York YCAS0130 manual Low Oil Differential Pressure Cutout, High Oil Temperature Cutout

Low Oil Differential Pressure Cutout:

S Y S	#	L O W	O I	L	D	I	F F
S Y S	#	L O W	O I	L	D	I	F F

The Low Oil Pressure Differential Safety assures the compressor receives proper lubrication by monitoring the differential between oil pressure returning to the compressor and suction pressure. Lack of a differential indicates that the compressor is not pumping and no oil is being pumped through the compressor to lubricate the bearings and rotors.

This type of oil failure will not be picked up by the High Oil Differential Safety since no flow will cause the dif- ferential through the oil piping to drop to zero.

During normal operation, differential oil pressure must be greater than 50 PSID. At start-up, the cut-out is ramped over time according to ambient temperature.

For ambients above 50°F (10°C), the Low Oil Differ- ential Safety is activated after 1 minute of compressor operation when the oil pressure differential must be greater than 10 PSID (.7 bar). After 2 minutes it must be greater than 20 PSID (1.4 bar); after 3 minutes, 30 PSID (2 bar); after 4 minutes, 40 PSID (2.7 bar); and from 5 minutes of operation and onwards, oil pressure must remain higher than 50 PSID (3.4 bar) or the system will be shut down. For lower ambients, the linear ramp times are as follows:

AMBIENT TEMP		RAMP TIME
>50°F	(10°C)	5	Minutes
>45°F	(7°C)	6	Minutes
>40°F	(4°C)	7	Minutes
>35°F	(2°C)	8	Minutes
>30°F	(-1°C)	9	Minutes
<=30°F	(-1°C)	10	Minutes

High Oil Temperature Cutout:

S Y S	#	H	I G H	O I	L	T E M P
S Y S	#	H	I G H	O I	L	T E M P

This safety assures oil temperature does not exceed a safe operating temperature which affects compressor lubrica- tion. Typical oil temperature during normal operation will be approximately 130 - 150°F (54 - 66°C).

The High Oil Temperature Safety is activated after 2 minutes of compressor operation, after which if oil temperature is above 225°F (107°C) for more than 3 seconds, the compressor will shut down.

FORM 201.19-NM1 (204)

Low Suction Pressure Cutout:

	S Y S	#	L O W	S U C T	P R E S S
	S Y S	#	L O W	S U C T	P R E S S
						8
The Low Suction Pressure Cutout aids in protecting the

evaporator from damage due to ice build up caused by operation at low refrigerant charge or restricted refrig- erant flow. A transient timer feature prevents nuisance trips during start-up, compressor loading, etc. The Low Suction Pressure Safety is programmable (see Section

8.2/ Page 167, Low Suction Pressure Cutout for more details).

The suction pressure cut-out is ignored for the first 45 seconds of operation. During the next 180 seconds of running, suction pressure may be lower than the cutout, but must be greater than:

SP Cutout= Programmed Cutout X (run Time - 25)

200

This cutout value increases with time (10% to 100%) until after 225 seconds it equals the programmed cut- out value. If suction pressure falls below the calculated cutout value before 225 seconds of run time, the system will be shut down.

The following graph shows a typical programmed suc- tion pressure cutout of 44 PSIG (3 bar) and its change from time = 0 sec of compressor run time to 225 seconds of compressor run time.

	45
Cutout	40
	35
	30
Pressure
	25
	20
	15
Suction
	10
	5
	0
	0	30	60	90	120	150	180	210	240	270	310
				Run Time (seconds)

Suction Pressure Cutout With	LD07013
44 PSIG Programmed Cutout

FIG. 48 – SUCTION PRESSURE CUTOUT

YORK INTERNATIONAL 141