How do you test whether a temperature sensor is functioning properly?

Release Date:

2023-05-20

Author:

A temperature sensor is essentially a negative temperature coefficient thermistor: as temperature rises, its resistance decreases. To assess the quality of a temperature sensor, first verify that its resistance varies with temperature, and then confirm that the measured resistance falls within the specified tolerance range.

The quality of a temperature sensor is assessed by testing its sensing element. When evaluating a sensor, only two aspects are typically considered: 1) it must function; and 2) it must perform well.

For temperature sensors, “usable” means they function when powered on. “Good performance” requires that their accuracy and response time meet the specified requirements. Therefore, whether a temperature sensor outputs resistance, current, or voltage, it must first be powered up and tested to verify the presence of an output signal. If an output is observed upon energization, the sensor can be considered functional. Next, use a reference standard to measure its temperature‑induced output and assess accuracy against the nominal specifications. Finally, evaluate the sensor’s response speed by examining the delay time in its temperature‑response curve; a t0.9 value of less than 30 seconds indicates compliance with the required standards.

There are four methods for determining whether a temperature sensor is functioning properly:

1. If a meter is available, connect the sensor to it, place the sensor in an ice–water mixture, and check whether the meter reads 0°C and whether the reading changes.

2. If no thermometer is available, consider the sensor’s temperature‑measurement range and explore the use of a three‑wire platinum resistance thermometer.

3. Place the sensor in an ice–water mixture and measure its resistance with a multimeter. Platinum resistance thermometers typically come in a few standard values: PT100, PT1000, and PT200. In an ice–water mixture, the corresponding readings are 100 ohms, 1000 ohms, and 200 ohms, respectively.

4. With the sensor held in hand, the reading varies accordingly, and the magnitude of the change remains consistent.

Method for Using a Multimeter to Test the Functionality of a Temperature Sensor

If the reading is several tens of thousands of ohms, or close to 0 ohms (e.g., below 0.1), then the sensor is definitely faulty. Alternatively, you can fill a paper cup with hot water, place the sensor inside, and use a multimeter to measure its resistance to see if it changes. If the resistance varies smoothly and stays within the normal range—around a few hundred to a thousand ohms (–40°C: 450 kΩ; 20°C: 2.5 kΩ; 130°C: 100 Ω)—then the sensor is functioning properly.

Huizhou Jin Yuan Xiang Electronic Co., Ltd. It is a high-tech enterprise that manufactures NTC thermistor NTC temperature sensor Temperature probe. Feel free to request a quote with images. Free sample available.

For more information on NTC thermistors, please visit our website at www.jyx-sensor.cn. If you have any questions, feel free to contact our team for assistance.

Previous Page: What types of temperature sensors are there?

Next page: What is the function of a temperature sensor?

Latest Updates