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
Thu, 05-16-2013 21:52
Looking good Bob! I hope to come out soon once I'm done with school.
Wed, 05-15-2013 21:28
I was not around at the time. General discussion suggests that it was "pretty marginal" in a number of areas. Nigel
Mon, 05-13-2013 11:08
"THUMBS UP!"
Fri, 05-10-2013 02:15
No, it will not be necessary to hold any of the work waiting for the plow to be turned, end for end. Weather will be the major factor, but there will [...]
Thu, 05-09-2013 19:54
The CGW X-38 plow is really coming to life. Bob Kutella and Vic and crew need to be very proud of your collective efforts. I am very appreciative of [...]
Thu, 05-09-2013 15:20
The snowplow looks great! Are you going to apply the door and upper windows befor it is turned to continue work?
Thu, 05-09-2013 09:09
Max, Is there any progress to report yet, in regards to the installation of the poles and overhead wires? Have a good day, sir.
Wed, 05-08-2013 18:40
Thanks for the update! I still don't understand why Commonwealth #5 was removed from service. Do you know why?
Tue, 05-07-2013 09:28
Mr. Kolanowski.....I was just wondering if the Spaulding webcam will be up and running soon for us stay-at-homes. Thanks!2FP
Mon, 05-06-2013 23:04
Max, Has work begun yet on the construction phase of erecting the poles and putting up the wire? Wish I could be there to watch it happen.
Mon, 05-06-2013 23:02
Keep up the good work, Bob. Wish I could be there to help!!!!!!!
Sun, 05-05-2013 18:53
Ah yes, I have made such Jibs myself. If it were me, I would add in each corner an angled piece from the base to the Jib to act as sway bracing. [...]