LED Lighting Permanent And Reliability Ground Continuity
LED lighting products, the general safety requirements, refers to the LED lamps should be designed and manufactured so that it can work safely in normal use, the people or the surrounding environment does not harm.
The protective earth terminal on the LED fixture is likely to become the most accessible part of the capacitor; the key to the protective earthing is the continuity of the ground and the continuity of the reliability ground, making the protection of the protective earth fault resistance ≤0.5 oh.
Then first to determine which parts to protect the ground, and then to solve the need to protect the ground between the components and the continuity between the terminals.
1, in the completion of the installation of lamps can be touched, and insulation failure can become charged parts;
2, when the lamp is clean and open when it can be touched, and the green may fail to become charged parts;
3, the safety parts in the lamp where the metal installation surface;
4, with the lighting of the safety components (such as wires, control devices) or may contact with the metal surface;
5, more importantly, from the structure to ensure continuity between them.
6, with yellow and green color lines for identification of the conductor, whether it is internal wiring or external wiring, should only be connected with the ground terminal;
7, with self-tapping screws can be used to protect the continuity of the ground, as long as the normal use will not hinder this connection, and each connection with at least two screws;
8, with aluminum and copper can not be directly connected to the ground, will play an electrochemical reaction caused by contact resistance becomes larger, affecting the ground continuous low resistance;
9, grounding resistance measurement, available measurement equipment transferred to 12V, 10A detection, resistance ≤ 0.5 Europe.
LED lighting is currently one of the biggest technical problems is the cooling problem, poor heat dissipation lead to LED drive power, electrolytic capacitors have become the further development of LED lighting fixtures, LED light source premature aging reasons. Only as soon as possible to export heat in order to effectively reduce the temperature inside the LED lamps in order to protect the power supply is not in the long-term high temperature environment, in order to avoid the LED light source due to long-term high temperature work and premature aging.
Because LED light source itself is not infrared, ultraviolet, LED light source itself does not have radiation cooling function, LED lighting cooling path can only be used with LED lamp beads plate close combination of heat sink to derive heat. Radiator must have the function of heat conduction, thermal convection, heat radiation.
Any radiator, in addition to the heat can be quickly transferred from the heat source to the surface of the radiator, the most important thing is to rely on convection and radiation to heat the heat to the air. Thermal conductivity only solves the heat transfer path, and thermal convection is the main function of the radiator, the heat dissipation performance is mainly determined by the capacity of the heat dissipation area, shape and natural convection strength, and the heat radiation is only auxiliary function. In general, if the heat from the heat source to the radiator surface distance of less than 5mm, then as long as the material thermal conductivity is greater than 5, the heat can be derived, the rest of the heat must be dominated by thermal convection.
Most LED lighting sources still use low voltage (VF = 3.2V), high current (IF = 200-700mA) LED lamp beads, because the work of high heat, you must use a higher thermal conductivity of aluminum. Usually die-cast aluminum radiator, extruded aluminum radiator, stamping aluminum radiator. Die-cast aluminum radiator is a pressure casting parts of the technology, the liquid zinc copper and aluminum alloy poured into the die-casting machine feed port, die-casting machine die-casting, casting mold design in advance shape of the radiator.