Why do LED lamps need single-ended power supply?
When LED lamps are certified, most organizations require single-ended power supply, but why do they require single-ended power supply? Are there any relevant documents restricting the export of double-ended power LED lamps in the EU? Does exporting to the EU have to be single-ended? Is double ended possible? For the LED lamp with double-ended power supply, the free end may be charged. How to test this point?
LED fluorescent tubes have been very popular recently, and they are likely to enter the lighting market instead of traditional lighting. Before the official implementation of the latest specification IEC62776, the current specifications for LED lamps are still: IEC/EN 60598-1, IEC/EN61195, IEC/EN62031, IEC/EN62471, EN61347-1, EN61347-2-13, and EMC The specifications of IEC/EN55015, IEC/EN61547, IEC/EN61000-3-2, IEC/EN61000-3-3.
In European and American shopping malls, because the LED fluorescent tube is charged at both ends, it will cause the risk of electric shock, so when designing LED fluorescent tube products, the practice of placing the driving power at both ends is not acceptable. Double-ended power supply LED lamps are subject to restrictions in the EU, mainly on whether to change the circuit restrictions, please refer to CTL Resolution 0702A. Although the usual organization only accepts single-ended power supply, some European countries allow it, such as Italy.
Regarding the drive power supply, whether to use isolation or right or wrong isolation power supply? This is unrestricted. Relatively speaking, if the lamp tube that blocks the power supply is selected, the output power supply is safe and low-voltage, and the lamp housing and hand touch can be regarded as a safe area. will be affected. When a non-blocking power supply is selected, the input and output of the power supply are not isolated, and the lamp is regarded as a live body, so the requirements for creepage distance and insulation will be higher, including between the lamp and the foot solder joint, the solder joint and the The distance between the aluminum substrates should be more than 5mm, and the distance between the two ends of the lamp beads and the aluminum substrate should also be more than 5mm.
Due to the obvious performance advantages and lower cost of non-isolated power supply under the same conditions, if it can meet various insulation requirements and pass tests such as withstand voltage, it will be more competitive in the market. However, LED fluorescent tube performance and safety regulations seem to be a pair of enemies that cannot be harmonious. When the fish and bear's paw cannot have both, the manufacturer will therefore increase more costs, and their own concept is to prefer the safety regulations.
There are two types of LED fluorescent lamp power drivers discussed in the market: non-blocking and blocking. The advantages are low cost and high power. It has little effect on LED light decay and temperature, but requires reasonable insulation of lamp structure design, which can easily pass UL, TUV, CE, and PSE. There are 5 domestic non-blocking power supplies that have passed UL. For example, the cost of blocking the power supply is high, the competitiveness of the market is not strong, and the fever greatly affects the life of the LED, which is at least 20% shorter. Since there are more components than non-isolation, the failure rate is relatively high, and the power is much lower than that of non-isolation, usually 78-82%, and the non-isolated power is 87-95%. From this point of view, non-blocking will become a certain advantage for the mainstream of the market in the future.
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