Canatal M52 - Chilled Water; DX Demand (Dehumidification); Rapid Dehumidification Feature (All Except China Units)

M52 Microprocessor User's Guide
M52UMCT Oct-03 7
• N/C auxiliary contact on compressor contactor opens and de-energizes crankcase heater.
• N/O auxiliary contact on compressor contactor starts remote condenser. (Air-cooled units only)
• Low-pressure switch remains closed after Pos. start time expires and compressor remains on.
Compressor stops when:
• Loss of demand
Compressor contactor opens
• Low pressure condition
Compressor stops when LP SW. opens. (Automatic reset) compressor contactor opens.
• Short cycling alarm
After three consecutive low-pressure alarms in 30 mins, compressor contactor opens. Manual
reset is required.
• High pressure condition
Compressor stops when HP SW. opens. (Manual reset)
Compressor contactor opens. Compressor will not start until HP SW. and controller are reset.
• Thermal protection opens (automatic reset)
Line voltage cut-outs on all compressors except Spectre compressor where the compressor
module causes a Compressor Overload alarm and stops the compressor through the
microprocessor. Compressor module resets after 30 minutes.
Note: Anytime the contactor opens the comp. elapse timer keeps compressor off for 3 minutes
(adjustable)
Chilled Water
On demand for cooling or dehumidification chilled water valve opens as demand signal ramps up
from 0 to 100%. Valve operates on 0-10 Vdc.
Valve closes when:
Loss of demand, signal diminishes to 0 Vdc
DX Demand (Dehumidification):
Cycles on compressors in stages 1 to 4 or 8 depending on Series and number of units connected
together with Co-Work as demand for dehumidification increases from 0 to 100%. The compressor
will continue to run for a minimum time of 1-5 minutes (default is 1 minute) to allow oil return to
the compressor.
Demand for compressor:
• Compressor contactor receives signal from microprocessor. Positive Start timer (Pos. start
delay) starts and bypasses LP switch for cold winter start-up. When HP switch is closed the
start circuit is complete and the compressor starts.
• N/C auxiliary contact on compressor contactor opens and de-energises receiver heaters.
(Flooded Condenser LAC)
• N/C auxiliary contact on compressor contactor opens and de-energizes crankcase heater.
• N/O auxiliary contact on compressor contactor starts remote condenser. (Air-cooled units only)
• Low-pressure switch remains closed after Pos. start time expires and compressor remains on.
Rapid Dehumidification Feature (All except China units)
If there is less than 20 percent demand for cooling and a demand for dehumidification the Dehum.
Solenoid valve closes.