The electrical supply requirements of my computer The electrical supply requirements of my computer are: - alternating current at the voltage 220 volts (V); - AC supply required frequency is 50 hertz (Hz); All the electronic devices are very sensitive to the quality of external supply. There are special requirements for consecutive energy supply, that's why I use single-phase uninterruptible source of energy which is composed of: - rectifier, to transform alternating current (supplied from power grid) to direct current, needed for rechargeable batteries; - rechargeable batteries; - inverter, to provide alternating current to the monitor and computer.