Question

A transformer rated for 500 kva,11kv/0.4 kv has an impedance of 10 % and is connected to an infinite bar .The fault level of th transformer is

Answer 1

Answer:

The fault level of transformer is 7216.87 K A .

Explanation:

Given as :

The rating of transformer = Base KVA = 500 KVA

The transformer is $\dfrac{11 KV}{0.4 KV}$

The impedance x = 10 %

Let The fault level of transformer = y

According to question

fault KVA = $\dfrac{\textrm Base KVA}{Impedance}$

i.e Fault KVA = $\dfrac{500}{0.1}$

Or, Fault KVA = 5000

Again

Fault level = $\dfrac{\textrm Fault KVA}{\sqrt{3}\times secondary voltage}$

Or, y = $\frac{5000}{1.732\times 0.4}$

∴ y =  7216.87 K A

So, The fault level of transformer = y = 7216.87 K A

Hence, The fault level of transformer is 7216.87 K A . Answer