Detcon 840 - Manual (Page 5)

840 Operators Manual
Model 840 Operator Manual Rev. 1.9 Page 1 of 29
1.
Description
Housed in a NEMA 4X weatherproof enclosure, the Detcon
Model 840-N4X Gas Detection Alarm System has the
capability to handle eight 4-20mA sensor inputs or eight RS-
485 serial sensor inputs. The remotely mounted gas sensor,
(purchased separately), can include any Detcon 4-20mA or
RS-485 serial input device such as combustible gas, toxic gas,
or oxygen deficiency sensors.
The system displays real time channel information on a
backlit LCD. Configuration inputs are completely field-
programmable and include channel number, gas type, and gas
concentration. It also shows the current Alarm/Fault status
via front panel LED indicators. Standard features include
recorded history of Time Weighted Average (TWA), Peak
readings, and Alarm/Fault/Maintenance Events. Additional
features include one-touch Alarm Reset and Alarm Silence
(Acknowledge) functions.
The Model 840-N4X has a built-in power supply, giving the user a multitude of power options. It can be
powered by either 115/230VAC or 11.5 to 30VDC, and has an optional one-hour battery backup in the
event of temporary power loss.
Each control channel has three field programmable alarm relays and one fault relay. The relays have two
discrete form “C” contacts and are rated for 5 Amps at 30VDC and 250VAC. The low, high, and high-high
alarms have individually field adjustable set points for each gas channel and include the provision to
configure the alarm relays in a normally energized (failsafe) or normally de-energized mode of operation.
The low, high, high-high and fault alarm relays may also be configured for latching / non-latching and
silenceable / non-silenceable operation.