Delmar's Standard Textbook Of Electricity
7th Edition
ISBN: 9781337900348
Author: Stephen L. Herman
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 32, Problem 3PA
You are an electrician working in an industrial plant. A 30-hp three-phase squirrel- cage motor keeps tripping out on overload. The motor is connected to a 240-volt line. Voltage measurements indicate the following voltages between the different phases: A-B = 276 volts, B-C = 221 volts, and A-C = 267 volts. Determine the percentage of heat rise in the winding with the highest current.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Q4. Figure Q4. shows a power system with one generator, two transformers, a line
and a load.
G
Vgen-415/0°V
от
R = 0.02
600 kVA
0.415/11 kV Y-Y
XT1=6%
ZLine=1+j0.1
tot
Zload=0.3+j0.102
500 kVA
11/0.415 kV Y-Y
XT2=5%
Figure Q4. A Simple Power System
a)
i.
ii.
The one-line diagram shown in Figure Q4. is a proposal for a new power
system. Assuming a base apparent power of 600 kVA and a base voltage
of 11 kV in the line section:
Calculate the Current magnitudes in the generator, line and load
sections
Calculate the overall system power factor
iii.
Obtain the system losses at rated operating conditions, and the potential
for series power factor correction, stating the value of the capacitor
necessary to bring the system power factor to unity.
b) A 230 V shunt DC motor is used for a check-out conveyer in a shop. The
motor has an armature resistance of 0.5 Q and a field resistance of 115 Q.
It draws a no-load current of 6 A and has a no-load speed of 1000 rev/min.
(i)
Draw the equivalent electrical circuit of the motor
(ii) When the supply current at a given load is 22 A, determine the motor
speed and motor efficiency.
c) Compare series and shunt DC motors in terms of their construction, torque-
speed characteristics, operational considerations to avoid possible risks
and applications.
Q1. a) A lift is driven by a 230 V series DC motor. The motor resistance is 0.5 Q
and the magnetic circuit is assumed unsaturated. The motor runs at 250
rev/min with a load current of 20 A.
(i) If more passengers come into the lift and the load torque is increased
by 21%, what would be the motor speed if the supply voltage is
unchanged?
(ii) In order to maintain the motor at 250 rev/min, what is the supply
voltage required?
Chapter 32 Solutions
Delmar's Standard Textbook Of Electricity
Ch. 32 - What are the three basic types of three-phase...Ch. 32 - What is the principle of operation of all...Ch. 32 - What is synchronous speed?Ch. 32 - What two factors determine synchronous speed?Ch. 32 - Prob. 5RQCh. 32 - Name three factors that determine the torque...Ch. 32 - Is the synchronous motor an induction motor?Ch. 32 - Prob. 8RQCh. 32 - Why must a synchronous motor never be started when...Ch. 32 - Name three characteristics that make the...
Ch. 32 - What is the function of the field-discharge...Ch. 32 - Why can an induction motor never operate at...Ch. 32 - A squirrel-cage induction motor is operating at...Ch. 32 - Prob. 14RQCh. 32 - Prob. 15RQCh. 32 - Prob. 16RQCh. 32 - Name three factors that determine the amount of...Ch. 32 - Why will the rotor of a wound-rotor motor not turn...Ch. 32 - Why is the starting torque per A of starting...Ch. 32 - When is a synchronous motor a synchronous...Ch. 32 - What determines when a synchronous motor is at...Ch. 32 - How can a synchronous motor be made to have a...Ch. 32 - Is the excitation current of a synchronous motor...Ch. 32 - Prob. 24RQCh. 32 - Prob. 25RQCh. 32 - You are working as a plant electrician. It is your...Ch. 32 - You have been given the task of connecting a...Ch. 32 - You are an electrician working in an industrial...
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
- b) Consider a buck converter driven at a switching frequency of 50 kHz, supply voltage is 200V DC, and duty cycle is 0.25; i) Sketch labelled waveforms for: 1- Inductor current Transistor current 2- 3- Diode current 4- Diode voltage 5- Transistor voltage. ii) What is the value of the output voltage? iii) What are the peak voltages appearing across the transistor and diode?arrow_forwardNEED HANDWRITTEN SOLUTION DO NOT USE AI OR CHATGPTarrow_forwardDo by pen and paper not using chatgpt or AIarrow_forward
- Don't use ai to answer I will report you answerarrow_forwardDO NOT USE AI OR CHATGPT NEED HAND WRITTEN ANSWERarrow_forward6 Multiple Choice 10 points Use the measured characteristics given in the figure. From the curves shown, this is 220V Start 160V Start 190V Start, DC series motor DC shunt motor DC separately excited motor DC series generator 160V Start 220V Start 190V Startarrow_forward
- 000 . Use the measured characteristics given in the figure. For Delta connected motor, the maximum load (N.m) you can put at starting is " 28 " 24 22 28 24 18 14 13 3.4 2.8 3.6 0.9 1800arrow_forwardCan I have a written solutionarrow_forwardA 100-kVA, 2500/125-V, 50-Hz, step-down transformer has the following parameters: R1= 1.5Ω, X1= 2.8Ω, R2= 15mΩ, X2=20mΩ, Rc1= 3kΩ, Xm1= 5kΩ The transformer delivers 85% of the rated load at a terminal voltage of 115 V and a power factor of 0.866 lagging. Determine (a) the efficiency, and (b) the voltage regulation. Draw the phasor diagram of the transformer. Use the approximate equivalent circuit referred to the secondary side.arrow_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