Hermetic compressor tripping

[chillyblue]

Hi

I have a hermetically sealed compressor, which is used on a machine which runs for 25-40mins to freeze, that is it's cycle and job.
When it is running system pressures are good and it does it's job
BUT!!!

Problem the compressor runs on R404a and has two cappillary tubes feeding two plates which it freezes.
The compressor is tripping after about 20 mins into it's cycle, i have changed the drier, cappillaries and vacuumed the system and recharged with fresh refrigerant to the manufacturers weight.
The compressor still trips, i've check the compressor capacitor and relay them seem OK
I've put high pressure OFN into the discharge pipe and i don't get anything come out the suction, so i assume the valves are OK, I have run the compressor totally disconnected and the amps read are still higher than the manufacturers name plate, i'm reading 6.4, name plate reads fla 4.5 and i'm assuming this is why the thermal overload trips.

Don't know what else to do apart from change the compressor???

Any ideas

CB

[paul_h]

So this compressor is CSIR?
Does the start relay disengage properly?
Can you get the compressors rated winding resistance from the manufacturer and compare to the actual?

[chillyblue]

Thanks paul

I have started the compressor manually and the amps are still high, thats how i know it's not the starting gear. I shall have to try and get the ratings.

CB

[Gary]

Check the voltage at the compressor while it is running. Loose or burnt connections or contacts anywhere in the circuit can cause a voltage drop, which increases the amperage.

If the voltage is ok, the relay may be stuck in the closed (start) position. You may want to try a new relay before replacing the compressor.

[Brian_UK]

What are the running amps when the compressor is connected ?

Some motors can tend to high amperage when there is no load on them.

[Peter_1]

Can you give the brand and type of the compressor?

[chillyblue]

Hi all

What are the running amps when the compressor is connected ?

Some motors can tend to high amperage when there is no load on them.

The amps are the same mate, as said before the rating plate shows 100v 50hz 4.5amps
115v 60hz 4.5amps

i'm running 110volt 50hz at between 5.3-6.7amps connected or disconnected.

The compressor is a Tecumseh AEZ2451Z

Thanks for the help

CB

[paul_h]

When you ay you started it manually, do you mean with an annie?
Or how else did you start it manually without using the possibly defective relay on the compressor?

[chillyblue]

hi Paul

No i just short the start winding in series with the start capacitor, from the run winding terminal.
Word of warning though BE CAREFUL!!!!..

CB

[nike123]

Did you mean Tecumseh AEZ2514Z. There is no AEZ2541Z in Tecumseh documentation.
Compare these data to your case, and if amperage you read and that in table are different more than 10% change the compressor.

[chillyblue]

Thanks Gary

Check the voltage at the compressor while it is running. Loose or burnt connections or contacts anywhere in the circuit can cause a voltage drop, which increases the amperage.

At what drop in voltage will it start to cause a problem??, And i suppose it is best to meter it at the compressor terminals (end of the line)

Cheers Nike

That looks handy software, can it be downloaded??

CB

[Gary]

Thanks Gary


At what drop in voltage will it start to cause a problem??, And i suppose it is best to meter it at the compressor terminals (end of the line)

You're welcome. Did you find the problem?

Generally, more than 10% drop in voltage is unacceptable... and yes it should be checked at the end of the line.

It is good practice, when replacing any power consuming (load) device, to check voltage at the device with that device operating.

When a load device burns out, it often burns contacts in switching devices due to the excess amperage passing through them in the burnout. Replacing the load device without resolving this can lead to another burnout.

[Peter_1]

That looks handy software, can it be downloaded??

CB

Snagit or the selection software?

[nike123]

Cheers Nike

That looks handy software, can it be downloaded??

CB

No, but you could request it on www.tecumseh-europe.fr by completing request form on Contact tab and they wil send it to you by mail.