What is the Difference Between NTC and PTC Thermistors?

NTC (Negative Temperature Coefficient) describes a thermistor whose zero-power resistance decreases with a corresponding increase in its body temperature. PTC (Positive Temperature Coefficient) describes a thermistor whose zero-power resistance increases with a corresponding increase in its body temperature.

What is a 10k Thermistor?

This refers to an NTC thermistor that has a nominal zero-power resistance value of 10,000 ohms at +25°C.

What is the Beta Constant?

An arithmetic estimation of the resistance versus temperature characteristics of a thermistor, based upon two resistance versus temperature points. Beta is expressed in Kelvin (K).

What is the Thermal Time Constant?

The time required for a sensor to register a change (typically 63.2%) of the difference between its initial and final body temperatures, when exposed to a step-function change in temperature under zero-power conditions.

Are Thermistors Linear?

No, NTC thermistors are very non-linear. Their resistance value drops rapidly and non-linearly with an increase in temperature.

How Accurate are Thermistors?

Standard thermistors are available with accuracies as tight as ±0.10°C (0°C to +70°C). Other temperature accuracy ranges are available. Custom sensors are available with accuracies of ±0.05°C over a limited temperature range.

What is Self-Heating?

The effect of passing current through a sensor, which results in raising the body temperature of the sensor above that of the ambient temperature

What is Dissipation Constant?

The amount of applied power required to raise the body temperature of the sensor element by +1° in a specific environment. The dissipation constant is typically expressed in milliwatts per degree Celsius (mW/°C).

What is Maximum Temperature Rating?

The maximum body temperature at which the sensor will safely survive for an extended duration. The body temperature of the sensor can be influenced by internal heating, external heating or a combination of internal and external heating. It is recommended that this temperature rating never be exceeded.

Frequently Asked Questions

Welcome to the EI Sensor Technologies FAQ page, where you'll find answers to common questions about thermistors, RTDs, temperature probe assemblies, and temperature sensing terminology. With over 30 years of experience in the temperature sensing industry, our team is committed to helping customers better understand the products and concepts that impact their applications. Whether you're selecting a sensor, reviewing technical specifications, or troubleshooting a temperature measurement challenge, this resource is designed to provide helpful guidance.

What is the Difference Between NTC and PTC Thermistors?
NTC (Negative Temperature Coefficient) describes a thermistor whose zero-power resistance decreases with a corresponding increase in its body temperature. PTC (Positive Temperature Coefficient) describes a thermistor whose zero-power resistance increases with a corresponding increase in its body temperature.
What is a 10k Thermistor?
This refers to an NTC thermistor that has a nominal zero-power resistance value of 10,000 ohms at +25°C.
What is the Beta Constant?
An arithmetic estimation of the resistance versus temperature characteristics of a thermistor, based upon two resistance versus temperature points. Beta is expressed in Kelvin (K).
What is the Thermal Time Constant?
The time required for a sensor to register a change (typically 63.2%) of the difference between its initial and final body temperatures, when exposed to a step-function change in temperature under zero-power conditions.
Are Thermistors Linear?
No, NTC thermistors are very non-linear. Their resistance value drops rapidly and non-linearly with an increase in temperature.
How Accurate are Thermistors?
Standard thermistors are available with accuracies as tight as ±0.10°C (0°C to +70°C). Other temperature accuracy ranges are available. Custom sensors are available with accuracies of ±0.05°C over a limited temperature range.
What is Self-Heating?
The effect of passing current through a sensor, which results in raising the body temperature of the sensor above that of the ambient temperature
What is Dissipation Constant?
The amount of applied power required to raise the body temperature of the sensor element by +1° in a specific environment. The dissipation constant is typically expressed in milliwatts per degree Celsius (mW/°C).
What is Maximum Temperature Rating?
The maximum body temperature at which the sensor will safely survive for an extended duration. The body temperature of the sensor can be influenced by internal heating, external heating or a combination of internal and external heating. It is recommended that this temperature rating never be exceeded.