Talk:Motor–generator

Quote: A motor-generator is physically different from a normal electric motor attached to a separate generator, in that both rotor coils of the motor and the generator are wound around a single rotor, and both coils share the same outer field coils or magnets. Typically the motor coils are driven from a commutator on one end of the shaft, when the generator coils output to another commutator on the other end of the shaft. The entire rotor and shaft assembly is only slightly larger in size than in a normal electric motor, and may not have any exposed drive shafts. In my book the above definition is wrong. It describes a rotary transformer rather than a motor-generator. A motor-generator does consist of two separate machines which may be coupled by a shaft or even a V-belt. This may be another US/UK difference. Can anyone confirm this? Biscuittin 20:42, 15 June 2007 (UTC)
 * The difference being a rotary transformer doesn't affect the frequency of the electric power; a motor-generator can convert AC to DC, DC to AC, or change frequencies of AC. It's one form of rotary converter. --Wtshymanski 21:11, 15 June 2007 (UTC)
 * I disagree, inserting the Merge-template now. --Pjacobi (talk) 21:10, 25 June 2009 (UTC)


 * Hi, I would like to know what your definition of a rotary converter is. The term rotary converter is very broad and can refer to any of the many types of rotating electrical machinery which converts one form of electricity into another. Though, in the classical sense the term rotary converter was used to refer to the synchronous rotary converter or synchronous converter. The motor generator set is in no way of similar construction as the synchronous converter. An MG set has two separate and distinct set of windings for both the motor and generator side. An MG set might even have a common shaft and housing but two separate rotor and stator cores for windings; IE they are electrically isolated from each other. The synchronous converter can be described as a commutating DC motor/dynamo which has a set of slip rings tapped into it rotor windings. It is a single machine with one rotor core and shared windings and a single stator. The merge is unnecessary as each of the two devices are completely different. MG sets are still in use today while the synchronous rotary converter has been obsolete for many decades and only survives in a hand full of rail sub stations. In fact there might be a few self contained 60Hz synchronous converters still in operation at Grand Central Station in New York City. The last of the 25Hz New York City MTA Synchronous converter substations were operated until 1999. I am going to watch this article for a bit and will remove the merge-template if no one else does. It is not necessary. Thaddeusw (talk) 16:22, 6 July 2009 (UTC)

Dynamotor
The dynamotor should have its own section. From my research it appears that the dynamotor is a DC only motor generator set. It should be made clear that the word dynamotor is not another name for a motor generator set but rater a dynamotor is a type of motor generator. One application of the dynamotor was to turn a 240V two wire power source into a 120/240V DC system by creating a neutral wire. DC cannot simply be balanced via transformers so a special MG set called a dynamotor was used. The balancing Dynamotor was simply two 120V motors (which can also act as dynamos) wired in series and connected across the 240V source. The wire that connected the two machines together was then tapped off to act as the neutral. This provided true 120V DC power for lighting and other 120V DC equipment from a 240V DC power source.

The Dynamotor could also have windings of two different voltages to act a a DC transformer. One common application of this type of dynamotor is to provide the high voltage necessary to drive the vacuum tubes in radio equipment which was powered by low voltage. One such application was in military radio sets that were powered by the vehicles 14 or 24 volt electrical system.

So in conclusion the dynamotor is a DC only machine, it did not run off or provide AC power. Another common feature was the both sides of the dynamotor were housed in a single unit and shared the same shaft with a commutator at each end. There might have existed very large dynamotor sets that could have been constructed by joining and wiring two DC machines together but the principal is the same. A MG set that is ran from AC and produces DC could fall under the term dynamotor. But in my research the term dynamotor was applied to MG sets that delt only with DC current. Thaddeusw (talk) 00:12, 15 July 2009 (UTC)


 * I agree that dynamotor needs its own section. It is of an entirely different construction than a motor-generator set. What's more, the image at the top of the article has a description that is just plain wrong. It shows a BC-456 modulator chassis on which is mounted a dynamotor, which should be the DM-33-A. This dynamotor produces (nominally) 500 VDC @ 200mA from a 24-28 VDC airplane battery. It's quite wrong to refer to the entire assembly as a motor-generator. This image is not representative of a motor-generator. Akld guy (talk) 00:13, 15 August 2017 (UTC)

Conversion to/from mechanical energy section needs a rewrite
This article is about the motor generator set, not an electrical machine which can be considered bi-directional. I will reword the entry to explain that a bi-directional electric machine is not an M-G set. This entry only serves to confuse the reader as to what a motor generator set really is. Thaddeusw (talk) 23:02, 16 July 2009 (UTC)

Motor-generator vs. motor-flywheel-generator vs. motor/generator
These are three different devices with significantly different purpose and construction. The article needs to make this clearer. Even a split could be considered: each one would be notable in isolation. Andy Dingley (talk) 15:33, 7 December 2015 (UTC)