chapter 12 three-phase analysis.ppt

Chapter 12 Three-phase Analysis
要求深刻理解与熟练掌握的重点内容有:,对称三相电路。
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要求一般理解与掌握的内容有:
不对称三相电路电压、电流和功率的计算。
难点:对称三相电路分析。
•12-1 Introduction
•12-2 Balanced Three-Phase Voltages
•12-3 Balanced Wye-Wye Connection
•12-4 Balanced Wye-Delta Connection
•12-5 Balanced Delta-Delta Connection
•12-6 Balanced Delta-Wye Connection
•12-8 Unbalanced Three-Phase Systems
•12-11 Summary and Review
•12-7 Power in a Balanced Systems
•12-10 Applications
In this chapter, our specific goals and objectives include
•Learning the distinction between single-phase and polyphase systems
•ing familiar with working with both Y- and △-connected three-phase sources
•ing familiar with working with both Y- and △-works
•Mastering the technique of per-phase analysis of three-phase systems
Introduction
neutral 中线
magnitude 幅值
polyphase 多相(电路)
perpendicular 垂直
aluminum 铝
configuration 形状、构造
stator 定子
rotor 转子
flux 磁通量
alternator 交流发电机
1. single-phase system

a) two-wire type
b) three-wire type


-phase three-wire system
As polyphase, the ac source operate at same frequency but different phase.
Or,equal magnitude and different phase
00
900
- phase four-wire system
Three-phase system are important for at least three reasons.
First,nearly all electric power is generated and distributed in Three-phase.
Second,the instantaneous power in a three-phase system can be constant.(not pulsating)
Third,for the same amount of power ,the three-phase system is more economical than the single-phase.
Balanced three-phase voltages
-subscript nation
The definition of the voltage Vab.
(b) Vad = Vab + Vbc+ Vcd = Vab + Vcd.