Definition: Electrical voltage is specified in volts and is one of the basic physical values. With the voltage as the cause of the electric current, the strength of a voltage source can generally be indicated.

For private consumers, the mains voltage is at different values worldwide. While voltages of 220 to 240 volts are common in Europe and Asia, in North and Central America voltages of 110 to 127 volts are common. Since industry demands higher power, a higher voltage is used in industrial plants. This is usually 400 volts, as this is the same voltage range that is used in large parts of the public supply network. Voltages of 500 or 690 volts are also common. These are still in the low-voltage range, but offer efficiency advantages and thus potential for cost reduction, for example in cabling. Exceptions are industries such as steel mills, where exceptionally high performance is required: In electric arc furnaces, for example, voltages of up to several kilovolts are common.

Industrial pumps are also supplied with low voltage power. In order to select the appropriate unit, it is nevertheless necessary to ensure that the pump can be operated with the mains voltage given in the system.