One,the street lamp power supply has only short circuit and overload protection but no leakage protection. The reason for not using leakage circuit b
One,the street lamp power supply has only short circuit and overload protection but no leakage protection. The reason for not using leakage circuit breakers is to fall into a misunderstanding. Some believe that the three-phase leakage circuit breaker has a dead zone in action and cannot reliably protect personal electric shock. It is better not to use it. Some believe that the normal leakage current may cause the leakage circuit breaker to malfunction and reduce the reliability of street light power supply. Some believe that there is irregularity in the street light installation, such as only leading the street light phase line and borrowing the neutral line from elsewhere, resulting Leakage circuit breakers can’t work normally, etc. Actually, as a safety appliance, the main function of leakage circuit breakers is to provide indirect contact protection. When a single-phase ground fault occurs, it can reduce the light pole contact voltage, which is beneficial to protect personal safety. If the rated leakage current of the leakage circuit breaker (I△n) is 200mA and the grounding resistance Rd is 200Ω, then the contact voltage = Rd*IΔn=200*0.2=40V, in the specified voltage range, take the author’s area as an example The average soil resistivity is 110Ω, and the measured average value of unipolar grounding resistance Rd is 58Ω. If there is no leakage protection and a single-phase grounding fault occurs, the contact voltage=Un*Rd/(R street lamp manufacturer d+R0)=220×58 /(58+4)=206V, which is close to the phase voltage, which is obviously very dangerous. After using the leakage circuit breaker, it can also prevent the cable from overheating due to the long-term existence of the leakage current, shorten the service life and damage the electrical equipment by the leakage arc current.
Second, the quality of street lamp electrical appliances, especially the ballast, is not good enough, heating is serious, and the insulation is easily broken, causing the lamp pole to be electrified. Once pedestrians touch it, the consequences will be disastrous.
Third, the circuit breaker has not been tested for sensitivity, and the rated trip current is selected too large. When selecting the circuit breaker, only short-circuit protection is considered, but overload protection and single-phase terminal short-circuit sensitivity verification are ignored. The circuit breaker is rated The trip current is selected too large, regardless of the nature of the load, it is always selected to be 100A or even 150A. This often causes the circuit breaker to still not trip and lose the function of the circuit breaker when the ground short-circuit current is large and the cable is heated.
Fourth, the use of cable metal sheath for PE main trunk line has a complicated process and low reliability. The construction process of using cable metal sheath as PE main trunk line is complicated. Each base street lamp must be welded with two solder joints, and each solder joint must be stripped and polished. Tinning, soldering, and cumbersome operation, the quality of the solder joints is difficult for street lamp manufacturers to guarantee. With so many solder joints in series, the reliability of the PE main line connection can be imagined. In addition, it is almost impossible for the cable to be completely moisture-proof. Moisture accumulates inside the cable, and rust and corrosion of the metal sheath is inevitable. Under normal circumstances, after 3-5 years, the metal sheath of the low-voltage street lamp will have rusty breakpoints and lose the protective effect of the PE main line. In this way, each street lamp Although the grounding protection is actually "independent", once a single-phase grounding fault occurs, dangerous voltage will exist for a long time.
High pole lamp: generally refers to a new type of lighting device composed of a steel cone light pole above 15 meters and a high-power combined lamp structure. It is composed of a lamp holder, internal lamp electrical, pole body and basic parts.
LED high pole lamp is a kind of lighting used on highways, roads and other places. It has beautiful appearance and strong decoration. Compared with street lamps, the lamp pole is much higher and the lighting area is larger. At the same time, the lighting effect is good, and the light source is concentrated. The illumination is uniform and the glare is small.
The lamp panel uses electric lifting, which is easy to operate. After the lamp panel is raised to the working position, the lamp panel can be automatically taken off, hooked and unloaded by the wire rope. The lighting control is divided into manual control, light control, time control and microcomputer control. Street lamp manufacturers are easy to control. service.
The shape of the lamp holder can be determined according to user requirements, surrounding environment, and lighting needs. The internal lamps are mostly composed of high-power LED floodlights and floodlights. The pole body is generally a pyramid-shaped single body structure and is made of steel plate. The height is 15-40 meters, mostly composed of two to three sections, the irradiation radius can reach 40-80m.
1. The light poles are eight-sided, twelve-sided, and eighteen-sided pyramidal poles, which are cut, bent, and automatically welded to form high-strength high-quality steel plates. The design maximum wind resistance capacity can reach 60 meters per second, and each specification ranges from 3 to 4 plug-in components. Equipped with flanged steel chassis, with a diameter of 1m to 1.2m and a thickness of 30mm to 40mm.
2. The functionality is mainly frame structure, and some are mainly decorated with steel through and steel pipes. Lamp poles and lamp panels are treated with hot-dip galvanizing.
3. The electric lifting system consists of an electric motor, a hoist, three sets of hot-dip galvanized steel wire ropes and cables, etc., installed in the light pole body, and the lifting speed is 3 to 5 meters per minute.
4. The guiding and unloading system is composed of guide wheels and guide arms to ensure that the lamp panel does not move laterally during the lifting process, and to ensure that the lamp panel can be automatically detached and locked by the hook when the lamp panel is raised in place.