[GreenKeys] Secret DC Basement in NYC - Great History

Wed May 13 00:29:32 EDT 2015

     DC power in the NYC area was a remnant of Edison.  His first power 
systems were DC and they remained until fairly recently.  DC is good for 
traction motors and some other uses but inferior in other ways.  Many 
ships had DC power and radio equipment used motor-generators to produce 
AC   There were some radio sets made for AC and DC.  In a few cases this 
was to save the cost of a transformer but also to permit them to be used 
where only DC power was available.  I don't know what cities in addition 
to NYC had DC power.
      Note that beside 60Hz AC there was also 50Hz and 25Hz used in the 
US.  50Hz was quite common but I think 25Hz was not supplied to homes 
here.  It was in Canada and I remember the flickering lights in Niagra 
Falls when I was there with my parents many years ago. 25Hz was used for 
traction motors and is still (I believe) in use for the electrified 
railway of the Pennsylvania RR.  In Los Angeles the city had 60Hz power 
but Burbank and Glendale had 50 Hz until the 1950s.  Stores had to carry 
electric clocks for both types.  When the local power companies wanted 
to get on a regional grid they had to adopt 60Hz power.

On 5/12/2015 6:40 PM, Bruce Gentry wrote:
> I have read about ships using 100-120 volts DC for radio equipment,
> motor generators or dynamotors provided high voltage for the
> transmitters. Supposedly this was to allow  for easy battery backup.
> I think the power on Liberty ships was all DC, I don't know about
> destroyers or escort carriers. The Titanic was DC, the Queen Mary was
> as well, probably still using some or all of the DC system until the
> ship was taken out of service.  The utility here in Syracuse provided
> DC from a central power station until 1953. They had to install
> hundreds of motor generator sets for elevators and theatrical arc
> lamps throughout the city, I believe I shut off and tore out  the last
> one  powering an elevator  in the city in the late 1990s.  There are
> still hundreds of elevators in Syracuse  that use MG sets powered by
> the AC line for variable voltage control. Because of the strong third
> harmonics typical single phase computer switching power supplies
> generate in a 3 phase four wire power system, there are a growing
> number of buildings or even neighborhoods where modern DC substations
> are once again becoming common. It is fairly easy to convert three
> phase AC to DC efficiently in one local substation to operate massive
> numbers of computers while generating very little third harmonic
> energy.  A surprising number of computers can be connected to 320-380
> volts DC with only minor  modifications because their switching power
> supplies already produce that voltage by rectifying and/or doubling
> the peak power line voltage.
>
>
>      Bruce Gentry, KA2IVY
>
> On 5/12/15 4:53 PM, David Christ wrote:
>> Someone else on the list should be able to confirm this, but ships
>> during and prior to WW II and even more recently ran on DC (220 V?).
>> The high voltage for the tubes was provided by motor generator sets.
>> And of course many of us recall the dynamotors used in many mobile
>> two-way radios used by police and taxis.
>>
>> David K0LUM
>>
>>
>> On May 12, 2015, at 2:31 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:
>>
>>> If you lived in a DC powered area of a city it was hard to build a ham
>>> transmitter of any power because you needed a motor-generator set to
>>> develop the high voltage DC for the amplifier tubes.
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-- 
Richard Knoppow
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WB6KBL