Varistors

Varistors are a type of non-linear device that provide excellent transient voltage suppression and features similar characteristics to Zener diodes. They are used to protect vulnerable electronic circuits and components from overvoltage conditions that can cause damage. Any potentially destructive overvoltage energy is dissipated as heat.

As essential passive components in industrial, automotive and consumer electronics design, varistors, including metal oxide varistors and MOV components, act as the first line of defence against damaging voltage transients.

RS Australia stocks a broad range of varistors including metal oxide varistors (MOVs), transient voltage suppression diodes, and multilayer varistors suited to signal, power, and high-energy suppression applications.

Key Uses of Varistors

Varistors serve a critical protection role across a wide range of electrical and electronic applications. Key uses include:

• Transient voltage suppression: MOV electrical components clamp voltage spikes before they reach sensitive downstream circuitry.
• Non-linear resistance: Varistors present high resistance under normal conditions and switch to low resistance during a voltage surge, diverting excess energy safely.
• Fast response time: MOV surge suppressors respond rapidly to voltage transients, minimising exposure time for protected components.
• Wide operating voltage range: Available for both low- and high-voltage AC and DC circuit protection applications.
• Flexible mounting options: Supplied in through-hole and surface-mount configurations to suit prototype and high-volume PCB assembly.
• Standards compliance: Many varistors carry UL, IEC, VDE and CSA approvals for use in regulated and safety-critical applications.

Shop Our Range of Varistors and MOVs

RS Australia stocks a comprehensive range of varistors and MOV components, covering through-hole and surface-mount formats across a wide range of voltage and energy ratings.

Metal Oxide Varistors (MOV)

Metal Oxide Varistors (MOVs) are typically constructed from zinc oxide and combined with small additions of other metal oxides such as cobalt, manganese or bismuth. These materials are sintered into ceramic casings during manufacture. Although MOVs are available in different formats, they are most commonly radial leaded discs.

A zinc oxide varistor is the most widely specified MOV component for metal oxide varistor surge protection in power supplies, consumer electronics and industrial equipment. Key specifications include varistor voltage, clamping voltage and energy rating in joules. MOV resistor components are available in radial, disc and through-hole formats to suit a broad range of PCB and panel designs.

Ceramic Transient Voltage Suppressors

Ceramic transient voltage suppressors are a type of variable resistor designed to respond to momentary conditions of overvoltage. They are more effective than other types of overvoltage protection components, such as varistors or gas discharge tubes, as they respond faster to changing conditions. This particular type of transient voltage suppressor is made from ceramic.

Their higher energy handling capability makes them well suited to harsh environments and high-power applications where standard MOV surge protection may be insufficient. Ceramic transient voltage suppressors are used as part of electrical circuits to protect data or transmission lines. They protect against both unidirectional and bidirectional electrostatic discharge, caused internally or externally, for example by lightning or motor arcing.

How to Choose the Right Varistor for Your Application

Selecting the correct MOV varistor or ceramic TVS requires matching the component's key ratings to the demands of the circuit being protected.

• Varistor voltage (Vnom): Must exceed the peak operating voltage of the circuit.
• Clamping voltage: Determines how much voltage passes through to downstream components during a surge event.
• Energy rating: Match the joule rating to the expected surge level for the application.
• Mount type: Through-hole for prototyping and lower volumes; SMD for high-volume PCB assembly.
• AC vs DC ratings: Confirm the operating voltage rating matches the circuit type.
• Operating temperature range: Particularly important for automotive and industrial deployments.
• Certifications: Confirm UL, IEC, VDE or CSA compliance where required by the application or end market.

Common Industry Applications for Varistors

• Power Supplies and SMPS: MOV surge suppressor components protect switched-mode power supplies from mains-borne transients.
• Industrial Motor Drives and Automation: MOV electrical components absorb switching transients from relay and inductive load operations.
• Telecommunications Infrastructure: Varistors protect signal lines from external surge events, including lightning strikes.
• Automotive Electronics and EV Charging: Zinc oxide varistors provide transient protection in vehicle electronics and charging systems.
• Consumer Electronics: TVs, PCs and air conditioners rely on metal oxide varistor surge protection to guard internal circuitry.
• Renewable Energy Systems: Solar inverters and wind turbines use MOV components to manage surge exposure on DC and AC lines.
• Building Electrical Panels: Surge protection in distribution boards uses MOV varistors to protect downstream equipment.

Your Trusted Varistor and MOV Supplier in Australia

RS Australia is a trusted supplier and distributor of varistors, metal oxide varistors and MOV components in Australia, stocking products from leading brands including Bourns, TDK and Panasonic. You can also find related products like thermistor ICs, surge suppressor units and switching spark gaps in our catalogue.

Full product specifications and datasheets are available online to support accurate component selection. Place your order today for fast, reliable delivery to your door across Australia. To find out more about our shipping options and timelines, please check out our delivery page.