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What's an offline UPS and is it better than online UPS?

What's an offline UPS? What's the difference between offline UPS and online UPSMany people may be confused about the different types of UPS. However, you will BETTER understand the concept after learning the different types of UPS topologies.  In this article, we will show you the definition,working principle, block diagram and other details of offline ups  

Kstar offline ups and standby ups for family computer

Offline UPS Definition

Offline UPS, sometimes described as standby power supply (SPS) are systems where the load is fed directly from the raw mains during normal operations instead of the inverter outputs. When the mains supply fails or fluctuates outside of the UPS's operating window, a relay connects the load to the inverter output (resulting in a 4-8ms transfer time). In normal operation, with mains supply present, both output voltage and frequency will track the input voltage and frequency respectively.

Working principle

Look at the offline UPS diagram below,you will understand why people also call it a "backup" or stand-by UPS.

offline ups diagram of kstar

Difference between online UPS and offline UPS

The key difference between Online UPS and Offline UPS lies in their work. An Online UPS supplies the AC power through a rectifier and inverter circuit even when the AC mains power is available.

online ups diagram of kstar

Advantages of offline UPS

1.Compared with online UPS price,offline UPS's are cheaper. 

2.High efficiency, making it the most commonly used for providing power supply for personal computers and is also used for office supply. 
3.Smaller size. The stand by UPS is available in small and compact sizes which is important when there is no big space available. Its compact size makes the stand by UPS's first choice when it comes to supplying computers in-home use.      

In a word, you can buy an offline ups to protect your equitment from power failure, sags and surges in a low price,  but if you want a UPS which can offers total power protection, you should get an online ups rather than offline.