RKI Instruments Digester Gas Monitor - Manual (Page 32)

26 • Wiring the Digester Gas Monitor Digester Gas Monitor Operator’s Manual
page 39 for a complete description of this feature and what type of battery to use. If DC
power is the primary power source, DO NOT connect AC power.
1. Turn off or unplug all incoming power to the Digester Gas Monitor.
2. Open the housing door, then place the power switch in the OFF position.
CAUTION: The power switch does not control DC input power.
3. Locate the DC input power terminals on the controller terminal strip near the lower
right edge of the main PCB (see Figure 5 on page 12). They are labelled EXT DC/24V
BATT+ and EXT DC/24V BATT -.
4. Install an appropriately rated cable bushing or conduit in an unused conduit hub on
the bottom of the Digester Gas Monitor housing.
5. Guide a DC power cord or two wires in conduit through the selected conduit hub on
the bottom of the Digester Gas Monitor housing.
6. Connect the DC power wires to the controller terminal strip as shown in Figure 14
below.
Figure 14: DC Power Wiring
NOTE: The Digester Gas Monitor will operate from the DC input down to 18.5 volts. If a
self contained backup battery is used, see its operator’s manual for a description
of its recharging characteristics. If your Digester Gas Monitor includes the battery
charging feature and a backup battery is used, the Digester Gas Monitor will
recharge the battery when AC power has returned after a power failure. See
“Battery Charging (Optional)” on page 39 for a complete description of the battery
charging feature.
RS-485 Modbus Wiring
See “Wiring the Digester Gas Monitor in a Modbus System” on page 68 for wiring
connections to the RS-485 Modbus terminals.
Connecting External Alarms
Before connecting any external alarm devices to the relay contacts, make sure you know
how you want the devices to operate. For example, confirm under what alarm condition
you want a device to turn on or turn off and what channel is going to control the device.
Also make sure that the parameter settings that apply to the relays in the Global Menu and
the Configuration Menu are set so that the desired alarm device operation is obtained.
See “Viewing and Changing Global Parameters” on page 47 and “Viewing and Changing
Channel Parameters” on page 51 for information about the relay parameters.
Perform the following procedure to connect external alarm devices to the Digester Gas
Monitor.
1. Turn off or unplug all incoming power to the Digester Gas Monitor.
DC Power In Terminals on
Controller Terminal Strip
EXT DC
24V BATT
DC Power
24 VDC