Extra-low voltage is an area of low voltage and therefore refers to all voltages below 50 volts for alternating current and everything below 120 volts for direct current. Extra-low voltages are divided into three different ranges. The safety extra-low voltage, which can be found in batteries or rechargeable batteries and has protection class III. Thanks to protection class III, this type of voltage offers protection against electric shock. The second is the safety extra-low voltage, which is found in audio devices and amplifiers. Thirdly, the functional extra-low voltage for which no special safety measures are required for voltage generation. This extra-low voltage is used in machine control elements, among other things.