HTC-307

A. Product Overview
Selec HTC307 is a panel-mount humidity and temperature controller designed for applications where both RH and temperature must be measured and controlled from one instrument. The product is specified as a 4-digit dual display unit with white + green display and a touch keypad. It supports RH sensor input and PT100 input, allowing a single controller to handle humidity and temperature measurement in HVAC and controlled environments. The controller provides 2 relay outputs for control and 2 relay outputs for alarm indication, making it suitable for humidity control (humidification/dehumidification) along with temperature control and alarm monitoring in the same panel. It also includes RS485 communication and a wide universal supply (90 to 270V AC/DC), supporting integration into industrial panels and building control systems.

B. Working Principle
The HTC307 reads two process values: humidity (from RH sensor wiring shown in the manual) and temperature (from RTD input wiring shown as RTD terminals). Based on configured setpoints and control action parameters, it switches internal relays to drive external loads or contactors. The manual shows separate wiring diagrams for main/control outputs and alarm outputs, indicating relay-driven switching for resistive loads and contactor drive with a recommended snubber arrangement. The controller includes programming levels for temperature module, humidity module, and alarm module, allowing setpoints, hysteresis, timer, and related parameters to be set from the front keypad. RS485 terminals are provided for communication wiring where required.

C. Key Applications

• HVAC humidity and temperature control panels (humidification / dehumidification)

• Clean rooms and controlled environment rooms requiring RH + temperature monitoring and alarms

• Pharmaceutical and laboratory environmental control where RH/temperature setpoints and alarm relays are used

• Utility and plant areas where RH sensor + PT100 inputs are needed with relay control outputs and RS485 integration

D. Why Industries Use This Product
Industries use combined humidity + temperature controllers to reduce panel complexity and standardize control logic for RH and temperature in one device. The HTC307 offers multiple relay outputs so control and alarm functions can be separated (2 control relays and 2 alarm relays). The manual specifies supply compatibility and relay wiring practices, supporting typical industrial panel installation. RS485 communication availability helps connect the controller to monitoring systems where communication is used. The installation section provides panel cutout guidance and terminal connection diagrams, which supports consistent installation across standardized panels and replacement of existing panel controllers.

E. Suitable Buyers

• OEMs building HVAC or environmental control panels needing RH + PT100 measurement with relay control and alarm outputs

• EPC contractors standardizing humidity and temperature control loops in building automation and industrial utilities

• Maintenance and utilities teams commonly using it for replacement in existing humidity/temperature control panels with RS485 needs

• Plant engineering and procurement teams preferring standardized installations with defined cutout, wiring, and relay outputs

FAQ SECTION

1. What is Selec HTC307?
   Selec HTC307 is a humidity + temperature controller with dual display (white + green) and touch keypad, designed for RH sensor input and PT100 input with relay outputs and RS485.

2. What inputs does HTC307 support?
   The product is specified with RH sensor input and PT100 input. The manual shows humidity sensor wiring terminals and RTD input wiring terminals.

3. How many relay outputs are available?
   HTC307 is specified to have 2 control relay outputs and 2 alarm relay outputs.

4. What is the supply range?
   The supply is specified as 90 to 270V AC/DC.

5. Does HTC307 support communication?
   Yes. It is specified with RS485 communication, and the manual shows RS485 terminals for wiring.

6. What panel cutout is required for installation?
   The instruction manual shows a panel cutout of 92 mm × 92 mm for mechanical installation.

7. Can the relays drive a contactor?
   The manual includes a wiring diagram for relay-to-contactor drive (single phase) and notes using a snubber arrangement to increase relay life.