In recent years, with the continuous expansion of the city's scale, pedestrians at night have brought convenience and improved the quality of urban street lights. On June 21, in a heavy rainy day in Weixian County, Xingtai City, Hebei Province, one person died due to a street lamp leakage. There are countless cases of electric shock on the Internet, a series of lively lives have brought heavy disasters to many families, and a series of accidents caused by electric shocks are shocking, making us feel the city crisis after rain.
This can not help but we do not pay attention to, do not think, how to solve the street lamp leakage safety problem? Let's explore the root cause of electric shock together.
1. Casualties caused by street lamp leakage are mainly concentrated in thunderstorm summer. On the one hand, wet weather, heavy rain, or flooding lead to leakage of street lights; on the other hand, due to the high temperature in summer, electrical facilities run at higher temperatures and humidity, the cable insulation layer is prone to aging and breakdown, resulting in electricity leakage. Your skin easily touches the light pole metal or the ground, and the AC power supply lines L and N are not isolated from the ground. As long as any part of the exposed human body is in contact with the charged body or the ground, it will form a loop and cause an electric shock.
2. Some people have suggested that installing electric leakage protection switches on all street lights can avoid electric shock casualties. Although the leakage switch can cut off the power immediately within 0.3s after the leakage current reaches the set operating value (mA level), after installation, frequent malfunctions may occur, causing many street lights to be off.
3. Because street lights illuminate the road and facilitate the functionality of pedestrian vehicles, management departments tend to be functional in terms of safety and functionality choices. In case of heavy rain, choose to turn off the gate to avoid electric shock.
As long as the street lights still use the traditional AC power supply and generate a loop with the ground, leakage and electric shock casualties are inevitable. Based on this, Sundar innovatively transformed the AC of the street lights into DC power supply, which essentially solved the problem of injury caused by the leakage of street lights.
First, using DC power supply, the safe and reliable AC power supply lines L and N lines are not isolated from the earth. The power supply lines naturally have a distributed capacitance to ground. AC will generate leakage current through this capacitance, and the capacitance will change due to changes in weather and other conditions. As a result, the leakage current changes with the environment, and the setting of the leakage protection is difficult to set. If the setting is too small, it is easy to malfunction in rainy days, and it is easy to refuse to operate when the failure is too large. There are several types of electric shock in traditional AC electric shock:
AC electric shock diagram The DC smart lighting system adopts floating design. The positive and negative DC lines of the output are relatively suspended (that is, isolated), and there is no line distributed capacitance leakage current, which fundamentally solves the traditional lighting circuit formation to ground. The problem of leakage, the human body will not cause an electric shock when it touches a certain wire alone.
2. Automatic monitoring to ensure safety Sunda DC smart lighting system converts AC power from the grid into high-voltage DC voltage and outputs it to LED lamps through DC centralized cabinets. There is no problem with the direction of the leakage current of the three-phase AC system. It is relatively easy to realize the leakage current Accurate detection can set relatively accurate leakage protection settings. In the Sundar DC intelligent lighting system, once an abnormal leakage occurs, the system automatically alerts or cuts off the lighting power supply line (users can set it according to the actual use situation), integrates leakage monitoring and insulation monitoring functions, and collects line leakage and insulation data in real time. With self-recovery function after clearing. No manual work is required, which greatly protects personal and property safety.