Some of you have been following along at home as we strive to understand and restore the carbon arc headlights on this locomotive. See the submitted BLOG comments for some good information and discussion.
John Nelligan has researched and come up with some very good 'new to us' information. I will repost his findings below. Thank you John and Steve Kraus, for making all of us a little bit smarter. Reading John's findings in light of Steve Kraus's comments makes sense. The brightness of a carbon arc light device requires the positive electrode placement to be just so, to give maximum efficiency. Reversing polarity with the DPDT headlight switch makes the other electrode the positive side, and it is now outside the optimum placement, making the headlamp seem 'dimmer' in that connection scheme. The arc itself is unchanged.
Steve's experience is with lower voltage arc lights. In the locomotive, the circuit receives a nominal 600 volts, but with the dropping resistance, the effective potential across the headlight is MUCH lower, after the arc is struck. In fact, maybe VERY MUCH lower since ionized air in an established arc provides almost ZERO resistance.
"Last Thursday, I got lucky when I googled carbon-arc headlights and found a
1909 GE bulletin describing exactly what is installed in the CCW 300 for
headlight operation. The venerable GE engineers discovered the when the
terminals of the headlight are hooked up with one polarity, the light emitted is
bright (1800' down the track) and when the polarity is reversed, the light is
not nearly as bright and suitable for street running in urban locales. Thus the
use of a DPDT (double pole double throw) switch that has been marked 1200 (incorrectly as has been observed). The only workable
configuration for the headlight resistance is to tap it with the same number of
resistors on each side of the tap pair. The current along each of the 2 equal
paths will be 3 Amps when 600 Volts is applied to the taps. This
arrangement serves both positions of the DPDT switch. There is no possible tap
arrangement that would not fry the resistor bank, were 1200 Volts to be applied across the taps."
Comments
Fri, 03-29-2024 21:26
We're slackers and spend more time working on the equipment in the shop than keeping all you readers updated. We'll work on it, but I'm sure updates [...]
Thu, 03-14-2024 08:02
What happened to the Department Blog? It's been over 2 years and I still regularly check for updates, but nothing comes...
Mon, 12-27-2021 16:28
Happy New Year to all the Departments at the Illinois railway Museum! Thanks for all the good work you do in railroad preservation. Ted Miles, [...]
Wed, 10-13-2021 13:33
Was the CB&Q 1309 every transported to IRM?I’ve been reading old issues of Rail&Wire and the car was mentioned several times.
Mon, 06-07-2021 22:40
I was wondering if in the model layout display what scale would you guys be using and would you be displaying model train history as well? Just [...]
Wed, 06-02-2021 17:27
Nice to see 428's cab back on. Looking forward to when it is operable!
Tue, 06-01-2021 16:47
I hope the work will continue on the UP #428. Now that they are the museum's connection to the national railroad network; she would be very [...]
Sat, 04-17-2021 23:07
What is the status of 126, the Milwaukee Buffet car that is in S. Dakota? Any guess on when or if it will get to IRM?
Wed, 04-14-2021 21:09
Perhaps it is time to scrap the remains of the c, B & Q 7128 to make room for the Villa Real. Ted miles, IRM member
Wed, 04-14-2021 15:26
Hi IRM my name is Jason and I was wonder If you guys would be willing to save a CN Dash8-40cm they are currently being retired by CN and being [...]
Fri, 04-09-2021 19:56
Bear in mind that the Nebraska Zephyr is an articulated train set, so cars cannot be inserted at will. Although cars and/or a second engine could be [...]
Wed, 03-31-2021 11:37
I believe Silver Pony is currently on the back burner, and has been put into storage in one of the barns. The car needs a lot of work done to it's [...]