The cycloconvertor
The cycloconvertor is a direct frequency convertor without an intermediate DC link which can convert power from one fixed frequency to a lower variable frequency. The cycloconvertor is a mains commutated system which has been known about since the advent of grid controlled mercury arc rectifiers in the 1930s. The system was then used extensively to produce 162 3 hertz power for traction applications, from the 50 hertz mains supply. Since that time, it has been used for induction heating and for low-frequency arc furnaces for slag refining. It has also been used for motor drives since the late 1940s, when it was used to supply low-frequency roller table drives in steel mills, using this time steel tank mercury arc rectifiers. It has been used more widely since the advent of thyristor switches and its most important application is for supplying large synchronous motors driving low speed cement mill furnaces where units up to 8,000 kW have been built operating at up to 10 hertz. It has been and still is being used, though less extensively, for a variety of low frequency applications from steel rolling mills and tables, for mine hoist drives and for ship propulsion drives.
The cycloconvertor, Page 1 of 2
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