The importance of the most complete switching power supply EMC
As early as the early 1980s, the infant mortality rate in the obstetric ward of a hospital in New Jersey, USA, was quite high. Late at night, the warning light on the baby monitor keeps going off for no reason. The nurses were annoyed by this, so they turned off the monitors and checked back and forth one by one.
After some preliminary investigation, the professor found out the truth of the matter. It turned out that the transmitter of a nearby TV station was licensed by the United States Communications Commission. It can increase its output power to a very high level after about midnight, but it must be done at six in the morning. point, or other specified time, to return to the original level. The connecting cable between the nurse's station and each baby's monitor resonates at these interfering frequencies, inducing voltages that turn off the monitor's warning light. Nearly six children died before the hospital discovered the problem.
Another example: There is a customer complaint that when a switching power supply is turned on in the computer room, the company's 100M speed LAN slows down and stops, while the 10M speed network is not affected. Turn off the power and the network returns to normal.
Later experiments found that the high-frequency interference signal of the switching power supply was coupled to the network line, causing the network to malfunction.
The history of EMC development: EMC was actually born with the rapid development of the modern electronics industry. By the end of the last century, with the rapid increase in electronic and electrical equipment. EMC has expanded to many fields. It is no exaggeration to say: wherever there are electronic products, there are EMC problems. Western countries are becoming more and more demanding in this regard, and EMC has become one of the trade barriers for electronic products from developing countries to enter the Western market.
