Offline, Line interactive, Online UPS difference

UPS power supply can be divided into backup type, online type and online interactive type according to its working principle. From the backup time, the UPS is divided into two types: (built-in battery) and (flexible battery configuration)

1.Offline UPS

The battery is usually charged, and the inverter is switched to the working state during a power outage, which converts the DC power provided by the battery into a stable AC output. Therefore, the backup UPS is also called offline UPS. The advantages of backup UPS power supply are: high operating efficiency, low noise, and relatively cheap price. It is mainly suitable for occasions with small fluctuations in mains power and low requirements on power supply quality, and is more suitable for household use. However, this UPS has a switching time problem, so it is not suitable for use in places where critical power cannot be interrupted. But in fact, this switching time is very short, usually between 2 and 10 milliseconds, and the computer’s own switching power supply should be able to maintain about 10 milliseconds when power is off, so personal computer systems generally do not appear because of this switching time problem. Back-up UPS generally can only supply power for several minutes to tens of minutes, mainly to allow you time to back up your data and end the work at hand as soon as possible, and its price is lower. For less critical computer applications, such as personal home users, a low-power backup UPS can be equipped.

2.Online UPS

This UPS always keeps its inverter in working state. It first converts external AC power to DC power through a circuit, and then converts DC power to high-quality sine wave AC power through a high-quality inverter and outputs it to a computer. The main function of the online UPS in the power supply state is to stabilize the voltage and prevent radio wave interference; when the power is off, the backup DC power supply (battery pack) is used to power the inverter. Since the inverter is always working, there is no problem with switching time, which is suitable for occasions with strict requirements on the power supply. The big advantage of online UPS is that it is different from the backup type in that the power supply lasts for a long time, usually several hours, and it can be as much as ten hours. Its main function is to allow you to work as usual in the event of a power failure. Obviously Because of its special function, the price is obviously a lot more expensive. This online UPS is more suitable for computers, transportation, banking, securities, communications, medical, industrial control and other industries, because computers in these areas generally do not allow power outages.

3.Line interactive UPS

This is a kind of intelligent UPS. The so-called online interactive UPS means that when the mains power is input normally, the inverter of the UPS is in reverse operation (that is, the rectifier working state) to charge the battery pack; when the mains power is abnormal The inverter immediately switches to the inverter working state and converts the battery pack power into AC power output, so the online interactive UPS also has a conversion time. Compared with backup UPS, online interactive UPS has stronger protection function, inverter output voltage waveform is better, generally sine wave, and its biggest advantage is that it has strong software functions, which can be easily connected to the Internet, Remote control and intelligent management of UPS. It can automatically detect whether the external input voltage is within the normal range. If there is a deviation, it can be stepped up or down by the voltage stabilization circuit to provide a more stable sine wave output voltage. And it can communicate with the computer through a data interface (such as RS-232 serial port). Through monitoring software, users can directly monitor the power and UPS status from the computer screen, simplifying and facilitating management, and improving the reliability. This UPS combines the advantages of high efficiency of backup UPS and high quality of online UPS power supply, but its frequency stabilization performance is not very ideal, and it is not suitable for UPS power with constant delay.