Question

A 10 kVA, 2000 / 100V transformer has R1=1.5 ohm,

R2=0.005 ohm, X1=2.5 ohm and X2=0.08 ohm. The equivalent resistance
referred to secondary winding is
a.
0.875 ohm
b.
0.0875 ohm
c.
0.00875 Ohm
d.
0.01

Answer 1

The equivalent resistance referred to the secondary winding (R_eq2) is approximately 0.01 ohm (option d).

Step-by-step explanation:

To find the equivalent resistance referred to the secondary winding, we can use the concept of impedance transformation in transformers. The equivalent resistance referred to the secondary winding (R_eq2) can be calculated as follows:

R_eq2 = R2 + (R1 * (V2 / V1))^2

Where:

R2 = Secondary winding resistance (0.005 ohm)

R1 = Primary winding resistance (1.5 ohm)

V2 = Secondary winding voltage (100V)

V1 = Primary winding voltage (2000V)

Let's plug in the values and calculate:

R_eq2 = 0.005 + (1.5 * (100 / 2000))^2

R_eq2 = 0.005 + (1.5 * 0.05)^2

R_eq2 = 0.005 + (0.075)^2

R_eq2 = 0.005 + 0.005625

R_eq2 = 0.010625 ohm

Now, let's check the answer choices:

a. 0.875 ohm - Not the correct answer.

b. 0.0875 ohm - Not the correct answer.

c. 0.00875 ohm - Not the correct answer.

d. 0.01 ohm - This is the correct answer.

The equivalent resistance referred to the secondary winding (R_eq2) is approximately 0.01 ohm (option d).