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young gun
31-05-2011, 10:05 AM
gday,

had a circuit break tripping on a little 'iarp 120m' display fridge today, after looking around, found it would not trip with the compressor disconnected. found the run/start capacitors to be fine, but found the start relay smelt like a smoke, but looked in good shape. i tested the compressor with a megger, and measured the resistances between windings, and compressor tested fine. tested the wiring from the relay to the compressor and was fine.

i changed the start relay, run/start capacitors and the o/l. After the new guts were installed, still trips the circuit breaker. But it trips the circuit break instantly, to fast to even get an amperage reading. I would think if compressor was seized it would usually try and start for at least a few seconds before tripping safetys...

Im sure it is a seized compressor, but just havent really seen one trip the circuit breaker so quickly. Everything else in the system runs fine while comrpessor is disconnected, and the compressor is fine electrically.

thoughts???

mikeref
31-05-2011, 11:36 AM
Young Gun, should have used the Megga to test windings to earth. Less than 2 megs to earth in Australia, and possibly elsewhere, will trip earth leakage and if less than 2,.. will drop circuit breaker..Mike.

young gun
31-05-2011, 12:18 PM
yeah mate i did test compressor with megger, and there is no earth leakage from compressor to earth. and also tested resistance between windings, had approx 9ohms, 7ohms, 2ohms..... Which seems pretty close to what it should be.. like i said compressor is electrically good. Cheers......

Tesla
31-05-2011, 12:54 PM
Hi Young Gun
The cct breaker or comp could be no good but try this, for a cold start when comp is cool, switch it on and in the first second or two while it is trying to start give the comp a little kick with your steel cap boot... I have done this and 8 out of ten times it has given life (limited sometimes). I would normally do this with a DOL tester - built with a slightly larger start cap and push button start with a 10A CCT breaker and a switch to bypass the run cap. If it had been sitting for a while and the internals got a little sticky the above method frees it up. I would include at the end of the report that the compressor could be worn and may fail.

monkey spanners
31-05-2011, 04:32 PM
Could be a duff breaker, could you try running it off another ring main?

chemi-cool
31-05-2011, 04:48 PM
Why messing about with it?
You have changed the starting components and ...nothing.

Even if you will make start somehow, its gone.
When there is a doubt, there is no doubt!! Replace it.

Grizzly
31-05-2011, 10:18 PM
Hi young gun.
I am with chemi with this one, although in fairness I may consider some of the other options mentioned if the costs of replacement were down to me!
Just one question are the 9,7 & 2 ohms values you mention. the readings you are getting across each pair of windings?
Because if they are you have a huge imbalance.
I have always worked upon within 10% difference max (Others may correct me there?).
Usually they are pretty close and certainly not anywhere near as bad as your readings.
Grizzly

install monkey
31-05-2011, 10:28 PM
its common/start/run values.
whats the locked rotor current when u fit a clip on ammeter
if resistance and insulation are ok,if the capacitors,relay are new-looks like ur compressor is siezed/siezing

Royal241
01-06-2011, 12:17 AM
a digital meter would not help, try an analog, the one with a needle, they tend to catch that locked rotor amperage.

young gun
01-06-2011, 06:58 AM
Hey guys, decided to change the circuit breaker just incase, and wamm... faulty circuit breaker... compressor is fine. thanks for the help guys....

chemi-cool
01-06-2011, 09:12 AM
Hey guys, decided to change the circuit breaker just incase, and wamm... faulty circuit breaker... compressor is fine. thanks for the help guys....

Well done!
This should have been your first stop.

There are digital ampermeters with a "peak" knob. Get one and you can read the starting currant.

Tayters
01-06-2011, 08:54 PM
Good on you for questioning what would on the face of it looked like the compressor - many people I know would have wrongly condemmed the compressor (maybe even me??!!)
And you left a Hero!

Cheers,
Andy.

install monkey
01-06-2011, 09:01 PM
thats why uk kit has a bs88 fuse in the plug. first point of call is test fuse,replace and watch for the spark and the bang, otherwise it runs all ok!

AUScooler:-)
02-06-2011, 08:43 AM
Was it the C/B in the fridge or the one in the s/board you had to replaced?

young gun
02-06-2011, 10:34 AM
Was it the C/B in the fridge or the one in the s/board you had to replaced?

in the fridge mate....

AUScooler:-)
02-06-2011, 10:59 AM
Just wondering cause there a quite a few of these fridges getting about. What was the rating of the one you replaced?

young gun
03-06-2011, 10:05 AM
Just wondering cause there a quite a few of these fridges getting about. What was the rating of the one you replaced?

20amp circuitbreaker