Offline UPS (VFD) UPS topology

“Voltage and frequency dependent” UPS in compliance with IEC 62040-3, also referred to as offline, protects against many problems in your network. Under normal conditions it conducts the input current to its outlet. When the power supply fails it switches over to a built in battery to compensate for any variations in the mains supply.
UPS topologies - offline VFD UPS

Advantages:

  • Small size
  • High efficiency
  • Low operating costs

 

Disadvantages:

  • transfer gap (some ms)
  • load is fed by unfiltered voltage (no correction by the inverter)
  • output voltage often not sinusoidal