Level 3 Engineering Principles - AC Circuits Info and Equations

Sinusoidal
Square / Rectangular
Saw Tooth
Triangular
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
Waveform Average Root Mean Square
(RMS)
Ave = 2 × Peak Value RMS
π
Peak Value
=
√2
Ave = Peak Value
RMS = Peak Value
Ave =
Peak Value
2
Peak Value
RMS =
√3
Ave =
Peak Value
2
Peak Value
RMS =
√3

Reactance and Impedance Equations
Subject Equation Variables and Units
Capacitative Reactance
(Capacitor)
X C = 1
2πfC
Inductive Reactance
(Inductor)
X L = 2πfL
XC = capacitative reactance
in Ohms (Ω)
f = supply frequency in
Hertz (Hz)
C = capacitance in Farads (F)
Passive Resistance - AC
(Resistor)
Total Impedance
(Resistor and Capacitor
in Series)
Total Impedance
(Resistor and Inductor
in Series)
R = V RMS
I RMS
Z = √X C 2 + R 2
ϕ = tan −1 ( −X C
R )
Z = √X L 2 + R 2
ϕ = tan −1 ( X L
R )
XL = inductive reactance
in Ohms (Ω)
L = inductance in Henries (H)
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
Total Impedance
(Resistor, Capacitor
and Inductor in Series)
Z = √(X L − X C ) 2 + R 2
ϕ = tan −1 ( X L − X C
)
R