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Model 5100-02-IT Combustible Gas Sensor Module
Page: 3
1. PRODUCT DESCRIPTION
1.1 GENERAL
The Model 5100-02-IT Catalytic Bead Combustible Gas Sensor Module
is a member of the Sentry Information Technology ”IT” family of gas
sensor transmitter modules. IT modules offer a broad array of features
including:
• Integral Alphanumeric display
• 180 day calibration frequency
• Integral alarm relays (3)
• 4-20 mA output
• Modbus
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RTU interface
• SMC Sentry interface
• 316 Stainless steel enclosure option
• Remote alarm reset
• Auxiliary relay option
• Remote sensor option
• Auxiliary connector option
IT modules are designed, and approved for installation and operation in hazardous locations.
1.2 PRODUCT CONFIGURATION
Various module configuration options are available. Where applicable, these options are factory configured
prior to shipment.
1.3 THEORY OF OPERATION
Catalytic bead gas sensors detect gas by comparing the resistance of two heated elements. One element is
catalytic to enhance the burning of combustible gases, the other element is passive. Electronic circuits are
used to compare the change in the catalytic bead resistance relative to the passive bead. The relative change
is calibrated to determine the concentration of the gas of interest.
1.4 MODES OF OPERATION
1.4.1 SENTRY INTERFACE
All IT gas sensor modules can be installed on Sierra Monitor Sentry Model 5000 controllers. Catalytic bead
modules communicate as a combustible gas sensor module (Type 2 communication) and are automatically
detected by the Sentry controller. When it is installed in a Sentry system the IT module must have a unique
address which can be established by setting an address between 1 and 8 on the rotary switch accessible
from the cover plate as illustrated in Figure 3-1. Figure 3-4 in this manual provides the wiring terminations
for connections to the Sentry controller.
When the module is operated in conjunction with a Sentry controller, the alarm relay setup (See section
4.3) should be set to “Sentry”, allowing the Sentry controller to manage alarm relay action rather than the
5100-02-IT Gas Sensor Module.
An available option, applicable only to Sentry installations, is a connector card which allows daisy chain
installation using the Sentry multiplex capability. Use of the connector card reduces costs by avoiding the
requirement for wiring junction boxes. The connector card has two sets of connections, allowing for a
continuous run to the next module.
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Registered trademark of Schneider Electric.