Usually, an online, double-conversion UPS is particularly used to compensate “short” power drops in the power grid, i.e. short fluctuations of the grid voltage like spikes, sags, outages and other anomalies. Accordingly, the online, double-conversion UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations, like sensitive electronic or IT equipment. However, depending on the size of the battery, also “l(fā)ong” power drops in the power grid may be compensated by the online, double-conversion UPS.

An online, double-conversion UPS moreover comprises a bypass switch connected between the UPS input and the UPS output, which is closed in case of excessive power demand and/or excessive voltage drop and/or excessive output current. Accordingly, the rectifier, the inverter, and the capacitor/the battery are bypassed, and the electrical consumer is directly switched to the power grid, i.e. AC mains. Usually, the power grid can drive much more power than the UPS, and by switching over to the bypass, the electrical consumer keeps in operation, even if the power demand excesses the power the UPS can drive.