LIGHTNING PROTECTION INSTALLATION LOCATION ON AC SUPPLY

I/. Lightning and the effects of lightning impulse propagation.

    Sét là hiện tượng thiên nhiên thường xuất hiện vào những mùa giông bão. Theo ước tính của các nhà chuyên môn, trên thế giới cứ mỗi giây có khoảng 40-50 cú sét đánh xuống mặt đất tương đương khoảng 1,4 tỷ tia sét xuất hiện mỗi năm. Sét không những gây thương vong cho con người, mà còn có thể phá hủy các công trình, các thiết bị điện, điện tử … và làm gián đoạn công việc như hoạt động hàng không, hoạt động của ngân hàng, hàng hải, các hoạt động của đài truyền thanh truyền hình, các hệ thống thông tin liên lạc…

As a result, lightning protection device installation is a necessity that must be completed immediately, as is determining the best location to install lightning protection devices for maximum efficiency. A balance must be determined between the installation of Surge device protections (SPDs) for distribution cabinets or "points of use" and for sensitive electrical and electronic equipment.

II/. Location of installation of surge arresters

      Here are 5 points to keep in mind when determining the installation location and selection of surge arresters to optimize your investment in lightning protection:

1. First layer of defense (primary lightning protection layer): install a suitable lightning protection device at the building's entrance to protect the equipment. This is usually the device with the greatest surge capacity, as it can be subjected to direct lightning currents. Normally, the required lightning-breaking capacity is 100 kA (8 mA). Primary surge arresters alone are generally suitable for protecting non-perishable electromechanical or electrical equipment such as heaters, lights, and motors.

2. For sensitive electrical and electronic equipment, a second layer of protection (secondary lightning cut-off stage) should be installed to reduce residual voltage (throughput voltage). In general, this applies to the selection of equipment at the branches of the distribution cabinet. The devices at this second stage must also meet the protection requirements of branch circuit equipment from surges generated internally in the circuit by the devices in that circuit, such as switching devices and pulse jammers. This pulse accounts for 70–85% of pulses that can be harmful to sensitive electrical and electronic equipment.

·    For sensitive electronic equipment requiring high protection. Surge arresters at this stage should use a lightning arrester connected in series in front of the equipment to be protected, including a primary cutoff stage, an LC low pass filter, and a secondary lightning cutoff stage.

3.   Circuits with noisy electrical equipment such as inverters and industrial equipment should also be protected to prevent electrical interference (or harmonic interference) back-feeding, causing damage to equipment in other circuits.

4.   In cases where sensitive electronic equipment is located more than 30' or 9m  from the nearest forward SPD surge arrester, an additional protective device should be installed. This device is called a "point-of-use" protection device and is installed as close to sensitive electrical and electronic equipment as possible.

5. The residual voltage of the lightning arrester is the remaining voltage after the lightning arrester is affected by lightning impulses, and surges, this voltage is as tiny as possible.

Điện áp dư # điện áp bảo vệ # điện áp thông qua: Voltage protection level # Let-through voltage (U_p).

Location of the installation of surge arresters