UPS type Line Interactive with VI technology (output voltage is independent of input voltage) are among the most widespread types of backup power sources. They are able to cover most faults in the electrical network. They are mainly used for non-critical loads for backup power supply of computers. The switching time is less than 4 ms. These AVR regulated UPSs stabilize the output voltage of the backup power supply over a wide range of input voltages. EMI filters serve to suppress peaks and transients. In the event of a failure or outage of the power supply network, the load is powered from the batteries. Unless the mains power is restored, the UPS supplies the load until the batteries are discharged to an acceptable level. When mains power is restored, the load will switch back to mains power after synchronizing with mains voltage. The batteries will start charging to be ready for any future power outages.