Requirements of computer room for lightning protection system
The hottest summer of the year is coming. Summer is a thunderstorm weather, so the data center should take lightning protection measures. The damage of lightning is mainly due to the violent discharge phenomenon when the potential difference between clouds or between clouds and the earth, as well as between clouds and air reaches a certain degree (25-30KV/cm). There are usually three forms of lightning strike: direct lightning strike, induction lightning strike and spherical lightning strike. How does the lightning protection system of the data center resist lightning strikes? Or what are the requirements for the lightning protection system of the data center?
Generally, we divide a complete lightning protection system into two parts: external protection and internal protection:
(1) The external protection system consists of lightning rod, downlead and grounding system.
(2) The internal protection system is to prevent damage caused by lightning and surge intrusion into energized equipment.
In order to achieve internal lightning protection and surge protection, additional equipment and devices such as equipotential bonding network, AC/DC power lightning arrester, signal lightning arrester and antenna feeder lightning arrester need to be installed to prevent damage caused by lightning induced overvoltage and ground potential counterattack.
The protection space of the data center can be divided into three zones: LPZ0, LPZ1, LPZ2, and LPZ0 can be divided into two zones: LPZ0A and LPZ02.
LPZ0A area: it can be subjected to direct lightning strike, and the electromagnetic field strength is not attenuated;
LPZ0B area: it will not suffer from direct lightning strike, but the electromagnetic field strength is still not weakened;
LPZ1 area: not only will it not suffer from direct lightning stroke, but also the electromagnetic field strength will be attenuated according to the shielding measures in the area;
LPZ2 area: in LPZ1 area, the follow-up protection area is added to further reduce the led lightning current or electromagnetic field.
Generally, the data center is located in a reinforced concrete multi-storey building, and this area will not be subject to direct lightning strikes. The power feeder and communication lines are introduced from the outside, crossing LPZ0B area. Therefore, the data center mainly protects against induced lightning and lightning overvoltage transmitted into the room by power lines and communication lines. Although the direct cumulative probability of the building where the data center is located is small, it cannot be avoided. Usually, we use equipotential bonding network for protection.
When computers, communication equipment and control cables span each zone, corresponding lightning arresters must be installed and equipotential bonding must be carried out. The requirements for lightning arresters in each zone are as follows:
LPZ0B: lightning arrester, class requirement B (≤ 4KV)
LPZ1: overvoltage protector, class requirement C (≤ 2.5KV)
LPZ2: overvoltage protector, class requirement D (≤ 1.5KV)
Several lightning protection areas shall be equipotential connected as required, and all power lines and signal lines shall be equipotential connected when entering the LPZ1 area of the protected space.
Whether the lightning protection system in the computer room is built according to requirements not only affects the normal operation of the computer room itself, but also directly affects the safety of staff. Therefore, the quality of the lightning protection system is directly related to the quality of the construction of a data center computer room.
