the subject of Motor Starter heaters.
I always go with the general protocol that more often than not, you are going to find a lot of starters set up wrong in the field in smaller commercial settings.
This has been my experience, so I never assume that the OL heaters or setting is correct until I can verify the motor nameplate.
 
General rule of thumb has 2 hp around 12 amps and fits with heaters that were in place. Doubtful that it was a 3 hp rated around 17 amps but heaters were picked based on actual running conditions.

Control pump might have brand and model number. I’m betting on time for a new pump.
 
Have you priced heaters lately? Holy crap! And that’s if your supply house can even get them. Last December, I replaced a 75 year old 40 hp lineshaft turbine Pump with a 30 hp. Needed to change the heaters. They were $100 each at my local supply hose and they only had two, needed three. Got them from a surplus breaker place for atop down $15-20 each. Got two sets of different amperage range so I was covered.

if I was to do it over again, I would have retrofitted a Symcom 777. Or even better the new Littlefuse MP8000.
 
Just an update for all of you who responded to this thread, the maintenance crew pulled the aerator out of the water and found a rope stuck in the impeller. They removed it and the unit has been working for several days now. I'll have to make a trip back and re-install the original heaters. Thank you all for your advice.
 
goldstar said:
Just an update for all of you who responded to this thread, the maintenance crew pulled the aerator out of the water and found a rope stuck in the impeller. They removed it and the unit has been working for several days now. I'll have to make a trip back and re-install the original heaters. Thank you all for your advice.
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That is one case where restricting the flow increases the amp on a centrifugal pump.:D
 
goldstar said:
Just an update for all of you who responded to this thread, the maintenance crew pulled the aerator out of the water and found a rope stuck in the impeller. They removed it and the unit has been working for several days now. I'll have to make a trip back and re-install the original heaters. Thank you all for your advice.
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I have run into that sort of thing several times - motor starts tripping an overload and you can't convince user that something has changed and you need to find what it is and not just turn up the protection level.
 
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