Real Transformers
JKWang 2014
Real transformers
have losses
have leakage flux
have finite permeability of magnetic core
Transformer Equivalent Circuit
1
Real power losses
Laminating the core reduces Eddy-Current Losses
Laminations 0.2 to 1 mm thick at 50/
ECE 5042
Homework #1
Due Fri. September 12
1. Refer to the circuit given below, the parameters and the variables are in per unit (for
simplicity). Vin=10. Draw two phasor diagrams; one phasor diagram should
illustrate the case for angle of I+45, and the o
Power Systems
Section 5:
Power Flow Analysis
Instructor: Jiankang (J.K.) Wang
Course Text: Bergen & Vittal, Power System Analysis, Second Edition (August 16,
1999), Prentice Hall.
References:
[1] Glover, Sarma & Overbye, Power Systems Analysis and Design,
Three Phase Transformers
There are 4 different ways to connect 3f transformers
Y-Y
D-D
JKWang 2014
1
3f Transformer Interconnections
Y-D
JKWang 2014
D-Y
2
Connection of Transformer Windings
(a)
(b)
JKWang 2014
Fig. 6-10 Winding connections in a three-p
ECE 5042
Homework 2
Due by 5pm September 24, Wednesday
1. For the overhead line of configuration shown in Figure 1, operating at 60 Hz, determine
(a) resistance per phase and
(b) inductive reactance in ohm/mile.
The resistance of each conductor in the fou
ECE 5042
Homework #1
Solution
Problem 1
The phasor diagram is as follows (@denotes),
Case 1:
Case 2:
Problem 2
S3=200 + j200tan(cos-10.707)= 200+j200 kVA, after reactive power compensation
we can obtain S3=200+j150 kVA.
Therefore, the resultant power fact
One-Line Diagram
JKWang 2014
Three-Phase Voltages
Fig. 2-11 Three-phase voltages in time and phasor domain.
JKWang 2014
(a)
Balanced 3 Phase () Systems
A balanced 3 phase () system has
three voltage sources with equal magnitude, but with
an angle shift