Breaker trips for Reach-in freezer

[jayryu]

The troublesome freezer is 2-solid door upright reach-in type. Only 3 years old. I've got 5 times service calls in a month from the customer and found the breaker for the freezer tripped. After resetting the breaker, it worked fine for days. And same condition repeats. I checked the current from the breaker and found 53 amps and the breaker trips in 5 seconds. But when I reset the breaker second time and the freezer works fine for days.
The data as follows.

Total design amperage : 11.0 amp 115V
Breaker rating: 15 amp
C/U : ASPERA T2180GK906HG68, 115V 60 Hz, 3/4Hp low temp. CSR , 404a , captube sys. air-cooled.
Amperage of compressor : 7.0 +- 5%

There is no abnormal sound or noise when the unit is working, only normally working sound. I think the breaker trips when the freezer cycles on. I couldn't check it because I can not stay the site all day. I hope you gentlemen to help me. If I missed something to post, teach me and I 'll correct asap.

[chemi-cool]

If everything you have checked is OK, then there could be problems with electric supply.

I would change the circuit breaker, they can be faulty.

If you can get a thermo-graphic picture, you can see in seconds where the problem is.

[That's too cold]

The manufacturer should have a minimum circuit breaker size. If so use it. If not use a 20 amp (or 30 amp) provided the wire size is large enough to handle 20 or 30 amps.

[chilliwilly]

What's the MCB/circuit breaker service rating? Is it designed for motor rated use? I know the CA code doesn't require a small hermetic to have a fuse rating or setting in excess of 200% overload, but sometimes when a pot gets older it behaves differently than it did when it was new.

Is it hot gas defrost or or electric? Maybe the defrost heater is starting to short somewhere on earthed/grounded parts. Or the defrost circuit is faulting.

Have you carried out an insulation test on the pot? Maybe that is on its way down and causing a higher starting and

It may be a hard starter developer, have you checked if the high and low side are balancing out when the pots at rest?

Or like the other poster says change just simply change the breaker the next time you call to it. And check the system over for faults and wear and tear.

[jayryu]

Hi, chemi-cool, what is a themo-graphic picture? How can I get it?
Hi, chillywilly, Here is some more data.
Breaker rating : 15A,
Defrost : Electric defrost controlled by PCB. I have checked the defrost heater insulation and it was OK.
Pressure balancing : Looks normal , balanced in 3 ~ 4 min.
I will try to change the breaker to 20A one, if it happens again.
Thank you everybody again.

[chilliwilly]

Hi, chemi-cool, what is a themo-graphic picture? How can I get it?
Hi, chillywilly, Here is some more data.
Breaker rating : 15A,
Defrost : Electric defrost controlled by PCB. I have checked the defrost heater insulation and it was OK.


What about the pot? AKA compressor.

[SOKAL GUY]

I had the same problem a couple months ago, the same machine was giving exisive sirvice calls, i checked amperage and resistance on everything i imagined was bad, i checked wire gauge running to unit and the hole nine yards. Long story short i replaced the breaker and problem solved

[That's too cold]

Occasionlly, if the compressor short cycles (restarts quickly before pressures can equalize) the lock rotor amps can easily trip the breaker. I don't no if Canada has HVACR type breakers that allow lock rotor amperage to pass without tripping. If not, a 20 or 30 amp breaker would work. Just make sure the power wires feeding the breaker is large enough.:D

[chilliwilly]

As far as I'm aware Canada has a very similar standard to the US. The main difference it has to be CUL and CSA, not just UL and NEEMA.

[chemi-cool]

For thermographic scan search google for Flir.

One more thing that came to my mind is the compressor capacitors, when one or both go wrong, the result is high currant draw, have them checked out.

[jayryu]

Thanks every gentlmen.
It is third day after last service call. I phoned to the customer and found The freezer works fine. I did nothing but reset the breaker. I checked both capacitors with capacitor tester and they were OK. I am waiting service call happen again and going to change the breaker. I 'll update.

[G Cook]

How about the compressor relay? Could it be sticking intermitantly when the compressor is trying to start and causing the breaker to trip?

[Tayters]

Could be many reasons. My turn. I'll say intermittant short to earth on drain heater.

Good Luck,

Andy.

[DTLarca]

Divide and conquer.

Take a handful of same size or smaller breakers and divide the different parts of the circuitry up. Wait for which breaker trips then divide again - if still necessary.

[jayryu]

I was called to the site today again. I checked amperage of the compressor on starting and found compressor itself was started but the peak amprerage varies 53 ~ 35 amp every trial and the amperage does not decrease at all and breaker trips.
It was the first time that I found the abnormal amperage draw on compressor during a month. On my every visit I found the amp of compressor was abt 18 amp peak and decreased to 8 amp imediately. I think the culprit was the seized compressor.
I did not changed the compressor yet because the customer hesitates to decide due to the high cost.

Thanks gentlemen. I am very happy to be a member of this forum and very much appreciate to every members.

[jayryu]

Hi G Cook,
Your guess was right. I thought the compressor seized. Two days ago, I have concluded the seized compressor as I posted. But it was almost impossible to find replacement compressor here in Toronto, Canada. I thought again if there is anything I missed. Today I tried again to check the relay and seemed to be normal but a little bit weak in my feeling. Anyway I changed the relay and the unit is working fine. I requested the customer to pay me with post dated cheque for fear of same trouble happening again.