[buug] BUUG 2007-10-04 NEMA (e.g. L6-30R, etc.)

[Michael Paoli]

BUUG 2007-10-04 NEMA (e.g. L6-30R, etc.)

I think it was the 2007-10-04 BUUG meeting we had some discussions on
various NEMA plugs/receptacles, and power, etc. (e.g. for larger UPSs).

Wikipedia has some quite good information, e.g.:
http://en.wikipedia.org/wiki/NEMA_connector
and there are some nice good reference links from there, which have,
e.g. some fairly concise array displays of types of connectors, e.g.:
http://www.nooutage.com/nema_configurations.htm

Note also that the NEMA voltage and current ratings are the RMS
maximums.  E.g. L6-30 is very commonly 208V rather than 240V or 250V.

208V is 2 legs of 3 phase:

c^2=a^2+b^2-2a*b*cos(120 degrees)
we'll start with unit (a=1, b=1), and multiply by 120 a bit later
c=(a^2+b^2-2a*b*cos(120 degrees))^0.5
and now dropping in the 120 factor:
120*(a^2+b^2-2a*b*cos(120 degrees))^0.5
120*(1+1-2*c(1/3*8*a(1)))^0.5
120*(2-2*c(8/3*a(1)))^0.5
120*e(0.5*l(2-2*c(8/3*a(1))))
207.84609690826527521880
208 (when rounded to the nearest unit)

references:
http://en.wikipedia.org/wiki/NEMA_connector
http://www.nooutage.com/nema_configurations.htm
http://en.wikipedia.org/wiki/Three-phase_electric_power
bc(1)