A
motor–generator (an
M–G set) is a device for converting
electrical power to another form. Motor–generator sets are used to convert
frequency,
voltage, or
phase of power. They may also be used to isolate electrical loads from the electrical power supply line. Large motor–generators were widely used to convert industrial amounts of power while smaller motor–generators (such as the one shown in the picture) were used to convert
battery power to higher DC voltages.