Chapter 10

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Transcript Chapter 10

Summary of Polyphase
• The first slide gives the definitions for polyphase
• The following 2 slides summarize the Y- and -Y
connections. They are not intended to be memorized.
• How to use them:
– Look at each diagram to decide which voltages (Line voltage and
Phase voltage) are equal and which currents (Line currents and
Phase currents) are equal.
– Those that are not equal are related by either  3 or 1/ 3.
– Use Ohm’s Law to find V from I and Z, or, I from V and Z.
• For phasors: V = I Z or I = V / Z
• For magnitudes only: | V | = | I | * | Z | or | I | = | V | / | Z |
Phase voltage
of the load
Phase current
of the generator
Line current
Phase voltage
of the generator
Line voltage
Phase current
of the load
Y-Delta and Delta-Y
Y-Y and Delta-Delta