Overtemperature Sensor: A Solution for Monitoring and Protecting Equipment Against Overheating Risks

Abnormally high temperatures can reduce performance, damage equipment, or create potential safety risks in technical systems. An overtemperature sensor helps monitor temperature, detect conditions that exceed predefined thresholds, and provide timely alarms or protection signals.

What Is an Overtemperature Sensor Used For?

An overtemperature sensor is a device used to detect when the temperature of an object or environment exceeds a preset threshold, then send an alarm signal or activate a protection function. The device is commonly installed in locations at risk of excessive heat, such as motors, electrical cabinets, HVAC equipment, and industrial machinery.

Depending on its design, the sensor may continuously transmit temperature readings to a controller or only change its output state when the temperature exceeds the specified threshold. When an abnormal condition is detected, the signal can be sent to a BMS, PLC, or alarm system for operator response, while also triggering measures such as load reduction, equipment shutdown, or protective functions.

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Structure of an Overtemperature Sensor

To accurately detect and respond to rising temperatures, an overtemperature sensor typically consists of several components responsible for measurement, signal processing, and signal transmission.

Temperature Sensing Element

This is the component that directly detects changes in temperature. Depending on the design, it may use thermistors, RTDs, or semiconductor sensing elements. The characteristics of the sensing element determine the sensor's measurement range, sensitivity, and accuracy.

Signal Processing Circuit

The electronic circuit receives signals from the sensing element, processes them, and determines the actual temperature or overtemperature condition. In electronic sensors, the signal processing circuit may also perform noise filtering, calibration, and signal conversion.

Signal Output

Depending on the model, the sensor may provide analog signals such as 0–10 V or 4–20 mA, relay switching signals, or digital communication interfaces for connection to a controller. The output type should be selected to match the signal input of the receiving device in the system.

Protective Housing and Connection Terminals

The protective housing helps protect internal components from dust, moisture, heat, and mechanical impact. Connection terminals and the installation method should also be suitable for the actual operating environment to ensure stable signal transmission during operation.

Criteria for Choosing the Right Overtemperature Sensor

Selecting an overtemperature sensor should be based on the characteristics of the monitored object and the requirements of the control system, rather than considering only the temperature range.

Measurement Range and Temperature Threshold

Determine the normal operating temperature, alarm temperature, and maximum allowable temperature of the equipment to select a sensor with an appropriate measurement range. Avoid selecting a sensor whose measurement limit is too close to the actual operating temperature.

Accuracy and Stability

For systems requiring precise temperature control, it is important to consider sensor error, repeatability, and long-term stability. These specifications are particularly important when sensor data is used for automatic control or alarm functions.

Output Signal

Check which signal type is supported by the existing controller or BMS/PLC before selecting a compatible sensor, such as RTD, thermistor, 0–10 V, 4–20 mA, relay, or digital communication.

Installation Environment

Temperature, humidity, dust, vibration, chemicals, and potential exposure to water can all affect equipment durability. For harsh environments, sensors with an appropriate protection rating and housing material should be prioritized.

System Integration Capability

If the sensor is integrated into a BMS or PLC, its compatibility with the required signal type, I/O module, and data communication method should be checked. This helps minimize the need for additional converters or intermediate devices during system deployment.

Applications of Overtemperature Sensors in Practice

Thanks to their ability to detect abnormal temperature increases at an early stage, overtemperature sensors are widely used in systems that require equipment monitoring and protection.

- Electrical cabinets and control panels: Monitor the internal cabinet temperature and detect heat buildup caused by overload, inadequate ventilation, or abnormal electrical equipment operation.

- Motors and machinery: Monitor temperatures at motors, bearings, or other locations prone to heat generation, providing early warnings before temperatures exceed safe limits.

- HVAC systems: Monitor temperatures at equipment, pipelines, or technical areas to support control functions and detect abnormal operating conditions.

- Industrial equipment: Used in heating machines, production lines, and thermal processing equipment to maintain temperature within specified technical limits.

- Machine rooms and technical areas: Integrated with BMS systems for continuous temperature monitoring, alarm generation, and support for operator response to faults.

- Environmental monitoring systems: In modern buildings, overtemperature sensors can be deployed together with CO sensors, CO₂ sensors, and air quality sensors to simultaneously monitor multiple environmental and safety parameters.

Guide to Proper Overtemperature Sensor Installation

The installation position and method directly affect measurement accuracy. Therefore, installation should be carried out according to the characteristics of each sensor and the equipment being monitored.

1. Determine the correct measurement location: Install the sensor at a point that accurately represents the temperature being monitored, avoiding locations directly affected by heat sources or unrepresentative airflow.
2. Ensure proper thermal contact: For sensors measuring surface or equipment temperature, ensure sufficient contact between the sensing element and the measured object to minimize measurement errors.
3. Connect the signal correctly: Check the wiring diagram, polarity, and output signal type before connecting the sensor to the PLC, BMS, or controller.
4. Minimize signal interference: For long signal cables or environments containing many high-power devices, use appropriate wiring and noise protection methods according to the manufacturer's recommendations.
5. Perform post-installation checks: Compare the sensor reading with a reference measuring device and test the alarm signal at the configured threshold before officially putting the system into operation.

An overtemperature sensor helps detect abnormal temperature increases at an early stage, supporting alarm functions and equipment protection in HVAC systems, electrical cabinets, machinery, and industrial applications. Choosing the right sensor type, measurement range, output signal, and installation position helps improve the accuracy and reliability of the monitoring system.

If you need advice on overtemperature sensors, environmental sensors, or solutions for BMS integration, contact Tri Viet Controls for support in selecting equipment that meets your project's technical requirements.