What is the use of varistor?
Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive transient voltages. When used as protection devices, they shunt the current created by the excessive voltage away from sensitive components when triggered.
Is varistor a semiconductor?
Nowadays the resistive body of a varistor is made from semiconductor material making it a type of semiconductor resistor with a non-ohmic symmetrical voltage and current characteristics suitable for both AC and DC voltage applications.
How do I choose a varistor?
Choose a varistor with an energy absorption rating that equals or slightly exceeds the energy values associated with the event the circuit may experience. If, however, the transient voltage is due to an external event, the magnitude of the source energy is unknown.
What happens when a varistor fails?
Varistors need to absorb the energy deposited by temporary overvoltage, switching surges, or lightning impulses. The energy absorption capability can be divided into thermal energy absorption capability and impulse energy absorption capability. …
Do varistors have polarity?
Does a varistor have polarity? In the case of metal oxide varistor, a zinc-oxide layer is basically sandwiched between two metal electrodes. As a result, there is no polarity.
How do I know if my varistor is bad?
Touch one meter probe to the free varistor lead and the other probe to the connected lead. Read the resistance on the meter. If it reads nearly infinite resistance, the varistor is still good. If it reads very low resistance, the varistor is blown.
Why would a varistor burn out?
When the varistor leakage current is too large, and the temperature rises to a certain extent, the low melting point metal is melted, thereby varistor from The cutting in the circuit can effectively prevent the varistor from burning.
How do I test a MOV varistor?
Touch the meter probe tips to the MOV’s leads and measure its resistance. If it has a resistance much under 100 ohms, it has blown. Desolder and remove the remaining lead and remove the MOV from the equipment. If the part has resistance over one million ohms, it is still good.
Can you remove a varistor?
You can replace it with a new one provided it is for the same voltage levels that it triggers. This AC and DC voltage ratings are the important parts and then the energy capacity. Energy cap. is not a major issue in Computer PSUs since the usually use a small varistor there.
How do you check if a varistor is working?
Are varistors polarity sensitive?
Does MOV have polarity?
Metal Oxide Varistors are similar to resistors and has only two leads. There is no polarity for these leads and hence can be connected in both directions.
