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

[Jim Becker]

Meanwhile, I have heard that 50 to 60 cycles is the optimum if you want to cause fibrillation.

My parent’s house, built in 1950, was wired with fuses rather than circuit breakers.  So the changeover was something after that.

If you go back 100 years or so, they wired houses with fuses on both sides of each circuit.  Eventually somebody realized that if the neutral fuse blew, you then had a non-functioning circuit that was still energized.  That probably was an unpleasant surprise for a lot of people before they realized it wasn’t a good idea to fuse the neutral.

Jim Becker

From: Stephen Offiler 
Sent: Saturday, December 21, 2019 7:10 AM
To: Antique Tractor Email Discussion Group 
Subject: Re: [AT] [OT] Has anyone seen one of these??

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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