Surge arresters
The surge arresters are designed for protection of electrical systems and consumers of transient over voltages and pulse currents, caused by lightning or commutation. The transient over voltage is peak of the voltage with short duration (less than milliseconds), which amplitude can reach twelve times the rated voltage.
The electrical and electronic equipment can withstand some level of over voltage (dielectric strength) due to their own isolation of the phases in respect to the neutral conductor or to the ground. The permissible values, which can be withstand by the insulation, can vary from several hundred volts for the electronic equipment to several kilovolts for the electrical motors. If there is no surge arrester installed, the over voltage reaches the electrical appliance. If the withstand voltage is exceeded, a rupture of the insulation occurs and the current impulse passes through it.
The surge arresters Type 1 are designed for lightning protection: they are designed to discharge the high energy of the current pulse, providing in such way equivalent potential junction, in case of direct lightning strike in the facility.
Surge arresters Type 1 are suitable for locations, exposed to risk of direct lightning strike, for example – infeed in building, protected with lightning receptacle and fed by overhead (aerial) line. These products shall be installed on the input point of the installation (The main distribution board).
The coordination of the surge arrester with the upstream circuit breaker excludes the possibility for erroneous tripping and guarantees power supply reliability.
The surge arresters of Type 1 are stable in case of voltage fluctuations up to 400 V, due to the high withstand ability to transient over voltages. The protection also has safe mode of the over voltages up to 1430 V (fire safety, indirect contact).
The surge arresters Type 1+2 combine the characteristics of the two types, which are preliminary coordinated. They can withstand the high energy of the direct lightning strike and provide good level of voltage protection of the electrical or electronic equipment.