detcon inc.
Detcon
Model 812B-FB
NEMA 4 Control Enclosure
Operator’s Installation & Instruction Manual
January 1, 1999 Document #2130 Rev. 1.0
FUSE
PRESS
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
ALARM 3
ALARM 2
ALARM 1
FAULT
ALARM
RESET/
Test
HOUSTON, TEXAS
detcon inc .
able
disable
ALARM
MODEL 12B
HYDROGEN
SULFIDE
MONITOR
ppm H2S
POWER
ON/OFF
FUSE
2 AMP
ALARM
DISABLE
HOUSTON, TEXAS
detcon inc.
Model
812B-FB
Table of Contents
1.0 Introduction
1.1 Description
1.2 Specifications
1.3 Multiple Alarm Relay Circuit
1.4 Alarm Disable
1.5 Remote Alarm Reset
1.6 Installation
1.7 Start-up
1.8 Maintenance & Repair
1.9 Spare Parts List
1.10 Warranty
1.0 INTRODUCTION
Detcon Model 812B-FB consists of 3 major assemblies:
1. The NEMA 4 fiberglass control enclosure.
2. The Model 12B single channel digital control modules.
3. The remote mount gas sensor assemblies.
The NEMA 4 control enclosure is detailed in section 1.0 of the manual, the control modules in section 2.0, and
applicable sensor assemblies in section 3.0.
1.1 D
ESCRIPTION
Detcon Model 812B-FB control enclosure, along with Model 12B digital control modules, is designed to serve as a
host assembly for up to eight remote mount gas detection sensor assemblies. The control enclosure is rated NEMA
4X, which is by definition rain tight, and therefore suitable for outdoor location in electrically non-hazardous environments.
The single channel modular design supports application f lexibility wherein multiple function gas detection systems
can be configured in any combination up to eight channels. All control modules are plug-in front panel accessible
for easy maintenance and repair. The system is powered by VAC line power and/or 24VDC unless otherwise specified at time of order.
The control enclosure includes, as standard operating controls; a power on/off switch, an alarm disable switch and
a line power fuse. Discrete output terminal strips located on the controller motherboard are provided for sensor terminations, Form C dry contact alarm outputs for three alarms plus fault (common and choice of normally open or
normally closed), 4-20 mA outputs for remote recording devices, and RS-485 serial Modbus™ output. Terminations
are provided for VAC power in, VDC power in, and remote alarm reset. A multiple alarm relay circuit card is also
provided along with its respective logic and power terminations.
The Form C relay outputs, may be discrete, zoned, or common by gold plated jumper tabs located on the controller mother board.
Model 812B-FB NEMA 4 Control Enclosure PG.2
1.2 SPECIFICATIONS
Electrical Classification
NEMA 4X
Dimensions
15.75''W x 18''H x 9.75''D
Capacity
8 single channels
Power Input
117VAC/24VDC
PPoowweerr CCoonnssuummppttiioonn
5 watts per channel (full alarm peak load)
OOuuttppuuttss
Discrete Analog 4-20 mA DC
Serial RS-485 Modbus™
Discrete or zoned alarm relays
Contacts include common with jumper selectable choice (on controller) of normally-open or normally-closed for four alarms
Resistive load: 5A, 250 VAC; 5A, 30 VDC
Inductive load: 2A, 250 VAC; 2A, 30 VDC
Max. operating current: 5A
OOppeerraattiinngg TTeemmppeerraattuurree RRaannggee
-40°F to +175°F
WWaarrrraannttyy
One year
1.3 MULTIPLE ALARM RELAY CIRCUIT
A multiple alarm relay circuit (referred to in further text as MARC) mounted on the controller mother board is
provided with each Detcon Model 812B-FB. The MARC (figure 1) consists of 4 interposing relays (contacts are
rated 10 amp @ 120 VAC/8 amp @ 30 VDC) with 24VDC coils as standard. Other coil voltage ratings must be
specified at time of order. The MARC can be configured to output Form C dry contacts (common, normally open
and normally closed), AC power or DC power. A 5 amp microfuse is provided for each relay and is configured in
series with the common pole of its respective relay. This configuration is functional regardless of whether Form C
dry contacts, AC power or DC power outputs are used.
An in/out termination is provided for applying AC or DC power into any one of the interposing relays. A gold
plated jumper tab is used to apply the in/out power option to its corresponding relay, thus the 4 relays may be
used in a combination of Form C dry contacts and DC outputs or Form C contacts and AC outputs.
The terminations labeled “Alarm Coil Power” located on the left of the 812B-FB motherboard are used only for coil
power. The “+” termination may be used to provide for various relay logic through the Form C dry contacts terminals of each individual Model 12B channel located on the 812B-FB motherboard. The “–” termination should be
wired into the common terminal (shown by a common symbol) located on the left of the MARC.
The terminations labeled “Alarm Power” located on the left of the 812B-FB motherboard are used for providing
power to the In/Out termination on the MARC. As can be seen in the 812B-FB schematic/wiring diagram (figure
2), the alarm power terminations for AC come directly from the AC input terminals located above on the 812B-FB
motherboard. The same is true of the DC power terminations.
NNoottee::
DC power used to drive alarms must be obtained through a remote DC power source. The remote DC
power source should be terminated to the terminals labeled “DC IN” located on the 812B-FB motherboard. The
“DC IN” terminations function as both an alternative DC source used to power the 812B-FB as well as provide
power for DC alarms. The 812B-FB power supply is not capable of providing power for alarm devices.
Mounting hardware is pre-installed on the 812B-FB motherboard for an additional multiple alarm relay circuit. See
section 1.9 for part number and ordering information.
Model 812B-FB NEMA 4 Control Enclosure PG.3
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