What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 1 - 8)

Time of issue:2023-05-12


UPS types, functions and principles


1. What is UPS


UPS-Uninterrupted Power System is an energy conversion device that uses battery chemical energy as backup energy to continuously provide (AC) electrical energy to user equipment when the mains power is out of power and other grid failures.


2. Why use UPS


Four major functions of UPS:

① Non-power failure function to solve the problem of power failure in the power grid.
② AC voltage stabilization function to solve the problem of severe fluctuations in network voltage.
③ Purification function, to solve the problem of power grid and power pollution.
④ Management function to solve the problem of AC power maintenance.


The main functions of UPS:

① Realize the isolation between the power grid and electrical appliances.
② Realize the uninterrupted switching of the two power sources.
③ Provide high-quality power.
④ Voltage conversion and frequency conversion functions.
⑤ Provide backup time after power failure.


3. Types of UPS


According to different working principles, UPS is divided into:


① Offline (backup UPS, interactive UPS)

② Online UPS


According to different power supply systems, UPS is divided into:


① Single-input single-output UPS.

② Three-input single-output UPS.

③ Three-input three-output UPS.


According to different output power, UPS is divided into:


① Mini <6kVA.
② Small 6-20kVA.
③ Medium 20-100kVA.
④ Large >100kVA.


According to different battery positions, UPS is divided into:


① Built-in battery UPS (standard model).
② Battery external UPS (long time delay model).


According to the different modes of multi-machine operation, UPS is divided into:


① Series hot backup UPS (used for small and medium power machines).
② Alternate series hot backup UPS (small and medium UPS).
③ Directly connect UPS in parallel (used for medium and high power).


According to the characteristics of transformers, UPS is divided into: 

① High frequency UPS (high frequency machine).
② Power frequency UPS (power frequency machine).


According to different output waveforms, UPS is divided into: 

① Square wave output UPS.
② Step wave (quasi-sine wave) UPS.
③ Sine wave output UPS.


4. The basic operation principle of UPS system


Operating principle of backup UPS


When there is mains power, the mains power is directly supplied to the load after the switch is switched, and the inverter does not work; in addition, the mains power is used to charge the battery through the charger.


After a power failure, the inverter is started, and the energy stored in the battery is supplied to the load through the inverter and the switch.


Power level is about 0.25-2KVA


Interactive UPS operating principle


The main difference between the online interactive UPS and the backup type is: the inverter and the charger are combined into one; the output is changed by the tap of the transformer to realize the segmented voltage regulation.


Power level around 0.7-20kVA


Operating principle of online UPS


Regardless of whether the grid voltage is normal or not, the AC voltage used by the load must pass through the inverter circuit, that is, the inverter circuit is always in working condition.


Power level is around 0.7-1500kVA


5. Composition of UPS power supply system


A complete UPS power supply system is composed of front-end power distribution (mains, generators, power distribution cabinets), UPS host, battery, back-end power distribution, and additional background monitoring or network monitoring software/hardware units. The monitoring platform is also one of the most important components of UPS.


UPS network monitoring system = intelligent UPS + network + monitoring software


The network monitoring software contains the following three parts:


SNMP card
Monitoring station software
Safe shutdown procedure
UPS monitoring network


What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 2 - 8)- UPS quality selection and configuration selection
What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 3 - 8)- UPS basic maintenance
What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 4 - 8)- 10 basic problems of UPS power supply