With the wide development of science and technology, the application field of capacitors has also been driven. Varistors are used in voltage protection, lightning protection, surge current suppression, spike absorption, amplitude limiting, high voltage arc extinguishing, noise suppression, and protection of semiconductor components. What are the applications of varistor in the circuit, the editor will introduce you in detail.
1) Circuit input overvoltage protection:
Atmospheric overvoltages are caused by lightning strikes, and most of them are inductive overvoltages. Overvoltages generated by lightning strikes on the transmission line discharge. The voltage value of this overvoltage is very high, which can reach 100 to 10000V, causing great harm. Therefore, measures must be taken for electrical equipment to prevent atmospheric overvoltage. Varistors can be used. It is generally used in parallel with the equipment. If the electrical equipment requires a low residual voltage, multi-level protection can be used.
2) Protection against operating overvoltage protection circuits:
Operating over-voltage is a kind of over-voltage generated when the circuit's working state changes suddenly, the electromagnetic energy is rapidly converted and quickly released. To prevent this over-voltage, a varistor can be used to protect various power equipment, motors, etc.
3) Overvoltage protection of semiconductor devices:
In order to prevent the semiconductor device from being burned when an overvoltage is generated due to some reasons, it is often protected by a varistor. The varistor is connected between the emitter and collector of the transistor or the transformer at one time, which can effectively protect the overvoltage Damage to the transistor. Under normal conditions, the varistor is in a high-resistance state, with only the desired leakage current, and when overvoltage is applied, the varistor quickly becomes a low-resistance state, and the overvoltage energy is absorbed by the varistor in the form of a discharge current After the surge voltage disappears, when the circuit or component withstands the normal voltage, the varistor returns to the high-resistance shape. For diodes and thyristors, the varistor is generally connected in parallel with these semiconductor components or in parallel with the power supply, and should meet two requirements: one is that the direction voltage of the repetitive action should be greater than the residual voltage of the varistor, and the other is the non-repetitive action The reverse voltage is also greater than the residual voltage of the varistor.
4) Contactor, relay protector:
When the circuit containing inductive loads such as contactors and relays is cut off, the overvoltage can exceed several times the power supply voltage. The overvoltage causes arc and spark discharge between the contacts, burning the contacts and shortening the life of the equipment. Due to the shunt effect of the varistor at high potential, the contacts are protected. When the varistor and the coil are connected in parallel, the overvoltage between the contacts is equal to the sum of the power supply voltage and the residual voltage of the varistor. The energy absorbed by the varistor is the energy stored by the coil. When the varistor is connected in series with the contact, the contact The overvoltage is equal to the residual voltage of the varistor, and the energy absorbed by the varistor is 1.2 times the stored energy of the coil.
After reading this article, do you have a thorough understanding of the application of varistor. If you have technical questions, please contact us, we will try our best to answer your questions. We specialize in the production of safety capacitors, varistors, film capacitors, ceramic capacitors, and more high-quality capacitors in JEC. The above information comes from the company's research and development department. For more information, please move to the website to get it.
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