Detcon 140 - Manual (Page 30)

140 Operators Manual
Model 140 Operator Manual Rev. 1.8 Page 26 of 29
8.
Options
8.1 Option for Battery Back-up Operation
This option provides a nominal 1-hour of battery back-up power to the Gas Detection Alarm System. The
battery back-up system consists of two 12VDC / 0.8 Amp-hour batteries in series, along with the requisite
low voltage cut-off circuitry. The batteries may be isolated during exchange or while in long-term storage
by using the battery disconnect switch shown in Figure 4. The low voltage cut-off circuit is designed to
disconnect the battery supply if the voltage is drained below 20VDC. This is for battery protection
purposes. There is a battery restore switch on the Motherboard PCB, which must be pressed after the low
voltage cut-off is triggered. This is only necessary if the unit is going to be restored under battery power.
It is not necessary if restored under VAC power.
8.2 Option for 4-20mA Output(s)
An optional PCB that plugs into the controller board is available for 4-20mA outputs. This PCB has four
channels of 4-20mA output. Only the first channel is used with the 140 Control Unit. See Figure 19 for the
correct installation and wire terminations for this feature.
Figure 19 Optional Plug-in Module for 4-20mA output and Remote Display
8.3 Optional Interface PCB for Remote Display
The same PCB that provides the 4-20mA output option is also used as the required interface for the Remote
Display option (Figure 19). The RS-485 terminal block labeled ‘A B S - TO REMOTE’ is used to connect
to the Remote Display. The actual Remote Display hardware is ordered separately as a Model 140-RD
Read-Only-Remote display.