The main customers of street lamps are government units, not ordinary consumers, so it is a relatively special and relatively closed industry. Street lamps have gone through a long development process from the initial sodium lamps and mercury lamps to LED lamps. At the same time, some technical problems have been encountered during this development process.

Today, LED street lights have been in China for about ten years, including power supply, power drive, heat dissipation technology, optical technology, etc. There are new breakthroughs every year, but some basic technologies have not been solved in China, LED street lights. Lightning protection is one of the problems to be solved.

The necessity of lightning protection for LED street lights

Lightning strikes are electrostatic discharge phenomena that typically carry millions of volts from a cloud to the ground or another cloud. During transmission, lightning generates electromagnetic fields in the air, inducing thousands of volts of voltage (ie, surges) to power lines and inducing currents that are transmitted several miles away. These indirect attacks usually occur on exposed wires outdoors, such as street lights. , traffic lights, base stations and other equipment emit surges. The surge protection module directly faces the surge interference from the power line at the front end of the circuit. It diverts or absorbs surge energy, minimizing surge threats to other operating circuits such as AC/DC power supply units in LED lighting fixtures.

For LED street lights, lightning generates an induced surge on the power line, and the energy of this surge will generate a surge on the wire, that is, a surge wave. The surge is transmitted through such an induction method, and a surge from the outside world The wave will generate a tip on the sine wave in the 220V power line, and this tip will enter the street light and cause damage to the LED street light circuit.

Street lights have existed for many years. Why is it only now that street lights need lightning protection? In fact, the high-pressure sodium lamps and traditional mercury lamps used in the past were designed with high-pressure bulbs, which themselves have the effect of lightning protection. In recent years, LED lights have gradually become popular, and LED lights need a lower power supply voltage. Usually, a power supply is used to convert alternating current into direct current to drive, which makes the lightning protection of LED street lights themselves. Therefore, it needs to be designed for street lights. Lightning protection module.

The importance of street light lightning protection is determined by the concept of payback period. Since the price of LED street lights is about twice as expensive as that of traditional street lights, the government invests a large amount at the beginning of the purchase, so it is necessary to gradually earn back the cost by saving electricity expenses during the operation process. Therefore, the life of LED lights is very important. If the LED lamp fails during the payback period before the cost is recovered, it will need to be repaired at additional cost. The labor cost during repair is twice as expensive as that during installation. Therefore, in the LED era, to achieve the effect of LED power saving and money saving, it is necessary to ensure that its lifespan can meet your expectations, that is, the product has a long shelf life. To achieve cost savings and ensure that street lamps are not damaged during the payback period, it is necessary to increase the reliability. This requires adding lightning protection modules to LED street lights to maximize economy.

Energy-saving street lamps have been made in China. The defined street lamp specifications are usually visible indicators such as brightness, luminous angle, light color, power consumption, etc., but the invisible indicator of lightning protection is often ignored. Not only the United States and Europe and other countries, in fact, countries with high lightning strikes, such as Malaysia, India and other countries have long established relevant standards that require local street lights to pass a set lightning protection test. In China, only coastal cities such as Hainan and Pearl River have more serious lightning strikes, while most inland areas are much better. Therefore, the relevant standards have not been introduced so far.

American three-level lightning protection standard

In the American National Standard released in 2015, three levels of lightning protection standards have been introduced, as shown in Table 1. The reason for the three levels is that there is a big difference in the situation of landslides in the east and west of the United States. The high landmine area can reach 30 to 40 times, while the low landmine area has only 1 to 2 times. Therefore, three levels of standards have been made, namely: 6kV, 10kV and 20kV. This also gives flexibility to lighting manufacturers and local governments, and local governments can decide to use corresponding standards according to the actual situation.

Relevant domestic standards to be formulated

There are similar standards for communication base stations in China. As early as ten or twenty years ago, when mobile phones were about to become popular, there were already relevant national standards for base station lightning protection. Since base stations are mainly installed on roofs or towers, lightning strikes will have a great impact on base stations. Due to the large differences between the north and the south of my country, the differences in the coastal and inland environments are also large, and the street lights are basically managed by each local government by themselves, specifying specifications, bidding, supervision, maintenance, etc. Therefore, there is still no comparable country. The standard is introduced.

With the highlighting of the relevant needs in recent years, there are already national standards related to lightning protection of LED street lamps under review in 2017 and 2018. With reference to the national standards of various countries in the world, if the drive power module only meets the fourth level (line-line 2kV) , line-ground 4kV), will not be enough to cope with the lightning surge threat that outdoor lighting may face, it is recommended to use a higher lightning protection level for street lamps and use lightning protection modules.