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UPS topic two: UPS classification




Today, we shall introduce three types of UPS power supply, off-line UPS/backup UPS, line interactive UPS, and online UPS.


off-line UPS/backup UPS


Backup UPS is low cost, to meet general customer requirements for UPS. main feature: small volume, low cost, but input voltage range is relative narrow, as well as output voltage stability accuracy, switching time 10ms, output modified sine wave. Due to the performance constraints, the capacity is generally only 0.5kva - 2KVA.


 The structure of power conversion main circuit of back-up UPS is simple, mainly composed of filter circuit and battery charge and inverter circuit, the filter circuit can restrain the interference in mains.


Line interactive UPS


Line interactive UPS features: a widely range of input voltage, low noise, small volume..., less switching time. When the mains is 220V+/-20%, UPS auto sense that mains is normal, AC charge was sent to the load by low frequency transformer; when the main up to 220V+/-20%, but between 150V to 276V, UPS through logic control, drive relay action, so that power frequency transformer tap boost or step-down, and then to the load supply. When the mains is below 150V or above 276V, UPS will start the inverter work, powered by battery inverter to load.


The difference between the line interactive UPS and the backup UPS is that the inverter is in a hot backup status, and the switching time of the mains/inverter is shorter than the backup type.


Online UPS


Online UPS adopt double-conversation, the feature is a wide input voltage range, no switching time and high voltage stability, especially suitable for the high power requirements of the occasion, but high cost. Now,  above 3KVA UPS is online UPS.


Online UPS has excellent electrical features:


  •  Can make the output voltage stability accuracy up to +/-0.5 5--+/-1%;


  • 2 Using the PLL synchronous circuit to ensure the output frequency of is locked in the same step in the synchronous window, when the synchronization window is exceeded, the UPS power supply is in the local oscillation state and the output frequency precision can reach 50hz+/-0.1%;


  •  Online UPS widely adopted SPWM technology, and output waveform distortion is below 3%. when the crest ratio 3:1, the distortion is lower than 5%;


  •  Due to adopt to the AC/DC, DC/AC double-conversation design, can completely eliminate any voltage fluctuations, waveform distortions, frequency fluctuations and interference from the mains. UPS Inverter provides high quality pure sine wave without interference to the loads;