AMC AMC-1228, Instructions Manual, Page: 9 / 15

AMC-1228 Multidrop
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4 INSTALLATION
This section relates to the proper installation of the AMC-1228 unit. The topics of proper
location, sensor wiring selection, and multi-unit interconnection are all discussed in detail.
4.1 LOCATION AND MOUNTING
Mount the sensor unit on a solid, non-vibrating surface or structure, easily accessible for status
checking and calibration. The unit must be mounted in an area where the local concentration of
gas is unaffected by the presence of ventilation systems.
NOTE:
Mounting arrangement of the housing depends on the location and mounting surface.
Mounting hardware is NOT supplied.
4.2 CABLE SELECTION AND WIRING
To gain access to the terminal blocks, remove the four (4) screws and front panel from the
housing. This will expose the field wiring terminals. The sensor module output (-,s,+) terminal
block, connects to the input terminal block of the previous unit, or to the sensor/transmitter
terminal block in the monitor, as shown in Figure 2.
NOTE:
Turn off the power supply before removing or replacing the sensor.
Connection should be made using 3-conductor, shielded cable (shield must be grounded at the
monitor). Run cable through steel conduit for best signal transmission and maximum noise
rejection. A maximum length of 150 feet of 18 AWG size cable is allowed between each unit as
well as between the monitor and first unit(s). For other distances or cable sizes, consult with
The Armstrong Monitoring Corporation.
4.2.1 MULTI-UNIT INTERCONNECTION
Each sensor module is designed to interconnect to other units in series and/or branching
configurations. Various typical configurations are shown in Figure 3, illustrating the versatility of
this type of system. Because each unit is pre-calibrated, additional units can be added to a
system without altering the monitor settings. When multiple units are interconnected, either one
or both jumpers need to be removed (refer to section 4.2.2 TERMINATION and Figure 2).
4.2.2 TERMINATION
For each unused input terminal block, the corresponding jumper MUST be left installed (as
shown in Figure 2). Failure to do so may cause the system to malfunction.