Electrical Engineering: Cables and Protection Systems
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Questions and Answers

What is the primary purpose of a voltage stabilizer?

  • To maintain a stable output voltage (correct)
  • To increase voltage levels
  • To automate the control of electrical systems
  • To measure electrical consumption
  • Which property of cables is most critical for ensuring safety in high-temperature environments?

  • Current carrying capacity
  • Flexibility
  • Fire resistance (correct)
  • Cost-effectiveness
  • What factor is NOT essential when selecting cables for specific applications?

  • Conductor size
  • Current carrying capacity
  • Voltage rating
  • Color of the insulation (correct)
  • What characteristic makes copper conductors preferable over aluminum in most applications?

    <p>Better conductivity (C)</p> Signup and view all the answers

    Which type of insulation material is best suited for environments with frequent bending?

    <p>Rubber (D)</p> Signup and view all the answers

    What is the primary purpose of insulation in electrical wiring?

    <p>To prevent electrical leakage and ensure safety (B)</p> Signup and view all the answers

    Which component serves as a central distribution point for incoming power in an LT system?

    <p>Main Distribution Board (A)</p> Signup and view all the answers

    What type of switch is specifically designed to disconnect a circuit for maintenance or safety?

    <p>Isolator (B)</p> Signup and view all the answers

    Which of the following circuit protection devices automatically trips in case of overcurrent?

    <p>Moulded Case Circuit Breaker (MCCB) (D)</p> Signup and view all the answers

    What is the purpose of earth electrodes in an earthing system?

    <p>To provide a low-resistance path to the ground (C)</p> Signup and view all the answers

    Which conductor type is most suitable for applications subject to movement or vibration?

    <p>Stranded conductors (D)</p> Signup and view all the answers

    What feature should be considered for wires that will be exposed to outdoor conditions?

    <p>UV resistance (D)</p> Signup and view all the answers

    Which configuration would a Normally Open (NO) switch have when at rest?

    <p>Contacts are open (B)</p> Signup and view all the answers

    What is the primary purpose of a distribution box in an electrical system?

    <p>To serve as a central point for distributing electrical power (A)</p> Signup and view all the answers

    Which factor is crucial when selecting a switch for handling a specific electrical load?

    <p>Current rating (B)</p> Signup and view all the answers

    What should be considered when selecting a distribution box for current demand?

    <p>The current rating in amperes (C)</p> Signup and view all the answers

    Which type of metering system is best for real-time power measurements?

    <p>Smart Meters (B)</p> Signup and view all the answers

    Which enclosure type is most suitable for industrial applications?

    <p>Metal Enclosure (D)</p> Signup and view all the answers

    What defines Time-of-Use (TOU) rates in electricity pricing?

    <p>Rates that change based on time of day (D)</p> Signup and view all the answers

    What is a primary consideration in evaluating a metering system's accuracy?

    <p>The level of precision required (A)</p> Signup and view all the answers

    What is the primary purpose of a fuse in an electrical circuit?

    <p>To protect against overcurrent conditions (B)</p> Signup and view all the answers

    Which characteristic defines a fast-blow fuse?

    <p>It quickly interrupts the circuit during short-duration over currents (D)</p> Signup and view all the answers

    What disadvantage is associated with fuses?

    <p>They need regular replacement after blowing (D)</p> Signup and view all the answers

    What does the breaking capacity of a fuse indicate?

    <p>The maximum current it can interrupt safely (C)</p> Signup and view all the answers

    What is the role of the fuse holder in an electrical system?

    <p>To secure the fuse and ensure electrical contact (A)</p> Signup and view all the answers

    What type of trip mechanism does a Miniature Circuit Breaker (MCB) use to respond to sustained over currents?

    <p>Thermal trip (C)</p> Signup and view all the answers

    Which voltage rating is NOT commonly associated with MCBs?

    <p>690V (C)</p> Signup and view all the answers

    What feature do some MCBs have that indicates the breaker has reached the end of its operational life?

    <p>End-of-Life (EOL) feature (B)</p> Signup and view all the answers

    What is the primary function of the arc chute in a Miniature Circuit Breaker (MCB)?

    <p>To extinguish electric arcs (B)</p> Signup and view all the answers

    Which statement correctly describes the breaking capacity of an MCCB?

    <p>It is the maximum fault current that the MCCB can interrupt safely (D)</p> Signup and view all the answers

    What is the primary purpose of an ELCB?

    <p>To detect and disconnect electrical circuits from leakage currents (B)</p> Signup and view all the answers

    Which type of ELCB operates by sensing an imbalance in current flowing through the live conductor?

    <p>Current-Operated ELCB (C)</p> Signup and view all the answers

    What feature of ELCBs ensures quick detection and disconnection of leakage current?

    <p>Sensitivity to leakage currents (A)</p> Signup and view all the answers

    How do inverse time characteristics influence tripping time of protective devices?

    <p>Tripping time decreases as current magnitude increases (A)</p> Signup and view all the answers

    What is indicated by the steepness of the slope on an inverse time characteristic curve?

    <p>The degree of the inverse relationship between current and tripping time (A)</p> Signup and view all the answers

    What is the main function of a contactor in an electrical system?

    <p>To switch an electrical circuit on or off (A)</p> Signup and view all the answers

    Which component of a contactor generates a magnetic field when energized?

    <p>Coil (A)</p> Signup and view all the answers

    What distinguishes an isolator from a contactor?

    <p>Isolators provide a visible break in the circuit. (C)</p> Signup and view all the answers

    Which feature is included in some isolators to enhance operational safety during maintenance?

    <p>Lockout/tagout provision (D)</p> Signup and view all the answers

    Which characteristic of contactors is essential for protecting against excessive current?

    <p>Overload protection (A)</p> Signup and view all the answers

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