Tutorial
Transformers
Problem!
R1 + jX1
+
!
V1
!
I1
Rc
Iex
jXm
N1 N2 R 2 + jX2
+
!
E1
-
Primary
Ideal
+
!
E2
!
I2
-
+
!
V2
-
Secondary
A 150kVa 2400/240-V transformer has the following parameters: R1=0.2W, R2=0.002W, X1=0.45W, X2=0.0045W,
Rc=10kW, and Xm=1550W, where these parameters are taken from the exact equivalent circuit of a transformer.
a. Draw the circuit with all the parameters referred to the primary.
b. From this circuit, calculate the voltage regulation of the transformer at rated load with a 0.8 leading
power factor.
c. What will the input current and total power dissipation if 240V is applied to the secondary and the
primary is unloaded? (Input current is secondary current)
d. What is the required primary voltage for rated current to flow in the primary when the secondary is
short circuited? What is the total power dissipated?
Solution for a
Solution for b
Solution for c
Solution for d