8
3.2.2 Field Wiring Instructions
Typical US field installation would include a 6 ft (2 m) AC cord wired and two (2) 1 ft (30 cm) AC receptacles (‘ON/OFF’
mode) or two (2) 10 ft (3 m) pump drive cables (‘PROPORTIONAL’ mode) installed. A BNC receptacle would be installed
for the pH probe.
Connect the two (2) pumps appropriately. Install the probe, run the cable back to the controller and attach to BNC receptacle.
If the probe is farther than 25 ft (7.6 m) from the controller, a pre-amp may be desirable to reduce noise effects. If this is
the case, run +5 V/-5 V as required by your preamp. Current draw must not be greater than 10 mA.
If a flow switch and/or low-level tank switch is available, run wires to the controller - entering through one of the spare
cable ports. Remove the appropriate jumper(s) and attach the external wires. Polarity does not matter. Wire size #20-22
is adequate.
Alarm relays 1 and 2 are provided to signal an out of tolerance condition externally. These are Form C contacts, providing
a common, a normally open and a normally closed connection.These terminals provide power output.
A solenoid drive relay is provided that can be connected to drain a tank when the pH is within programmed limits. This
form C contact provides a common, a normally open and a normally closed connection. A delay can be programmed after
initially entering this programmed zone, to allow conditions to settle within the tank. The duration of solenoid ON time
is separately programmable. Wire size #16-18 is adequate. These terminals provide output power (main voltage).
The optional 4-20 mA PCB provides a fully programmable 4-20 mA output based on the pH readings. The optional PCB
plugs into the back of the computer pc board, as shown in Figure 6.
Figure 6: Circuit Board
(866) 433-6682 • (281) 359-8538 • [email protected] • www.novatech-usa.com
