As a result of atmospheric electricity discharges, network switching or switching of high-power consumers, electrical networks experience a sharp spike in voltage that lasts for a fraction of a second, but can cause irreparable damage not only to the network itself but also to the devices connected to it. SPD is a device for protecting against impulse overvoltages will help to avoid serious consequences from such surges.

When, for whatever reason, the mains voltage increases sharply, the resistance of the semiconductor element (varistor) of the SPD instantly drops to its minimum value. As a result, current begins to flow through the protective device to the grounding circuit, creating an artificial short circuit that trips the input circuit breaker and, as a result, de-energises the mains. If the overvoltage was insignificant, the SPD indicator will remain green and the circuit will continue to operate as normal; if the overvoltage was significantly higher than the maximum operating voltage, the indicator will change to red, indicating that the SPD needs to be replaced.

There are three classes of SPD:

I (B) class. This class of SPD is installed at the power supply entrance to the building in the main switchboard. It is designed to protect against direct lightning. It blocks atmospheric or switching overvoltages. It is mandatory for installation in detached buildings with overhead power supply. The pulse waveform is 10/350 µs.

II (С) class. This class of SPD is used as the next element of external lightning protection of a private house after the SPD of I class. It neutralises surge residuals. It is mounted in switchboards. The pulse waveform is 8/20 µs.

III (D) class. SPD of this class protect against high-frequency interference caused by the neutralisation of the discharge by the previous classes of protection. The pulse waveform is 8/20 µs.

Аssortment range

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