Compressor thermal overload cut out.

[HARRY 7]

Hi to everyone.I have a problem with a york ycam.
I found the alarm compressor thermal overload cut out.
I started the unit and it worked ok.
Could this had happened from instantaneous loss of electric power?Or is something else??

[NoNickName]

Hi to everyone.I have a problem with a york ycam.
I found the alarm compressor thermal overload cut out.
I started the unit and it worked ok.
Could this had happened from instantaneous loss of electric power?Or is something else??

Overload cutout, among other reasons, may also be caused by winding overheating. If the unit has been off for some time, winding may have cooled down in the meantime.
Loss of power on one phase may also be a cause for it, but I don't think loss of power on all phases is.

[HARRY 7]

I see white foam in compressor's sight glass.
Could it be something else for the alarm?
I have correct superheat 10C.

[NoNickName]

Is it a reciprocating unit? If so, foam should not be there... in a screw compressor unit, though, some foam may not be ruled out...

[HARRY 7]

It is a copeland reciprocating D8SJ-6000 in a york chiller.
The unit has two compressors.
The other is working ok.

[NoNickName]

Foam is a bad sign. Any more data about evap, cond, SH and SC?

[HARRY 7]

low pressure 60 psi
suction temperature at compressor inlet 12C
high pressure 290 psi
subcooling 8C
liquid temp 44C

[HARRY 7]

I forgot it is R22.

[NoNickName]

Ok, so 60 psig are 4.1 barg and 290 psig are 19.7 barg (Are you not using SI units in greece?)

This means that you are evaporating at +1/+2°C, and you have got a correct SSH of 10K.
Condensation at 52°C, liquid 44°C, subcooling 8K. Your data are exactly correct.

I don't know what foaming comes from, but I suspect a blow by from piston rings or valve plates.

[HARRY 7]

Thanks nonickname for the reply.
Could it be water in the system?
The compressor is new and the old one had broken valves and pistons.

[NoNickName]

If this is so, I suspect some sort of reaction between the existing oil and the new oil. Have the new compressor been supplied with mineral oil or POE?

[HARRY 7]

Mineral oil 3GS.

[NoNickName]

Then moisture or acidic residuals from burn out are our last chance.

[chemi-cool]

Foam in the crankcase is usually from boiling refrigerant.
If its so, check your super heat

[HARRY 7]

The superheat is ok chemi-cool.
How can i test for moisture or acid?
The previous compressor did not burn out.

[Grizzly]

Foam in the crankcase is usually from boiling refrigerant

Absolutely correct, Your "foaming sight-glass" could be down to a quantity of refrigerant sat in the oil.
Which is boiling off following start-up!
The turbulence created by the crankshaft "splashing " through the oil in the sump. When there is to much oil in the sump.
Can cause foaming also, but normally it is a sign of liquid refrigerant within the oil.
Particularly common when plant has been off for sometime, causing the comp to cool down.
Worth checking whether the crankcase heater is working?
Grizzly

[NoNickName]

We've already ruled out superheating, as you can see from the previous posts. It was way too obvious.

[HARRY 7]

Do you beleive that compressor contamination can cause
compressor thermal overload?

[NoNickName]

No, but it's evidence of something not right.

[nike123]

How can i test for moisture or acid?
The previous compressor did not burn out.

Moisture with sight glass.
Acid with this:
http://www.rectorseal.com/index.php?...&product_id=22

[HARRY 7]

Thanks nike.I will check it.
If i have problem with water from the heat exchanger.
What would be the results??
May that foam i see is water from heat exchanger??

[NoNickName]

May be... it surely is a pollution of some sort.

[Magoo]

Look at oil separator float valve dumping red hot vapour back into sump. The float mechanicals could be worn or restricted from closing. Assuming of course there is an oil separator.

[HARRY 7]

There is no oil serarator in circuit magoo.