Kiloamp Technology - The Global Provider of Electronic Security Protection
Kiloamp 2018-08-28 594
1. Project Overview
The main causes of damage to the LED street light system caused by the surge are:
1.1 Inductive lightning: High-voltage surges caused by lightning hitting distant power supply lines or generating strong electromagnetic induction due to frequent discharges between clouds, causing damage caused by power transmission lines invading the system.
1.2 Grid overvoltage: excessive fluctuation of the power grid or power system high power load on or off, ground short circuit, power line short circuit, etc., can generate high voltage surge on the power line, the surge voltage can reach the normal voltage 3- 5 times, can seriously damage the equipment.
2. The composition of LED street lamp power supply system and lightning protection measures.
2.1 LED street light power supply system generally consists of the following methods:
As shown in the above figure, the LED power supply line is connected after the high-voltage line is transformed by the transformer and then distributed to the distribution box. Any part of the three-phase line of the high-voltage power supply line, the three-phase power supply line, and the single-phase power supply line may be damaged by direct lightning strikes or surges and overvoltages that may invade the LED street lights.
2.2 Lightning protection measures
According to GB50343-2012 "Building Electronic Information System Lightning Protection Technical Specifications", the power supply system should carry out multi-level lightning protection. According to the actual situation of the LED street light system, a B-class large-flow lightning protection module should be installed at the distribution box. The maximum flow rate can be selected from 60KA and 100KA. As the first-level lightning protection, the bleeder comes from the high-voltage line and the three-phase power supply line. Invasive surge.
The distance between the distribution box and the LED street light is generally more than 100 meters. If the single-phase power supply line generates a surge, it will directly invade the LED street light system, and the residual pressure will be higher after the large-flow lightning protection device discharges the amplified energy surge. Generally, it is around 2500V. In order to limit the residual voltage and prevent the intrusion of the single-phase power supply line, the LED street light lightning protection device should be installed in front of the LED switching power supply for the final lightning protection.
Refer to the figure below:
3, lightning arrester grounding
In the LED street light system, it is not recommended to directly connect the grounding wire of the LED lightning arrester to the PE wire of the power supply system or the metal sheath of the armored wire. In this case, the grounding point of the LED lightning arrester from the PE wire will actually have a long distance and distance. Too long will affect the bleeder release effect. It is recommended to make separate grounding. The commonly used materials for grounding are: copper clad steel grounding rod, grounding module, galvanized flat steel, galvanized angle steel, etc. In consideration of cost, it is recommended to use galvanized angle steel and flat steel for grounding.
If the grounding resistance of the LED street lamp pole steel structure is below 10 ohms, this does not need to be used as a ground net. If it is above 10 ohms, it should be grounded next to the steel structure, using 5*50*50*2000mm. The galvanized angle steel is driven into the ground, and the galvanized angle steel is connected by 4*40mm galvanized flat steel, and then the artificial mesh is connected with the steel structure by the flat steel.
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