[Data-modeling] electricity in the commons

[Paul Houle]

Reilly Hayes wrote:
>
> It seems to me that you are trying to model more than types of 
> current.  You are trying to model power-systems.  For example, 
> alternating current used in both single and polyphase (two phase and 
> three phase) power systems.
>
    It can get pretty complicated.  Let's just imagine that we're 
talking about a system that supplies a single "rail" of power (not sure 
I'm using the right vocab here.)  Some obvious parameters for a "Power 
Supply" are:

Alternation: DC, 2-phase AC, 3-phase AC
Voltage: measured in volts (I think this is typically root-mean-square)
Maximum current: measured in amps
Frequency: Hz (cycles per second).  Only relevant for AC,  or always 0 
for DC.

Note that many systems have a power supply that supplies multiple 
"rails" that have different parameters:  tube radios,  for instance,  
have very different power supplies for different uses in the system:   
you need a lot of current to keep filaments hot,  and a lot of voltage 
to charge up the plates:

http://www.antiqueradio.org/bsupply.htm

On the other hand,  the power supply plug that goes to a PC motherboard 
has multiple 'rails' at +- 3.3V,  +- 5.5V, +- 12V.  One of the 5V rails 
stays on when the machine is in standby mode.