30gtn100 T118-T119 random alarms

[mpalmer821]

I have a Carrier chiller with intermittent low oil pressure that will cycle between A & B circuit every 2 - 4 days. When I check the net oil pressure it runs 30psi on one circuit and 25 on the other; well above the 6psig cut out. Also I just changed the sat suction and gas entering sensors for both circuits, problem still persists. Oil levels look normal and I have not seen any foaming. Has anyone experienced this persistent problem?

Mike

[install monkey]

crankcase heater ok? liq floodback washing out oil during low load?? seems strange that both circuits so low load or low setpoint??

[mpalmer821]

Install Monkey, Thank you for your reply.
I have not checked the crankcase heaters, being in central Florida I did not think it would be an issue. However without the heater, liquid could settle and boil off on start-up, especially on the lag circuit. I have monitored the chiller running at minimum load for prolonged periods, superheat in the 20's to 30's according to the sensor @ the compressors. The set-point is set for 47F. I have also raised set point to 60, allowed the EWT to rise to that level, then lowered SP to 42F to allow it to start under load and observe the chiller staging up over 50% and pulling down to the lower 42F SP. During this testing, the lag circuit (B), the lead compressor (B1) did trip out on oil safety. Unfortunately I did not have my gauges monitoring it nor was I looking at the sight glass. I repeated the test afterwards while monitoring closely, but it worked perfectly.

[install monkey]

is the oil pressure switch like the penn type with the manual reset? if so then on start up does the little heater on the pressure switch actually delay as it states- 90-120seconds. if its transducer type then is there a setting in the controls to delay this? cant find exact install manual to check this

[mpalmer821]

If I recall correctly its a Danfoss non-adjustable with a 6psig cut out. According to the manual a 9 psig cut in. It connects directly to the processor board through via digital input (dry contacts), no transducer. There is a 2 min bypass during startup by the processor board.

[moideen]

I have a Carrier chiller with intermittent low oil pressure that will cycle between A & B circuit every 2 - 4 days. When I check the net oil pressure it runs 30psi on one circuit and 25 on the other; well above the 6psig cut out. Also I just changed the sat suction and gas entering sensors for both circuits, problem still persists. Oil levels look normal and I have not seen any foaming. Has anyone experienced this persistent problem?


Mike

30 GTN chiller equipped with 06e compressor .required deferential oil pressure is 16 to 22psid.as you said the cut out is 9 psid. Probably this alarm will occur on 30 GTN due to the loose connection of the input signal from oil safety switch on processor board. Check the connection terminal J7 wire no 1, 2, 3, 4(color code orange and violet) and tight properly, and I have attended before the same case many times.