Electrical Apparatus and Safety: Measurement of Voltage and Current
40 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the unit for current?

  • Watts (W)
  • Ohms (Ω)
  • Volts (V)
  • Amps (A) (correct)

    • How should an ammeter be connected in a circuit to measure current?

  • In parallel
  • At the power source
  • In series (correct)
  • Opposite to the load

    • What should be avoided to prevent short-circuit currents in an ammeter?

  • Removing the protective cover
  • Using high resistance
  • Connecting in parallel (correct)
  • Connecting in series

    • What is the unit for voltage?

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

    How should a voltmeter be connected to measure potential difference?

    <p>Between two points at different potentials</p> Signup and view all the answers

    Why is it crucial to always connect a voltmeter in parallel in a circuit?

    <p>To minimize the loading effect and improve accuracy of the reading</p> Signup and view all the answers

    Which type of instrument uses an iron plate that moves in response to the magnetic field of the stationary coil?

    <p>Moving Iron Instrument</p> Signup and view all the answers

    What is the main advantage of a Moving Iron Instrument over other types of instruments?

    <p>Universal use for both AC and DC</p> Signup and view all the answers

    In a repulsion type instrument, why does the moving coil start moving away from the fixed vane?

    <p>Due to force of repulsion between the vanes</p> Signup and view all the answers

    What is a disadvantage of the scale of moving iron instruments?

    <p>Non-uniform scale leading to inaccurate readings</p> Signup and view all the answers

    What is the primary difference between AC and DC calibration of instruments?

    <p>The calibration frequency</p> Signup and view all the answers

    What is the purpose of the fixed coil in the electrodynamometer wattmeter?

    <p>To produce a uniform electric field</p> Signup and view all the answers

    Why is a spring control system used in the electrodynamometer wattmeter?

    <p>To facilitate pointer movement</p> Signup and view all the answers

    What prevents the use of other types of damping in the electrodynamometer wattmeter system?

    <p>Destruction of magnetic flux</p> Signup and view all the answers

    Which factor can create serious errors in a dynamometer wattmeter at low power factors?

    <p>Stray magnetic fields</p> Signup and view all the answers

    What is the material used for designing the moving coil in a PMMC instrument?

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

    Which material is used for the permanent magnets in a PMMC instrument?

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

    What produces the damping torque in a PMMC instrument?

    <p>Eddy Current</p> Signup and view all the answers

    What opposes the deflecting torque in a PMMC instrument at steady-state conditions?

    <p>Control Spring</p> Signup and view all the answers

    Which part of the PMMC instrument indicates the measured current value?

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

    What are some advantages of PMMC instruments?

    <p>Consumes low power</p> Signup and view all the answers

    What does earthing in electrical systems help to protect against?

    <p>Electric shock</p> Signup and view all the answers

    Why is the body of electrical equipment connected to earth instead of the supply neutral?

    <p>Due to limited availability of neutral wire</p> Signup and view all the answers

    What is a method of earthing mentioned in the text?

    <p>Copper wire plate earthing</p> Signup and view all the answers

    What necessity led to the development of electrical earthing?

    <p>Protecting personnel from electric shock</p> Signup and view all the answers

    What is the purpose of the Braking System in an energy meter?

    <p>To reduce the rotation of the aluminium disc</p> Signup and view all the answers

    What material is the core of the electromagnet in the Driving System made of?

    <p>Silicon steel lamination</p> Signup and view all the answers

    Which main part of the energy meter is responsible for recording the number of rotations of the disc?

    <p>Registration (Counting Mechanism)</p> Signup and view all the answers

    What happens to the aluminium disc in the Moving System when power is consumed by the device?

    <p>It starts rotating</p> Signup and view all the answers

    In the context of energy meters, what does PMMC stand for?

    <p>Permanent Magnet Moving Coil</p> Signup and view all the answers

    What is the purpose of embedding the plate in alternate layers of coal and salt for a thickness of 15 cm?

    <p>To decrease the resistance value</p> Signup and view all the answers

    Why is water poured around the earth electrode in plate earthing?

    <p>To increase the efficiency of the earthing system</p> Signup and view all the answers

    What is the benefit of placing the GI iron pipe vertically at a depth of 4.75m in pipe earthing?

    <p>To decrease resistance</p> Signup and view all the answers

    What is one electrical safety precaution mentioned in the text?

    <p>Using insulated tools while working</p> Signup and view all the answers

    What is the danger of working on receptacles with wet hands?

    <p>It increases the conductivity of electric current</p> Signup and view all the answers

    What is recommended to do in case of accidental contact with a live wire?

    <p>Switch off the main switch and provide non-conducting support</p> Signup and view all the answers

    How can the danger of accidental shock be reduced according to the text?

    <p>Properly earthing all electrical appliances</p> Signup and view all the answers

    What is NOT a recommended practice during electrical work based on the text?

    <p>Handle electrical appliances with wet hands</p> Signup and view all the answers

    Why should all electric connections at switches, plugs, sockets, and junctions be tight?

    <p>To prevent electrical accidents</p> Signup and view all the answers

    What should be done immediately in case of short-circuiting or accidental contact with live wires?

    <p>Switch off the main switch and provide non-conducting support</p> Signup and view all the answers

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser