[AT] [OT] Has anyone seen one of these??

[Stephen Offiler]

I'll admit I had no idea there was ever much of a DC grid, beyond the
earliest of early days when Edison supported DC and Tesla supported AC and
electric power was an untamed frontier.

Carl's comment about working with AC vs DC might refer to the workings of
the appliance.  Agreed, generally, volts times amps equals watts and it
doesn't matter AC vs DC.  That is 100% true for resistive loads like
lightbulbs.  It is not quite true for inductive loads like motors, but OK
as a first-pass approximation.

The major difference with having DC around is safety.  If you get zapped by
120VAC, the reversing polarity means crossing thru 0 volts 120 times per
second, which tends to kick you away.  DC does not reverse, and the steady
voltage tends to lock up your nervous system and kill you.  Back in the
early days, conductor insulation was not exactly up to modern standards,
nor was there much in the way of safety watchdogs like Underwriter's Labs
etc., so electric shock was more of a threat.

Steve O.


On Fri, Dec 20, 2019 at 4:37 PM <szabelski at wildblue.net> wrote:

> Working with a 115VDC system would be no different than working with a
> 120VAC system. You house has a 100A or 200A  service, that doesn’t mean you
> can draw that current at every wall plug. Your breakers would limit the
> current and trip if you try to pull more than rated.
>
> I would guess that a house back in the day of 115VDC had a standard series
> of four cell fuse blocks with 2, 3, 5, 10, and maybe a couple of 15A fuses.
> When I was a kid in Detroit, our house had such a set up for our old 80A
> 120VAC house service (it was mounted on the back porch, outside, but
> sheltered from the weather.). Fuses were still in use up to the 40’s - 50’s.
>
> Carl
> ----- Original Message -----
> From: szabelski at wildblue.net
> To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
> Sent: Fri, 20 Dec 2019 16:05:51 -0500 (EST)
> Subject: Re: [AT] [OT] Has anyone seen one of these??
>
> Cecil, this would only be about 5 to 6 amps at 115VDC. If you want it to
> run, you’ll have to put 10 car batteries in series to get it to do so.
>
> Putting 10 car batteries in series could give you a potential DC current
> equal to about the current from the weakest battery.
>
> Batteries add voltage when in series, and maintain the current rating of
> one individual battery. Batteries in parallel maintain the voltage level of
> one individual battery, and the current add together.
>
> On the Abrams we used a series-parallel combination of six 12V, 100 AH,
> batteries to get a battery system rated at 24 VDC and 300 AH. Three sets of
> 2 batteries in series, connected in parallel.
>
>
>     Carl
>
>
> ----- Original Message -----
> From: Cecil Bearden <crbearden at copper.net>
> To: at at lists.antique-tractor.com
> Sent: Fri, 20 Dec 2019 09:42:32 -0500 (EST)
> Subject: Re: [AT] [OT] Has anyone seen one of these??
>
> OK, this is old, I have found ads dating back to 1912 showing this.  It
> is an old shop vacuum.  When it was mounted on casters it was used in
> the home.  US radiator corp owned the invincible vacuum mfg co.  I don't
> know if I can use it for cleaning out the tractor cab, the motor states
> 3/4 hp on the nameplate.  It also mentions DC, so I have to inspect when
> I get it this afternoon. 115 V on D.C would knock you into the next
> room....   My wife wants to turn it into a table lamp....    I am more
> of a purist, I want to see it work....
>
> Cecil
>
>
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