carrier screw compressor oil problems

[redroge]

im having intermitant problems with a carrier 30gx chiller.one system keeps coming up with prelube fault and the other with difference between discharge pressure and oil pressure to great codes are 50 and 64

[Supernova86]

firstly check your oil level switch contact is closed this can be done on the prodialog, if so its not a oil level fault, make sure your oil pump runs, had one fail on me recently.
as for the other circuit sounds as if the oil filter may need changing
discharge pressure - oil presure >340kpa for more than 6 seconds will shut the circuit down and give you your alarm 64

[goshen]

Originally Posted by Supernova86

firstly check your oil level switch contact is closed this can be done on the prodialog, if so its not a oil level fault, make sure your oil pump runs, had one fail on me recently.
as for the other circuit sounds as if the oil filter may need changing
discharge pressure - oil presure >340kpa for more than 6 seconds will shut the circuit down and give you your alarm 64

sounds very familiar had the same problem we ended up changing pump ,this solved the problem!

[redroge]

Originally Posted by goshen

sounds very familiar had the same problem we ended up changing pump ,this solved the problem!

thanks but i can here the pump making a clacking noise and this is an intermitant fault.
i,ve changed the nrv and the oil, all the oil heaters are ok and the oil pressure is ok when the compressor is running

[iceman007]

Originally Posted by redroge

thanks but i can here the pump making a clacking noise and this is an intermitant fault.
i,ve changed the nrv and the oil, all the oil heaters are ok and the oil pressure is ok when the compressor is running

I would make sure the problem isn't with the oil solenoid (found on the compressor near to the internal oil filter) and also check the plug connection on the oil level switch as they can get corroded over time.

[redroge]

been back to site today both compressors had tripped again,looking back through the alarm log all the trips happen in the night,reset the trips and ran the chiller on full load both compressors working ok oil pressures spot on
disconnected the oil level sensor this caused the compressor to switch off but did not bring a fault up on the controller also the contactor for the sep.and oil line dropped out should disconnecting the oil level sensor show up as a fault any idea's

[willow]

Yes this should show a low oil level alarm. You say the oil pressure is ok what is the pressure drop across the internal filter.If its over 220kpa this could be the problem.

[redroge]

Originally Posted by willow

Yes this should show a low oil level alarm. You say the oil pressure is ok what is the pressure drop across the internal filter.If its over 220kpa this could be the problem.

thanks the pd is 80kpa i suspect the problem is low oil level at night and the controller not showing a fault !

[serviceman]

replaces the internal oil filtor, verifies also external oil on the 50 codes filter and 64 verifies the configuration of the machine (50) .retira transducers of the machine and verifies measure atmospheric pressure permissible maximum must be 5psig if more high cambialos or calibralos(solo_con_el_hsio) .analiza oil that solenoid also not fuge internally because the oil pressure transducer should register prelubricacion pressure

[furryfrog]

If you disconnect the oil level switch the chiller will go into alarm eventually
If you look at the inputs on the pro dialog control it should show low oil level if you disconnect the switch
I think you need to forget about the oil level switch as this does not relate to the problems you are getting
You need to monitor the difference between oil pressure and discharge pressure for 10-15 mins. It does not really matter what the compressor has loaded up to but if the difference is above 120 KPA
then you need to change the external and internal oil filters.
You do need to check that your oil heaters are working though. Best to check the discharge on top of the oil sep is warm first thing on a cold morning before chiller starts...... if you can

[redroge]

Originally Posted by furryfrog

If you disconnect the oil level switch the chiller will go into alarm eventually
If you look at the inputs on the pro dialog control it should show low oil level if you disconnect the switch
I think you need to forget about the oil level switch as this does not relate to the problems you are getting
You need to monitor the difference between oil pressure and discharge pressure for 10-15 mins. It does not really matter what the compressor has loaded up to but if the difference is above 120 KPA
then you need to change the external and internal oil filters.
You do need to check that your oil heaters are working though. Best to check the discharge on top of the oil sep is warm first thing on a cold morning before chiller starts...... if you can

when you say eventually how long , i waited 5 minuets after the compressors had switched off.
the discharges are warm in the morning and when the alarms are reset the compressors will run, to start with the pd is around 250kpa after a while this comes down to around 80kpa, all the oil filters have been changed

[furryfrog]

If you disconnnect the oil level switch the compressor will stop. The oil sep heater contactor will also drop out at this point. The alarm can take 30 mis plus to register - Sorry i can't give you an exact time but there is a time delay. Have you changed the internal and external oil filters ?
I know you said the discharge was warm in the morning before you reset the alarms but if the oil sep contactor is energised just check that you are pulling amps on the heaters

[redroge]

thanks furry, all the oil filters have been changed the oil has been changed, carrier have been out twice! the last time they recommended changing the nrv's which we have done, still the same problems tripping at night, having now spoken to one of their commissioning guys he recommends to try adding an extra 5lts of oil

[Gibbo]

How much oil did you pull out when you changed over the oil.

