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Useful Formulas
Ohm’s Law:
V = I x R
I = V ÷ R
R = V ÷ I
Single-Phase AC Power:
P (watts) = V (volts) x I (amps) x Power Factor
Three-Phase AC Power:
P3∅ (watts) = V (volts) x I (amps) x Power Factor x 1.732
Power Factor:
PF = cosine (phase angle)
PF = Power (watts) ÷ [ V (volts) x I (amps)]
PF = Real Power (watts) ÷ Apparent Power (VA)
Apparent Power:
Apparent Power (VA) = V (volts) x I (amps)
Peak Voltage:
Vpeak = Vrms x 1.414
RMS Voltage:
Vrms = Vpeak x 0.7071
Inductive Reactance:
XL (ohms) = 2 x π x ƒ x L
where XL is the inductive reactance, π is pi (3.14), ƒ is the frequency in hertz, and L is the inductance in henrys
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