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SURGE ARRESTOR

It is the low voltage unit with simple and strong working mechanism that allows protection of electrical/electronic devices against lightning strikes in all industrial and commercial buildings. Provides effective protection from 5 kA to 60 kA in B, C, D types.

Surge arrestors are used for protecting electrical systems against overvoltage pulses. Surge arrester are protection elements that are connected in parallel to the system, normally in passive state and that protect electrical systems against sudden overvoltage pulses. These sudden overvoltage pulses may be lightning or internal overvoltages, and these voltages are in microseconds level.

Surge arresters are insulator in case of normal operation, but when they receive a pulse, they start transmission and send pulse to ground. Therefore, business is protected against pulses without any interruptions. Surge arresters have 3 basic duties;

1- They protect against lightning pulses. (10/350 microseconds curve)
2- They protect against internal overvoltages (8/20 microseconds curve)
3- Protecting Sensitive devices

Characteristics

In regions where lightnings occur intensively or less intensively, 10kA or 5kA level surge arresters should be used. If surge arrester is used in low voltage network, a surge arrester with 1.5kA pulse rated current value should be used. If surge arrester is used in medium voltage transformation substation, surge arresters having 2.5kA or 5kA pulse rated current values should be used. If surge arresters are used in power plants and substations, surge arresters with 10kA pulse rated current value should be used.

  • Transformer inputs
  • Main transformers
  • Auxiliary panels
  • LED lighting systems
  • CCTV, camera, fire alarm systems
  • Renewable energy systems
  • Used in automation and communication lines

Surge selection is very important. Surge Arresters should be selected by considering three important points including voltage value, shock rated current and short circuit.

Surge arresters conduct shutting of system and prevent damage to device and systems. For surge arresters to conduct shutdown, working voltage should be lower than voltage determined over the portion with the weakest insulation point on the system. If voltage value is high, Surge Arrester will not be able to shutdown, and prevent damage to the system under protection.

Surge Arresters should be used by considering pulse rated currents to use in various load intervals. Surge Arresters are produced by considering this property, and they are presented in the market according to pulse rated current values and short-circuit current values.

High voltage causes failures in devices connected to transmission and distribution lines. Because of high voltage occurring in the system, insulators used to protect devices against voltage are damaged. As a result, short circuit occurs in device or transmission line, and system can be damaged. High voltages are divided into 2 parts based on their occurrence ways such as internal (occurring within system) and external (occurring due to natural causes) high voltages. Internal high-voltages occur in electrical networks. Network sourced problems may emerge including contact with ground, contact of two phases, neutral and ground contact. External high voltages stem from natural events and they occur due to reasons such as potential rise of soil as a result of lightning, lightning strike on phase or ground lines, magnetic field occurring as a result of lightning strike. Circuit designs can be made for protection purposes against internal high voltages that may occur in electrical devices originating from network. However, surge arresters should be used to protect system from external high voltages.

Surge arrester should have short circuit current value level similar to cutter in closest vicinity. If short circuit resistance is selected low, surge arrester may be fragmented and result in great damages to its place. Surge arresters are usually produced at 10, 20, 40 and 60kA short-circuit current level. It is very important to determine location of surge arresters, and to place them in suitable locations in the system due to lightning discharges.

If surge arrester is not suitable for its place, it may create damage rather than benefit and turn into a source failure. Surge arresters are connected to phase-ground in parallel with electrical systems to be protected. Surge arresters should be close to electrical systems as much as possible.

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