Chapter 4 Applications for the heat pump configuration
18 CNT-SVX06B-EN
Compressor line-voltage monitoring
By connecting BI4 and V4 to a field-supplied current-sensing relay, the
controller will monitor the operation of the first compressor. Install the
current-sensing relay onto the line-voltage wiring going to the compressor
(see Figure 6). When the refrigerant circuit experiences an abnormal
pressure condition, the high- or low-pressure cutout switch will trip the
safety circuit, causing the compressor contactor to de-energize and the
compressor operation to be locked out. This will result in the controller
generating a High/Low Pressure Cutout diagnostic. This option may be
required on heat pumps that use older lockout relays and in cases where
the compressor contactor is inaccessible. BI5 and V5 will perform the
same function for the second compressor.
Figure 6. Compressor line-voltage monitoring
Figure Note:
For units with two compressors, wire BI5 and V5 in the same way.
High/low pressure switch monitoring
By removing both the high- and low-pressure switches from the safety cir-
cuit and wiring them, in series, directly to BI4 and V4, the controller will
monitor the operation of the first compressor. When the refrigerant cir-
cuit experiences an abnormal pressure condition, the high-and low-pres-
sure cutout switches will open. This will result in the controller
generating a high- or low-pressure cutout diagnostic and disabling com-
Note:
With the compressor line-voltage monitoring option, a control-
ler will generate a High/Low Pressure Cutout diagnostic when
any safeties, including the freeze-protection switch and the con-
densate overflow switch, remaining in the safety circuit trip the
lockout relay.
Current-sensing relay
Compressor 1
Line voltage
Compressor
contactor 1
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