Rotary converter
Encyclopedia : R : RO : ROT : Rotary converter
Rotary converter refers to a class of electrical machinery that was used to convert one form of electrical power into another form. There are several types of "rotary converter". They are:
- Rotary Phase Converter (RPC) - for converting the phase of electrical power; such as single phase to three phase power. See Rotary phase converter.
- Rotary Frequency Converter - for converting the frequency of an AC supply; e.g. converting 60Hz (US household frequency) to 50Hz (UK household frequency). See Frequency converter.
- Rotary AC to DC Converter - for converting AC to DC power or DC to AC. See below.
The rotary converter can be thought of as a motor-generator where the two machines share a single rotating armature and set of field coils. The usual practice, in fact, was to have two commutators, one at each end of the armature (or, for AC-to-DC machines, a set of slip rings and a commutator). The advantage of the rotary converter over the discrete motor-generator set is that the rotary converter avoids converting all of the power flow into mechanical energy and then back into electrical energy; some of the electrical energy instead flows directly from input to output, allowing the rotary converter to be much smaller and lighter than a motor-generator set of an equivalent power-handling capability. The advantages of a motor-generator set include complete power isolation, harmonics isolation, voltage output control, greater surge and transient protection, and sag (brownout) protection through increased momentum.
(One way to envision what is happening in an AC-to-DC rotary converter is to imagine a rotary reversing switch that is being driven at a speed that is synchronous with the power line. Such a switch could rectify the AC input waveform with no magnetic components at all save those driving the switch! The rotary converter is somewhat more complex than this trivial case because it delivers near-DC rather than the pulsating DC that would result from just the reversing switch, but the analogy may be helpful in understanding how the rotary converter avoids transforming all of the energy from electrical to mechanical and back to electrical.)
AC to DC Rotary converters have essentially been made obsolete by smaller, cheaper, far more reliable semiconductor rectifiers. For railway electrification via a catenary wire there has also been a tendency to switch from medium-voltage DC or low-frequency AC to high-voltage, mains-frequency AC, thus eliminating the need for any rectification or frequency conversion.
See also
External links
- [Rotary Phase Converter Technology Ratings - U.S. Phase Converter Standards Organization]
- [An article about AC-to-DC rotary converters used for traction power]
- [PhaseConverter.com Loaded with Rotary Converter Articles, Comparison Charts, Sizing Diagrams and other useful Phase Converter and Frequency Converter Information]
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.