Unit installation

OMRCPMICRO 33
Circuit Alarm Conditions
The "Circuit Alarm Conditions" are those alarms which only affect one circuit and cause the compressors of
the affected circuit to be staged down (pre-alarm condition), temporarily shut off (autoclearing alarm) or locked
out (alarm condition), whichever applies.
If a pre-alarm condition occurs, MicroTech will display the appropriate message and the "Alarm Status" light
will pulse until the condition is corrected or the unit goes into full alarm. If an alarm occurs, the display will
show which alarm condition has occurred and the red light will be solid. Operation will not resume until the
alarm is cleared manually at the keypad. If an autoclearing alarm condition occurs, the display will show it and
the red light will be solid. The unit will resume normal operation once the alarm causing condition has been
corrected and the anti-cycle timers have cleared.
Compressor motor protection
Comp#1MtrProtect
Comp#2MtrProtect
Comp#3MtrProtect
Comp#4MtrProtect
During normal operation, each compressor's Motor Protection (MP) contacts and Motor Protection Relay
(MPR) contacts will be closed. The MP contacts and associated MPR contacts will open on a high motor
temperature condition or motor overload and the compressor will stop. The MP contacts will automatically
reset after 2 minutes, however, the controller will temporarily lock out operation of the respective circuit until
the condition is corrected and the contacts remake. This is an autoclearing alarm.
High condenser pressure
This high pressure cutout alarm condition is in response to the signal sent by the discharge pressure
transducer; thus it is a software controlled set point and alarm condition.
If the condenser pressure rises to within 30 psi of the Hi Pres set point, the controller will override any
requests to increase current capacity and invoke the "HiCondPresStgHld" pre-alarm. The controller will hold
the current capacity stage until the pressure is more than 30 psi below the Hi Pres set point.
If the condenser pressure rises to within 20 psi of the Hi Pres set point, the controller will automatically stage
down every 10 seconds until the condenser pressure falls below the 20 psi Hi Pres set point band. The
"HiCondPrssStgDwn" pre-alarm condition is invoked during this time.
If the condenser pressure reaches the Hi Pres set point, the "Hi Cond Pressure" alarm will be logged and the
respective circuit will be locked out until cleared manually.
For WHR units setting = 360 psi
For THR units setting = 380 psi
For ALR units setting = 380 psi
Mechanical high pressure
During normal operation the HP1 and HP2 high pressure relay contacts will be closed. If the HP1 or HP2 relay
contacts open, the controller will lock out operation of the respective circuit. The high pressure relay indicates
a high compressor discharge pressure. The circuit will remain locked out until the alarm is cleared. The
Mechanical High Pressure switches— MHP1, 2, 3, and 4—must be reset first and the alarm on MicroTech
cleared second. MHP1-4 can be found in the upper right-hand corner of the control box. In all cases the high
pressure condition will be detected first by the MicroTech "Hi Cond Pressure" alarm.
The Mechanical High Pressure switches should be set a minimum of 20 psi above the software controlled High
Pressure Set Points. Recommended set points are shown below.
For WHR units setting = 380 psi
For THR units setting = 400 psi
For ALR units setting = 400 psi