Quiz II PS-I

The over-voltage surges in power system may be caused by

• Lightning

• Resonance

• Switching

• All of these

The protection against direct lightning strokes and high voltage steep waves is provided by

• Ground wire

• Lightning arresters

• Lightning arresters and ground wires 

• Earthing of neutral

Lighting arresters are used in power system to protect electrical equipment against

• Direct stokes of lightning

• Over-voltages due to indirect lightning stroke

• Power frequency Over-voltages

• Over-currents due to lightning

Surge absorbers are used for protection against

• High voltage low frequency oscillations

• High voltage high frequency oscillations

• Low voltage high frequency oscillations

• Low voltage low frequency oscillations

Surge absorber ____________  the energy of travelling waves

• Absorbs

• Reflects

• Diverts

• Partly absorbs and partly doverts

The method of neutral grounding affects the

• Positive-sequence network

• Negative-sequence network

• Zero-sequence network

• Both Positive- and Zero-sequence network

Switching over-voltages are more hazardous than lightning surges in case of 

• Low voltage system

• 33 kV system

• EHV and UHV systems

• All of these

For protection of rotating machines against lightning surges  ___________  is used.

• Lightning arrester.

• Capacitor

• Combination of lightning arrester and capacitor

• Lightning conductor and arrester

Which of the following is the protective device against lightning over-voltages?

• Rod gaps

• Surge absorbers

• Horn gaps

• All of the above

Overhead ground wires are used to protect a transmission line against

• Line-to-ground faults

• Arcing earths

• Voltage surges due to direct lightning stroke

• High voltage oscillations due to switching