First, the electromagnetic compatibility of UPS
With the continuous development and utilization of electromagnetic waves by human beings, people are paying more and more attention to the harmful side of electromagnetic waves while benefiting human beings. Therefore, in recent years, relevant electromagnetic compatibility standards have been successively regulated in developed countries and regions. There are also many internationally renowned electromagnetic compatibility certification bodies. For example, electronic products sold to Europe must pass CE certification, and the United States requires FCC certification. China is now gradually requiring CEMC certification.
As an uninterruptible power supply (UPS) for power protection of IT products in the information age, it is a high-power density power supply product integrating automatic control technology and power electronics technology. It is itself a large electromagnetic wave emission source, which may be applicable to the surrounding environment and The equipment generates electromagnetic interference, and its own control system may be disturbed by the surrounding electromagnetic environment, causing the UPS to work or even be damaged. Therefore, high quality UPS must have good electromagnetic compatibility.
Second, the standards and requirements related to UPS electromagnetic compatibility
In view of the electromagnetic compatibility characteristics of UPS, the current relevant standards mainly include CISPR22-1997 "Measurement Methods and Limits of Radio Disturbance of Information Equipment" and CISPR-24-1997 "Measurement Methods for Immunity of Information Equipment" of the International Radio Interference Special Committee. And Limits, European EN50091-2 (1995) "EMC Requirements for UPS", China's CISPR standards related to GB9254-1998 "Measurement methods and limits for radio disturbance of information equipment" and GB/T17618-1998 Information equipment immunity limits and measurement methods.
Although the standards are different, they are all based on CISPR, so the basic limits of the standard are the same. The main requirements for UPS are as follows:
1. Conducted disturbance limit of the input power terminal
Table 1 shows the contents of the national standard and CISPR standard. The limit does not take into account the capacity of the UPS. There is obviously unreasonable place. In the European standard EN59001-2, the power capacity of the UPS is divided into two limits, that is, below 25A. Different from the limit of 25A or above, it is relatively reasonable. The same is true for the radiation disturbance limit. The limits in 2 below are also required by the national standard and CISPR.
2. Radiated disturbance limit (10m) (Table 2)
If the 3 m method is used, it can be seen from the relevant formula that all of the above values ​​are added by 10.
3. Other relevant requirements
Battery-side harassment: For UPS battery-side harassment, it can be considered as part of the UPS system. All UPS test indicators are based on the UPS system, so it can be considered separately;
Communication interface harassment: For the communication interface harassment of UPS, it is generally not directly related to the strong electric signal, and it is easy to meet the relevant requirements. There is no specific limit given here; the detailed requirements can find the relevant standards.
Output power terminal harassment: For the conducted disturbance of the output power terminal of the UPS, the current national standard and the CISPR standard do not give very clear requirements. The usual practice is to use the disturbance limit of the input power terminal, but the test method is somewhat different; and in Europe In the standard, it is clearly specified that the input power terminal limit is 14dB, which is relatively loose.
Immunity requirements: For the UPS equipment chassis port, signal port, telecommunication port, power input port, etc. must also carry out relevant immunity experiments, including electromagnetic field interference experiments, electrostatic discharge experiments, surge impact experiments, electrical fast transients Pulse experiment, etc.; unlike the above-mentioned various UPS external disturbances, the immunity of the UPS reflects the ability of the UPS to work normally under various electromagnetic interference environments. When a problem occurs, it directly appears as a UPS malfunction, and the user is easy to find the problem, so The reliability problems that UPS manufacturers pay more attention to; from the current UPS market, most UPSs have better compliance in this respect.
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