·The Necessity? of? Using? Uninterruptible Power Supply (UPS)
1. Surge (power surges): means the output voltage RMS is higher than 110% rating, and the duration of up to one or several cycles. Surge was mainly due to electrical line connected to a large electrical equipment shutdown, power grids, generated due to sudden unloading of high pressure.
2. high voltage spikes (high voltage spikes): refers to the peak reached 6000v, lasting from seconds to one half of one ten thousandth cycle (10ms) voltage. This is mainly due to lightning, arc discharge, static discharge or large electrical equipment arising from switching operations.
3. transient over-voltage (switching transients): means the peak voltage up to 20000V, but the duration to one ten thousandth millionth of a second sector in the second pulse voltage. The main reason and the possible damage is similar to high voltage spikes, but there will be differences in the solution.
4. the voltage subsidence (power sags): refers to the mains voltage RMS rated between 80-85% of the low-voltage between the state and duration of up to one to several cycles. Start large-scale equipment, large motor starting, or access to large power transformers can cause this problem.
5. wire-noise (electrical line noise): means the radio frequency interference (RFI) and electromagnetic interference (EFI), as well as other various high-frequency interference. The motor running, relay action, motor controllers work, radio transmission, microwave radiation, and electrical storms, etc., would give rise to line noise.
6. the frequency offset (frequency variation): refers to the mains frequency changes over more than 3Hz. This is mainly run by the instability of the emergency generator, or by frequency instability due to the power supply.
7. continuous low voltage (brownout): means the electricity voltage is lower than the rated RMS, and continued a long time. Its causes include: large-scale equipment start-up and application, the main power line switch to start the big motor, circuit overload.
8. mains interruption (power fail): means the interruption of electricity, and continue for at least two cycles to a few hours the situation. Its causes are: line of the circuit breaker tripping, electricity supply disruptions, power failures.
For the computer, the monitor and a host of work requires a normal supply of electricity, particularly in memory, a higher power supply requirements. It is a reliance on energy storage devices, need to constantly refresh the movement to keep the store content. Once the power outage, the stored content disappear. If a non-normal power, resulting in too late to save the information in memory to the hard drive and other storage device, it will cause a complete loss of information due to incomplete or become lost value, and thus a lot of work wasted energy, time, and even causing enormous economic loss. The UNIX operating system, such as, if not a normal shutdown, the memory in the system information on the hard disk is not write back, but also may cause system crashes, cannot be started again. In addition, the computer hard drive, although the application of the magnetic storage media, will not be lost due to power failure information, but a sudden power failure will make the ongoing work to read and write heads of hard disk physical damage, or system files in the maintenance of the file system , resulting in file allocation table errors, resulting in scrapping the entire hard drive.
In addition, the current operating system, most of them can set the virtual memory, due to sudden power outages, making the system too late to cancel the virtual memory, causing the hard disk in the "information pieces" not only a waste of hard disk storage space, but also led to the machine to run slowly. PC power supply is a rectifier power supply, high voltage rectifiers may cause burning. The voltage spike and transient over-voltage and power supply noise and other interference may enter through the rectifier board, affecting the normal operation of the machine, and even burned the host line. In short, the power issue is a major threat to computer work. However, with the computer and network applications become increasingly important and extensive, safe and reliable power supply has been a network design and management have had to seriously face the important issues. "Requires the first driving force for social development" in this context, UPS (uninterruptible power supply) came into being, accompanied by the development of power electronics technology, continues to introduce new rooms in more than a decade, not only created a brand-new industry, but as time goes on more will have a prosperous development and bright future.
At present, only a few areas have just solved the problem of power shortage in most areas and large cities are facing power shortage of pressing issues, power quality is not guaranteed. But even in already electrified the United States and other Western countries, the quality of the grid is far from reliable. As the power grid itself, there are problems with the quality of the role of various causal factors, voltage surges, electromagnetic noise, continuous high-voltage power grid and other undesirable phenomena are commonplace in developed countries, and even short-term power outages may occur. The undesirable elements from the grid are: supply voltage transient or a long period of subsidence, surge, and interrupted power supply frequency drift and instability, power input waveform distortion, all kinds of interference and noise spikes. All of this is a sensitive high-precision instruments and equipment cannot be interrupted is very serious. For example: power outage or a computer at work, there is a relatively large voltage is low, it may result in the memory on the hard disk information is obliterated and the consequences of data loss. In the hospital, electronic medical equipment to stop working if a power outage, the effect on patients is fatal. In fact, data loss caused by a variety of factors, the power failure in 45.3% of the chance of the first place, several other key factors are: 9.4% storms, fires 8.2%, 8.2% of hardware and software failures, floods, 6.7 %, an earthquake of 5.5%.
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