Varistors for overvoltage protection

Connect varistors in parallel

At Rotima, we understand the importance of reliable protection components in electronic circuits, which is why our range of varistors is specifically designed to meet the needs of modern electronic systems. Our range includes a variety of varistors that are characterized by their high quality and durability, ideal for applications that require effective protection against overvoltages. With our expert team, we offer not only products but also advice and support to ensure our customers find the optimum varistors for their specific applications.

Large selection of varistors
For electrical engineering and electronics business

Swiss quality
On the market for 60 years

Varistors in our range:

This flexibility allows developers and engineers to select the optimal surge protection for their specific project. By combining standard products with the ability to develop customized varistors, suppliers can cover a wide range of applications to meet a variety of customer needs.

Our varistors from Bourns

Multilayer Varistors (MLV) Bourns®

Multilayer varistors consist of many layers of MOVs stacked on top of each other. They inherently provide a matched voltage. An MLV is usually offered in a size 2220 package. With an Imax of 2 kA, an MLV can easily outperform a single layer MOV in a 4032 package that is twice the size (Imax rating = 1200 A). Due to their small size, most MLVs are designed for low voltages, usually below 200 V at 1 mA.

Link Bourns®: Multilayer Varistors (MLV)

Metal Oxide Varistors (MOV) Bourns®

Metal oxide varistors (MOVs) are bi-directional and non-linear surge protection devices used in a variety of applications to limit voltage during an overvoltage or transient event. These highly reliable and robust surge protection devices are available in various form factors and surge protection ranges. An MOV is a non-linear device, which means that its characteristics do not change gradually but suddenly when the voltage reaches or exceeds its parameters. An MOV also has non-resistive current-voltage characteristics similar to those of a diode. However, unlike a diode, an MOV has the same characteristics for both directions of the current flowing through it.

Link Bourns®: Metal oxide varistors (MOV)

Our official sales partner: Bourns

ROTIMA is an official and long-standing distribution partner of Bourns.

Bourns® is a varistor design and manufacturing company specializing in electronic components. It supplies various industries such as automotive, industrial applications, measurement technology, medical devices, consumer electronics and mobile technologies with its products.

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Standard and customized varistors

Varistors are essential components in the field of surge protection that are used in various electronic applications. There are two main types of varistors on the market: metal oxide varistors (MOV) and multilayer varistors. Metal oxide varistors are particularly popular for their ability to absorb high transient voltage peaks, making them ideal for protecting household appliances and industrial equipment.

Multilayer varistors, on the other hand, are predestined for use in mobile devices and other miniature applications due to their compact design and excellent performance at lower voltages. In addition to the standard products offered, manufacturers and distributors also offer customized solutions to meet specific requirements in terms of voltage levels, energy capacity and form factors.

What can we do for you?

Contact our product experts

Marco Saner

Head of Internal Sales Electrical Engineering, Sales & Product Management

+41 44 927 26 51

[email protected]

Andrei Jantea

Sales- and Productmanagement

+41 44 927 26 44

[email protected]

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Varistors

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Further information on varistors

Varistors are electronic components used in electrical engineering to protect electrical circuits from overvoltage by changing their resistance with the applied voltage. Here you will find a comprehensive collection of frequently asked questions about varistors, providing detailed and informative answers about their operation, applications and benefits.

What are varistors?

Varistors are passive semiconductor components that change their electrical resistance depending on the voltage applied. They are known to offer a high resistance at low voltage and drastically reduce their resistance when a certain voltage limit (the so-called response voltage) is reached. This property makes them ideal components for overvoltage protection in electronic devices, as they can absorb excess voltage and thus protect other components in the circuit. Varistors are available in different sizes and voltage ranges to meet different requirements. They are widely used in household appliances, industrial equipment, telecommunications equipment and power supply technology.

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Why are varistors used?

Varistors are used to protect electronic devices and systems from overvoltages that can be caused by lightning strikes, switching operations or other disruptive events. These overvoltages can damage or destroy electronic components, leading to failures or malfunctions. Varistors limit the voltage to a safe level by greatly reducing their resistance when a certain voltage is exceeded, thus dissipating most of the excess energy. This protects the downstream components from damage. Their fast response time makes them particularly valuable for protecting sensitive electronics.

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How do varistors work?

The core of a varistor consists of a semiconducting material, usually metal oxide, which is pressed between two electrodes. At normal operating voltages, the varistor behaves like an insulator with high resistance. However, when the voltage exceeds a critical value, the unique property of the semiconducting material causes the resistance of the varistor to drop abruptly. This sudden drop in resistance allows the varistor to conduct a large current flow and thus safely dissipate the excess voltage. After the overvoltage has subsided, the varistor returns to its original high-resistance state.

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What types of varistors are there?

There are two main types of varistors: metal oxide varistors (MOV) and silicon carbide varistors. MOVs are the most widely used and offer excellent protection against overvoltages at a relatively low cost. They are made of zinc oxide (ZnO) and other metal oxides and are known for their high energy absorption capacity and long service life. Silicon carbide varistors are older and have largely been replaced by MOVs, but are still used in certain applications due to their thermal stability and robustness to high temperatures. Each type of varistor has specific properties that make it more suitable for certain applications.

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