Description
Honeywell 05701-A-0302
Technical Specifications Single channel for catalytic bead gas sensor; output signal 4-20mA proportional to gas concentration; supply power obtained from System 57 rack backplane; sensor excitation circuit for catalytic bead bridge; operating temperature 0℃ to 55℃; storage temperature -40℃ to 85℃; humidity 5% to 95% non-condensing; supports sensor zero and span calibration through rack local interface; conforms to gas detection safety standards and ATEX related requirements.
Functional Features It supplies constant excitation current to the Wheatstone bridge of catalytic combustible gas sensor. It converts the resistance variation caused by combustible gas combustion on the bead into linear 4-20mA output. It supports on-site zero adjustment and span calibration for the matched gas sensor. It continuously monitors sensor wire breakage and sensor element failure. It sends fault alarm signals to the System 57 main controller and display panel. It maintains stable signal output under long-term cabinet temperature fluctuation.
Application Scenarios Combustible gas concentration detection loop in oil and gas compressor stations; catalytic sensor signal conditioning in refinery gas detection cabinets; flammable vapor monitoring for chemical plant tank farms; gas safety monitoring for offshore platform enclosed compartments.
Performance Parameters 4-20mA output linearity error less than 1% full scale; response speed matches catalytic bead sensor dynamic characteristic; wire break detection response time is less than 2 seconds; output signal ripple controlled within the allowable range of gas system controller.
Material Composition Circuit substrate is FR4 flame retardant PCB with conformal coating; bridge drive circuit uses industrial precision resistors and operational amplifiers; edge connector is gold-plated; front panel is anti-corrosion coated cold rolled steel; internal insulation materials are high temperature flame retardant plastic.
Structural Characteristics Standard vertical plug-in card for System 57 rack; front panel carries power, sensor fault and signal status LED indicators; elastic locking latches on both sides of the card body; internal DIP switches for channel address setting; passive convection cooling without fan.
Working Principle The rack backplane provides working power to the module. The module forms a complete Wheatstone bridge together with the external catalytic bead gas sensor. When combustible gas contacts the sensing bead, combustion heat changes the resistance value of the bead, unbalancing the bridge circuit. The conditioning circuit amplifies and converts the unbalanced signal into 4-20mA standard current signal. The fault detection circuit judges sensor open circuit or element damage and triggers alarm state.
Installation Requirements Insert the module vertically into the designated slot of System 57 gas detection rack. Complete sensor wiring according to terminal definition on front panel. Set correct channel address through on-board DIP switches. Use shielded twisted pair cable for sensor connection. Separate sensor signal cables from high voltage power cables. Cabinet grounding resistance ≤4Ω.
Usage Notes Calibration must be carried out with standard combustible gas after sensor replacement. Do not use this module for toxic gas electrochemical sensors. Wear anti-static wrist strap during card replacement. Verify fault alarm function after commissioning.
