The need to use UPS
edit: chuangneng click: 6 date: 2019-05-19
There is a common misconception that the utility power we use is continuous and constant except for occasional power outages, but it is not. As a public power grid, the mains system is connected to thousands of various loads. Some of the larger inductive, capacitive, switching power supplies and other loads not only get power from the grid, but also in turn cause the grid itself. Affects the deterioration of the power supply quality of the grid or local grid, causing distortion or frequency drift of the mains voltage waveform. In addition, accidental natural and man-made accidents, such as earthquakes, lightning strikes, disconnection or short circuit of power transmission and transformation systems, can damage the normal supply of electricity, thus affecting the normal operation of the load. According to the test of electric power experts, the following problems occur frequently in the power grid and cause interference or damage to computers and precision instruments:
1. Power surges: The output voltage rms value is 110% higher than the rated value and lasts for one or several cycles. The surge is mainly due to the high voltage generated by the sudden unloading of the grid when the large electrical equipment connected to the grid is shut down.
2, high voltage spikes (high voltage spikes): refers to the peak value of 6000V, the duration of the voltage from one ten thousandth of a second to one half of the cycle (10ms). This is mainly due to lightning strikes, arcing, static discharges or switching operations of large electrical equipment.
3. Transient overvoltage: refers to a pulse voltage with a peak voltage of up to 20000V but a duration of one millionth of a second to one ten thousandth of a second. The main reason and possible damage is similar to high-pressure spikes, but there are differences in the solution.
4. Power sags: A low-voltage state in which the rms voltage is between 80% and 85% of the rated value and lasts for one to several cycles. Large equipment startup, large motor start-up, or large power transformer access can cause this problem.
5, electrical line noise (electrical line noise): refers to radio frequency interference (RFI) and electromagnetic interference (EFI) and other various high-frequency interference. Motor operation, relay operation, motor controller operation, broadcast emissions, microwave radiation, and electrical storms can cause line noise interference.
6. Frequency variation: It means that the change of the mains frequency exceeds 3HZ. This is mainly caused by the unstable operation of the emergency generator or by the power supply with unstable frequency.
7. Continuous low voltage (brownout): It means that the rms voltage of the mains voltage is lower than the rated value and lasts for a long time. Causes include: large equipment start-up and application, main power line switching, starting large motors, and line overload.
8. Power fail: Refers to the situation where the mains is interrupted and lasts for at least two cycles to several hours. The causes are: circuit breaker trip on the line, mains supply interruption, grid failure.
For computers, both the display and the mainframe work require a normal power supply, especially memory, which requires more power. It is a storage device that relies on electrical energy and needs to constantly refresh actions to keep the content stored. Once the power is turned off, the saved content disappears immediately. If the power is abnormally interrupted, the information in the memory cannot be saved to a storage device such as a hard disk, which may result in loss of value due to complete loss or incompleteness, thereby wasting a lot of work effort, time, and even a huge economy. loss. An operating system such as UNIX, if it does not shut down properly, the system information in the memory is not written back to the hard disk, and may also cause the system to crash and cannot be started again. In addition, the hard disk in the computer, although the application of the magnetic storage medium, will not lose information due to power failure, but sudden power failure will damage the physical head of the hard disk that is being read and written, or the system file is in the maintenance of the file system. Causes a file allocation table error, which causes the entire hard disk to be scrapped.
In addition, most of the current operating systems can set virtual memory. Due to the sudden power failure, the system can't cancel the virtual memory, which causes the "information fragmentation" in the hard disk, which not only wastes the hard disk storage space, but also causes the machine to run slowly. The computer power supply is a rectified power supply. Excessive voltage may cause the rectifier to burn out. Interferences such as voltage spikes and transient overvoltages and power noise may enter the motherboard through the rectifier, affecting the normal operation of the machine and even burning the host line. In short, the power problem is a major threat to computer work. But with the increasing importance and breadth of computer and network applications, safe and reliable power supplies have become an important issue that network design and management personnel have to face seriously. "Need to be the first driving force for social development", in this context, UPS (uninterruptible power supply) came into being, and with the development of power electronics technology, constantly innovating, in a dozen years, not only created a brand new Industry, and will have a prosperous development and bright prospects over time.
At present, only a few regions in China have just solved the problem of power shortage. Most regions and large cities are also facing urgent problems of power supply shortage, and the quality of power supply cannot be guaranteed. But even in the United States and other Western countries that have already achieved electrification, the quality of the grid is far from reliable. Due to the quality of the power grid itself and various accidental factors, voltage surges, electromagnetic noise, high continuous voltage and other abnormal grid phenomena are common in developed countries, and even short-term power outages may occur. Bad factors from the power grid include: instantaneous or long-term sagging, surge and interruption of the power supply voltage, drift and instability of the power supply frequency, distortion of the power input waveform, various spike interferences and noise. All of this is very serious for high-precision sensitive instruments and equipment that cannot be interrupted. For example, if the computer loses power during work or if there is a relatively large voltage drop, it may cause the memory information to be washed away and the hard disk data to be lost. In hospitals, if the medical device stops working because of a power outage, the impact on the patient is fatal. In fact, among the various factors causing data loss, power failures ranked first with a 45.3% probability. The other major factors were: 9.4% for storms, 8.2% for fires, 8.2% for hardware and software, and 6.7% for floods. The earthquake was 5.5%.