Products / Temperature & Humidity Controller
THC-303
THC-303 Multi-Zone Temperature & Humidity Controller
When three temperature and humidity measurement zones, Modbus RTU communication and configurable relay logic are required in metal-clad switchgear or multi-compartment electrical enclosures, the THC-303 is what we specify. Three external sensors and four individually programmable relays support application-specific control of heaters, fans, alarms and other circuits.
About this product
Application
THC-303 is a configurable multi-zone temperature and humidity controller for metal-clad switchgear, multi-compartment MV panels, transformer enclosures and control cabinets. It monitors three separate measurement points from a single controller, with each external sensor measuring both temperature and relative humidity.
The controller is used to manage enclosure conditions, prevent condensation and reduce partial-discharge and surface-flashover risk. It does not perform partial-discharge measurement or monitoring.
Operating Principle
Separate temperature and relative humidity thresholds can be defined for each of the three sensors. The controller evaluates the measurements from each point and operates its relay outputs according to the configured sensor and threshold conditions.
When a configured temperature or humidity condition is reached, the assigned relay can activate the relevant control or alarm circuit. This allows the enclosure environment to be managed according to the requirements of each measurement zone.
Configuration and Relay Logic
THC-303 has four relay outputs, and each relay can be programmed individually. Relay operation can be configured according to selected sensor inputs, temperature thresholds, relative humidity thresholds and the required control response.
The programmable outputs can be used to control heaters, fans, alarms or other control circuits. This configuration structure allows different measurement zones and control functions to be managed from one device without applying a fixed relay logic to every installation.
Communication and Local Indication
Modbus RTU communication allows temperature, relative humidity and device-status information to be integrated into an automation or remote-monitoring system.
The device also provides a local display and LED indicators, allowing measurements and operating states to be checked directly from the front panel.
Mounting Versions
THC-303 is available in two separately orderable mounting versions:
- THC-303 DIN Rail Mount: Designed for installation on a DIN rail inside the electrical enclosure.
- THC-303 Flush Mount: Designed for installation on the panel surface, providing front access to the display and controls.
The required mounting version and its official ordering code must be confirmed when preparing the quotation.
Selection Guidance
THC-303 is intended for applications requiring three measurement points, Modbus RTU communication and configurable relay operation.
For simpler local control of a single environment, THC-100D, THC-102 or THC-202 may provide a more appropriate configuration. THC-303 should be selected where multiple measurement zones and application-specific output logic must be managed from one controller.
Technical Specifications
| Applications | Metal-clad switchgear, Multi-compartment MV panels, Transformer and control enclosures |
| Function | Condensation prevention and reduction of partial-discharge and surface-flashover risk |
| Control Principle | Evaluates three temperature and relative humidity measurement points and operates four relays according to configured sensor and threshold conditions |
| Sensor Configuration | 3 external temperature and humidity sensors |
| Measurement Points | 3 |
| Measurement | Temperature and relative humidity at each sensor |
| Sensor Thresholds | Separate temperature and relative humidity thresholds for each sensor |
| Display | Yes |
| LED Indication | Yes |
| Relay Outputs | 4 |
| Relay Logic | Each relay is individually programmable |
| Control Applications | Heaters, Fans, Alarms, Other control circuits |
| Communication | Modbus RTU |
| Sensor Fault Detection | Yes |
| Mounting | THC-303 DIN Rail Mount, THC-303 Flush Mount |
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