often used to provide the high-current D.C. power for carbon arc lamps in large movie projectors in the 1950-60's era, before the carbon electrode arc light was replaced with modern xenon arc lamp projection systems (starting in 1963 in the U.S.). In industrial settings where harmonic cancellation, frequency conversion, or line isolation is needed, MG sets remain a popular solution. A useful feature of motor–generators is that they can handle large short-term overloads better than semiconductor devices of the same average load rating. Consider that the thermally current-limited components of a large semiconductor inverter are solid-state switches massing a few grams with a thermal time constant to their heat sinks of likely more than 100 ms, whereas the thermally current limited components of an MG are copper windings massing sometimes hundreds of kilograms which are intrinsically attached to their own large thermal mass. They also have inherently excellent resistance to electrostatic discharge (ESD). Modern use of the term In principle, any electrical generator can also serve as an electric motor, or vice versa. In hybrid vehicles and other lightweight power systems, a "motor–generator" is a single electric machine that can be used as an electric motor or a generator, converting between electrical power and mechanical power. From the 2014 season, Formula 1 racing cars will have two of what are described as 'motor-generator units' (MGU) This makes the cars more fuel-efficient by harvesting energy from the turbocharger and under braking. However these are not motor-generators as described here, but are more like dynamotors, single units which can act as either a generator or a motor. They can be used to provide an additional 160 BHP to the wheels to aid acceleration and overtaking, or can be used to spin the turbo to increase boost pressure faster, thereby reducing turbo lag. See also Booster (electric power) Cascade converter Diesel generator Engine-generator Frequency converter Harry Ward Leonard Head-end power Inverter (electrical) Rotary converter Rotary phase converter Three-phase electric power References Electric power systems components