Breakers, overload tripping

[icefield]

Sorry for long post.Anyone have much problem with breakers.I have two reach in units that are tripping breakers, cannot catch in the act. Different customers, different locations.Unit one-Freezer - adjusted CPR to reduce amp draw after defrost was at >13A, now does not go above 12A (15A breaker) when I watch it, I left site and reportedly the same problem.Unit two-Cooler, compressor draws only 8A, unplugged cabinet lights and just running cold pack to isolate problem, changed wall receptacle and plug end because they showed signs of arc/heat damage.Thinking this the likely cause, left site with unit running and called back - breaker tripping.Couple hours ago I switched to another circuit for testing on another breaker.I suspect compressor windings have dead spot that show up on start up when I am not there - is this possible? Unit three -Delfield prep table- is short cycling on compressor overload (34Amps at overload, 1/2hp comp), runs for about 8sec then opens overload, resets after 15sec, starts again for 8sec etc. Could this be the result of bad bearings or sticking start relay? What experiences have others had with these scenarios?

[bananas]

Could be a number of things. I had a reach in trip the beaker due to light ballast in reach in.

[hoshiscotsmanito]

For 1/2 hp remove all start component and install a 3in1 or SPP8 check amp draw, if high check for slugging comp. If not slugging and high draw prepare to replace comp. If amp draw is within limits replace start components ASAP.

For cooler 12 to 13 amps is high for a 15 amp breaker. On start-up it will probably trip. What is recommended amp draw? If in limits try moving unit to a 20 amp circut. If high check individual components to isolate problem.

Freezer check draw at startup if high look at start components since you have eliminated other sources of draw.

If customers are like mine every outlet has something plugged into it. Make sure they have not moved something to a new place and check draw at breaker. Make sure overload is not comming from another piece of equipment and boxes getting the blame

[icefield]

Thanks a bunch, will try your suggestions.
I found faulty start relay on the 1/2hp unit, didn't let the start winding drop out - hence high amperage tripping overload - should have checked this before, my brain shut down at the time.

[Freezeking2000]

15A breaker is too small, maybe when in defrost the amps rise while heaters and compressor is pumping down if equiped with a pump down.

[markettech]

Originally posted by hoshiscotsmanito
If customers are like mine every outlet has something plugged into it. Make sure they have not moved something to a new place and check draw at breaker. Make sure overload is not comming from another piece of equipment and boxes getting the blame

Had a customer that had a similar problem - traced it out to the cleaning crew plugging a vacuum cleaner into the same outlet as refr. unit.

Check amp draw at breaker and also check to make sure wiring is tight at breaker as I have also seen breakers trip from overheating.

[Dowadudda]

3 different accounts. 3 different compressors, three different applications. Just how thee he ll do I even try to guess. There is simply no way anyone here could give you an answer exactly. The best thing a guy could do is to list each and everything someone would normally check. But I am too lazy to list them. Anyone else?

[idontgetit]

Have had a TON of mystery breaker trips caused by fan motor wires worn through, check all the evap fan wires, condenser fan wires, it happens a LOT!

[rocket]

turn to turn shorts may be your answer
easy to check, read winding eresistance and compare to published specs, should be within 5%

this is quite common but few check for it

[jaybee]

I had one today where i could not find the breaker had no power in the kickplate( feed ).What is the best type of circuit tracer to use .

[icefield]

Thanks again for the input everyone. hoshiscotsmanito and Freezeking2000 - with regards to using a larger breaker, coldstream rates this as a 12.2 amp unit and further specs it for use with a 15 amp circuit(RFSC 48 ALC). I would like to try suggestion of 20amp circuit, however very difficult in this case as the building is a relocatable structure, multiple units (skid shacks) placed together to make a modular work camp in a remote bush camp - very common for my neck of the woods - you may be familiar? Anyway, long drive from home and I hope to get it right the next trip I make to site. As you can imagine the electrical is not configured for anything but the required equipment as spec'd and installed. I may have to get creative to try 20 amp circuit. Would a hard start kit cause long term damage to a properly functioning compressor - if further tests show that this unit trips on start up and I install a hard start to reduce start amp draw? May this allow unit to operate on the 15 amp breaker? I have never installed one of these, which is most recommended for a cap tube 3/4hp,115V freezer?
As for my other breaker tripper, start relay appeared ok but when I pulled it out it broke apart on me and contacts looked burnt, compressor ohmed out fine and ran within amperage rating (don't have a meggar), so I ordered new electrics and hopefully this takes care of problem. Hey, do things like this ever fall into that 'hopefully I got it right' category for others, or do you all just gitter right first time?
Recommendations have been good food for thought so far. Newbie to site and very appreciative to have found a bunch of expertise so readily available, as I'm fairly inexperienced and on my own in a small town. If I can pass any of my knowledge on I would also be glad to - its the thought that counts right? I'll work at shorthand and abreviating to make shorter messages.

[mccool]

20 amp breaker for the 2 door Coldstream, we have lots of the same scenario always get wired to a 15 amp breaker and eventually become nuisance trip problems, change to 20 amp all good.

Another item that has helped me out in the past is the Supco "SUPR" relay, universal potential relay that works on a time function, can be used to replace all kinds of start relays, always had problems with Hussmann self contained merchandisers at some stores tripping breakers, installed the SUPCO and problem was solved.

[conaire-one]

Wire size is determinded by the overcurrent (Breaker) size, which is determined by the unit ampacity,.

The unit should have a minimum circuit ampacity listed on its nameplate.

NEC(2002) 240.4(D) The overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper. After any corrections factors for ambient temperature and number of conductors have been applied.

[mccool]

Agreed wire size must be right, these were all 12 gauge with 15 amp breaker, safe to bump to 20 amp.

[icefield]

Went to Coldstream freezer - wires are #14 and so cannot just increase breaker, although I switched breaker with another 15A - they said they had another 'weak' breaker and changed - solved tripping issue. I'll know tomorrow.

[icefield]

Haven't solved problem. Lengthy discussion with Coldstream technical support, they say that changing to 20A does not solve the issue as they are actually drawing LRA when this occurs. They admit it happens with these models on occasion, but does not know reason? He recommends recording voltages when the trips occur due to the generated power on site, but I ain't gots no fancy data recordin' instruments in ma truck. There is an identical unit beside this one that does not have any problems - I don't see power supply being the problem, I got 121V. So after every possible other thing has been eliminated to their satisfaction they will warranty a compressor replacement which will rectify tripping (unit is Aug05). Off I shall go to change a mystery compressor! Thanks for the help - will post results later. Hopefully we get it going and others can just change the freakin' compressor without spending a day trying to figure out other electrical problems. So simple, cross fingers. Good thing customer has lots of $ and just wants it fixed!

[icefield]

Done. New comp. and all is well. Obvious?