Overvoltage Protection

A surge protection device (SPD) is a device that protects electronic devices and systems from overvoltages and voltage peaks. These are usually caused by lightning strikes, power failures, switching operations or malfunctions in the power grid. Without surge protection, they can lead to an overload and thus damage to the electronic devices.

A surge protection device, also known as a surge arrester, ensures that excess voltages are limited and discharged. This prevents the overvoltage from reaching the connected device and instead safely discharges it. It is there to protect valuable electronic devices.

Good to know: Netgear, an internationally renowned manufacturer of network switches, recommends overvoltage protection in every professional installation.

Overvoltages can have various causes

  • Lightning strikes (lightning electromagnetic pulse)
  • Sudden load drop / load increase
  • Switching operations (switching electromagnetic pulse)
  • Electrostatic discharge (electrostatic discharge)

There is a three-stage concept for protection against overvoltages. These are categorised by the International Electrotechnical Commission (IEC) and referred to as “protection classes”.

Protection class 1

A coarse protection device (SPD type 1, Surge Protection Device) protects against high-energy faults. For example, it prevents lightning from penetrating the cable to be protected. It is designed to limit the residual voltage to 1300 to 6000 V.

Protection class 2

A centre protection device (SPD type 2) is usually located in floor distribution boards. It is designed to limit overvoltages to 600 to 2000 V.

Protection class 3

Fine protection (SPD type 3) refers to the protection of sockets and plug connectors.

A class 3 surge protective device is usually installed close to the device to be protected and consists of a combination of protective components, such as varistors or gas arresters. These components have a high electrical conductivity and therefore dissipate overvoltages before they can reach the connected appliance.

In practice, class 3 surge protection is often used in combination with other protective measures, such as a lightning protection system or class 2 surge protection, in order to achieve the most comprehensive level of protection possible.

The technical design of a surge protective device (SPD) usually consists of a series of metal oxide varistors (MOVs) connected in parallel to the electronic device. When a voltage spike occurs, the MOVs conduct the excess current away from the device and limit the voltage to a safe level.

A high-quality surge protection device does not use MOVs alone, but a combination of several, such as a gas arrester. GUDE also uses this high-quality surge protection, also known as hybrid surge protection, in its reliable products.

Typical application scenarios for surge protection include the protection of sensitive electrical appliances in companies and households against damage caused by lightning strikes or power fluctuations. Surge protection devices are also used in industry to protect the sensitive electronic components of machines and systems.

Typical areas of application for overvoltage protection:

  • IT and communication systems: computers, servers, routers and telephone systems
  • AV and consumer electronics: televisions, hi-fi systems, media players
  • Industrial control systems (ICS): automation and control systems in production facilities
  • Photovoltaic systems and charging stations for electric vehicles

The use of devices with overvoltage protection is particularly important in environments with high overvoltage risks, such as near lightning conductors or in industrial areas with many switching operations.

The main advantages of overvoltage protection are

  • Protection against damage: Surge protection protects electrical devices and systems against damage caused by power fluctuations and lightning strikes.
  • Extended service life: The use of devices with surge protection extends the service life of electrical devices and systems.
  • Safety: Surge protection devices help to make circuits and electrical systems safer by helping to prevent damage and fires.
  • Cost efficiency: The use of surge protection devices helps to reduce the costs of repairs, replacement devices, spare parts and operational downtime
  • Sustainability: Protecting electrical devices and systems from damage benefits the environment as less electrical waste is generated.

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