OM 200MICRO
43
Alarms
Any condition that requires corrective action by the controller that overrides normal chiller operation
or any condition that initiates an emergency chiller shutdown can be considered to be an alarm.
Alarms are arranged in increasing priority with higher priority alarms replacing any lower priority
alarms that may exist. Once the abnormal condition is corrected, the alarm may be cleared by pressing
the "CLEAR" key.
Alarms fall into three distinct categories:
Warnings
,
Problems
, and
Faults
.
Warnings
A warning is enunciated whenever an abnormal condition exists which does not affect chiller
operation.
WARNING
CONDITION
DISPLAY
Liquid Line Refrigerant
Temperature Sensor Fall Warning
Sensor is shorted or open
Liq Line T Sen Warn
Entering Evaporator Water
Temperature Sensor Fall Warning
Sensor is shorted or open
Ent Evap T Sen Warn
Leaving Condenser Water
Temperature Sensor Fail Warning
Sensor is shorted or open
Lvg Cond T Sen
Low Discharge Superheat
Discharge Superheat temperature
is lower than acceptable range for
more than 3 minutes (adjustable)
Low Disch Superheat
High Discharge Superheat
Discharge Superheat temperature
is lower than acceptable range for
more than 3 minutes (adjustable)
Hi Disch Superheat
Problems
A problem condition exists whenever the MicroTech controller must override normal chiller operation
in order to keep the unit on line.
PROBLEM
CONDITION
DISPLAY
ACTION
CLEAR
Entering Evaporator
Water Temperature
Sensor Fail Problem
Sensor is shorted or
open
and
Leaving Water
reset is based on
Entering Water
Temperature
Ent Evap T Seen Probe
Leaving Water reset will
change to No Reset
Manual - Reset will
revert back to Entering
Water on clearing
Outside Air Temperature
Sensor Fail Problem
Sensor is shorted or
open
and
Leaving Water
reset is based on
Outside Air Temperature
Outside T Seen Probe
Leaving Water reset will
change to No Reset
Manual - Reset will
revert back to OAT on
clearing
Low Evaporator
Pressure - Inhibit
Loading
Sensor Pressure is less
then low limit (38 psig)
Lo Evap Press-NoLoad
Inhibit loading
Automatically when:
Evaporator Pressure
rises above set point
plus differential
Low Evaporator pressure
- Unload
Evaporator Pressure is
less then low limit (31
psig)
Low Evap Press-Unload
Unload to minimum
position
Automatically when:
Evaporator Pressure
rises above set point
plus differential
High Discharge
Temperature - Load
Discharge temperature
> high limit (120°F)
and
Suction Superheat < Low
Limit (15°F)
High Discharge T-Load
Load compressor
Automatically when:
Discharge Temperature
< High Limit - Diff (3°F)
or Suction Superheat >
Low Limit + Diff (3°F)
Condenser Freeze
Protect
Condenser Refrigerant
Temperature <
Condenser Freeze
Protect Set Point (34°F)
Cond Pres Lo-Freeze
Start the Condenser
pump
Condenser Refrigerant
Temperature >
Condenser Freeze
Protect Set Point +
Differential (2°F)
