Posted by Archimedes' Lever on August 13, 2009, 9:27 am
>Paul Keinanen wrote:
>> On Mon, 10 Aug 2009 22:05:42 -0400, clare@snyder.on.ca wrote:
>>
>>> The 6 amp motor means it draws 6 amps from the mains. It does not mean
>>> ANYTHING as far as how much power it produces, other than that it
>>> cannot produce more than 690 watts at 115 volts
>>
>> Have you returned to constant current power distribution with 6 A
>> circuits ?
>>
>> Arc lamps in the 1880's were specified by the number of amperes
>> (typically 6 A for street lighting). All lamps were series connected
>> and you could operate 20-25 of these in series from a 6 A DC generator
>> producing a 1000-1500 V DC loaded voltage. Thus, the voltage drop
>> across each arc lamp was about 55 V on average.
>>
>> Paul
>>
>That's interesting. How would you strike an arc on series wired arc
>lamps? Seems near impossible...?
One at a time while the others are shorted.
Posted by Mycelium on August 13, 2009, 9:47 pm
wrote:
>On Thu, 13 Aug 2009 06:41:41 +0300, Paul Keinanen wrote:
>> On Mon, 10 Aug 2009 22:05:42 -0400, clare@snyder.on.ca wrote:
>>
>>>The 6 amp motor means it draws 6 amps from the mains. It does not mean
>>>ANYTHING as far as how much power it produces, other than that it
>>>cannot produce more than 690 watts at 115 volts
>>
>> Have you returned to constant current power distribution with 6 A
>> circuits ?
>>
>> Arc lamps in the 1880's were specified by the number of amperes
>> (typically 6 A for street lighting). All lamps were series connected
>> and you could operate 20-25 of these in series from a 6 A DC generator
>> producing a 1000-1500 V DC loaded voltage. Thus, the voltage drop
>> across each arc lamp was about 55 V on average.
>>
>And, like the series Xmas lights of yore, when one goes out, they all
>go out.
Not if it fails shorted.
Posted by ingvald44 on August 14, 2009, 8:11 am
Mycelium wrote:
> wrote:
>
>> On Thu, 13 Aug 2009 06:41:41 +0300, Paul Keinanen wrote:
>>> On Mon, 10 Aug 2009 22:05:42 -0400, clare@snyder.on.ca wrote:
>>>
>>>> The 6 amp motor means it draws 6 amps from the mains. It does not mean
>>>> ANYTHING as far as how much power it produces, other than that it
>>>> cannot produce more than 690 watts at 115 volts
>>> Have you returned to constant current power distribution with 6 A
>>> circuits ?
>>>
>>> Arc lamps in the 1880's were specified by the number of amperes
>>> (typically 6 A for street lighting). All lamps were series connected
>>> and you could operate 20-25 of these in series from a 6 A DC generator
>>> producing a 1000-1500 V DC loaded voltage. Thus, the voltage drop
>>> across each arc lamp was about 55 V on average.
>>>
>> And, like the series Xmas lights of yore, when one goes out, they all
>> go out.
>>
>
>
> Not if it fails shorted.
Yeah about 25 pct of the time. Good idea, poorly executed.
Posted by Rich Grise on August 14, 2009, 3:17 pm
On Thu, 13 Aug 2009 18:47:56 -0700, Mycelium wrote:
>>On Thu, 13 Aug 2009 06:41:41 +0300, Paul Keinanen wrote:
>>> On Mon, 10 Aug 2009 22:05:42 -0400, clare@snyder.on.ca wrote:
>>>
>>>>The 6 amp motor means it draws 6 amps from the mains. It does not mean
>>>>ANYTHING as far as how much power it produces, other than that it
>>>>cannot produce more than 690 watts at 115 volts
>>>
>>> Have you returned to constant current power distribution with 6 A
>>> circuits ?
>>>
>>> Arc lamps in the 1880's were specified by the number of amperes
>>> (typically 6 A for street lighting). All lamps were series connected
>>> and you could operate 20-25 of these in series from a 6 A DC generator
>>> producing a 1000-1500 V DC loaded voltage. Thus, the voltage drop
>>> across each arc lamp was about 55 V on average.
>>>
>>And, like the series Xmas lights of yore, when one goes out, they all
>>go out.
>
> Not if it fails shorted.
You must be very young. I remember, oh, about a half-century ago, laying
the Xmas tree lights out on the floor, and if the string didn't light,
we'd take a known good bulb and go down the string swapping out bulbs,
one at a time; if the string didn't light, we'd take the bulb we just
removed from its socket and swap it out with the next one, and so on.
When the string lights up, you'd throw away the bulb that you just
removed/replaced.
Nowadays, they apparently do have low-V bulbs that are designed to fail
short; I'm danged if I know how they accomplish it. :-)
I can guess - one of the filament supports is springy - when the filament
opens, that support springs back, contacting another electrode, shorting
the bulb - but wouldn't that be kinda expensive?
Thanks,
Rich
Posted by Spehro Pefhany on August 14, 2009, 5:16 pm
wrote:
>I can guess - one of the filament supports is springy - when the filament
>opens, that support springs back, contacting another electrode, shorting
>the bulb - but wouldn't that be kinda expensive?
That's not how they work. It's generally a wire-wound shunt across the
filament supports that has enough oxide that it breaks down well below
line voltage (when the lamp fails) but not at the operating voltage of
the lamp (a few volts). Costs next to nothing to wind a few turns of
wire around the filament supports.
>Thanks,
>Rich
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>> On Mon, 10 Aug 2009 22:05:42 -0400, clare@snyder.on.ca wrote:
>>
>>> The 6 amp motor means it draws 6 amps from the mains. It does not mean
>>> ANYTHING as far as how much power it produces, other than that it
>>> cannot produce more than 690 watts at 115 volts
>>
>> Have you returned to constant current power distribution with 6 A
>> circuits ?
>>
>> Arc lamps in the 1880's were specified by the number of amperes
>> (typically 6 A for street lighting). All lamps were series connected
>> and you could operate 20-25 of these in series from a 6 A DC generator
>> producing a 1000-1500 V DC loaded voltage. Thus, the voltage drop
>> across each arc lamp was about 55 V on average.
>>
>> Paul
>>
>That's interesting. How would you strike an arc on series wired arc
>lamps? Seems near impossible...?