Overview
The WHD Series Temperature and Humidity Controller is specifically designed for internal environment control of medium and high voltage switchgear, terminal boxes, ring main units, and substations.
By precisely monitoring and regulating internal temperature and humidity, it effectively prevents equipment failures caused by extreme temperatures, as well as creepage or flashover accidents induced by moisture or condensation, thereby enhancing the safety and reliability of power distribution systems.
Highlight
Sensor Capacity & Compatibility
- Up to 3 sensors
- WH-3 T&H sensor
- Sensor cable ≤20m
Measurement Accuracy
- Temperature: ±1℃
- Humidity: ±5%RH
- Range: -40~99℃, 0~99%RH
- Hysteresis: 5 (adjustable)
Output & Options
- Relay: 5A/AC250V
- Options: RS485, Alarm, 4-20mA
- Manual override (heater/fan)
Robust & Reliable
- Operating temp: -20~+60℃
- Insulation ≥100MΩ, 2kV
- MTBF ≥50,000 hours
Function
| Temperature and Humidity Measurement & Control | Automatically activates heater or fan based on preset thresholds to maintain stable internal environment. |
| Multi-channel Independent Regulation | Supports up to 3 independent channels (model dependent), each with its own sensor and control outputs for zoned control. |
| Adjustable Control Parameters & Hysteresis | Flexible setting of heating/cooling temperature, humidity thresholds, and hysteresis to prevent relay chattering. |
| Manual Override | Long-press directional keys to force heater or fan on, convenient for on-site testing and maintenance. |
| Fault Alarm (Optional -J) | Dedicated alarm output for heater break or sensor failure, ensuring timely fault notification. |
| Transducer Output (Optional -M) | Converts measured temperature or humidity into a standard 4-20mA analog signal for PLC integration. |
| RS485 Communication (Optional -C) | Supports MODBUS-RTU protocol for remote monitoring and integration with SCADA/EMS. |
| Local LCD Display & Status LEDs | Real-time display of temperature, humidity, channel, and operating status (heating/fan/alarm) with intuitive LEDs. |
Specification
| Parameter | Value |
| Measurement Range | Temperature: -40.0℃～99.9℃ Humidity: 0%RH～99%RH |
| Accuracy | Temperature: ±1℃ Humidity: ±5%RH |
| Control Parameter Setting Range | Heating (Temp): -40.0℃～40.0℃ Cooling (Temp): 0.0℃～99.9℃ Humidity Control: 20%RH～90%RH |
| Output Contact Capacity | 5A / AC250V (resistive load) |
| Hysteresis | 5 (default, configurable) |
| Auxiliary Functions (Model Dependent) | RS485 Communication (MODBUS-RTU), Alarm Output, Transducer Output (DC 4～20mA) |
| Communication Interface | RS485, MODBUS-RTU protocol |
| Auxiliary Power Supply | Voltage: AC 85～265V or DC 100～350V Power Consumption: Basic (≤0.8W) + Relay (≤0.7W per channel) |
| Insulation Resistance | ≥100MΩ |
| Dielectric Strength | 2kV/1min (AC, RMS) between power supply and enclosure/other terminals |
| Operating Environment (Controller) | Temperature: -20℃～+60℃ Humidity: ≤95%RH, no condensation, no corrosive gases Altitude: ≤2500m |
Show More
Model Differences
| Model | Channels | Standard Function | Optional Function | Installation | Compatible Sensor |
| WHD48-11 | 1 | Temp/Humidity Control | -C (Communication) | Embedded (45x45mm) | WH-3 (1 pc) |
| WHD46-11 | 1 | Temp/Humidity Control | -J / -C / -M (One of three) | Embedded (116x56mm) | WH-3 (1 pc) |
| WHD46-22 | 2 | Temp/Humidity Control | -J / -C / -M (One of three) | Embedded (116x56mm) | WH-3 (2 pcs) |
| WHD46-33 | 3 | Temp/Humidity Control | -J / -C / -M (One of three) | Embedded (116x56mm) | WH-3 (3 pcs) |
| WHD72-11 | 1 | Temp/Humidity Control | -J / -C / -M (Select one) | Embedded (67x67mm) | WH-3 (1 pc) |
| WHD72-22 | 2 | Temp/Humidity Control | -J / -C / -M (Select one) | Embedded (67x67mm) | WH-3 (2 pcs) |
| WHD20R-11 | 1 | Temp/Humidity Control | -J, -C (Both selectable) | DIN Rail (35mm) | WH-3 (1 pc) |
| WHD20R-22 | 2 | Temp/Humidity Control | -J, -C (Both selectable) | DIN Rail (35mm) | WH-3 (2 pcs) |
FAQ
This depends on the model. WHD48 and WHD20R-11 support 1 sensor; WHD72 and WHD20R-22 support up to 2 sensors; WHD46 supports up to 3 sensors, with each channel controlling its own heater and fan.
The sensor and controller must be connected using a 4-core shielded cable, and the length should not exceed 20 meters to ensure accurate signal transmission.
Hysteresis is the difference between the start value and the stop value for an action. For example, if the heating start temperature is 5℃ and the hysteresis is 5, the heater will stop when the temperature rises to 10℃. This prevents the relay from chattering on and off.
Yes, models with the “-C” option feature an RS485 interface and support the standard MODBUS-RTU protocol, allowing for easy integration with SCADA, PLC, or other energy management systems.
The “-J” (Alarm) option provides a dedicated relay output for fault signals like a heater break. The “-M” (Transducer) option outputs the measured temperature or humidity as a continuous 4-20mA analog signal for direct reading by a PLC or analog meter.
Summary
The WHD Series Temperature and Humidity Controller is a robust and reliable solution for protecting critical electrical assets from environmental threats. With options for multi-channel control, various mounting styles, and auxiliary functions like communication and alarm output, it provides the flexibility to meet diverse project requirements. Its precise control and high reliability help extend equipment life, reduce unplanned downtime, and ensure continuous power supply.