[GHAZ]

Hi ,pump it down into the condensor and then then start the system to push the oil out off the evaporator and then moniter pressures to see if its not short of gas.even with oil seperators the oil can through to the evaporator and at low loads it trips out .

[El Padre]

Had same problem on a site with two Trane screws, they struggle with continuous operation at low load, followed the same route, never got them to work within design parameters off season or at night, could your application support cycling them off for a few hours at night?

Cheers

[redroge]

here we go again! war and peace.
been back to site today both systems have had same trips again, tried checking oil level with two gauge lines and site glass as seen on another thread no luck,when oil was changed at carriers suggestion 18kgs was taken out of one system and 12kgs out of the other the same amount was replaced ,checked the oil level alarm again it took 50mins to register after compressor had switched off.
checked oil sep heaters they keep sep at approx 49c though book says this should be 85c? the heaters cycle on their internal klixon about a minute on and 5 mins off, not sdded any extra oil yet.

[furryfrog]

First things first.
Do not add oil for the sake of it.
If you add oil you have to ask the question why are you adding oil. Unless you have an oil leak you have to assume at this stage the oil quantity is correct. However much you try you will not get all the oil out.
Do not pump the system down into a vaccum - The 06N screw compressors do not like it
I am also confused as to what your problem actually is now.
Is this chiller production - does it have to run at night
If you are getting low oil level alarms due to low load then its plan B!
Let us know what the exact problem is and what the load conditions are

[redroge]

the chiller is for airconditioning of a large university building ie labs and clean rooms 24/7
the fault codes are 50 and 64
compressor a1 prelube fault and compressor b1 difference between oil and discharge pressures above 320kpa

[Gibbo]

when you say you removed 18 and 12 kg of oil don't you mean litres. There should be 20 litres per compressor in each seperator. You have changed both internal and external oil filters. Most of the time the internal filter will clear the oil diff problem.

[furryfrog]

Circuit B
when you reset the alarm and run the chiller are you getting constant overides - yellow light on circuit flashing? monitor this for as long as you can and let us know
Your problem appears to be a blockage and as recently stated the internal oil filter is the main culprit
Circuit A
As previously stated I would not just add oil for the sake of it..... but at this stage its process of illimination and considering you have not got a laptop as per Carrier engineer, I would add 4 - 5 litres of oil. If you keep getting the same fault you can always remove what you have put in (it may be a waste of money but thats life!).
What might also be of some use is a running log i.e - disch pressure, oil pressure, oil diff and loading % on each circuit as much info as you can.

PS - 1 litre of 220 oil is 1kg in weight give or take 0.20 gramms

[redroge]

have changed the internal filter this has made no difference,checked the
pd across the external filter thats ok,
had data loggers on the sep heaters for two nights and they keep a temp.of between 55/60c when the comps are not running.
when i reset the comp after being off alnight it runs for a few minutes then trips on 64,resetting it again it runs up with a diff of 100kpa.
circuit a has had afew 50 faults but these seem to reset themselves at midnight ? the oil pump has quite a few goes at getting the pressure up and is noisy, but if i switch the comp off after 5mins then restart it ,it sometimes starts ok

[hiitsme]

Is the transducer good for the application (winter Option?) and is it accurate?

[redroge]

what do you mean by winter option as i have not seen this mentioned in any paperwork,the transducer reads 60kpa different to a gauge connected to the top of the comp.
back today and ran circuit b on full load to return oil to sep.then drained off oil until low level alarm activated removed 6.5kgs, added 4kgs of new oil as per carrier spec.(dont know if oil has been added by previous maintenance company). still getting intermitant trips

[furryfrog]

Sorry! but the alarm bells are ringing!
You do not appear to be taking any notice to what I have previously stated.
If you have taken 6.5 Litres of oil out - why are you only putting 4 Litres back in ???
You stated ( as per Carrier spec ) What Carrier spec ???
I think you need to think more logically as to what you are doing
Am I wasting my time?

[Gibbo]

It seems to me that with all of the bodies who have had a play with this chiller nobody can be sure exactly how much oil is in the circuit to start with.
Why not remove all of the oil and then make sure you are starting with 20 litres (assuming it is a single compressor on each circuit) in the seperator then see what happens.

[redroge]

the carrier manual states that if the compressor is tripping on low oil level add no more than 4lts. so if i made it trip on low oil that is why i only added 4lts.

[Gibbo]

I think you need to get Carrier back out to site otherwise you will be going round in circles