The principle and characteristics of PTC thermistor

时间:2019-05-21 丨 预览:107 人次

Working principle of ptc thermistor:

The ptc thermistor will be in an inactive state for a long time; when the ambient temperature and current are in the c zone, the heat dissipation power of the thermistor is close to the heating power, so it may or may not operate. When the thermistor is at the same ambient temperature, the operating time decreases sharply as the current increases; the thermistor has a shorter operating time and a smaller maintenance current and operating current when the ambient temperature is relatively high.

1. The ptc effect is a material that has a ptc (positive temperature coefficient) effect, that is, a positive temperature coefficient effect, which only means that the resistance of this material will increase with increasing temperature. For example, most metal materials have ptc effect. In these materials, the ptc effect shows that the resistance increases linearly with increasing temperature. This is known as the linear ptc effect.

2. Materials with non-linear PTC effect undergoing phase change will exhibit a phenomenon in which the resistance increases abruptly in the narrow temperature range by several to dozens of orders of magnitude, that is, non-linear PTC effect, and many types of conductive polymers will exhibit this phenomenon. Effects, such as polymer ptc thermistor. These conductive polymers are very useful for manufacturing overcurrent protection devices.

3. The polymer ptc thermistor is used for overcurrent protection. The polymer ptc thermistor is often referred to as a self-recovery fuse (hereinafter referred to as the thermistor). Because of its unique positive temperature coefficient resistance characteristics, it is extremely suitable Used as an overcurrent protection device. The use of the thermistor is like a normal fuse, which is used in series in the circuit.

Characteristics of ptc thermistor:

1. The sensitivity is high, the resistance temperature coefficient is 10 to 100 times greater than that of metal, and the temperature change of 10-6 ℃ can be detected;

2. Wide operating temperature range, normal temperature devices are suitable for-55 ℃ ~ 315 ℃, high temperature devices are suitable for temperatures higher than 315 ℃ (currently up to 2000 ℃), low temperature devices are suitable for -273 ℃ ~ 55 ℃;

3. Small size, able to measure the temperature of voids, cavities and blood vessels in the body that cannot be measured by other thermometers;

4. Easy to use, the resistance value can be arbitrarily selected from 0.1 to 100kΩ;

5. It is easy to process into complex shapes and can be produced in large quantities;

6. Good stability and strong overload capacity.

ptc thermistor is mainly used in battery, security, medical, scientific research, industrial motor, aerospace and other electronic and electrical temperature control related fields.