Varistors for Surge Protective Devices

Varistors, also known as voltage-dependent resistors, are used as part of surge protective devices (SPDs). Varistors are designed to provide protection against transient overvoltages by limiting the voltage across the device to a safe level. Varistors are usually composed of sintered material consisting of zinc oxide grains embedded in a ceramic matrix. When an overvoltage occurs, the surge varistor exhibits a low resistance, allowing a large current to flow, thereby reducing the voltage across the device. Varistors are available in both AC and DC versions, with a variety of ratings to suit different applications.

Types of Varistors for Surge Protective Devices
Printing MOV Disk
Finished MOV Disk

What to Consider When Selecting Varistors for Surge Protective Devices
Clamping Voltage: Select a spd varistor with a clamping voltage that is below the maximum voltage the mov spd is expected to encounter.

Energy Absorption: Select a surge varistor with an energy absorption rating that meets or exceeds the level of protection required.

Response Time: Choose a varistor for surge protection with a response time that is fast enough to protect against high surge currents.

Size: Choose a varistor with a size that fits well with the SPD design and does not interfere with other components.

TGE MOV
The Impact of Varistors on Surge Protection Performance
As a type of zinc oxide blocks, varistors are an important component in surge protection systems, as they help to absorb and divert excess electrical energy away from sensitive electronic devices and circuits. As for metal oxide varistor surge protection, a varistor is a semiconductor device that acts as a voltage-dependent resistor, meaning that its resistance changes with voltage, and can be used to protect against large voltage spikes, or transients. When a varistor is placed across the power supply line of a circuit, it acts as a 'clamp', limiting the voltage to a safe level and reducing the risk of a surge or spike damaging the circuit. The mov protection device uses are wide, these varistors can also be used in surge protection circuits to divert the excessive energy away from the protected device and prevent damage to it.