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Choose the UPS system that meets your needs


There are many types of UPS systems on the market today. It is important to understand how different devices work and the strengths and weaknesses of each system.

It is generally accepted that there are only two types of uninterruptible power supply (UPS) systems: standby UPS and online UPS. As is well known, these two terms do not apply to many UPS systems on the market today. Many misunderstandings of the UPS system can be eliminated if different types of UPS topologies are correctly identified.

UPS systems are designed to improve the quality of AC power and provide uninterrupted operation of AC power equipment. To perform these functions, UPS has obtained universal quality AC power from local power companies and offers two enhancements: improved power quality and redundant (or standby) power.

Power quality defects that UPS may improve include power surges, noise, and drops. In the event of a main power failure, the UPS system will also provide redundant power by providing backup power. The backup power source usually comes from the battery.

A universal uninterruptible power supply can be used as a backup UPS or an online UPS. The main difference in operation is that the selected power path is primary. For standby UPS operation, set the transfer switch to select the filtered AC input as the primary power source. If the utility fails, it will switch to the battery/inverter as a backup power source. For online operation, set the transfer switch to select the battery/inverter as the primary power source and switch to the AC input as the backup power source in the event of a battery/inverter failure. The difference between online and standby UPS operations is very simple, but it can lead to some important operational differences.

For example, the interesting difference between this type of UPS in standby and online operation is how the UPS operates when the input AC power fails. In standby mode, the transfer switch must be switched to the battery/inverter as a backup power source. However, in the case of online operation, a fault in the input AC does not activate the transfer switch because the input AC is not the primary power source (but the backup power source in this mode of operation). Therefore, during the input AC power failure, the transmission time is not generated when the online operation is converted to the standby power supply.

On the other hand, when the power from the primary battery charger/battery/inverter power path fails, the online operating mode will display the transmission time. This can happen when any device in this power path fails. If the inverter is subjected to a sudden load change, or if the inverter encounters an internal control fault, the power supply will be briefly de-energized, causing a transmission.

Therefore, the actual online UPS system does have transmission time, and in actual installation, the transmission frequency may be as frequent as the standby UPS system. However, the online UPS transmission is independent of the standby UPS and is independent of the AC input power failure.

The choice of the backup UPS greatly affects the size of the battery charger compared to the online operation of the online UPS. When used in online mode, the battery charger must be large enough to withstand all output power to prevent the battery from discharging. When used in standby mode, the battery only needs to provide a relatively small charging power.

When the general purpose UPS is operating in online mode, the uninterruptible power supply generates more heat. Power flow through the battery charger and inverter can result in 25% to 30% power loss. This power loss generates heat, which shortens the life of the electronic components in the UPS and greatly reduces battery life. (If you place the battery in a separate cabinet, you can eliminate the negative impact on battery life.)

When the UPS is operating in standby mode, the power loss of the filter and surge suppressor is negligible from 1% to 2%. The additional (and wasted) power costs required for the UPS to operate in online mode over its lifetime will account for a significant portion of the original cost of the UPS itself.

If you want know more, please contact Daopulse.