I always encounter customers asking whether it is better to quarantine or not to quarantine? What is the difference between isolation and non-isolation? ~~~~~So I wrote a post to summarize it, hoping it can help everyone and clear up their doubts.
PK is mainly carried out from 4 aspects:
1. Security
Let’s first introduce what isolation is. Isolated power supply means that the input and output are electrically connected through a transformer. The conversion process of the transformer is: electric-magnetic-electric. It is not connected to the earth, so there is no risk of electric shock. In the non-isolated circuit, the input power is directly applied to the LED load after being boosted and buckled, which poses a risk of electric shock.
Therefore, it is troublesome to pass UL, CE…these safety certifications without isolation. The insulation and creepage distance are not enough, so we can only design from the physical structure of the lamp. Lamp tubes are acceptable, and there are also full-plastic ones, but bulbs are basically aluminum shells, so the PCB board and the shell must be insulated. Originally, the available space for the bulb power supply is very small, and this coupled with strict creepage requirements. complicated.
As a product that can be used safely by end users, the reliability of insulation and isolation must be considered.
2.Performance
Since non-isolation reduces the energy loss of transformer, the efficiency can generally reach more than 91%, and it has a higher power factor. Isolation generally has an energy efficiency of 88%, depending on the power, so the isolated power supply generates a relatively large amount of heat.
Non-isolation has fewer components but poorer stability, but why? The reason is that non-isolated circuits are very sensitive to surges and have poor suppression capabilities. In fact, it refers to non-isolated power supplies. When shipped in batches, the repair rate is higher than that of isolated LED driving power supplies, mostly due to damage. The probability of an isolated power supply blowing up is much smaller, and the non-isolated power supply is generally around 2% to 3%. Many power grid voltages are unstable, and non-isolation will result in 300V direct output, damaging chips and burning out LED loads. Isolation can also occur. The phenomenon is that the chip, MOS tube, and constant current loop are all burned out, but isolation is relatively less. Therefore, non-isolated anti-surge varistor is essential, and anything without a varistor warranty is just a cloud.
3. Cost and volume
Compared with isolated power supplies, non-isolated power supplies mainly reduce the number of transformers, use the least materials to design the structure, and achieve the same product functions, so non-isolated power supplies have greater advantages in cost. This is probably why non-isolated power supplies are very popular in China, haha.
4. Loading range
Generally speaking, the output load range of an isolated power supply is 30-42V, and the output load range of a non-isolated power supply can be 30-84V. When choosing a power supply, many LED manufacturers require the power supply to be able to adapt to the full voltage of 90-265V input for overall adaptability, and the load range is also required to be as high as 84V. There are certain risks and hidden dangers in such a choice. When 90V is input, the power supply may lose its constant current function and THD.
Non-isolation is suitable for high voltage and small current. The cost of making large current is not cheaper than isolation.
Comprehensive comparison, these two power supplies have their own advantages. The non-isolated power supply focuses on higher power factor and efficiency, reducing energy loss, while the isolated power supply focuses on the safety of life and the overall use safety of fluorescent lamps. In terms of power factor and efficiency It is slightly inferior to non-isolated power supply in terms of power supply, so different choices are a matter of opinion.
Please correct me if there are any mistakes~·