First: to determine the quality of a power supply, first check whether it has passed the necessary safety certification.
1. Generally speaking, the more certified items, the more reliable the power quality. At present, the power supply sold in the market can only be sold after passing the national compulsory 3C certification system. The existing 3C certificate has four versions: CCC (s) safety certification, CCC (SE) safety and electromagnetic compatibility certification, CCC (EMC) electromagnetic compatibility certification and CCC (f) fire protection certification. CCC (s) only represents the adoption of safety standards.
CCC (S & E) certification standard is being used, which puts forward two requirements for power supply safety and electromagnetic compatibility. Seeing CCC (S & E) mark on the power supply can be understood as that it has passed 3C certification. This is also the standard that any power supply product must meet, which does not mean that it is of excellent quality. Some small brands do not pass 3C certification, Will use forged signs to deceive consumers.
2. In addition to 3C certification, UL certification mark can also be seen on some advanced power supplies. It is one of the most stringent certification in the world. There are relevant restrictions on the structure, materials, test instruments and methods of power supplies. Some high-quality power supplies will also pass FCC certification, which is a certification on electromagnetic interference. A power supply that has passed FCC certification will shield the electromagnetic interference generated during its operation and eliminate the harm to human body.
Second: to improve the safety and stability of the circuit.
1. Lightning protection circuit: when the commercial power generates high pulse voltage due to lightning strike or other factors, the equipment on the circuit will be damaged. The function of power lightning arrester is to release a large amount of pulse energy generated by induced lightning strike on the circuit to the safety ground wire in the shortest time, so as to protect the user equipment on the circuit. This is the core function of lightning arrester.
2. EMI filter circuit: EMI filter circuit is mainly used to filter out the interference of high-frequency pulse of external power grid to the power supply, and also to reduce the electromagnetic interference of switching power supply itself to the outside world. EMI is an important content of CCC certification.
3. PFC circuit: that is, "power factor correction" is mainly used to characterize the utilization efficiency of electric energy by electronic products. The higher the power factor, the higher the utilization efficiency of electric energy. The computer power supply certified by CCC must add PFC circuit to reduce the harm caused by the reduction of line power factor.
The quality index of power adapter should be based on the first principle of safety and reliability. Under the condition that the electrical technical indexes meet the requirements of normal use, a variety of protection circuits must be designed to make the power supply work safely and reliably in harsh environment and sudden failure.
