Basic knowledge of UPS power supply

Why use UPS

People have a common misconception that the use of electricity in addition to the occasional power outage, continuous and constant is given, it is not. The system as a public utility power grid, connected above thousands kinds of loads, which some larger inductive, capacitive , switching power supply load not only draw power from the grid, the grid will in turn present themselves It will affect the power supply quality of the power grid or local power grid and cause the mains voltage waveform distortion or frequency drift. Other than accident of natural and man-made catastrophes, such as earthquakes, lightning, power transmission system, open or short circuit, will endanger the power of positive constant supply, thus affecting the normal workload. According to the tests of power experts, the problems that often occur in the power grid and cause interference or damage to computers and precision instruments are the following:

1.Surge

The RMS value of the output voltage is 110% higher than the rated value, and the duration is one or several cycles. The surge is mainly due to the high voltage generated by the sudden unloading of the power grid when large electrical equipment connected to the power grid is shut down.

2.High-voltage pulse reduction

Refers to a voltage with a peak value of 6000v and a duration from one ten-thousandth of a second to one-half cycle (10ms). This is mainly caused by lightning strikes, arc discharges, static discharges, or switching operations of large electrical equipment.

3.Transient overvoltage

Refers to a pulse voltage with a peak voltage up to 20000V, but with a duration in the range of one millionth of a second to one millionth of a second. The main reason for and possible damage caused by high voltage spikes similar to, but there will be differences in the solution.

4.Voltage sag

Refers to a low-voltage state where the effective value of the mains voltage is between 80% and 85% of the rated value and has a duration of one to several cycles. Large equipment startup, large motor startup, or large power transformer access can cause this problem.

5.Wire noise

Refers to radio frequency interference (RFI) and electromagnetic interference (EFI) and various other high-frequency interference. The operation of the motor, the action of the relay, the operation of the motor controller, broadcast transmission, microwave radiation, and electrical storms, etc., can cause line noise interference.

6. Frequency offset

Refers to the change in the frequency of the commercial power supply above 3 Hz. This is mainly caused by the unstable operation of the emergency generator, or by the power supply with unstable frequency. For computers, normal power supply is required for the display and the host to work. Especially memory, the power requirements are higher. It is a storage device that relies on electrical energy and requires constant refreshing actions to maintain the stored content. Once the power is turned off, the saved content disappears immediately. If the power is abnormally shut down, the information in the memory will not be saved to storage devices such as hard disks, which will cause the information to lose value due to complete loss or incompleteness, thereby wasting a lot of work energy, time, and even causing a huge economy. loss. For an operating system like 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 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 sudden power failure will damage the physical head of the hard disk that is performing read and write operations, or system files when maintaining 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 the sudden power failure, the system has no time to cancel the virtual memory, resulting in "information pieces" 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 rectified power supply. Excessive voltage may cause the rectifier to burn out. Interferences such as voltage spikes, transient overvoltages, and power supply noise may enter the motherboard through the rectifier, affecting the normal operation of the machine and even burning the host circuit. In short, the power problem is a major threat to computer work. However, with the increasing importance and wide application of computers and networks, safe and reliable power has become an important issue that network design and management personnel have to face seriously. "Need is the first driving force for social development." Under this background, UPS (Uninterruptible Power Supply) came into being. With the development of power electronic technology, it has been constantly innovating. In the past ten years, not only has it created a brand new Industry, and with the passage of time, there will be vigorous development and bright prospects.

What is UPS

UPS (Uninterruptible Power System), that is, an uninterruptible power supply, is an uninterruptible power supply that contains an energy storage device and has an inverter as the main component. Mainly used to provide uninterrupted power supply to a single computer, computer network system or other power electronic equipment. When the mains input is normal, the UPS supplies the mains with stabilized voltage to the load. At this time, the UPS is an AC mains voltage regulator, and it also charges the battery in the machine; when the mains power is interrupted (accident power outage) At this time, the UPS immediately supplies the 220V AC power to the load through the inverter conversion method to maintain the normal work of the load and protect the load software and hardware from damage.

As a protective power supply device, UPS's performance parameters are of great significance and should be the focus of our consideration when purchasing. A wide mains voltage input range indicates a strong ability to use mains power (reducing battery discharge). Output voltage, frequency small frequency range, it indicates that the electrical adjustment of the city strong, stable output. The waveform distortion rate is used to measure the stability of the output voltage waveform, and the voltage stability indicates the stability of the output voltage when the UPS suddenly increases from zero load to full load. There are UPS efficiency, power factor, the conversion time are all important parameters to characterize the performance of UPS, Paul decided to load protection and capacity utilization of the mains. The better the performance, the stronger the protection ability . In general, the offline UPS has the worst protection for the load, and the online interactive mode is slightly bet ter. The online mode can solve almost all common power problems. Of course, as this also rises with enhanced performance. Therefore, when choosing a UPS, users should choose different types of UPS according to the load's requirements for power and the importance of the load.