 ## Basic Formula Table Electrikgrid Website

Revised 05/2014, J Allen

/=divided by *=multiplied by sq root=square root of…
NERC Area Control Error:
ACE= (NIa-NIs)-10β(Fa-Fs)-Ime
Single phase kVA= kV * amps, Single phase kW= kV*amps * power factor
3 phase kVA= kV*amps*1.73 3 phase kW= kV*amps*power factor*1.73
Total kVA for three banked identically rated 1 phase transformers= 3*kVA of a single transformer
Maximum amps= (kVA rating of equipment)/ (kV*1.73)
Maximum transformer short circuit amps= (transformer maximum amp rating/% Z)*100
Regulator maximum amps=(nameplate kVA of regulator)/(kV*1.73*% regulation in decimal format)
Conversion 120 VAC secondary to primary kV:
For phase to ground potential: primary volts= secondary phase to ground volts PT ratio*1.73
For phase to phase potential: primary volts= metering phase to phase volts* PT ratio
RPM for 60 Hz= (frequency in Hertz*120)/poles

Basic electricity:
E/R when I=amps, E=volts, R=Ohms resistance
Hydroelectric highlights
1 hp= 746 watts= 0.746 kW= 33000 ft/lbs per minute
1 acre foot (AF) = 43,560 cubic feet
cubic feet per second * hours*0.0826= AF for given period
1 cubic foot per second (CFS) for 24 hours = 1.98 AF
kW= (CFS*head in feet*efficiency in decimal)/11.8
1 foot head= 0.4335 psig
Water flow through an orifice= coefficient*opening in square feet*[sq. root (64.4*head in feet)]
1 gallon= 231 cubic inches= 0.13368 cubic feet= weight of 8.33 lbs
Fundamental trigonometric relationships
Sin (sine)= opposite/hypotenuse; cos (cosine)= adjacent/hypotenuse; tan (tangent)= opposite/adjacent; c2=a2 + b2 MVAR= sq root(MVA2-MW2)
amps/volts)= phase angle difference  Other:
Inches*0.0254= meters; miles*1.609= kilometers; liters*0.2642= gallons; 1 inch Hg= 0.491 psi; watts=btu/min*17.57; kilometers*0.621=miles;
F= (9/5*C)+32 C= 5/9(F-32)

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