I am not involved with this item, just sharing something that might be of interest.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... SS:US:1123

So that's where the Moon went.....I traded it to the late Jack Anderson for something - an injector I think - many years ago. Interesting to see where it finally turned up. If it hasn't been mistreated it was in decent condition when I sent it out NW.

dave

110 Volts DC was typical for shipboard installations. Back in 1971 I stayed in a long-gone hotel in Chicago that had a DC electric system. The one outlet in my room had a sticker warning guests not to plug in "AC-only" devices, and the only appliance in the room was an electric fan with a US Navy Bureau of Ships nameplate. Some of Thomas Edison's first lighting systems were installed aboard steamboats. As far as rail applications are concerned, I believe some passenger cars had 110 VDC systems. One place where a somewhat "hotter" version of 110 VDC is still common is electric utilty substations, where a 130 VDC rectifier/battery setup powers the control system.

There is (or was) a lot of 250 VDC left in Manhattan. Several years ago I worked for a company that built DC power supplies, and one of their big customers was ConEd. They had a program to retire all the DC mains, used for powering elevators and fire pumps. Their solution was to provide (or subsidize?) rectifiers to their customers, which would be installed in each building. 208 Volt 3 phase AC in, 250 VDC out; and ConEd could stop supplying DC.

The funny thing is that two weeks before I took that job, I had interviewed at a shop that offered a package for upgrading elevators with new variable frequency AC drives. I found it curious that I would see two different approaches to the same "problem" within such a short period of time.

If you Google Con Edison DC you'll see stories going back quite a few years about how they planned to finally get rid of the last bit of DC service. And each time apparently it never quite happened. Some old buildings with DC fire pumps, elevators, etc. just wouldn't budge no matter what surcharges were levied. It looks like it did finally happen 2 years ago this week.

As for elevators, substituting a rectifier setup...or more precisely, a customer-owned rectifier (since Con Ed's DC just comes from a utility-owned rectifier out in a manhole or substation somewhere) means they can leave everything else alone. Changing to a variable frequency drive means a new elevator machine and controls etc.

What's interesting is that even when the power feed is AC, many of the older machines are driven by motor-generators, not rectifiers. That's because the MG set is part of the control system and not just a source of DC where you could easily just drop in a rectifier to replace it. With the MG they are controlling the generator's field to smoothly operate the elevator motor so to get rid of the MG set it means all new control electronics.

As long as this topic is wandering all over the place I'll also mention that utility power in large chunks of the LA area was 50 Hz until the late 1940's.

It is now gone - I think it all went away 2 or 3 years ago. A buddy working at a big film processing plant showed me the old installation, and the new rectifier ConEd put in.

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Will

230 VDC was far more common, but yes, 115 VDC was still kicking around during World War 2.

-
Will

The Southern Pacific Budd-built cars for the Sunset Limited had 110-volt DC batteries. But, these were really complex cars. There were four different voltages and types of current inside the electrical locker. I knew someone who owned one of the 10-6 sleeping cars in the 1970s.

1. The gene-motor was driven by a Spicer drive from one of the axles and it out put 110v DC (actually the regulator was set at about 134v -- if I recall correctly) that charged the batteries.

2. Stand-by (yard) power was the 3-phase 220v AC that was typical. This drove the motor part of the gene-motor.

3. There was 110v DC "emergency" lighting within the car.

4. An amplidyne provided 220v AC from the base 110v DC electric system. This was used to run the fluorescent lights in the car.

5. Then for the 110v AC circuit for the shaver outlets there was a 220v to 110v transformer.

More weird voltages: In the 1970's I was told that Michigan State University's Natural Science Building had a bunch of 32-volt DC service with Safety Company hardware. Apparently DC was wanted for sensitive experimental purposes. I never found any of the hardware, though.

Aarne Frobom
Collegeville, Michigan

Thankfully it is now gone, but my building had a large 600 hertz computer installation - I think the voltage was 120/240. All that is left is an empty substation housing, and the stubbed-off chilled water lines that cooled the CPUs.

32VDC isn't oddball, pretty much standard in steam locomotives.

dave

McHugh Bros. - New Hope & Ivyland ex Copper Range Baldwin Diesel witchers 100 and 101 have 112 volts of battery for a "110 - 120 volt" D.C. system. The voltage regulator was to be set at 128.8 volts. 101 is now on SMS in Pureland, N.J., 100 was scrapped by McHugh in late '89, some of the remaining parts sold 9/26/92.

Control Data machines used 400 Hz, IBMs (and Japanese clones) used 415 Hz. It is easier to make power supplies for these power suckers when 400 Hz is used over 60 Hz.

"Thankfully it is now gone" brings up something to think about. There are indeed people that are saving the classic old mainframes for museums. When one gets scrapped, it has the same effect on them as the scrapping of a steam locomotive has on us. Extra painful if done in the recent past.

Anyway, I recently acquired a few solid state Leibert 400 Hz converters out of an old Control Data pile, so I can start my evil plan to make a 25 Hz converter.

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Will