Induction Motor Control and Braking Systems
41 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 component is used to minimize the ripples in the D.C output for the induction motor?

  • Thyristor bridge
  • L.C filter (correct)
  • Transformer
  • Slip ring

    • A.C must be left connected while feeding D.C to the stator of the induction motor.

    False

    What is the purpose of the braking thyristor controller in the system?

    To control the dynamic braking of the induction motor.

    The DC output from the thyristor bridge is fed to the _______ of the induction motor.

    <p>stator winding</p> Signup and view all the answers

    Match the components with their functions:

    <p>Thyristor bridge = Rectification of A.C to D.C L.C Filter = Filtering D.C output Dynamic braking controller = Regulating braking torque Slip ring = Variable resistance</p> Signup and view all the answers

    Which of the following statements about the 3-phase slip ring induction motor is correct?

    <p>It has the ability to control rotor resistance.</p> Signup and view all the answers

    What happens to the input A.C voltage when it is fed into the thyristor converter?

    <p>It is stepped down to a lower voltage.</p> Signup and view all the answers

    What is the value of the initial braking current calculated?

    <p>107.44 A</p> Signup and view all the answers

    The thyristor converter must have a higher voltage rating when the input A.C voltage is stepped down.

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

    What is the formula used to calculate the initial braking torque?

    <p>T_p = (3 * I_braking * R) / w</p> Signup and view all the answers

    The speed difference $N_{speed}$ when the speed is 940 r.p.m. is equal to ___ r.p.m.

    <p>60</p> Signup and view all the answers

    Match the following variables with their respective values:

    <p>Pole pairs (P) = 3 Speed (N) = 1000 r.p.m. Initial braking torque (T_p) = 103.04 N-m Angular velocity (w) = 104.72 rad/sec</p> Signup and view all the answers

    What occurs during regenerative braking?

    <p>The induction motor operates as a generator</p> Signup and view all the answers

    During rheostatic braking, the stator winding is connected to an AC supply.

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

    What happens when the rotor speed falls to synchronous speed during regenerative braking?

    <p>Regenerative braking comes to an end.</p> Signup and view all the answers

    Rheostatic braking involves disconnecting the _____ winding from the AC supply.

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

    Match the braking methods with their descriptions:

    <p>Rheostatic braking = Uses a DC source for stator winding Regenerative braking = Rotor runs above synchronous speed Dynamic braking = Involves controlling speed through resistors Mechanical braking = Involves physical friction to slow down</p> Signup and view all the answers

    What is the relationship between rotor speed and synchronous speed during regenerative braking?

    <p>The rotor speed must be greater than synchronous speed</p> Signup and view all the answers

    The power returned to the supply during regenerative braking is constant, regardless of rotor speed.

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

    What does negative slip indicate in the context of an induction machine?

    <p>The induction machine operates as an induction generator.</p> Signup and view all the answers

    During regenerative braking, when the load forces the motor to run above synchronous speed, it is in the _____ quadrant.

    <p>2nd</p> Signup and view all the answers

    Which statement describes a benefit of using a current source inverter (CSI) over a voltage source inverter (VSI)?

    <p>CSIs have inherently better protection against short circuits.</p> Signup and view all the answers

    CSIs have a wider speed range compared to VSIs.

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

    What is the main reason the torque-slip relationship of a 3-phase induction motor needs to maintain constant air-gap flux?

    <p>To provide high torque throughout the control range.</p> Signup and view all the answers

    The ______ provides the rated motor torque and speed for an induction motor running at 1200 rpm.

    <p>inverter frequency</p> Signup and view all the answers

    Match the following components with their primary characteristics:

    <p>CSI = Higher cost and weight VSI = Can feed multiple motors in parallel Induction Motor = Operates on slip speed Torque-slip relationship = Maintains torque when flux is constant</p> Signup and view all the answers

    At what frequency is the motor operating when determining stator current and torque for rated slip speed?

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

    A single CSI can be used to feed multiple motors in parallel.

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

    What is the rated stator voltage for the Y-connected squirrel cage induction motor described?

    <p>400V</p> Signup and view all the answers

    The induction motor operates at a speed of ______ when powered with 50 Hz.

    <p>1370 rpm</p> Signup and view all the answers

    Which of the following is a consequence of using a large inductance in the DC link for CSI drives?

    <p>Higher cost and weight</p> Signup and view all the answers

    What is the total equivalent impedance (Z) of the induction motor?

    <p>24.7463 + j20.3543</p> Signup and view all the answers

    The stator current at full load is 7.21 A.

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

    What is the synchronous speed of the motor at 30 Hz?

    <p>900 r.p.m.</p> Signup and view all the answers

    The full load torque, T, of the induction motor is ______ N-m.

    <p>22.73</p> Signup and view all the answers

    Match the following components with their values:

    <p>Full Load Stator Current = 7.21 A Full Load Rotor Current = 5.865 A Full Load Torque = 22.73 N-m Slip Speed = 130 r.p.m.</p> Signup and view all the answers

    What is the full load rotor current of the induction motor?

    <p>5.865 A</p> Signup and view all the answers

    The motor speed is 770 r.p.m. when the synchronous speed is 900 r.p.m.

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

    What does the variable 's' refer to in the context of induction motors?

    <p>Slip speed</p> Signup and view all the answers

    The equation for the total equivalent impedance Z includes R and ______ components.

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

    What is the formula to calculate synchronous speed in RPM for an induction motor?

    <p>$N_s = 120f/P$</p> Signup and view all the answers

    Study Notes

    Topic: Electrical Drives

    • Electrical drives convert electrical energy to mechanical energy. They are used to control the motion of machinery.

    Topic: Components of Electrical Drives

    • Load: The equipment or mechanism being driven.
    • Motor: The source of mechanical power.
    • Power modulator: Adjusts the power flow to the motor.
    • Control unit: Controls the power modulator to adjust the motor speed.
    • Source: The electrical supply source.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Electric Drive Braking Methods PDF

    Description

    This quiz covers key concepts related to the control and braking systems of induction motors. It includes questions on components like thyristor converters, braking current calculations, and the functions of various motor parts. Test your understanding of these essential topics for effective motor operation.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser