Carrier 30XW-v310 Oil Pressure Fault

[Dicko100]

Hi Im chasing an oil pressure fault on a 3 year old Carrier 30xw-v310. This is a 2 circuit machine but only getting this fault occurring on circuit A. Happens once every 3-4 weeks .
I did have an issue through winter with inverted starts which would cause this circuit to fault on oil pressure on start up.Reset once and gets away.
We made some adjustments to condenser flow and field settings which resolved it happening every day in winter below 15 degrees c . We dont use condenser bypass much here in Perth Western Australia.
I have never caught it faulting and when I arrive and reset it , it runs really good .
When comparing the 2 circuits they run very close together. I have checked oil pressure drop across filter check valve etc but cant nail it.
I did have both fault on oil pressure last week in the arvo and this was the first time I have seen circuit b fail.
Ambient temps on the last couple of faults have been around 26 degrees C.
I reckon it is happening on circuit startup and have put circuit b to lead but this has only prolonged the fault occurring .Attached a screenshot of operating pressures this morning .
Also I have checked transducers and sensors, all ok.
Any suggestions.
Cheers

[pumpdown]

you know its funny, I know the metric system and what it means when i hear 20C outside and how to dress, but when the outdoor temp if given in F, I have no friggin idea what it means lol. So when it comes to troubleshooting chillers i need the pressures in PSIG and the temperatures in F.
I would check the accuracy of the transducers and is the chiller short cycling? I know as well the dishcharge muffler they have been having problems with and the oil filter could be partial plugged, I am running into the same issue and changing the oil filter and maximizing the off cycle time that has taken care of the intermittent oil failure. But I have also had a problem with the oil float wiring and I ended up replacing the cable and problem solved (again intermittent). I would look at when your oil float is open or closed when the other circuit is running.
I hope this helps somewhat
from your fellow british colony eh

[Dicko100]

Thanks mate, I have verified the transducers and sensors. Im only getting about 40kPa pressure drop across the filter check valve etc, so wouldnt have thought filter restricted. Not sure about the off cycle but think its not long from what i have seen. Yesterday was 42C ambient so didnt cycle until large chiller took over. How did maximizing the off cycle help? I am thinking its something like when it cycles off and kicks back in its failing sometimes later in the day , but as its so intermittent I have never witnessed it.

[pumpdown]

Another thought are the flows, are the pumps VFD?

[Dicko100]

Yes they are vfds. I have suspected flows as this was the cause originally in winter. My flows everytime when measured are at or near design. I may have to check the flow log history at the time of fault. Maybe something happening to the pumps when staging up and down throughout the day. Chilled water bypass operation etc.
Its always circuit A that faults though .
Tomorrow I will be taking circuit B off lead and will monitor remotely throughout the week.

[Gibbo]

You need to look at oil pressure on start up. You mention sometimes it alarms late in the day so the alarm history shows different times of the day.
Oil Pressure Alarm Trip conditions see below

Oil _sp1 = 0.7x (dp-sp) + sp
Oil _sp2 = sp +7.2 psig (15 seconds after start)
Oil _sp2 = sp + 14.5 psig (45 seconds after start)
sp = suction pressure
do = discharge pressure.
Check your cable terminations at the SCPM board for re oil transducers.

Gibbo

[Dicko100]

Thanks Gibbo , is there a way to calibrate the transducers on this type of touch pilot controller .
Cheers

[Dicko100]

Gibbo correct me if Im wrong but
Oil_sp2 means oil differential needs to be 50kpa (7.2 psi) above suction pressure after 15 secs
Oil_sp3 means oil differential needs to be 100 kpa(14.5 psi) above suction pressure after 45 secs.

Not sure I understand Oil_sp1, Im assuming this is to start the compressor.
I have attached a photo of standing pressures yesterday although it got away fine as it always does.Failed the day before I noticed though.
Circuit A oil diff always reading -10 even after changing the transducers and cables over with circuit b.

Cheers

[Gibbo]

oil_sp1 is while running
oil_sp2 = 15 secs after start is mainly used for low ambients below 2c
oil_sp2 = 45 secs after start would be the normal oil pressure trip point on start up.
Oil pressure has to be greater than both oil_sp 1 and oil_sp2 while running.
Transducers can't be calibrated, as a general rule if they are more than 15 kpa out then replace them
Most likely it's an oil_sp2 trip issue.
If oil filter was plugged it would show up as a higher than usual oil differential, you can compare it to the opposite circuit.
Discharge pressure seems a bit low at 600+ kpa how are you controlling the condenser water temp.
Normally it's recommended to control to 26c temp on to condenser.

Gibbo

[Dicko100]

Chiller 2 has been running everyday for the last 2 1/2 weeks fine with no faults. I attended today to find it had faulted once again this morning on startup, oil pressure fault circuit A again. F.M reset it and no probs ran all day.
I looked at the trend logs to find the condenser water temp was 22c and chw temp was 21 at startup.Trend logs also show discharge and oil pressure did not rise much at all on startup. Startup lift -5kPA 2mins later 35Kpa
When the compressor does start it sits at 10% capacity for a minute or so and then slowly loads . Can this start capacity be increased to increase compression ratio and make oil pressure sooner?
I also noticed a couple of settings which Im not sure about,
Fast Loading Ssequence = 0
Staged Loading Sequence =NO
Ramp Loading Select= YES
It looks like the chiller controls condenser pump VFD and tries to maintain 35c condensing temp
.I also increaased the cond water entering to to 28c couple of weeks back and that has increased discharge from 600 to 800 kPa .

[carriermechanic]

Install a head pressure control valve on leaving side of condenser water. We’ve done this on a few XW’s and 23XL’s. The xw can control the valve to maintain head pressure on startup which helps a ton with oil pressure. This got rid of our nuisance oil pressure faults

[Luke424au]

Hey Carrier mechanic, does the 30xw have preprogrammed the saturated condensing temp or something you have to setup? I know the 30hxc you can set your SCT on the pro dialog plus.