Industrial Motor Control
7th Edition
ISBN: 9781133691808
Author: Stephen Herman
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Concept explainers
Question
Chapter 38, Problem 1RQ
To determine
The reason for the why it is desirable to disconnect the autotransformer from the circuit when the motor reaches the run state.
Expert Solution & Answer
Explanation of Solution
Consider the autotransformers are used in the starting of the squirrel cage induction motor. The autotransformer reduces the voltage that is applied to the motor to reduce the inrush current at the starting.
As the motor reaches 75% of the normal speed the motor is in the run stage.
As the rotor reach the run stage of the normal speed is applied the full voltage.
After the run stage autotransformer to supply the full load voltage is the waste of energy as the same voltage is applied by connecting the motor to the supply.
Therefore, it is desirable to disconnect the transformer as the motor reaches the run stage to save the energy and extend the life of transformer.
Want to see more full solutions like this?
Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
1. Consider a
circular shaft in torsion
that
of radius r=b
has a key way
as shown,
circle of
radius a
Let us try the solution
x₁
(5,0) = k (6² = r²) (1- 2 awso
1.1 Does this solve the problem for the
stres rer
1,2 Solve for
is and 23.
3.
-
a
For
an elliptical cross
that
the
tangent to
section
resultant shear
can
you s
stress is
show
ellipse with the same
24
i ratio of
eccentricity, in
passes through to point
alb
that
in question, it
+
P
2.
Consider the rod with an elliptical
that
strain
4
a
Cross
secton
considered in class, Integrate the
was
displacement
displacements,
relations to
obtain the
Chapter 38 Solutions
Industrial Motor Control
Ch. 38 - Prob. 1RQCh. 38 - Explain the differences between open and closed...Ch. 38 - Prob. 3RQCh. 38 - Refer to the circuit shown in Figure 382. Assume...Ch. 38 - Prob. 5RQCh. 38 - Prob. 6RQCh. 38 - Prob. 7RQCh. 38 - Refer to the circuit shown in Figure 385. Explain...Ch. 38 - Prob. 9RQCh. 38 - Refer to the circuit shown in Figure 38–5. Assume...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- Please answer Oxygen at 300 kPa and 90°C flowing at an average velocity of 3 m/s is expanded in an adiabatic nozzle. What is the maximum velocity of the oxygen at the outlet of this nozzle when the outlet pressure is 60 kPa? Use the table containing the ideal gas specific heats of various common gases. The maximum velocity of the oxygen at the outlet of this nozzle is 532.5 Numeric ResponseEdit Unavailable. 532.5 incorrect.m/s.arrow_forwardA container filled with 70 kg of liquid water at 95°C is placed in a 90-m3 room that is initially at 12°C. Thermal equilibrium is established after a while as a result of heat transfer between the water and the air in the room. Assume the room is at the sea level, well sealed, and heavily insulated. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Determine the amount of heat transfer between the water and the air in the room. The amount of heat transfer between the water and the air in the room is kJ.arrow_forwardA strain gauge rosette that is attached to the surface of a stressed component gives 3 readings (ɛa = A, b = B, &c = C). If the strain gauge rosette is of the D° type (indicating the angle between each of the gauges), construct a Mohr's Strain Circle overleaf. You should assume that gauge A is aligned along the x-axis. Using the Mohr's Strain Circle calculate the: (i) principal strains (ε1, 2)? (ii) principal angles (1, 2)? You should measure these anticlockwise from the y-axis. (iii) maximum shear strain in the plane (ymax)?arrow_forward
