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Author Topic: need a wiring diagram for Hertner Transverter Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 05-07-2016 12:34 AM                    Bringing up this thread to ask if, before silicon rectifiers, were arc lamp supplies always M-G sets (AC motor spinning DC generator) or were they ever rotary converters like Stephan Shelley was discussing. Like this: https://en.wikipedia.org/wiki/Rotary_converter I'll summarize in case the link ever fails that it was like a motor and generator merged into one but some of the energy can go directly (via brushes, slip rings, and commutator) while some moves mechanically (compared to an M-G where all the power goes through mechanically). They were common for electric railways. I'm wondering if maybe the power output wasn't smooth enough for projection arc use where non smooth power would cause flicker as it interacted with the shutter. Or maybe they were only practical in very large sizes and for lamps an M-G was more cost effective.  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 05-07-2016 01:32 AM                     quote: Steve Kraus were arc lamp supplies always M-G sets (AC motor spinning DC generator) or were they ever rotary converters In the very early days, huge mercury vapor rectifier tubes were used to supply the DC for the arcs. I actually encountered a few of these still in use in the early 1970's! Here's a front & rear picture from a 1926 projection manual I have in my collection: The tubes looked like some apparatus out of Frankenstein's lab. I came across one of these mercury rectifiers in an old theater:  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 05-07-2016 12:42 PM                     I have heard from others that on rare occasions rotary converters were used in theatres for the DC supply for the arc lamps. The big drawback is they don't always sync the same and the polarity is a 50/50 chance of being correct. Usually theatres that used rotary converters would have a polarity reversing switch. In the case of the railway power rotary converter there is a startup sequence done by a drum switch sequence and the motor that drives the drum switch also runs a small generator that polarize the field on startup so it always sync the correct way. Sacramento Northern portable sub 1 is the one I am familiar with and was designed to run automated and unattended. When the voltage dropped below the threshold level for an specific amount of time it would fire up and after the train passed shut down again all on it own. This is late teens electro/macanical tech. In this case made by GE.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 05-08-2016 12:52 AM                    Funny you mention that as the Illinois Railway Museum is just outside the little hamlet of Union, Illinois and utilizes about 4.5 miles of the right of way of the old Elgin & Belvidere electric interurban (trolley) line which folded around 1930. Union warrants a footnote in trolley history as the location of the first automated substation, working just as you describe.  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 05-08-2016 01:39 AM                     The one I am referring to is now at the Western Railway museum near Rio vista CA. Years ago it was the sole source of 600 volt DC power for the museum now it is in standby service. I think they fire it up once a month. A sister machine also from the Sacramento Northern but was a fixed location is at the railway museum near Pairs CA. Interestingly the build that that rotary was in is at the Western Railway museum and houses a solid state supply. The Western Railway museum operates a section of the Sacrament Northern. Back to the mercury valve rectifiers they were also used for railway power. No glass but metal enclosers. There is also the sister Ignitrons developed by Westinghouse.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 05-09-2016 10:17 AM                     Those mercury arc rectifiers are tiny. Much larger ones exist, even as glass bulbs. Railways used both types; the Manx Electric Railway retired their last ones just a couple of years or so ago, and even the London Underground had some large glass bulb types, there used to be some in a substion next to one of the stations, and at night you could see the weird blue glow inside. The biggest steel tanks I have seen are 12 anode ones, about two metres in diameter. There's an old pumping station in London with two very large triple expansion engines and two steam turbine sets, which is now a museum. The electrics are 200 V d.c. The original rectifiers were scrapped, but the museum people managed to obtain suitable replacements from the Royal Opera House of all places. web page Still quite small. I believe that the glass bulbs were blown by hand; must have been quite a job.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 05-09-2016 11:52 PM                     Here is the link to a video of a large mercury arc rectifier in action..The Manx Railroad on the Isle of Man: Manx Mercury Arc Rectifier  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 05-10-2016 12:31 AM                     I mean, I know those are "reliable" and "relatively safe" but dear god am I the only one that would not dare go near one of those things??  |  IP: Logged Alan Plester Expert Film Handler Posts: 209 From: great yarmouth england Registered: Apr 2001 posted 05-10-2016 06:53 AM                     Fascinating thread and pictures. we had the cage of the old mercury rectifier in the defunct projection room , I often wondered what it really looked like when operating, my old chief, described it as a large octopus, and recalled the day it went bang, nasty mess  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 05-10-2016 09:09 AM                     quote: Buck Wilson am I the only one that would not dare go near one of those things?? and quote: Alan Plester recalled the day it went bang, nasty mess No, Buck, you are not alone. The very first theater I was permanently assigned to had one of these monstrosities. It was a big, high-voltage device in an open frame crammed into a small booth, and I was always a bit apprehensive around it. My fears were not unfounded, as one night the thing "went bang" when I came into work and threw the knife switch that turned it on. I was peppered with glass shards, and fortunately I happened to be looking away from it when it exploded or I might have gotten glass (and worse yet- - mercury!) in my eyes. I was finding little balls of mercury all over the booth for weeks afterwards. Believe it or not, they had a 'spare' tube, and continued to use the unit for about another year before they replaced it with a "Sil-Tube" rectifier when one of the transformer or choke windings in it overheated and began to belch smoke and then 'flame-out' and burn up. But as long as they continued to use the old unit, after the 'exploding bulb' incident, I had always kept my distance and always turned my back to it when switching it on at the beginning of my shift.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 05-10-2016 03:19 PM                     I don't mind Mercury rectifiers, but I think I'd keep my hands a bit further away than the man in the video. Xenon lamps on the other hand do worry me.  |  IP: Logged David Buckley Jedi Master Film Handler Posts: 525 From: Oxford, N. Canterbury, New Zealand Registered: Aug 2004 posted 05-10-2016 09:14 PM                        We had a mercury arc rectifier in our booth until relatively recently: And, of course, there is the old, now removed, mercury arc based New Zealand HVDC link, some really big mercury arc valves in that! (PDF).  |  IP: Logged Alan Plester Expert Film Handler Posts: 209 From: great yarmouth england Registered: Apr 2001 posted 05-11-2016 05:25 AM                     WOW, they be some seriously big tubes.  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 05-12-2016 03:51 PM                     The Royal Opera house may have had to do with spotlight power. Also some stage houses back in the day like to use DC for incandescent light sources so there is no flicker. There were some places like Shay's Buffalo that had 25 HZ AC. The flicker was noticeable.  |  IP: Logged

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