Electromotive amplifier
An electromotive amplifier (EMC) is a high-performance amplifier constructed as a combination of a three-phase motor and a modified alternating voltage generator. With an electric motor amplifier, large loads could be moved electrically remotely. The output power of an electromotive amplifier can be up to several tens of kilowatts with a power amplification of 10 4 to 10 5 . The electromotive amplifier was developed by the electrical engineer Ernst Alexanderson during the Second World War under the name Amplidyne (a brand name of General Electric ).
functionality
The electromotive amplifier works as a regulated converter. A powerful motor as a three-phase synchronous machine is rigidly connected to a modified alternating voltage generator. The motor rotates at a constant speed. The generator is equipped with a field excitation controlled by DC voltage. If the excitation voltage for the magnetic field in the generator is zero, there is no output voltage at the generator, although the motor is working at full speed. With just a few watts of power for the excitation field, the generator generates an output voltage that is designed for a high current load. A powerful electric motor as a three-phase asynchronous machine is usually used as the load .
application
Electromotive amplifiers were used to control guns during World War II ; in the post-war period also in downstream systems for large radar antennas . Such an electromotive amplifier for a smaller secondary radar antenna (for example the NRS-12 for the P-12 ) weighed around 50 kg; for the follow-up system to the PRW-13 altitude search radar , this assembly weighed several tons.
With the availability of semiconductor components that can also switch powers in the range of several kilowatts, electromotive amplifiers have completely lost their importance.
Individual evidence
- ↑ https://www.google.co.in/patents/US2236984
- ↑ Большая советская энциклопедия. Retrieved on February 10, 2013 (Russian, German about "rotary amplifier").
- ^ EFW Alexanderson, MA Edwards, KK Bowman: Dynamoelectric Amplifier for Power Control . In: Transactions of the American Institute of Electrical Engineers . tape 59 , no. December 12 , 1940, p. 937-939 , doi : 10.1109 / T-AIEE.1940.5058071 .