Electrical Engineering: Surge and Lightning Arresters
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Questions and Answers

What is the main function of the horn gap arrester?

  • To ionize the air during a voltage rise
  • To eliminate the need for grounding
  • To provide a physical barrier against lightning
  • To allow fault current to pass through a small air gap (correct)
  • Which arrester operates based on the principles of an electrolytic cell?

  • Horn Gap Arrester
  • Metal Oxide Lightning Arrester
  • Thyrite Lightning Arrester
  • Electrolytic Arrester (correct)
  • What material is the base of the metal oxide lightning arrester?

  • Copper
  • Aluminium
  • Steel
  • Zinc (correct)
  • What must be done to minimize the soil resistivity when installing lightning arresters?

    <p>Add minerals or a backfill compound</p> Signup and view all the answers

    What distinguishes the surge arrester from the lightning arrester?

    <p>The lightning arrester primarily protects from outside surges</p> Signup and view all the answers

    What is defined as an increase in voltage for a very short time in a power system?

    <p>Voltage surge</p> Signup and view all the answers

    Which of the following is NOT a cause of external over voltage?

    <p>Voltage regulation failure</p> Signup and view all the answers

    What potential difference is necessary for a lightning flash to occur between clouds and the ground?

    <p>5 to 20 million volts</p> Signup and view all the answers

    Transient over voltages can be generated at which of the following frequencies?

    <p>High, medium, and low frequency</p> Signup and view all the answers

    Which type of lightning stroke is characterized by a direct hit?

    <p>Direct lightning stroke</p> Signup and view all the answers

    Which of these is a common internal cause of over voltage?

    <p>Load switching</p> Signup and view all the answers

    What type of over voltages arise from atmospheric disturbances primarily due to lightning?

    <p>External over voltages</p> Signup and view all the answers

    Electrostatic induced over voltages can occur due to which of the following phenomena?

    <p>Presence of charged clouds</p> Signup and view all the answers

    What is the primary cause of switching over voltages in a power system?

    <p>Faults in the network</p> Signup and view all the answers

    Which voltage surge is caused when a no load transmission line is suddenly switched on?

    <p>Switching impulse</p> Signup and view all the answers

    What effect does a Ferranti effect have on a long unloaded power line?

    <p>Increases the voltage at the receiving end</p> Signup and view all the answers

    What is a likely consequence of frequent over voltages occurring in a power system?

    <p>Damage to electrical equipment</p> Signup and view all the answers

    What is identified as a transient voltage or voltage surge in a power system?

    <p>Sudden increase in voltage to a high peak</p> Signup and view all the answers

    Which overvoltage protection method is commonly used over electrical substations?

    <p>Earthing screen</p> Signup and view all the answers

    During which operation is over voltage due to current chopping most likely to occur?

    <p>Switching off a loaded line</p> Signup and view all the answers

    What type of overvoltage is most likely to cause substantial damage in a power system?

    <p>Lightning impulse overvoltage</p> Signup and view all the answers

    What characterizes the transient nature of voltage surges?

    <p>Existence for a very short duration</p> Signup and view all the answers

    Why is it important to have protection against abnormal over voltages in a power system?

    <p>To eliminate risk of equipment damage</p> Signup and view all the answers

    What is the primary function of an overhead earth wire in electrical transmission networks?

    <p>To divert lightning strokes to the ground</p> Signup and view all the answers

    How does a lightning arrester function during an overvoltage event?

    <p>It offers a low impedance path for excess charge to ground</p> Signup and view all the answers

    What is a key goal of insulation coordination in electrical power systems?

    <p>To localize insulation failures to easily repairable components</p> Signup and view all the answers

    What type of lightning arrester is currently most commonly used for overvoltage protection?

    <p>Gapless ZnO lightning arrester</p> Signup and view all the answers

    Which of the following best describes the term 'Nominal System Voltage'?

    <p>The phase to phase voltage for equipment design</p> Signup and view all the answers

    What is the primary function of an overhead ground wire?

    <p>To intercept and conduct lightning strikes</p> Signup and view all the answers

    Which material is commonly used for overhead ground wires due to its lightweight and corrosion resistance?

    <p>Aluminium</p> Signup and view all the answers

    Why are ground wires placed as the topmost conductor in high voltage transmission lines?

    <p>To provide protection against lightning strokes</p> Signup and view all the answers

    What is the purpose of grounding the overhead ground wire at substations?

    <p>To dissipate lightning energy safely into the ground</p> Signup and view all the answers

    What action does a lightning arrester take under normal voltage conditions?

    <p>It functions as an electrical insulator</p> Signup and view all the answers

    What is a critical angle for the effective shielding of line conductors by ground wires?

    <p>30°</p> Signup and view all the answers

    What key property must an overhead ground wire possess to minimize voltage stress on phase conductors during a lightning event?

    <p>Sufficient conductivity</p> Signup and view all the answers

    Which of the following describes the behavior of a lightning arrester when voltage levels rise?

    <p>Resistance decreases with voltage</p> Signup and view all the answers

    What is the role of the corona ring installed on an overhead ground wire?

    <p>To reduce radio interference and corona discharge</p> Signup and view all the answers

    What is a characteristic of overhead ground wires in relation to lightning strikes?

    <p>They provide multiple pathways to the ground for lightning strokes</p> Signup and view all the answers

    Which of the following types of lightning arresters involves a gap between the ends of two rods?

    <p>Rod Gap Arrester</p> Signup and view all the answers

    What does the spacing between the overhead ground wire and phase conductors ensure?

    <p>Provides necessary clearance to prevent flashover</p> Signup and view all the answers

    In a lightning arrester, what mechanism is used to discharge high voltage through the ionization of air?

    <p>Corona discharge</p> Signup and view all the answers

    What does the proper installation of overhead ground wires contribute to in power transmission systems?

    <p>Enhanced reliability and safety</p> Signup and view all the answers

    What aspect is NOT considered when determining the size of an overhead ground wire?

    <p>Seasonal weather patterns</p> Signup and view all the answers

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