Temperature and Humidity Sensors for Distribution Substations and Ring Main Units

Distribution Substations

With the continuous development of the power sector in China, ensuring the safety of electricity production has become an integral part of distribution substations and ring main units. Temperature and humidity are crucial indicators in managing distribution substations, making real-time monitoring of these parameters essential in the substation monitoring system. 

Maintaining optimal temperature and humidity levels is important to ensure a conducive environment for efficient electricity transmission. In this blog, we will explore the details.

Recommended Temperature and Humidity Ranges:

Low Voltage Switchgear: Temperature should be below 15°C, and relative humidity should be below 75%RH.

High Voltage Switchgear: Temperature should be below 25°C, and relative humidity should be below 50%RH.

General guidelines for indoor environments: Temperature should be controlled below 30°C, and relative humidity should be maintained below 70%.

Importance of Temperature and Humidity Monitoring:

Distribution substations house various equipment such as switchgear, distribution cabinets, and ring main units that operate continuously. The heat generated by these components can significantly impact indoor temperature and humidity. 

Real-time monitoring of the environmental conditions is necessary to prevent exceeding the recommended limits. Installing temperature and humidity sensors in distribution substations enables the collection, display, analysis, and alarm triggering based on these parameters. This ensures a comfortable working environment and prevents safety incidents that could disrupt the functioning of the equipment.

Preventive Measures for High-Temperature and High-Humidity Environments:

To mitigate the risks associated with high-temperature and high-humidity environments in distribution substations and ring main units, the following measures can be implemented:

Utilize Temperature and Humidity Monitoring Equipment: Real-time environmental monitoring using temperature and humidity sensors allows for integrating ventilation systems, fans, and air conditioning units. When temperature and humidity values exceed the recommended limits, appropriate measures can be taken promptly to maintain a safe operating environment for the electrical equipment.

Ensure Adequate Ventilation: Regularly ventilating the substation interior helps prevent excessive heat and humidity accumulation. Proper airflow and ventilation systems can help dissipate heat and maintain optimal conditions within the substation.

Training and Coordination: Conduct safety training for personnel working in the substation environment, emphasizing clear roles and responsibilities. Strengthen patrol and inspection procedures to minimize safety accidents and promote a proactive approach to safety.

Recommended Temperature and Humidity Sensors:

Several temperature and humidity sensors are recommended to effectively monitor and control temperature and humidity in distribution substations. Here are two examples:

HTW-211 Temperature and Humidity Sensor Module by Samyoung (South Korea): This sensor module is based on HumiChip® technology, providing accurate and reliable humidity measurements. It features robust molded packaging and coating materials for enhanced durability and resilience in harsh environments. The HTW-211 offers a linear voltage output, which can be directly connected to microcomputers with ADC inputs. It operates within a humidity range of 0-100%RH and a temperature range of -40 to 85℃, with humidity accuracy of ±3%RH and temperature accuracy of ±0.3℃. The sensor is suitable for mass production and applications that require high measurement precision.

CAEL-HTB/HT/HTA Series Multifunctional Temperature and Humidity Sensors by Serial (Taiwan): This series of sensors meet the highest demands for temperature and humidity measurements in challenging environmental conditions. They can calculate additional humidity parameters such as dew point temperature, absolute humidity, wet bulb temperature, and enthalpy. The series offers wall-mounted, duct-mounted, and separate probe options. The sensors provide analog output and can be configured for current or voltage output. They also support RS485 communication for remote monitoring and data recording. The LCD display allows for simultaneous visualization of multiple parameters, and the touch buttons facilitate easy configuration and adjustment.


Temperature and humidity are critical parameters to monitor in distribution substations and ring main units to ensure safe and efficient electricity transmission. Real-time monitoring using temperature and humidity sensors allows for prompt action in case of deviations from recommended limits. By implementing these sensors and following preventive measures, distribution substations can maintain a comfortable working environment, mitigate safety risks, and enhance the reliability of power distribution systems.

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