请拨打24小时电话
139-2433-8586
Power class
您的位置: 首页 > SUPPORT > Power class
.

What are the applications of piezoresistors in circuits?

发布时间:2021-09-09 15:44:52人气:

What are the applications of piezoresistors in circuits?(图1)


Varistors are used in voltage protection, lightning protection, surge current suppression, peak pulse absorption, amplitude limiting, high voltage arc extinguishing, noise elimination, protection of semiconductor components, etc. What are the applications of piezoresistors in circuits?


I. circuit input overvoltage protection. 


Atmospheric overvoltage caused by lightning strikes mostly belongs to inductive overvoltage. The overvoltage caused by lightning strikes on transmission lines has a high voltage value, which can reach 100~10000V, causing great harm. Therefore, measures must be taken to prevent atmospheric overvoltage for electrical equipment. A piezoresistor can be used, which is generally connected in parallel with the equipment. If the residual voltage of the electrical equipment is very low, multi-level protection can be used.


2.to prevent operation overvoltage protection circuit. 


Operating overvoltage is a kind of overvoltage produced when the working state of the circuit suddenly changes and the electromagnetic energy is rapidly transformed and released. To prevent this overvoltage, various power supplies and motors can be protected with piezoresistors.


3.Overvoltage protection of semiconductor devices. 


In order to prevent the semiconductor devices from being burned when overvoltage occurs due to some reasons during operation, piezoresistors are often used to protect them. Connecting a varistor between the emitter and collector of a transistor or at the primary of a transformer can effectively protect the transistor from damage caused by overvoltage. In the normal state, the piezoresistor is high impedance state, with only a desired leakage current. When it is subjected to overvoltage, the piezoresistor quickly becomes a low-resistance state, and the overvoltage energy is absorbed by the piezoresistor in the form of discharge current. After the surge voltage disappears, when the circuit or component is subjected to normal voltage, the piezoresistor returns to a high-resistance state. For diodes and thyristors, piezoresistors are generally connected in parallel with these semiconductor elements or with power supply, and two requirements should be met: first, the direction voltage of repeated actions should be greater than the residual voltage of piezoresistors; Second, the reverse voltage of non-repetitive action should be greater than the residual voltage of varistor.


4.contactor relay protector. 


When the circuit containing inductive loads such as contactors and relays is cut off, its overvoltage can exceed several times of the power supply voltage, which causes arc and spark discharge between contacts, burns contacts and shortens the service life of equipment. Because of the shunt action of varistor at high potential, the contacts are protected. When varistor and coil are connected in parallel, the overvoltage between contacts is equal to the sum of power supply voltage and residual voltage of varistor, and the energy absorbed by varistor is the energy stored by coil.

推荐资讯