Trane Tracer ZN511 Installation And Operation Manual page 29

CNT-SVX06B-EN
Binary inputs for water-source heat pump applications
To ensure that compressor contactor monitoring is functioning, perform
the following test:
1. Using a voltmeter, place the probes across the 24-V side of the com-
pressor contactor. When the compressor is in operation, the voltmeter
should register a value close to 24 V.
2. Cause a fault to occur in the unit (example: manually close the water
valve to lock the unit out on high pressure). The voltmeter should now
register a value below 10 V.
If the voltmeter registers a value less than 10 V (most lockout relays will
register a value less than 1 V), the controller will detect a lockout condi-
tion and generate a High/Low Pressure Cutout diagnostic. If the voltme-
ter registers a value greater than 10 V, the controller will not detect a
lockout condition and will not generate a High/Low Pressure Cutout diag-
nostic. In this case, the compressor line-voltage monitoring option,
described in the next section, should be used.
Figure 5. Compressor contactor monitoring
Lockout
relay
LPC
HPC
Figure Note:
For units with two compressors, wire BI5 to compressor contactor 2 in the same way.
Condensate
Freezestat
overflow
Compressor
contactor 1
17