Freezer keeps tripping circuit breaker

[olivero]

Not a bad idea, I will do that and let you know what happens.

 

Regarding the refrigerant pressure, the machine had been running for 2 years, 24/7 with no issues. Then this started, I would suspect a low pressure more than a high pressure but the cooling efficiency has not decreased, It is still keeping its desired range of -2 – 4 degrees. So I doubt it being low pressure and considering it ran for 2 years with no issues until this, I would doubt it being high pressure as well.

 

I have gone the route of looking for overheating connections, in fact, that’s what I originally thought it was, maybe a loose connection or something. I have measured the load on its circuit without anything plugged in and its 0. As soon as I turn on the freezer, the load goes up to 9-10 Amps and stays there. The first thing I found was the plug or cord cap (depends on who taught ya) had one of the prong bases slightly melted, looked like it got too hot, so i changed the plug. Did not solve it, So I changed the outlet, then the breaker and it is still the same problem.

 

is getting like 112 V, no significant voltage drops anywhere.

[badbozo2315]

>I have gone the route of looking for overheating connections, in fact, that’s what I originally thought it >was, maybe a loose connection or something.

 

I would like to point out to future troubleshooters, just to keep you straight, a loose/overheating/burnt connection will, by itself, never cause an overload condition- a circuit will not draw more amperage than normal through a loose connection.  Doesn’t work like that. Go back and read up on Ohm’s law, and consider what happens at a loose connection.

 

A loose/corroded/etc connection will cause voltage drop, perhaps, and arcing maybe, that might build up carbon that may track to ground at high voltages. Or burn away yer trusty orange wirenut.

[cliffie]

Since your solutions so far haven’t worked, and you have run a load check and you don’t think the amperage is spiking to trip breaker you might try inter-changing 20 amp breakers in load center to make sure you don’t have a defective breaker. One other thought is: the evap. coil not clogged, or coil fan dirty?

[olivero]

The evaporator is fine and clean, we keep a dacron (r) filter on it and have changed it so its clean, I already changed the circuit breaker in the panel to a new one and that did not solve it.

[hdrco]

I would like to clarify does it trip the breaker overnight or when is in use. Is some one there when this occurs? Also you said light bulbs so i suspect there are door switches.

[olivero]

The unit is on 24/7. when this issue originally came about it was every 5 or 6 hours. Then i changed start components to the compressor and the problem “went away” for 1 week and a half. Then it tripped again, but It was only doing it every day or 2. Now its doing it every week or so which is why its difficult to tell what solutions are working as I won’t know until a week later. I changed the door switch and the light bulb already, I doubt its that.

[fixbear]

Were you amp readings taken at the original 5 to 6 hour trip or later? Before the change out of the start relay/cap’s or later. Did you check the thermal overload face for damage The overload on these compressors are a very small diameter so the accuracy and consistency of them suffers.

 

          You originally said you megged the compressor windings, but the values you showed indicate that I believe you performed a resistance test. If that was a megger test you have a short with such low ohm’s. Meggers supply high voltage to test insulation and read the value of leakage to ground. Usually in milliamps.

.

     Make certain that the unit’s polarity is correct. It’s troubling that the overload is not tripping before the breaker. This would indicate a short to ground if the breaker is HVAC rated.Off the top of my head I believe the overload is 14.2 amp. Been a long time so I may be off a amp or 2..

     . Is the breaker HVAC rated?.  Aluminum or copper buss in the panel?  Make/ style of breaker?

 

     When you replaced the start components, did you us the Danfoss box or aftermarket components?

Hopefully I have provided a bit of food for thought. Good luck and let us know what you find. I hate intermittent faults.

[olivero]

I used Danfoss OEM parts. I don’t know if the breaker is HVAC operated, considering I have 3 more of these units around the building, installed the same way, I doubt that would be the problem. I did Amp readings before and after and they have not changed in the long run, I cn only assume they spike at some point and trip,but I have monitored it for 8 hours every 30 minutes I went and checked amp draws and just as I came to check it again, it tripped the breaker. This was back when it tripped every 5-6 hours. But for that entire period there were no changes in Amp draws, they were steady at 8 or 9 Amps.

 

 

Here is a picture of when  it was Megged. (its a very chinese Megger)

[ectofix]

Thanks for the pictures.  Those tell me something.

 

Regarding the megger reading:

 

If I’m reading that right, it’s around 600-700 KΩ.  I don’t like that.

Now, there’s much deliberation on what an acceptable megger reading should be.  Some folks abide by a 1000Ω per volt rule-of-thumb…so you’d be good.  Others go so far as to say 100MΩ is a minimum acceptable reading.  If any less, then it’s done.

 

ME? If I see less than 2MΩ in a 120vac component when read to ground with my Fluke DMM, then I go get my megger to confirm there’s insulation breakdown.  Usually…BAM!  It’s done. replace it.

 

Where I got 2MΩ?  That’s just from my own experience. 

 

Regarding that compressor:

 

Another thing which concerns me is that compressor braze joint in your picture.  THAT’S not factory.  That compressor has been replaced before.  Then I did a quick internet inquiry that told me the system you’re working on should be charged with R404A.  That means POE oil is in it.

 

If that system wasn’t properly flushed during the compressor’s replacement, some traces of old oil might have been left behind in the system.  Otherwise, if the system was improperly evacuated, the new compressor lost its nitrogen cap before install…or other possibilities…then there’s acid in there.

 

Polyolester (POE) oil is hygroscopic and, when mixed with moisture, forms acids.  Those acids can effectively break down a compressor’s motor winding insulation.

 

The combination of a formerly replaced compressor and the relatively low megger reading concerns me.  I’d be one to say…do an acid test.

 

If there’s acid in there, then replace the compressor.  But correctly.

 

I’m not declaring I’m any refrigeration expert.  I only did it a mere ten years and DON’T do it anymore.  But that’s what I’m seeing nonetheless.

[badbozo2315]

I see the problem.  Your meters are too clean. 

 

In fact, the inside of that sled area and the surrounding kitchen look like no place I get to work in.