Description
Honeywell 82408470-001
Technical Specifications
- Temperature input channels: 3 independent PT100 sensor inputs
- Measurement range: -20 °C to +80 °C
- Measurement accuracy: ±0.5 °C
- Alarm thresholds: Software configurable, default high alarm at 55 °C, low alarm at 0 °C
- Supply power: 24 V DC from cabinet power bus
- Operating temperature: 0 °C to +60 °C
- Alarm output: Passive dry contact, contact rating 24 V DC, 0.5 A
- Communication interface: Connects to TDC3000 cabinet I/O terminal block
Functional Features Three sensors distributed across cabinet top, middle and bottom positions, covering the full vertical temperature gradient inside the cabinet. When over-temperature alarm triggers, the board signals cabinet roof fans to run at full speed to accelerate heat exchange. On-board LED numeric display shows live cabinet temperature, allowing maintenance staff to read values locally without opening the upper HMI. Automatic sensor open-circuit and short-circuit diagnosis, triggers channel fault alarm. Digital temperature sampling filter, eliminates reading fluctuation from fan start-stop cycles. All alarm events include time-stamped records, uploaded to DCS event logs.
Application Scenarios Internal thermal environment monitoring for TDC3000 control cabinets Over-temperature warning and cooling linkage during high summer ambient temperatures Spare part replacement for aged temperature sensors in legacy cabinets Environmental safety monitoring for unmanned remote DCS stations Temperature protection unit for PLC/DCS cabinets in high-temperature workshops
Performance Parameters
- Temperature sample rate: 1 Hz
- Alarm response latency: ≤500 ms
- Sensor break detection response: ≤300 ms
- Temperature drift: ±0.1 °C per 10 °C ambient change
- Dry contact withstand voltage: 1500 VAC for 1 minute
Material Composition FR4 flame retardant PCB substrate PT100 constant current excitation circuit 16-bit ADC conversion chip LED numeric display Alarm relay TVS surge protection components Tin-plated copper screw terminals UL94 V0 flame retardant plastic enclosure
Structural Features Small rectangular board form factor, fixed on the middle cabinet upright. Front panel features a 3-digit LED temperature display and 3 channel status LEDs. Terminal block on the board edge connects PT100 sensors and 24 V power supply. Mounting holes positioned for standard cabinet upright screw fixation. Sensor leads run through cabinet cable trays to top, middle and bottom positions.
Working Principle On-board constant current sources inject stable small current into each PT100 sensor. The ADC circuit measures voltage drop across each PT100, calculating real-time process temperature. On-board logic compares measured temperature against preset alarm thresholds. When temperature exceeds the limit, the alarm relay activates, sending a dry contact signal to the DCS alarm loop while signaling fans to run at full speed. Sensor open-circuit faults are identified via loop impedance monitoring, generating a channel fault flag. Temperature values display locally on the LED screen, and upload to the DCS operator station.
Installation Requirements Install the three PT100 sensors respectively at cabinet top air outlet, middle section, and bottom air intake positions. Connect 24 V DC supply with correct polarity to avoid circuit damage. Wire alarm dry contact signals to the DCS cabinet temperature alarm input channel. Calibrate zero point for all three channels after power-up, ensuring consistent measurement accuracy. Use shielded compensation cable for sensor runs, single-point shield grounding.
Usage Notes Do not install sensors directly against heat-generating power modules, this causes localized temperature measurement error. LED brightness dimming over long service life is normal and does not affect temperature measurement function. Modifying alarm thresholds requires heat load calculation to avoid setting limits too high and losing protection. Relay contact wear prevents alarm signal transmission; test contact operation reliability regularly.
