Why use an online UPS? There is a common misconception that the utility power we use, except for occasional power outages, is continuous and constant, 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 obtain power from the power grid, but also cause damage to the power grid itself. Affect and deteriorate the power supply quality of the power grid or local power grid, resulting in the distortion of the mains voltage waveform or frequency drift. In addition, unexpected natural and man-made accidents, such as earthquake, lightning strike, open circuit or short circuit of power transmission and transformation system, will endanger the normal supply of electricity, thus affecting the normal operation of the load. According to the tests of electric power experts, the main problems that often occur in the power grid and cause interference or damage to computers and precision instruments are as follows:
1. Power surges: Refers to the rms value of the output voltage being 110% higher than the rated value and lasting for one or several cycles. 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: refers to the voltage with a peak value of 6000v and a duration from 1/10,000th of a second to 1/2 cycle (10ms). This is mainly due to lightning strikes, arcing, static discharges or switching operations of large electrical equipment.
3. Switching transients: refers to the pulse voltage with a peak voltage of up to 20,000V, but a duration of between one millionth of a second to one millionth of a second. The main causes and possible damage are similar to high-voltage spikes, but the solution is different.
4. Voltage sag (power sags): refers to the low-voltage state in which the effective value of the mains voltage is between 80% and 85% of the rated value, and the duration is one to several cycles. This problem can be caused by the startup of large equipment, the startup of large electric motors, or the connection of large power transformers.
5. Electrical line noise: refers to radio frequency interference (RFI), electromagnetic interference (EFI) and various other high-frequency interferences. The operation of the motor, the action of the relay, the operation of the motor controller, the broadcast emission, the microwave radiation, and the electrical storm, etc., will cause line noise interference.
6. Frequency variation (frequency variation): refers to the variation of the mains frequency exceeding 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) means that the effective value of the mains voltage is lower than the rated value and lasts for a long time. The causes include: large equipment startup and application, main power line switching, starting large electric motors, and line overload.
8. Mains failure (power fai1): refers to the situation where the mains is interrupted and lasts for at least two cycles to several hours. The reasons for this are: tripping of circuit breakers on the line, interruption of mains supply, and grid failure.
For a computer, normal power supply is required for the operation of the monitor and the host computer. In particular, memory has higher requirements for power. It is an electrical energy-dependent storage device that requires constant refresh action to keep the stored content. Once the power is turned off, the saved content disappears immediately. If the power is turned off abnormally, the information in the memory will not be saved to storage devices such as hard disks in time, which will cause the information to lose its value due to complete loss or incompleteness, thus wasting a lot of work energy, time, and even causing huge economic losses. loss. For an operating system such as UNIX, if the system is not shut down normally, the system information in the memory is not written back to the hard disk, which may also cause the system to crash and fail to start again. In addition, although the hard disk in the computer uses a magnetic storage medium, information will not be lost due to power failure, but a sudden power failure will damage the physical head of the hard disk that is reading and writing, or the system files will be in the maintenance of the file system, resulting in an error in the file allocation table, resulting in the scrapping of the entire hard disk. In addition, most of the current operating systems can set virtual memory. Due to a sudden power failure, the system has no time to cancel the virtual memory, resulting in "information fragmentation" in the hard disk, which not only wastes the storage space of the hard disk, but also causes the machine to run slowly. The computer power supply is a rectifier power supply. Excessive voltage may cause the rectifier to burn out. The voltage spikes, transient overvoltages, and power noises may enter the motherboard through the rectifier, affecting the normal operation of the machine, or even burning the host circuit. In conclusion, power problems are a major threat to computer work. But with the increasing importance and wide range of computer and network applications, safe and reliable power supply has become an important issue that network design and management personnel have to face seriously. "Need is the first driving force for social development", in this context, UPS (Uninterruptible Power Supply) came into being, and with the development of power electronic technology, it has been constantly innovating. industry, and with the passage of time, there will be vigorous development and bright prospects.
It can be seen how important the role of online UPS is. It can ensure a certain period of power supply in the event of a power failure. During this period, we can back up important things to avoid data loss, which may bring immeasurable benefits loss.