3 - 5 ton compressor trip breakers after ice storm

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bmense

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Hi,

I'm dealing with a new problem that requires me to ask for some assistance. I was called in by an HVAC contractor on a problem he is having with some compressors.

There are 3 different compressors installed on 50amp breakers. They have been working for the past 10+ years until a recent ice storm hit the area. Now none of them will function and all exhibit different symptoms.

The first compressor when activated by the thermastat immediatly trips the 50 amp breaker.

The second compressor's fan runs, but when the relay is closed to start the compressor the main 200 amp breaker in the panel box trips, not the 50 amp that is connected to the compressor. Both the 50 and 200amp breakers have been replaced and the same event continues to happen.

The third compressor appears to be a locked rotor. The load on the line reached 150amps and the thermal overload on the compressor kicks in and stops the unit.

Now I have to add a disclaimer here, this is what I have been told by the HVAC company owner. This was not one of there technicians. Who by the way is really good and I'm pretty sure he is the facts correct. With that said he also told me that a number of 'do gooders' have taken a look at this and they are all scratching their heads.

I'm looking for some ideas from other experts out there as this sounds really strange to me. The only 'event' that has occured since they were working was an ice storm. Any ideas on what to look for and what to check out on this?

I'm purposely leaving the question very broad as I want to hear all the simple and advanced ideas out there. This might be very simple to fix once I'm out there, but based on the information, I haven't yet heard of a situation like this.

I'm heading out there tomorrow, so any quick replies greatly appreciated.

Thanks,
Brian
 
I will guess they compressors are all junk.

During the ice storm they ran (or tried to run) with one phase lost or severely under voltage.
 
I might agree with iwire unless he is wrong.

The cold may also have damaged some of the internal parts.

Not really being familiar with ice storms as such, when it froze it may have created a path between, who knows what, phases, ground, maybe locked the blades.

Do let us know what you find.
 
compressors

compressors

brian
i have a couple of questions

1 are all three located in the same panel box

2 since all three are old what are the lra's for these units

3 are they single phases or three phase

afw.
 
There was probably a surge of sorts during that ice storm (such as a downed primary line on the secondary) that blew all those compressors at the same time.

Not much you can do except replace all those units.
 
bmense said:
Hi,



The first compressor when activated by the thermastat immediatly trips the 50 amp breaker.

The second compressor's fan runs, but when the relay is closed to start the compressor the main 200 amp breaker in the panel box trips, not the 50 amp that is connected to the compressor. Both the 50 and 200amp breakers have been replaced and the same event continues to happen.

The third compressor appears to be a locked rotor. The load on the line reached 150amps and the thermal overload on the compressor kicks in and stops the unit.
Click to expand...

Brian, first thing off check voltage. Make sure you have the correct voltage whether it is 1 phase or 3 phase. Then look at the contactors to make sure they are in decent shape. Then when they start put an amp meter on each leg to see what the load is when it kicks off. Check the voltage when they are trying to start. Sometimes if you have a loose connection it will show up under a load. Sometimes it may sound like a locked rotor but it may be a single phase situation. If it is a locked rotor then all three phases will be high. Just remember when you are troubleshooting to stay with your basics. Keep us posted, Good Luck !
 
dduffee260 said:
Brian, first thing off check voltage. Make sure you have the correct voltage whether it is 1 phase or 3 phase. Then look at the contactors to make sure they are in decent shape. Then when they start put an amp meter on each leg to see what the load is when it kicks off. Check the voltage when they are trying to start. Sometimes if you have a loose connection it will show up under a load. Sometimes it may sound like a locked rotor but it may be a single phase situation. If it is a locked rotor then all three phases will be high. Just remember when you are troubleshooting to stay with your basics. Keep us posted, Good Luck !
Click to expand...
This is a great plan to follow. The first thing to do is make sure your voltage is proper. If this is a three phase system this could be single phasing(trying to run with less than three phases.),however, it sounds alot like three bad compressors or the oil in the compressors could be too cold. Do like ptonsparky said and check your compressors phase to phase with an ohmmeter and phase to ground with a meggar if this tests good try heating up your compressors with a portable heater.
 
iwire said:
I will guess they compressors are all junk.
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Right as usual. The only one that ever stands a chance of working again is the one that is tripping the overload. If the compressor thaws out then there is a very slight chance. When they trip a 50 Amp breaker I have never needed a megger just an ohmmeter. Those winding are probably shorted dead to ground. It's not my problem to figure out what caused it. AC units are not designed to work below around 60 degrees F.

I can't believe that an HVAC Tech. has any problem figureing this out. Sounds more like a homeowner or handyman.
 
Obviously compressors and HVAC implies air conditioning. The original poster did not give his location but the presence of and ice storm and considering that this is January, why would they need air conditioning?
~Peter
 
peter said:
Obviously compressors and HVAC implies air conditioning. The original poster did not give his location but the presence of and ice storm and considering that this is January, why would they need air conditioning?
~Peter
Click to expand...
Or a heat pump
 
Hi All,

First let me say thank you for everyone's suggestions, comments, and assistance. I did make it out there today and wanted to followup with everyone to address what was discovered.

I was a bit surprised when I got there to find that the systems where not heat pumps, but geothermal systems. Since they are geothermal the condensors are all inside the building. So any direct affect by the ice is not a consideration.

Not all the systems failed right away according to the staff. It took a period of 3 days for them to fail. One failed each day. In addition to those systems they also had a recirculation pump fail, a septic system pump fail, and a PA system reset.

All the systems single phase and are connected into the same panel. All the voltages test out fine.

The unit that was tripping the main breaker had a short to ground in the condensor.

The unit that tripped the breaker had a short in the winding.

The unit that pulled 150amps, well I'm not sure what it really the problem with it. It simply pulls almost 150amps and then the thermal overload protection kicks in. I'm guessing that it does have a locked rotor.

Since the condition that caused the failures has since gone away, I'm not able to pin down an exact cause. But I'm confident that some event accured with the electrical supply that caused the failures.

The part that makes me question the concept of a drop in one leg is that the contacts should have released and terminated the circuit eliminating the undervoltage situation.

That is about it. Thanks again and if you any other comments please post them and I'll attempt to let you know what I know.

Brian
 
ptonsparky said:
A drop in one leg does not necessarily mean that the control circuit drops out in time to save the motors. Use a phase loss monitor to achieve this protection. Economical ones for HVAC systems are available from Johnstone Supply.
Click to expand...
we use them all over the place and they save us a bunch of $$$$$$$$$$$
 
bmense said:
Not all the systems failed right away according to the staff. It took a period of 3 days for them to fail. One failed each day. In addition to those systems they also had a recirculation pump fail, a septic system pump fail, and a PA system reset.


Since the condition that caused the failures has since gone away, I'm not able to pin down an exact cause. But I'm confident that some event accured with the electrical supply that caused the failures.
Click to expand...


I would check to see if others in the area have had similar problems ( the only test after the fact ). If it was a power company surge that caused the problem then they should pay for repairs. It would make the customer real happy.
 
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