Can varistors be used in DC circuits for overvoltage protection?
Can varistors be used in DC circuits for overvoltage protection?
A varistor is a resistor made of varistor ceramic material, usually made of metal oxide powder mixed with organic polymer. They are widely used in electronic circuits and have the advantages of fast response, high power consumption, and high voltage protection, so they are used for various types of circuit protection. In DC circuits, varistors can play the role of overvoltage protection. When the circuit is subjected to an overvoltage shock, the resistance of the varistor will drop rapidly, forming a current path to flow the excess charge to protect other electronic components. First, varistors work based on the electric field effect. When the intensity of the electric field exceeds the voltage that the varistor can withstand, the resistance will drop sharply. This is because the material of the varistor has a special voltage-sensitive property, that is, under a high electric field, ionization occurs between electrons and ions to form a conductive path. Secondly, varistors have the characteristics of fast response. When the circuit is subjected to an overvoltage shock, the varistor can immediately sense and change its own resistance. This ability to respond quickly allows the varistor to quickly transfer the overvoltage to the ground line to protect other electronic components from damage. In addition, varistors are also able to absorb electrical energy and convert it into heat energy. When the circuit is subjected to an overvoltage shock, the voltage difference of the varistor will cause a large amount of current to pass through the resistor, thereby generating a large amount of heat. This high energy consumption characteristic can help convert overvoltage into heat and avoid overloading other components. The ability of a varistor to act as an overvoltage protection in a DC circuit mainly depends on its rated voltage and operating characteristics. Choosing a suitable varistor requires considering the voltage range of the circuit, as well as the rated voltage of the components and equipment being protected. Generally, the rated voltage of the varistor should be slightly higher than the rated voltage of the protected component or equipment. In summary, varistors can be used in DC circuits to act as overvoltage protection. By using special varistor materials and fast response characteristics, they can quickly reduce resistance when the circuit is subjected to an overvoltage shock and transfer the overvoltage to the ground line. This protection mechanism can protect other electronic components from damage and ensure stable operation of the circuit. Therefore, using varistors as overvoltage protection is a reliable and effective method when designing and arranging DC circuits.
