There are the following differences between online UPS and backup UPS:
1. Working principle
Online UPS: When the mains power is normal, it is converted into DC power by the rectifier, providing power for the inverter. The inverter then inverts it into pure AC power for the load and charges the battery. When the mains power fails, the battery supplies power to the inverter, which maintains the AC power supply to the load.
Backup UPS: When the mains power is normal, the mains power directly supplies power to the load through a bypass channel, and the UPS internal charger charges the battery. When the mains power fails. UPS switches to battery power mode, and the inverter converts the DC power of the battery into AC power to supply power to the load.
2. Quality of output power supply
Online UPS: The output AC power is very pure, which can effectively isolate interference and fluctuations in the mains power. The output voltage and frequency are stable, and the waveform distortion is low. It can provide high-quality power for devices that require high power quality.
Backup UPS: When the mains power is normal, the output is mains power and only simple filtering is performed. The power quality depends on the mains power situation. When the mains power is abnormally switched to battery power, the output power quality is not as good as that of online UPS, and there may be voltage fluctuations and frequency changes at the moment of switching.
3. Switching time
Online UPS: There is almost no switching time from mains power to battery power because the load is always powered by the inverter. In case of mains power failure, only the battery takes over to provide energy for the inverter, achieving true uninterrupted power supply.
Backup UPS: There is a brief switching time from mains power to battery power, usually between 10 milliseconds and several tens of milliseconds. Although most devices can withstand it, it may have an impact on some devices that are very sensitive to power outages.
4. Efficiency
Online UPS: When the mains power is normal, the mains power is supplied to the load through rectification and inversion, which results in certain energy loss and relatively low efficiency, generally around 80% -90%.
Backup UPS: When the mains power is normal, it directly supplies power to the load, and only supplies power through the inverter in case of mains power failure. It has low losses and high efficiency, usually reaching over 90%.
5. Price and Cost
Online UPS: Due to its complex circuit design, good performance, and high-quality output, the price is relatively high, and the price difference becomes more significant with higher power. Meanwhile, due to relatively low efficiency, the long-term electricity cost is also high.
Backup UPS: The structure is relatively simple, the price is relatively cheap, and it is suitable for users who do not have particularly high requirements for power quality and have limited budgets. Its high efficiency also results in relatively low long-term usage costs.
6. Applicable scenarios
Online UPS: Suitable for places with extremely high requirements for power quality and stability, such as data centers, hospital operating rooms, core data centers of financial institutions, etc. These places do not allow any power interruption or fluctuation, otherwise it may cause serious losses.
Backup UPS: suitable for scenarios such as homes and small offices where power quality requirements are not very strict. It is mainly used to provide temporary power support for devices such as computers and routers in the event of a brief interruption of mains power, preventing data loss or equipment damage.