Critical Voltages

Which type of voltage stress is not considered for designing the insulation of transmission lines?

• Switching overvoltage
• Lightning overvoltage
• Thermal overvoltage
• All of the above

Which of the following determines the power factor of the insulator?

• Voltage gradient
• Current gradient
• Both voltage and current gradients
• None of the above

What is the critical disruptive voltage gradient of an insulator?

• It is the voltage gradient at which corona occurs
• It is the voltage gradient at which sparkover occurs
• It is the voltage gradient at which breakdown occurs
• None of the above

Which of the following is not a factor affecting the critical disruptive voltage gradient of an insulator?

• Length of the insulator
• Diameter of the insulator
• Shape of the insulator
• Color of the insulator

Which type of voltage stress is higher, the switching overvoltage or the lightning overvoltage?

• Switching overvoltage
• Lightning overvoltage
• Both are the same
• It depends on the system design and operating conditions

Which of the following is not a method to increase the critical disruptive voltage gradient of an insulator?

• Increasing the diameter of the insulator
• Using a longer insulator
• Making the insulator thicker
• Using a smaller insulator

In what way does the corona effect reduce the effective working voltage of a transmission line?

• It produces radio interference
• It causes heating of the line conductor
• It increases the loss in the line
• It reduces the voltage drop across the line