What are thermistors?

Thermistors are available in two types: Negative Temperature Coefficients (NTC thermistors) and Positive Temperature Coefficients (PTC thermistors). NTC thermistors’ resistance decreases as their temperature increases, while PTC thermistors’ resistance increases as their temperature increases. NTC’s are the most commonly used in temperature measurement.

Thermistor characteristics are defined based on the composition of materials with known resistance. As the temperature increases, an NTC thermistor’s resistance will increase in a non-linear fashion, following a particular “curve.” The shape of this resistance vs. temperature curve is determined by the properties of the materials that make up the thermistor.  Thermistors are accurate to approximately ± 0.2°C within their specified temperature range. They’re generally durable, long-lasting, and inexpensive. They are typically epoxy coated to provide the optimum performance in heavy duty environments. Thermistors and especially NTC’s are mainly applied in a temperature range from -50°C to +150°C with typical resistance values between 2,000Ω and 10,000Ω.

Common applications:
In Senmatic NTC thermistors are primarily used for low temperature application within the refrigerated cargo industry, also know as reefer containers. They are either used to measure and monitor the refrigeration unit or as a cargo temperature probe, commonly known as USDA probes.