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Analysis of the Separation and Non-isolation of LED Driving Power


At present, in the general LED lighting market, there are non isolated design and isolated driving power supply. The non isolated design is limited to double insulated products, such as alternative products of light bulb, in which led and the whole product are integrated and sealed in non-conductive plastic, so the end user does not have any risk of electric shock. The secondary products are all isolated and relatively expensive, but this kind of product is essential where the user can access the LED and output wiring (usually in the case of LED lighting and street lighting applications).

LED drive power with isolation transformer or electrical isolation means that the LED can be directly touched by hand without electric shock. While the LED driving power supply without isolation transformer can still achieve partial mechanical insulation with the help of protective shell, but at this time, the LED can not be directly contacted during operation.

Insulated bulb will become the mainstream in the future

The physical design determines whether the drive is isolated or not. Security rules usually require two separate layers of isolation. Designers can choose two kinds of physical isolation layer, namely plastic astigmatism cover and glass cover, and use non isolated power supply. If the cost of physical isolation is too high, mechanical difficulties exist or too much light is absorbed, the problem of electrical isolation must be solved in the power supply.

Isolated power supply is usually larger than non isolated power supply of the same power level. Lighting designers have to do a lot of cost and design optimization in every product they design. As it is suitable for different applications, designers will always have different opinions on whether to use isolated insulated transformer or isolated protective lamp housing from different perspectives.

Generally, they will analyze from many aspects, such as cost and manufacturing process, efficiency and volume, insulation reliability and safety specification requirements, etc. The driving cost with transformer is higher, but it also makes LED lamps more practical, which can meet the needs of the end users accidentally contacting led. When the glass shell of incandescent lamp is easily damaged, an ordinary bulb of model E27 can be replaced with LED lamp.

In addition, in the industrial area or office equipment applications, the lamps do not need to contact the end users, such as street lamps and shopping mall lighting. At this time, the LED lamps do need isolation transformers.

As a product that can be used safely by end users, the reliability of insulation and isolation must be considered. As a complete product, the parts that the user can touch on the surface of the product must be isolated, and no electric shock is allowed. From the perspective of the whole product system, isolation is inevitable. The difference is only that the location of isolation is different. Some designers use isolated transformer design, so they can simplify the design of heat dissipation and lampshade. If non isolated drive design is used, reliable insulation requirements must be considered in the structure of lamp shell and other structures. Therefore, as a power driver, isolation and non isolation schemes always exist at the same time.

The main challenge that Chinese LED drive power manufacturers may face is to find low-cost AC / DC drives to achieve more stringent power factor and efficiency performance in low-cost power systems. In the future, it will not be free to use high-quality and reliable power supply in systems with limited space and difficult heat dissipation (such as LED lamps). However, it is very difficult to prove its high quality before the end users use many bulbs with a lifetime of about 10000 hours.

Transformer based isolated LED driving power will be the mainstream

There are advantages and disadvantages of isolated and non isolated LED drive power schemes. Industry insiders believe that ClassII will be the mainstream, because it simplifies the LED cooling problem. The classi or II system relies on the grounding system, which in most cases has a lot to do with the installation site. ClassII is more common. It requires two-stage or reinforced isolation, that is, magnetic winding, insulating tape and physical isolation of transformer. Classi system requires a grounding shell and / or mechanical barrier, which is not required by classi system.

At present, there are several trends promoting the development of LED lighting market. First, the continuous improvement of high brightness LED efficiency and the continuous emergence of highly efficient and reliable constant current LED driving power supply. Second, the global legislation prohibits incandescent lighting (due to its low efficiency) and the gradual fading out of CFL energy-saving lamps (if broken, it will flow out mercury harmful to the environment). The combination of these factors is making LED lighting a long-term development trend. Of course, low system cost (including LED, thermal management system and LED driver) will always be the driving force for consumers to widely adopt LED general lighting.

In fact, in many LED lighting products, failure is a common phenomenon, most of which is due to power failure, not led failure. At the design level, this means that OEMs must become experts in system thermal design. LEDs provide high efficiency, but they also generate more heat than incandescent or energy-saving lamps.


Because many LED lighting applications are enclosed in a very small space, it is difficult to use ventilation to dissipate heat. Without careful thermal design, led and power drive circuits are prone to degradation or permanent failure due to high temperature.

Yiwu Fuwei e-commerce firm (IACS Co., Limited) is a very professional Led manufacturer who produces high quality outdoor led light. Our popular products are solar led lights, UFO lights, underwater lights and so on. If you have any question about the led product, please feel free to contact us.