Level 3 Engineering Principles - AC Circuits Info and Equations

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