PTC components and their applications
- Nov 05, 2018 -

   The PTC element is a thermosensitive resistor with the correct temperature coefficient. It is made of barium titanate (BaTiO3) as the main raw material, and added with trace rare earth elements (such as strontium, lanthanum, etc.).

   The resistance - temperature characteristics of the PTC element have a minimum resistance value (the corresponding temperature point is the Curie point) and a maximum resistance value as the temperature increases.In the range of positive temperature coefficient, when the current flowing through the element increases, the electric power increases. When the temperature of the element increases, the resistance value increases, resulting in the reduction of current and power.When temperature rise and heat dissipation balance caused by electrical power, the temperature and resistance are no longer changed.This automatic control function of PTC element is often used for current control and temperature control of electronic equipment. It is also used for manufacturing thermostatic heaters, such as electric iron, dryer and anti-mosquito device.

  The volt-ampere characteristic of PTC element can be inferred from the resistance - temperature property.If the current flowing through the PTC element suddenly increases for some reason, the sudden increase of electrical power will make the element rapidly assume a high-resistance state, so that the current is reduced to close to zero, acting as a "self-limit" of current and temperature.Therefore, PTC components can be used for over current protection of electronic equipment, over heat protection, such as motor over heat protection.

  The current - time characteristic of PTC component indicates that there is a delay process from large to small. This delay function is often used to start motor and refrigerator compressor.The PTC element is connected in series in the startup winding. When the power is switched on, the PTC element is in a low resistance state, so there is a large current flowing through the starting winding group.After starting up, PTC element is in high resistance state, so the current is very small, only the running winding has a large current.In conclusion, PTC components can be used in different applications due to their different structure and parameters.