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bernard
09-09-2004, 05:50 PM
can anyone please tell me at what temp does the discharge klixon go o/c on scroll compressers copelland

bernard

chemi-cool
09-09-2004, 07:26 PM
Hi Bernard.

According to Copeland, discharge temp, should not go higher then 150C.
I guess the clickson will trip at about 170C

Go to www.copeland-corp.com
register and get all the info you need.

Chemi :)

Peter_1
09-09-2004, 08:03 PM
Opens at 143°C (+/*- 5K) and closes back at 60°C (+/- 5K)
If it brakes internally, the nyou can order a clamp kit thermostat (order nr :8502293)
Install it 150 mm away downline from the compressor shell.
Can be installed in any position.
Never bypass it.
You also have the internal pressure relief valve which opens at a DP of 28 bar +/- 3 bar (not in all the types)

bernard
09-09-2004, 08:21 PM
Thanks all

I loooked at a pack with 7 scroll compressor,one of the compressors was throwing up a fault.Every thing was running when i got there but six out the seven compressors had there discharge klixons disconnected and the one which was still connected was the one with the fault the discharge pressure was 13.5 bar suction 3.5 bar R404a.I will be returning later due to limited time.There is obviously a problem here that has been ignored by previous engineers. What symtoms would you expect if there was two much oil in the system.Sorry for the lack of info but any pointers would be appreciated

ps the condenser is showing signs of corrosion due to its seaside location the fault were throwing up betwween 1 and 4am so it was not the midday sun

regards bernard

Latte
09-09-2004, 09:57 PM
Hi Bernard,

Well first of all 13.5 bar on R404a at the moment seems low.
With the heat at the moment and the fact you say the condensers are in a poor state i think this is too low.

Suction about right assuming it is a HT pack.

If the head pressure is low then it could effect the oil distribution around the system. What type of system is it running in ELM ?. does the system have an oil pressure readout if so if there was a problem with the amount of oil i would have thought i wold have brought up a fault.
Are all the condensers fans running continiously, Is it a critical charge pack. I may not have the answers buy this is the sort of thing he out and out supermarket pack guys will ask.

Regards

Raymond

Peter_1
10-09-2004, 06:00 AM
There is no oilpressure read out --> scrolls ;)
I should start with a too high superheat.
All compressors in the right direction, remember that it are scrolls.
This is now the kind of job where you can prove that you're better than the previous techs.
They haven't overlooked something Bernard, they were complete incompetent. Disconnecting a safety device is never a solution for a problem.
Check condenser fans. I suppose it's one big condenser with several fans. So even a corroded condenser at partial load Will still be big enough to to the job, so the pressure readings can be correct.

Mark
11-09-2004, 12:06 PM
Hello bernard :)

Once had this problem a while back on a scroll pack,the hp klixons were to near the compressor body causing intermidate trip,How long has the problem occured.If possible look on the alarm data stored on the front end ,pull up a graph of what the discharge/suction done at that time.
13.5 bar on the discharge,is around the desired set point ,the suction setting of 3.5 bar is a tad high try 3.2 bar (3.0bar)SST around -8/-10(R404A).Depends on field conditions.
What about condenser fan pressure,cycling,timing and compressor on/off delay,refrigerant charge,. All things to take into account.

Best regards.Mark :)

dallan
11-09-2004, 04:24 PM
With the discharge temperature klixons what you need to check is the discharge temperature and the suction temperature at the compressor inlet. For example if you have a refrigerant shortage and the suction temperature is elevated this will cause the discharge safety to trip. The discharge and suction pressure would only become relevant if you had a high compression ratio or an increased condensing temperature through a condenser fan failure for example and this caused the superheat to increase.

With the regards to the klixon position it is my understanding that this should be positioned around 6 inches from the compressor.

David

chillyhamster
11-09-2004, 05:16 PM
How are the klixons attached to the pipework ?, On early plant it was common to attach with jubilee clips, which tended to crush the sensor. (loosening allowed klixon to work properly but became insecure) The currently supplied clip works fine and should be retrofitted. ;)

bernard
11-09-2004, 08:24 PM
Checked alarm records,alarms most common late night or morning when system is not under so much load i.e when night blinds down.Have connected all klixon 150mm from compressor.Oil system is ac&r magic eye,this is where I think the problem is have changed magic eye on the last alarming compressor which filled straight away will return monday to check alarm record.Any ideas why alarms most common out of hour.Elm front end.



Regards :)

dallan
12-09-2004, 08:28 PM
Mark,

I would agree that pulling up graphs should help diagnose, however your description of HP klixons confuses me a bit.

It is my understanding that they are over temperature klixons, in place to prevent the compressor from overheating. If there was any problem with a nrv sticking or condenser fans failing wouldn't you expect the HP switch to open well before the klixon reached it's limit.

Apart from logging the suction & discharge temperatures you could check that the pack controller is set up properly and not starting the compressors too frequently, you could also check that the pack is not over condensing at night and causing a liquid delivery problem.

As I mentioned previously the suction temperature and the discharge temperature are what really matters if the problem lies with the discharge klixon, if as Marc mentioned you hook up a logger overnight, once you overlay these graphs with the Elm information you would have more than enough information.

One point on the original post, is it really the discharge klixon that is causing the alarm? A lot of engineers presume because it has tripped and reset it must be the klixon, pull it off the compressor as some sort of test and leave.

bernard
14-09-2004, 06:32 PM
Hi all ,no it s not the klixon causing the problem it was the oil sensing system.I don,t know why the klixons have been disconnected.Anyway its all up and running now thanks for everyone advice.

regards bernard

Peter_1
15-09-2004, 06:01 AM
Anyaway, I should reconnect them all.

And what oil sensing system? What was wrong whit it? Was it wrong on all the compressor at the same time?
We all helped you, at least we tried,...so tell us a little bit more then just 'It's running again'

bernard
15-09-2004, 08:33 PM
Hello peter

Sorry for my short explaination.I am new to the supermarket game,the work is really great and enjoyable but very time consuming.I am trying to balance my job with my family life and therfore do not get as much time on this site as I would like.But you are correct if people have taken time to to try and help me I should take the time to answer them sorry ;) .The elm front end in the alarm log just stated compressor fault and compressor number.On looking at the pack I presumed because the rest of the klixons were disconnected that this was the problem.I was wrong, why they were all disconnected I don,t know but they are all connected now.What I did find was the compressor oil sight glass was running empty for approx 30 mins before refilling.Each compressor has a Henry S-9400 oil sensor Magic eye as we call it.It uses light reflecting from a glass prism as a means of detecting the absence of oil.I therfore replaced this and have no alarms since.If you would like more details on this oil system let me know.Thanks for eveyones help.P.S isn,t the money great :eek:


Regards bernard

bernard
16-09-2004, 07:46 PM
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Mark
16-09-2004, 08:25 PM
http://www.henrytech.com/home.html

Ps did the compressor survive this ordeal.

bernard
16-09-2004, 08:31 PM
Hi mark

Yes its ok,Have you expierence with this oil system


Regards bernard