LEVEL 3 ENGINEERING PRINCIPLES - AC CIRCUITS INFORMATION AND EQUATIONS Waveform Characteristics Waveform
Characteristics A = amplitude / peak value P2P = peak to peak value T = periodic time (s) f = frequency (Hz) = 1/T O = offset φ = phase angle (degrees / rads)
AC Waveform Average and RMS Values Average
RMS =
Square / Rectangular
2 × Peak Value π
Ave = Peak Value
Saw Tooth
Ave =
Root Mean Square (RMS)
Ave =
Peak Value 2
RMS =
Triangular
Sinusoidal
Waveform
Ave =
Peak Value 2
RMS =
Peak Value √2
RMS = Peak Value
Peak Value √3
Peak Value √3
Reactance and Impedance Equations Subject Capacitative Reactance (Capacitor)
Equation
XC =
Variables and Units
1 2πfC
Inductive Reactance (Inductor)
XL = 2πfL
Passive Resistance - AC (Resistor)
VRMS R= IRMS
XC = capacitative reactance in Ohms (Ω) f = supply frequency in Hertz (Hz) C = capacitance in Farads (F) XL = inductive reactance in Ohms (Ω) L = inductance in Henries (H)
Total Impedance (Resistor and Capacitor in Series)
Total Impedance (Resistor and Inductor in Series)
Total Impedance (Resistor, Capacitor and Inductor in Series)
Z = √X C 2 + R2
ϕ = tan−1 (
−XC ) R
Z = √X L 2 + R2
ϕ = tan−1 (
XL ) R
Z = √(XL − XC )2 + R2 ϕ = tan−1 (
XL − XC ) R
R = resistance in Ohms (Ω) VRMS = root mean square voltage in Volts (V) IRMS = root mean square current in Amps (A) Z = total impedance in Ohms (Ω) φ =phase angle in degrees / radians