- Q1. If the yield stress (σy) of a material is 375MPa, determine whether yield is predicted for the stresses acting on both the elements shown below using: (a) Tresca Criterion (b) Von Mises Criterion P Element A R S Element B Note: your values for P (vertical load on Element A) should be negative (i.e. corresponding to a compressive vertical load).arrow_forwardQ. After a puncture a driver is attempting to remove a wheel nut by applying a force of P KN to one end of a wheel brace as shown in Fig. 1. In cross-section the brace is a hollow steel tube (see section aa) of internal diameter r mm and external diameter q mm. wheel nut n Position S P m r q Section aa Fig, 1 (a) Calculate (i) the twisting moment, (ii) the bending moment, and (iii) the shear force in the brace at position S due to the applied load P. (b) Calculate (i) the shear stress due to twisting, and (ii) the bending stress at position S. Note that the shear force will not produce any shear stress at S. (c) Calculate the maximum shearing stress in the brace at position S using the Maximum Shear Stress Criterion. 2 Mechanics of Materials 2 Tutorials Portfolio: Exercise 5 (d) If the maximum permissible shear stress in the steel is 200 MPa, determine the maximum torque that can be applied by the brace without the risk of failure at S.arrow_forwardCalculate the first 5 Fourier series coefficients (A0-4 and B1-5 ) for the estimated R wave.arrow_forward
- Refrigerant-134a is expanded isentropically from 600 kPa and 70°C at the inlet of a steady-flow turbine to 100 kPa at the outlet. The outlet area is 1 m2, and the inlet area is 0.5 m2. Calculate the inlet and outlet velocities when the mass flow rate is 0.65 kg/s. Use the tables for R-134a. The inlet velocity is m/s. The outlet velocity is m/s.arrow_forwardA container filled with 70 kg of liquid water at 95°C is placed in a 90-m3 room that is initially at 12°C. Thermal equilibrium is established after a while as a result of heat transfer between the water and the air in the room. Assume the room is at the sea level, well sealed, and heavily insulated. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Determine the final equilibrium temperature. Use the table containing the ideal gas specific heats of various common gases. The final equilibrium temperature is °C.arrow_forwardSteam at 100 psia and 650°F is expanded adiabatically in a closed system to 10 psia. Determine the work produced, in Btu/lbm, and the final temperature of steam for an isentropic expansion efficiency of 80 percent. Use steam tables. The work produced is Btu/lbm. The final temperature of steam is °F.arrow_forward
- Complet the solution : Vavg Ti Te Ts Q hexp Nuexp htheo Re Nutheo Error (m/s) (*C) (*C) (*C) (W) 2.11 18.8 21.3 45.8 2.61 18.5 20.8 46.3arrow_forwardA 48-kg iron block and a 76-kg copper block, both initially at 80°C, are dropped into a large lake at 15°C. Thermal equilibrium is established after a while as a result of heat transfer between the blocks and the lake water. Determine the total entropy change for this process. The specific heat of iron at room temperature is cp = 0.45 kJ/kg·K. The specific heat of copper at 27°C is cp = 0.386 kJ/kg·K. The total entropy change for this process is kJ/K.arrow_forwardPlease help Air at 4.4 MPa and 500°C is expanded in an adiabatic gas turbine to 0.2 MPa. Calculate the maximum work that this turbine can produce in kJ/kg. Use the table containing the ideal gas specific heats of various common gases. The maximum work that this turbine can produce is kJ/kg.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Understanding Motor ControlsMechanical EngineeringISBN:9781337798686Author:Stephen L. HermanPublisher:Delmar Cengage Learning
Electrical Transformers and Rotating MachinesMechanical EngineeringISBN:9781305494817Author:Stephen L. HermanPublisher:Cengage Learning
Refrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning
Understanding Motor ControlsMechanical EngineeringISBN:9781305498129Author:Stephen L. HermanPublisher:Cengage Learning
Understanding Motor Controls
Mechanical Engineering
ISBN:9781337798686
Author:Stephen L. Herman
Publisher:Delmar Cengage Learning
Electrical Transformers and Rotating Machines
Mechanical Engineering
ISBN:9781305494817
Author:Stephen L. Herman
Publisher:Cengage Learning
Refrigeration and Air Conditioning Technology (Mi...
Mechanical Engineering
ISBN:9781305578296
Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Publisher:Cengage Learning
Understanding Motor Controls
Mechanical Engineering
ISBN:9781305498129
Author:Stephen L. Herman
Publisher:Cengage Learning