Protocol
Control
System
Users
Manual
2/12/01
Figure 3 - PCS Expansion Board
5.2.1 Input Power
The Controller uses 24 VAC (+10%/-15%,
50/60 Hz) (Class II) power at 15 VA. Note that
if using the same transformer to power the
controller and expansion board, care must be
taken to connect the G terminals on both boards
to the same side of the transformer and the G0
terminals on both boards to the same side of the
transformer.
5.2.2 Mounting
The Expansion board is mounted via standoffs.
5.2.3 Fuse
The Expansion board has an internal fuse. If the
Expansion board will not power up and you
have verified that the controller is getting input
power, you should replace the fuse. Always
replace with the same type of fuse.
5.2.4 Expansion Board Wiring
The field wiring for the expansion board
consists of the temperature probes and defrost
termination sensors. Refrigeration valve relays
are factory wired to terminal blocks. Figure 4
shows the connection points for the field wiring.
Figure 4- Expansion Board Wiring
5.3 Pressure Transducer
The PCS system uses a 4/20 milliamp pressure
transducer. Inputs are provided for reading suction
pressure (optionally a second suction group pressure) and
discharge pressure. The same type of pressure
transducer is used for reading suction and discharge
pressure. The transducer is a 2 wire connection and is
polarity sensitive (refer to the Protocol schematics for
details). The system reads 0 to 362 PSI.
The wiring for the pressure transducer should not be
routed near cables carrying high voltage.
Figure 5 shows a picture of the pressure transducer.
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