Question

A 25 KVA and 11 kV generator on this base per
unit impedance value is 0.25 W for a new base
50 KVA and 3 kV find new per unit impedance
value
Option 1:
0.382 PU
Option 2:
7.25 PU
Option 3
1.399 PU
Option 4:​

Answer 1

Answer:

ok

Step-by-step explanation:

Graphical

H. It refers to the use of tables, graphs, and information maps to visually

Representation

display and interpret vital data.

Answer 2

None of these.

Concept:

The transformer converts power from one circuit to another circuit. This is accomplished using electromagnetic induction. It's called a voltage converter because it can convert high voltage to low voltage and vice versa. A transformer's impedance is the overall resistance it provides to alternating electricity.

Given:

$V_{base(old)}= 11KV\\S_{base(old)} = 25KVA\\R_{old} = 0.25\\V_{base(new)}= 3KV\\\\S_{base(new)} = 50KVA$

Find:

The value of the impedance $R_{new}$.

Solution:

The value of resistance $R = R_{old}*\frac{V^2_{base(old)}}{S_{base(old)}}$.

$R = 0.25*\frac{(11kv)^2}{25KVA}} \\\\R = 1.21k \Omega$

The value of new impedance is

$R_{new} = \frac{R}{\frac{V^2_{base(new)}}{S_{base(new)}} } \\\\R_{new} = \frac{1.21k}{\frac{(3kV)^2}{50KVA}} \\\\R_{new} = \frac{1.21*50}{9} \\\\R_{new} = 6.72$

Hence, the value of the new impedance is $6.72$.