Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
thumb_up100%
Chapter 27, Problem 1SQ
Why is it desirable to remove the autotransformers from the line when the motor reaches its rated speed?
Expert Solution & Answer
To determine
Explain the reason why it is desirable to remove the autotransformer starters from the line when the connected motor reaches its rated speed.
Explanation of Solution
Autotransformer starter is placed between the motor and supply power lines to limit the supply voltage that is provided across the terminals of the motor during accelerating of the connected motor. With the lower accelerating voltage, motor draws less current and produces less torque in motor. Taps are provided on the autotransformer starters to permit the user to initiate the motor at an increasing speed from 50 percent, 60 percent, 75 percent or 85 percent of the line voltage.
The autotransformer starters are removed from the line connection when the motor attains the rated speed to obtain the required electrical energy by removing the magnetizing current, iron, and copper losses. Generally, the insulating life of the autotransformers may extend due to reduced heat and voltage applications.
Conclusion:
Thus, the reason why it is desirable to remove the autotransformer starters from the line when the connected motor reaches its rated speed is explained.
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
A single phase a.c. distributor AB has:
The distance from A to B is 500 m. The distance from A to C is 800 m.
The impedance of each section is (6+j 8) /km.
A
B
C
The voltage at the far end is maintained at 250 volt.
Find: sending voltage, sending current, supply power factor and
80 A
60 A
total voltage drop.
0.8 lag. P.f
0.6 lead. p.f
A 3-phase, 4-wire distributor supplies a balanced voltage of 400/230 V to a load consisting of 8 A at p.f. 0-7
lagging for R-phase, 10 A at p.f. 0-8 leading for Y phase and 12 A at unity p.f. for B phase. The resistance
of each line conductor is 0.4 2. The reactance of neutral is 0.2 2. Calculate the neutral current, the supply
voltage for R phase and draw the phasor diagram. The phase sequence is RYB.
The three line leads of a 400/230 V, 3-phase, 4-wire supply are designated as R, Y and B respectively.
The fourth wire or neutral wire is designated as N. The phase sequence is RYB. Compute the currents
in the four wire when the following loads are connected to this supply:
From R to N: 25 kW, unity power factor.
From Y to N: 20 kVA, 0-7 lag.
From B to N: 30 kVA, 0-6 lead.
Chapter 27 Solutions
Electric Motor Control
Ch. 27 - Why is it desirable to remove the autotransformers...Ch. 27 - What is meant by an open transition from start to...Ch. 27 - Which of the following applies to an...Ch. 27 - How are reduced voltages obtained from...Ch. 27 - Prob. 5SQCh. 27 - What is a disadvantage of starting with...Ch. 27 - What is one advantage of using an autotransformer...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, electrical-engineering and related others by exploring similar questions and additional content below.Similar questions
- A 3-phase, 50 Hz, 132 kV overhead line transpose system of bundle conductors .a radius of conductor is 0.5 cm. Calculate the total inductance of the line. 4m bi 4m C1 C1 im am biarrow_forwardInth big below:- A 500m B Zoom с 180011 I=50A I-60A I-804 06 ·0.7 0.8 lag. unit) Teading Pf P.F Pl A I sing phase distributor of 3/cm = The distance from point A To B is 500m distance from point A To C is /200m The distance from point A To D is 3000m The impedance of each part is. ZAB-0.51j0.8 -2/km ZBC= 0.7+71.2 12/1cm ZCD = 1.3772.5 -2/1cm The voltage of end for is VD= 220 Volt Find : 1- sending Voltage senting power 2- 5arrow_forwardConsider the circuit diagram below, where the load is indicated by the dashed box. Compute the apparent power and power factor of the load. Use power factor correction to correct the power factor of the load to 0.8 lagging. Your solution should include a circuit diagram of your modified circuit.arrow_forward
- Consider the circuit diagram below. What is the power factor of the circuit? Is it leading or lagging? Draw the power factor triangle of the circuit without calculating the individual power consumption of each component.arrow_forwardExplain what is wrong with each diagram in Fig. 6.41 if the two op amps are known to be perfectly ideal.arrow_forwardAmplitudes are given in peak values. Use node analysis to determine the voltage at nodes a and b. Express the voltages as sinusoids in the time domain with phase angles measured in radians. You may solve the system of equations using MATLAB or a similar software, but you must include the code you ran as part of your solution.arrow_forward
- Q3a [3 points] Simplify the following Boolean function using K-map: f= (0,2,8,9,10,12) & don't care X= (1,7,14) Put each cell number in the cell left upper corner. Put 1, O or X inside each cell. Circle your groups Write the simplified function f in terms of x, y, z and w ESM MZ f= Q3b [2 point] Design the above simplified Boolean function f after k-map using iCircuit then post your design screenshot here:arrow_forwardQ1a [2 points] Convert the binary into octal and hexadecimal? (10101111101)2 = ( )2 = ( )8 (10101111101) = ( )2 = ( )16 Q1b [2 points] Convert the decimal number 91.125 into binary? 91/2 = 91.25=( )2 0.125x2 = Q1c [1 point] Convert (101110), into decimal?arrow_forwardQ2 [5 points] Given the following Truth Table: f m X M 0 0 0 0 1 1 0 0 1 1 2 0 1 0 1 3 0 1 1 0 4 1 0 0 1 5 1 10 1 0 6 1 1 0 1 7 1 1 1 1 [1 point] Find the Boolean Function f in Minterms form: f=m( [1 point] Find the Boolean Function f in terms of x, y and z: f= [3 point] Simplify the above Boolean Function f in the sum form using k-map: Put each cell number in the cell left upper corner. Put 1's or 0's in each cell Circle any group of 4 ones, if not, circle any group of 2 ones Write the simplified function f in terms of x, y and z Narrow_forward
- Q4) A: Derive with the aid of diagrams the critical clearing angle for synchronous generator connected to infinite bus bar through parallel transmission line when fault occurs at the sending end of the lines.arrow_forwardQ3) A:A 60 Hz, 4 pole turbo-generator rated 10 MVA., 20 KV has stored energy in the rotor at synchronous speed of 90 MJ. (a) Find. M the anguler momentum. (b)If the generator supply 10 MW load at synchronous speed, find rotor acceleration in degrees/sec.² and in rpm/sec if the rotor drop to 5MW. (c) If the rotor acceleration calculated in part (b) is maintained for 12 cycles, find the change in torque angle and rotor speed in rpm at the end of this period.arrow_forwardChat gpt responses and ai responses are reported immediately reported please solve this question step by step handwritten solution thanksarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Electricity for Refrigeration, Heating, and Air C...Mechanical EngineeringISBN:9781337399128Author:Russell E. SmithPublisher:Cengage Learning
Electricity for Refrigeration, Heating, and Air C...
Mechanical Engineering
ISBN:9781337399128
Author:Russell E. Smith
Publisher:Cengage Learning
TRANSFORMERS - What They Are, How They Work, How Electricians Size Them; Author: Electrician U;https://www.youtube.com/watch?v=tXPy4OE7ApE;License: Standard Youtube License