Introduction to AC Circuits

Question 1

What is the main advantage of Ac systems over dc systems

Answer 1

Voltage levels can be changed with transformers to reduce transmission losses

Question 2

What do 3ph ac power systems consist of

Answer 2

3ph ac generators
3ph transmission lines
3ph loads

Question 3

What are some advantages of having 3ph power systems over 1ph ones

Answer 3

more power per KG from a 3ph machine
power delivered by 3ph is constant instead of pulsating
3ph systems also make this use of inducton motor easier by allowing them to start without special auxiliary starting windings.

Question 4

What does a 3ph generator consist of

Answer 4

3 1ph generator with offset phases by 120 degrees

Question 5

What are the three things in a balanced power system

Answer 5

Three generators have same voltage magnitude and phase difference is 120degrees
Three loads are equal and magnitude and angle
Neutral is actaully unnecessary and we could get away with three wires instead of six

Question 6

Phase quantites

Answer 6

voltages and currents in a given phase ( Van Vbn Vcn)

Question 7

Line Quantities

Answer 7

Voltages between lines and current in the lines (Vab, Vbc, Vca)