Topic 2 phasors topic a2

Bài giảng ngành Điện: Giải các bài toán trong mạch điện điện thế thấp một pha và ba pha (Phần A) gồm các chủ đề sau Solve problems in single and threephase low voltage circuits Part A Content Topic 1 Sinusoidal Alternating Voltage and Current_Topic_A1 Topic 2 Phasors_Topic_A2.ppt Topic 3 Resistance in AC Circuits_Topic_A3 Topic 4 Inductance in AC Circuits_Topic_A4 Topic 5 Capacitance in AC Circuits_Topic_A5 Topic 6 AC Circuit Analysis_Topic_A6 Topic 7 Resonance_Topic_A7 Topic 9 Harmonics_Topic_B9

Solve problems in single and

three-phase low voltage circuits

Part A

Topic 2: Phasors

Review

understanding of AC waveforms, including:

Phasor Diagrams

representing the values and relationships of multiple waveforms without needing to draw

a waveform diagram.

(phasors) to represent a particular waveform, with the length of the line dictated by the

value of the waveform.

Phasor Diagrams–Reference

Waveform

Position: 00EPosition: 00E

Phasor diagram representationWaveform diagram representation

Phasor Diagrams–Reference

Waveform

Position: 900E

900E

Phasor Diagrams–Reference

Waveform

Position: 2700E

2700E

3600EOne cycle completed

Phasor Diagrams

direction around the centre point.

addition eg Voltage phasors

Phasor Diagrams-Multiple Waveforms

In-Phase RelationshipPhase angle 00E

Phasor diagram representation

VA

VB

VA

VB

Phasor Diagrams-Multiple Waveforms

Phasor Diagrams-Multiple Waveforms

Conversion of Waveform Diagrams to Phasor Diagrams

waveform

Conversion of Waveform Diagrams to Phasor Diagrams

separate sheet.

Phasor Addition

Head-to-Tail Method

Phasor Addition

vectorily using phasor addition.

more phasors of a scaled phasor diagram are combined to produce a resultant phasor.

normally the “Head-to-Tail” method

Phasor Addition: In-Phase Phasors

Phase angle Ø

Phasor Addition:Out-of-Phase LEAD

Phase angle Ø

Phasor Addition: Exercises

previously to determine the resultant phasor value and phase angle for each question.

Conversion of Waveform Diagrams to Phasor Diagrams

V2 = 310V

V = 415V VRes = 590V

Ø = 42 deg lag

Phasor Addition: Exercises

Phasor Addition: Prac

utilize this information to draw phasor diagrams and determine the resultant phasor for each circuit – compare this resultant

value with the RMS voltage measured by the multimeter across BOTH components.

Phasor Addition

Determining the Reference Phasor

Phasor Addition: Determining the

Reference Phasor

circuit, and a PARALLEL circuit.

component, yet the voltage drops may vary Therefore, CURRENT is the reference phasor for a series circuit (with all

of the voltage drops oriented to this phasor).

component, yet the branch currents may vary Therefore, VOLTAGE is the reference phasor for a parallel circuit (with all branch currents oriented to this phasor)

Phasor Addition:Exercises

VA=116V phase)

(in-VB=210V lead

by 900E

VSƒ

IB=18A lag by 550E

IA=20A (in-phase)

VSƒ

IS

IS

Phasor Addition:Exercises

VA=80V phase

in-VB=200V lead

by 300E

VSƒQ3 Determine the supply voltage and phase angle

VC=140V lag

by 900E

IS

Phasor Addition: Answers to Exercises

 VS = 256V at 90E Lag the reference

understanding of using phasors to represent

AC waveforms, including:

phasors; and

resultant phasor.