Question

A long transmission line is energized at the sending end but kept open circuited at the receiving end. If the sending end voltage is \(100\ \text{kV}\), the receiving end voltage is likely to be

• A. \(90\ \text{kV}\)
• B. \(100\ \text{kV}\)
• C. \(105\ \text{kV}\)
• D. \(0\ \text{kV}\)

Hint:

Ferranti effect occurs in long transmission lines under no-load or light-load condition, causing receiving end voltage to rise.

Answer 1

The Correct Option is C

Concept: In a long transmission line, the receiving end voltage may become greater than the sending end voltage under no-load or light-load condition. This is called Ferranti effect.

Step 1: The line is open circuited at the receiving end.

Step 2: Under no-load condition, line charging current flows due to line capacitance.

Step 3: This charging current causes a voltage rise at the receiving end.

Step 4: Therefore, the receiving end voltage becomes greater than the sending end voltage.

Step 5: Since sending end voltage is: \[ 100\ \text{kV} \] the receiving end voltage may be slightly higher, such as: \[ 105\ \text{kV} \] Therefore: \[ \boxed{105\ \text{kV}} \]