YORK YCAV — SYS X HIGH DISCHARGE PRESSURE

The panel shows the fault as SYS X YYYYYYYY HIGH DISCHARGE PRESSURE in the system safeties (faults) group. X is the number of the affected system, and YYYYYYYY is the status word printed in its place: FAULT for a condition that restarts automatically, or LOCKOUT. The manual calls this the High Discharge Pressure Cutout (Software) Fault.

A software system safety has tripped on the affected system: the discharge pressure rose above 274 PSIG for 0.5 seconds, and the system shuts down with a controlled ramped shutdown. The status word in the message tells you where things stand — FAULT means the system may restart by itself once conditions allow, LOCKOUT means the system has locked out on this fault and stays off until it is reset manually.

• The discharge pressure rises above the 274 PSIG software cutout threshold and stays there for 0.5 seconds — this is the trip condition the manuals give as the cause; no other cause is listed for this safety.

• Trip threshold: discharge pressure above 274 PSIG for 0.5 seconds.
• Restart and start-inhibit threshold: 259 PSIG — the system may restart when the pressure falls to 259 PSIG, and it is inhibited from starting while the pressure is above 259 PSIG.
• Anti-recycle timer: 120 seconds before an automatic restart takes place.
• Lockout count: any 3 faults on the same system within 90 minutes lock the system out on the last fault.

A FAULT clears itself: once the discharge pressure falls to 259 PSIG, the system restarts automatically when the 120-second anti-recycle timer times out. After 3 faults on the same system within 90 minutes, the system locks out on the last fault and needs a manual reset — a lockout requires a manual reset by cycling the respective system switch OFF and ON. One of the manuals adds that on lockout the system will not restart until the operator clears the fault using the keypad.