Electrical Transformers and Rotating Machines
4th Edition
ISBN: 9781305494817
Author: Stephen L. Herman
Publisher: Cengage Learning
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Chapter 18, Problem 21RQ
Why can a multispeed fan motor be operated at lower speed than most induction motors without harm to the motor windings?
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A 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.
Please 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.
Chapter 18 Solutions
Electrical Transformers and Rotating Machines
Ch. 18 - Prob. 1RQCh. 18 - Prob. 2RQCh. 18 - Prob. 3RQCh. 18 - Prob. 4RQCh. 18 - What is the advantage of the capacitor-start...Ch. 18 - Prob. 6RQCh. 18 - Prob. 7RQCh. 18 - Prob. 8RQCh. 18 - Prob. 9RQCh. 18 - Prob. 10RQ
Ch. 18 - Prob. 11RQCh. 18 - Prob. 12RQCh. 18 - What type of single-phase motor develops the...Ch. 18 - What is the principle of operation of a repulsion...Ch. 18 - What type of commutator is used with a...Ch. 18 - When a repulsion-start induction-run motor reaches...Ch. 18 - Prob. 17RQCh. 18 - Prob. 18RQCh. 18 - Prob. 19RQCh. 18 - How is the speed of a consequent pole motor...Ch. 18 - Why can a multispeed fan motor be operated at...Ch. 18 - What is the speed of operation of the Warren...Ch. 18 - What is the speed of operation of the Holtz motor?Ch. 18 - Prob. 24RQCh. 18 - Prob. 25RQCh. 18 - What does the term bifilar mean?
Ch. 18 - Why do stepping motors have teeth machined in the...Ch. 18 - Prob. 28RQCh. 18 - Prob. 29RQCh. 18 - Prob. 30RQCh. 18 - Prob. 31RQCh. 18 - What is the function of the compensating winding?
Ch. 18 - Prob. 33RQCh. 18 - Prob. 34RQCh. 18 - Explain how to set the neutral plane position of...Ch. 18 - Explain how to set the neutral plane position by...
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- Saturated water vapor at 150°C is compressed in a reversible steady-flow device to 1150 kPa while its specific volume remains constant. Determine the work required in kJ/kg. Use steam tables. The work required is kJ/kg.arrow_forwardThree lbm of R-134a is expanded isentropically in a closed system from 100 psia and 100°F to 10 psia. Determine the total heat transfer and the work production for this process. Use the tables for R-134a. The total heat transfer is Btu. The work production for this process is Btu. Three lbm of R-134a is expanded isentropically in a closed system from 100 psia and 100°F to 10 psia. Determine the total heat transfer and the work production for this process. Use the tables for R-134a. The total heat transfer is Btu. The work production for this process is Btu.arrow_forwardOxygen 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 m/s.arrow_forward
- The well-insulated container shown in the given figure is initially evacuated. The supply line contains air that is maintained at 150 psia and 110°F. The valve is opened until the pressure in the container is the same as the pressure in the supply line. Determine the minimum temperature in the container when the valve is closed. Use the table containing the ideal gas specific heats of various common gases. A valve is shown at the vertical tube. The minimum temperature in the container when the valve is closed is °F.arrow_forwardDuring the isothermal heat addition process of a Carnot cycle, 1050 kJ of heat is added to the working fluid from a source at 400°C. NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Determine the total entropy change for the process. The total entropy change for the process is kJ/K.arrow_forwardQuestion 6 What kind of problem would arise if components of the strain tensor were defined as varrow_forwardplease show steps, thanksarrow_forwardYou design a pin joint. The pin is made of a material with the yield strength of 325 MPa and ultimate strength of 500 MPa. The maximum allowed stress in service is expressed as a tensor 0 100 0 σ 100 0 0 MPa 0 0 Evaluate the safety factor SF for stress in this design. Write answer unitless rounding to 2 decimal places and enter decimals even if those are zeros.arrow_forward2. A single crystal of aluminum is oriented for a tensile test such that its slip plane normal makes an angle of 28.1° with the tensile axis. Three possible slip directions make angles of 62.4°, 72.0°, and 81.1° with the same tensile axis. (a) Which of these three slip directions is most favored? (b) If plastic deformation begins at a tensile stress of σ x = 1.95 MPa (280 psi), determine the critical resolved shear stress for aluminium. (c) If this single crystalspecimen is loaded under the new stress state: σ x =1.2 MPa σ y = -0.8 MPa, and τ xy = 0.6 MPa, howmuch is the resolve the shear stress along the most favored slip direction?arrow_forwardPlease explain how to do each part and tell me if my drawing is correct. thank youarrow_forward4. Determine which of the following flow fields represent a possible incompressible flow? (a) u= x²+2y+z; v=x-2y+z;w= -2xy + y² + 2z a (b) V=U cose U coso 1 (9) [1-9] Usino |1 (4)] [+] V=-Usin 1+1arrow_forward3. Determine the flow rate through the pipe line show in the figure in ft³/s, and determine the pressures at A and C, in psi. 5' B C 12° 20' D 6"d 2nd- Water Aarrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
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