Chemgard Infrared Gas Monitor
Section 2, Installation and Setup
•
4-20 mA, isolated, current sourcing
•
0-10 VDC
These voltage and current outputs are
proportional to the displayed gas concentration.
Connections are made to terminal strip J17 located
on the lower left side of the main circuit board
(FIGURE 2-6). Analog output wiring should enter
the unit through the hole provided on the left side
of the unit. The terminal portion of the connector
can be removed from the circuit board for easier
connection. The maximum wire size
that these
connectors can accept is Listed #12 AWG; the
maximum cable length is 500 feet (152 m).
It is suggested that Listed #18 AWG, twisted-pair
wire be used. If shielded wire is necessary,
ground the shields of all cables at the receiving
end of the signal. Do not ground or connect the
shields at the Chemgard Monitor.
4-20 mA
The 4-20 mA output sources current to a
separate return. Connections are made to
terminals 2 (I+) and 3 (RTN) on terminal strip J17.
1-10 VDC
The 0-10 VDC output sources voltage to 2 K ohms
maximum load. Connections are made to terminals
4 (V+) and 5 (COM) on terminal strip J17.
The voltage output can be programmed to
correspond to the channel presently being
sampled. The front-panel screen shows:
1V/PT IF OUT = 1-10V
(indicating one volt per point
if output equals one to 8 volts).
When enabled, and the unit is monitoring from:
•
channel 1:
voltage output is one volt
•
channel 2:
voltage output changes to two volts.
RS 232 Output
•
See Appendix C for wiring information.
Ferrite Bead Installation
Some models are shipped with ferrite beads.
Follow the instructions below for proper installation.
•
Input and output signals must be connected
by using twisted, shielded wire pairs.
•
The shield or its drain wire (FIGURE 2-7)
must be connected to the grounding terminal
on the power supply plate.
•
Each unit is supplied with Thora-Electronik
#16-28-9 or equivalent ferrite (P/N 10017468).
•
The shield must also be connected to ground
at the receiving equipment.
•
The RS 485 communications lines to a relay
module must be wired in a similar manner.
See Appendix B for more information on t
he
relay module.
CAUTION
Bundle low voltage wiring together (lower than
30 volts), separate from high voltage wiring
(higher than 30 volts); otherwise, incorrect
readings could occur.
Optional Alarm Beacon
Your unit may have an optional alarm kit installed.
This kit is made up of a beacon on the top of the
unit. It is factory-wired so no additional wiring is
necessary; it lights when any alarm indication is
given by the instrument. This function parallels
the audible alarm output (when the horn sounds,
the beacon lights).
Relay Outputs
Alarm Relays
There are three alarm relay outputs:
•
Caution (factory-set to trip at 9 ppm)
•
Warning (factory-set to trip at 29 ppm)
•
Alarm (factory-set to trip at 700 ppm)
Each relay can be set up as latching/non-latching
and/or normally-energized/normally de-energized.
Contacts are Form C at 240 Volts AC 8 amps
resistive. Connect wiring to Terminal Strip J29. User
can adjust alarm trip points via the front panel
(see Section 3, FIGURE 3-13).
Alarm Relay Connections Wiring
Three gas level alarm relay outputs are provided.
All alarm relays are Form C, SPDT relays which
can be wired to either closed or opened contacts
in an alarm condition.
Each relay has contacts for:
•
NORMALLY OPEN (NO)
•
COMMON (COM)
•
NORMALLY CLOSED (NC)
The function of each relay connector terminal is
indicated on FIGURE 2-6. Relay wiring should
enter the unit through one of the openings on the
right side of the unit. Connections are made at
the internal terminal strip labeled J29, located on
the right side of the circuit board (FIGURE 2-6).
The terminal portion o
f the connector can be
unplugged from the circuit board for easier wire
connections.
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