York YCAS0130 manual Micro Panel Contents, Flow Switch Open, High Discharge Pressure Cutout

Micro Panel Contents

Flow Switch Open:

S Y S	#	N O	R U N	P E R M
S Y S	#	N O	R U N	P E R M

Closure of the flow switch is monitored to check that flow is present in the evaporator when a compressor is running. Any external cycling devices fitted by the customer are connected in series with the flow switch. YCAS 2 System chillers require a single flow switch wired to the control panel. If the flow switch opens, all systems will shut down and a NO RUN PERM (Per- missive) message will be displayed. Closing of the flow switch, when flow is present, will cause the message to disappear and auto-restart to occur.

Never bypass a flow switch. This will cause damage to the chiller and void any warranties.

2.6SYSTEM FAULT (SAFETY) STATUS MESSAGES

A System Fault will shut the affected system down whenever a preset safety threshold is exceeded for 3 seconds. Automatic restart will occur after the first 2 shutdowns when the anti-recycle timer times out and temperature demand exists. After any combination of 3 Manual Reset Safeties in a 90 minute time period, the affected system will shut down and lock out on the last fault. When one or more systems are shut down on one of these safeties, a message will appear on the Status display informing the operator of the problem.

The High Motor Current Safety is a unique safety which will lock out a system after only a single fault.

To reset a locked out system, turn the System Switch for the affected system to the OFF position, then back to the ON position (see Section 1.11, Page 130, Fig. 46 for switch locations).

Before returning a locked out system to service, a thorough investigation of the cause of the fault should be made. Failure to repair the cause of the fault while manually allowing repetitive restarts may cause further expensive damage to the system.

			FORM 201.19-NM1 (204)
High Discharge Pressure Cutout:
S Y S	#	H I G H	D S C H P R E S
S Y S	#	H I G H	D S C H P R E S

The Discharge Pressure Safety prevents system pressure from exceeding safe working limits. This safety is a backup for the mechanical High Pressure Cutout in each system. The Discharge Pressure Safety is programmable for a range of values below the system upper limit (see Section 8.2 / Page 166, High Discharge Pressure Cutout for more details).

High Discharge Temperature Cutout:

S Y S	#	H I G H	D S C H	T E M P
S Y S	#	H I G H	D S C H	T E M P

This safety protects the compressor rotors from damage due to overheating, expansion, and breakdown of the oil film seal between the rotors. It also protects against ex- cessive oil temperature in the discharge oil separator.

For the first 4 seconds of operation discharge tem- perature is ignored. After 4 seconds of operation the compressor will shut down if the discharge temperature exceeds 260°F (127°C).

High Oil Differential Pressure Cutout:

S Y S	#	H	I	G H	O	I	L	D	I	F F
S Y S	#	H	I	G H	O	I	L	D	I	F F

The High Oil Pressure Differential Safety protects the compressors against loss of proper lubrication due to oil line blockage. The “differential oil pressure” for this safety is computed by measuring discharge pressure and subtracting oil pressure returning to the compressor (Discharge - Oil = Oil PSID). Under normal operation, the oil pressure differential display will be less than 25 PSID (1.7 bar), typical 2 - 10 PSID (0.1 to 0.7 bar). If oil pressure at the compressor drops due to filter block- age, the differential pressure on the display will increase and when the maximum limit is reached, the compressor will be shut down.

This safety is activated after 3 minutes of operation. Oil pressure must be less than 65 PSID (4.4 bar) for R22 models as long as the compressor continues to run.

140 YORK INTERNATIONAL