Operating instructions

98
Possible Causes — If this condition is encountered, check the
following items:
• entering and leaving fluid thermistors for accuracy
•water flow rate
• loop volume — low loop volume at nominal flow rates can
in extreme cases bypass cold water to the cooler
• freezing conditions
• heater tape and other freeze protection items for proper
operation
• glycol concentration and adjust LOSP accordingly
• If the Leaving Water Set Point is above 40 F (4.4 C) and
there is glycol in the loop, consider using the Medium
Temperature Brine option (Cooler Fluid Type, FLUD=2)
to utilize the brine freeze point instead of 34 F (1.1 C)
Condenser Freeze Protection
Alarm 53 — Circuit A (P.02)
Alarm 54 — Circuit B (P.03)
Alarm 55 — Circuit C (P.04)
NOTE: Alarms 53-55 are not used or supported. If this condi-
tion is encountered, confirm machine configuration.
Low Saturated Suction Temperature
Alarm 56 — Circuit A (P.05)
Alarm 57 — Circuit B (P.06)
Alarm 58 — Circuit C (P.07)
Criteria for Trip — The criteria are tested only when the
circuit is ON. This alarm is generated if one of the following
criteria is met:
• If the circuit Saturated Suction Temperature is below –13 F
(–25 C) for more than 30 seconds or 40 seconds if OAT is
less than 14 F (–10 C) or LWT is less than 36 F (2.2 C).
• If the circuit Saturated Suction Temperature is below –22 F
(–30 C) for more than 10 seconds, or 20 seconds if OAT less
than 50 F (10 C).
Action to be Taken — The circuit is shut down immediately.
Prior to the alarm trip, the control will take action to avoid
the alarm. See Operating Modes 21, 22 and 23 on page 68.
Reset Method — Automatic, first occurrence in 24 hours.
Manual, if more than one occurrence in 24 hours.
Possible Causes — If this condition is encountered, check the
following items:
• sensor wiring to Main Base Board (Alarm 56 and 57) or Fan
Board C (Alarm 58)
• board for a faulty channel
• faulty suction transducer
• cooler water flow
• loop volume
• EXV operation
• liquid line refrigerant restriction, filter drier, service valve,
etc.
• refrigerant charge
• If the Leaving Water Set Point is above 40 F (4.4 C) and
there is glycol in the loop, consider using the Medium
Temperature Brine option (Cooler Fluid Type, FLUD=2)
to utilize the brine freeze point instead of 34 F (1.1 C).
• Closed suction service valve on DX Cooler units.
High Suction Superheat
Alarm 59 — Circuit A (P.08)
Alarm 60 — Circuit B (P.09)
Alarm 61 — Circuit C (P.10)
Criteria for Trip — The criteria are tested only when the cir-
cuit is ON. This alarm is generated if all of the following crite-
ria are met:
• The EXV position is equal to or greater than 98%.
• The circuit’s Suction Superheat (Suction Gas Temperature –
Saturated Suction Temperature) is greater than the super-
heat control set point.
• The circuit’s Saturated Suction Temperature is less than
Maximum Operating Pressure (MOP) set point (EXV
MOP Setpoint, MOP) for more than 5 minutes.
Action to be Taken — The circuit is shut down normally.
Reset Method — Manual.
Possible Causes — If this condition is encountered, check the
following items:
• suction pressure transducer wiring to Main Base Board
(Alarm 59 and 60) or Fan Board C (Alarm 61)
• board for a faulty channel
• a faulty suction transducer
• suction gas thermistor wiring to EXV Board 1 (Alarm 41)
or to EXV Board 2 (Alarm 43)
• suction gas thermistor sensor for accuracy
• for EXV Board 1 (Alarm 41) or EXV Board 2 (Alarm 42)
faulty channel
• EXV operation
• a liquid line refrigerant restriction, filter drier, service valve,
etc.
• refrigerant charge
Low Suction Superheat
Alarm 62 — Circuit A (P.11)
Alarm 63 — Circuit B (P.12)
Alarm 64 — Circuit C (P.13)
Criteria for Trip — The criteria are tested when the circuit is
ON. This alarm is generated if the following criterion is met:
The EXV position is equal to or less than 5% and the cir-
cuit’s Suction Superheat (Suction Gas Temperature – Saturated
Suction Temperature) is less than the Suction Superheat Set
Point (EXVA Superheat Setpoint, SHP.A, EXVB Superheat
Setpoint, SHP.B, or EXVC Superheat Setpoint, SHP.C) by at
least 5° F (2.8° C) or the circuit Saturated Suction Temperature
is greater than Maximum Operating Pressure (MOP) set point
(EXV MOP Setpoint, MOP) for more than 5 minutes.
Action to be Taken — The circuit is shut down normally.
Reset Method — Automatic, first occurrence in 24 hours.
Manual, if more than one occurrence in 24 hours.
Possible Causes — If this condition is encountered, check the
following items:
• suction pressure transducer wiring to Main Base Board
(Alarm 62 and 63) or Fan Board C (Alarm 64)
• board for a faulty channel
• faulty suction transducer
• suction gas thermistor wiring to EXV Board 1 (Alarm 41)
or to EXV Board 2 (Alarm 42)
• suction gas thermistor sensor for accuracy
• EXV Board 1 (Alarm 41) or EXV Board 2 (Alarm 42)
faulty channel
• EXV operation
• confirm maximum operating pressure set point
• refrigerant charge level
Alarm 65 — Interlock Failure (P.14)
Criteria for Trip — The criteria are tested whether the unit is
ON or OFF. This alarm is generated if the lockout switch
(located in the Energy Management Module) is closed during
normal operation.
Action to be Taken — All compressors are shut down immedi-
ately without going through pumpdown. and is not allowed to
start.
Reset Method — Automatic, first occurrence in 24 hours.
Manual, if more than one occurrence in 24 hours.
Possible Causes — If this condition is encountered, check the
following items:
• chilled water flow switch operation
• water flow. Be sure all water isolation valves are open and
check water strainer for a restriction
• interlock wiring circuit