When I first started with the power company my job from time to time was to baby sit the 25 cycle motor-gen for Amtrak. As I marveled at the "freq" what we call it on my very first day on the job, the senior operator said "hmm, in 5 years this will be gone" almost 28 years ago now the "freq" is still going strong.

BTW, built by the PRR in 1927.

I've attached some 3-phase to 6-phase info for some light bathroom reading.

Nice to see Buck Rodgers type of equipment saved. This is where my day job and my hobby meet.

Scott

Rotary converters are extremely efficient. One very old textrbook give the total power in vs. power out at 95%. The motor that makes it revolve is a three-phase synchronous motor. There is some bearing friction, brush friction, and motor coil heating involved. All the rotary converters I have seen blow a lot of air around so there will be some power used in moving the air.

The brushes work in exactly the same way as they do in an old automobile generator.

Rick, what a cool "save" of really neat equipment. Good luck with using it, should not be too hard with the right research and backup team.

As a trained Electrical Engineer (aka a "sparky") I love that old stuff, I still have an old "core" memory circuit board for a PDP 10 computer. The "core" memory was literally a whole bunch of tiny little "donuts" (or "cores") of ferrite material. Each "core" was a tiny little transformer and by quickly applying current and then coming back a little while later to read the state of the "bit" it was possible to store information. I think it was a "high density" memory board that held 8 kilobytes of data.....

As I've heard; They've been studying it for years, nobody knows how the heck electricity works......

Good luck, Kevin.

http://www.youtube.com/watch?v=joK6RgPPmik

Wonder if this equipment is still around?

Surprisingly little is available on YouTube of rotary converters. You see plenty of newer home-made installations, but little of the period stuff.

We do have one video from Westinghouse of a converter under test. Man, look at the lack of safety gear, open belt drives, all sorts of hazardous stuff back in 1904:

http://www.youtube.com/watch?v=xmiLZNVRvZU

A bit off topic, but associated with this video are a number of others of various electrical equipment under construction or test.

A relatively small steam turbine; I can imagine what it sounded like, having been next to one used in the engineering school at West Virginia Institute of Technology at Montgomery, W.Va.:

http://www.youtube.com/watch?v=12wHYgR6HiA

http://www.youtube.com/watch?v=SGIa4RIstX0

Other Westinghouse videos:

http://www.youtube.com/watch?v=exUaIydhhuQ

http://www.youtube.com/watch?v=jP4aIUeQnt4

Surprising how many women were at work in the Westinghouse plant in 1904:

http://www.youtube.com/watch?v=ORaj1udZtHI

http://www.youtube.com/watch?v=7Ua7clPBvg8

Generator assembly; interesting to see how many people look fairly well dressed. I can't help but think that either electrical equipment assembly was a good deal cleaner than a lot of other work, or that a lot of this was staged.

http://www.youtube.com/watch?v=0HPcXc-zjy0

http://www.youtube.com/watch?v=2uvOgWapG2g

Steam hammer work:

http://www.youtube.com/watch?v=p-7bz7bmDg4

Casting work at the air brake works. Aren't you glad you have nice, easy job by comparison?

http://www.youtube.com/watch?v=q6O932trtlU

http://www.youtube.com/watch?v=98eaQR27HqQ

http://www.youtube.com/watch?v=LYs9Arg7AkI

Back to the electrical side, manufacture of trolley motors; lots of management types walking around (company goons?), two small electric works locomotives are also visible, and at 1:05 or so, something falls from above, including a piece of wood; safety in 1904 does not seem to have been as paramount as it is today.

http://www.youtube.com/watch?v=4pLSfpk9m5E

Where all this took place:

http://www.youtube.com/watch?v=vI1Htf-1m5A

I'm really glad to see the machine saved. Dayton had three Westinghouse 2000 kW units (trolleybus) at 4th Street Station operating until the early 1980's.

I would use a little caution in using the unit to provide a very small DC load as it must be up to speed and synchronized to produce DC and the losses to maintain this would be something like 4-5% nameplate, a pretty costly number. Starting could be an issue also. The softest start would be to use a DC drive to bring it up. Actually, it was quite common on the NY subway to bring machines up from the DC buss.

The Pennsylvania Trolley Museum has the former 500 kW Thompsonville sub converter and most of the equipment needed to make it go. This machine was the unit used to power the three original cars to the museum site in 1954 before the Washington interurban was scrapped. The building still stands. A long term goal might be to set it up but much more important needs such as a new Visitor's Center are way ahead of this.

Now, while I have to floor so to speak, the Grand Rapids Electric Railway formerly Waterfront Electric Railway had a 200 kW converter and a 300 kW rectifier from the Acme Station of Toledo Edison. Do they still exist?
Dennis Bockus, BSEE

We plan to do some experimenting with the converter to see what is possible regarding starting and running on reduced voltage and output. AC power will be provided with a diesel generator thus avoiding huge electric bills from high power demand. I am inviting any electrical engineers/enthusiasts to come participate in this project. Its going to be interesting.

I imagine there must be a sync interlock, somehow I think if the unit looses sync the consequences would be dire!

Sync....all on one common shaft?

dave

In sync with the 60 cycle power grid. (or 25 cycle, as the case may be).

Thanks...that makes sense.

dave

At National Capital Trolley Museum we display an "exciter" used to provide the trickle charge to get the rotary or dynamo going(?). The exciter was used at the Chevy Chase, MD power plant of Capital Traction Company. Perhaps someone here at RyPN U. can explain the function of this device. I will see if I can get a photo to post.

Wesley

Another interesting feature of rotary converters is that they can synchronize with either positive or negative voltage DC output. One I saw has a device with a horseshoe magnet to determine which polarity is coming out of the convererter. Then it throws a large relay to connect the proper polarity to the trolley wire.

As I said, you can NOT run the motor on less then rated voltage, it won't like that. You will pretty much be forced to feed it 440/480. It has to reach rated speed to work, and running a synchronous motor on reduced voltage causes the amperage draw to go up, that causes excessive heating and failure. At 208 vs 480, it will try to pull at least double the current.

If this was a MOTOR, or a motor/generator, that might be true.

However, this is a rotary converter, and the rules are a bit different. The only "load" on the "motor" is it's own inertia while starting, and drag from the bearings.
It basically functions as a rotary transformer, with the commutator serving to rectify the output.
As such, a reduced input voltage (within reason) will simply result in a proportionately reduced output voltage.

Jeff