The main purpose of power lightning protection is to prevent lightning and other internal overvoltage from invading equipment and causing damage. The power lightning arrester can release a large amount of pulse energy generated by lightning induction on the circuit in the shortest possible time, short-circuit and release it to the ground, reduce the potential difference between equipment interfaces, and thus protect the equipment on the circuit.
First level lightning protection for power supply
For the three-phase four wire system of urban power supply network, four high-energy lightning arresters are used for the lightning protection of the first level power supply. On the three live lines, one zero line is connected to the ground in parallel with one high-energy lightning arrester.
When the rated current of the power supply circuit fuse F1 (or air switch) is greater than 250A, it is necessary to install a 250A fuse F2 (or air switch) on the parallel branch (live wire) of the high-energy lightning arrester, otherwise it is not necessary.
Secondary lightning protection for power supply
The second level power supply adopts four overvoltage protectors for lightning protection, with one overvoltage protector connected to the ground on each of the three live lines and one neutral line.
Under normal circumstances, the protector is in a high resistance state. When the power grid has an instantaneous pulse voltage due to lightning stroke or switch operation, the zinc oxide Varistor element in the module hidden in the overvoltage protector will be quickly turned on within nanoseconds, and the pulse voltage will be short circuited to the ground to discharge, so as to protect all equipment. When the pulse voltage flows through the protector, the protector will become a high resistance state again, so as not to affect the power supply of equipment.
When the rated current of the power supply circuit fuse F1 (or air switch) is greater than 125A, it is necessary to install 125A fuse F2 (or air switch) on the parallel branch (live wire) of the overvoltage protector, otherwise it is not necessary.
Third level lightning protection for power supply
The third level of lightning protection is used to protect the power supply system and electronic equipment of important equipment for precise overvoltage protection. Install on the rack mounted lightning protection power supply or power lightning protection socket ( PDU lightning protector) of important equipment.
Principle of power lightning arrester
The damage caused by lightning and other strong disturbances to communication systems and the resulting aftermath are serious, and lightning protection will become necessary. Lightning is composed of high-energy low-frequency components and highly permeable high-frequency components. It mainly comes in two forms: a power lightning arrester is a device that directly conducts lightning damage through metal pipelines or ground wires; One is that the lightning Electromagnetic pulse of lightning channel and discharge channel induces metal pipeline or ground wire to generate surge damage equipment in various coupling ways. The vast majority of lightning damage is caused by this induction. For electronic information equipment, the hazard mainly comes from the coupling energy of lightning Electromagnetic pulse caused by lightning, and the transient surge generated through the following three channels. Surge generated by metal pipeline channels, such as water pipes, power lines, antenna feeders, signal lines, aviation obstruction light leads, etc; Ground wire channel, geoelectricity counterattack; Space channel, radiation energy of power lightning arrester.
The surge in the metal pipeline channel and the ground potential counterattack in the ground wire channel are the main causes of damage in electronic information systems. The most common form of damage is caused by lightning damage on the power line, so it needs to be a key focus for anti expansion. Due to the ubiquitous invasion of electronic information systems by lightning, lightning protection will be a systematic project. The central content of lightning protection is discharge and balance.
The above is an introduction to power lightning protection and power lightning protection devices.