Electric Motor Control
10th Edition
ISBN: 9781305177611
Author: Herman
Publisher: Cengage
expand_more
expand_more
format_list_bulleted
Concept explainers
Question
Chapter 2, Problem 5SQ
To determine
Explain about the consequence when the heater element is not installed in a two-pole manual starter.
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
. Two wattmeters connected to measure the input to
a balanced three-phase circuit indicate 2500 W and
500 W respectively. Find the power factor of the
circuit: (a) when both readings are positive; (b) when
the latter reading is obtained after reversing the con
nections to the current-coil of one instrument. Draw
the phasor and connection diagrams.
ANS:
0.655, 0.359
Explain the advantage of connecting the low-voltage
winding of distribution transformers in star.
A factory has the following load with power factor of
0.9 lagging in each phase. Red phase 40 A, yellow phase
50 A and blue phase 60 A. If the supply is 400 V, three
phase, four-wire, calculate the current in the neutral
and the total active power. Draw a phasor diagram for
phase and line quantities. Assume that, relative to the
current in the red phase, the current in the yellow phase
lags by 120° and that in the blue phase leads by 120°.
ANS:
17.3 A, 31.2 kW
A three-phase, 400 V system has the following load
connected in delta: between the red and yellow lines,
a non-reactive resistor of 100 Ω; between the yellow
and blue lines, a coil having a reactance of 60 Ω and
negligible resistance; between the blue and red lines,
a loss-free capacitor having a reactance of 130 Ω.
Calculate: (a) the phase currents; (b) the line currents.
Assume the phase sequence to be R–Y, Y–B and
B–R. Also, draw the complete phasor diagram.
ANS:
4.00 A, 6.67 A, 3.08 A, 6.85 A, 10.33 A, 5.8 A
Chapter 2 Solutions
Electric Motor Control
Ch. 2 - If the contacts on a manual starter cannot be...Ch. 2 - If the handle of an installed motor starter is in...Ch. 2 - How may an automatic operation be achieved when a...Ch. 2 - What does the term trip-free mean as it relates to...Ch. 2 - Prob. 5SQCh. 2 - Prob. 6SQCh. 2 - Prob. 7SQCh. 2 - Prob. 8SQCh. 2 - Select the best answer for each of the following....Ch. 2 - Select the best answer for each of the following....
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
- With the aid of a circuit diagram, show that two wattmeters can be connected to read the total power in a three-phase, three-wire system. Two wattmeters connected to read the total power in a three-phase system supplying a balanced load read 10.5 kW and −2.5 kW respectively. Calculate the total active power. Drawing suitable phasor diagrams, explain the significance of: (a) equal wattmeter readings; (b) a zero reading on one wattmeter. ANS: 8 kWarrow_forwardA factory has the following load with power factor of 0.9 lagging in each phase. Red phase 40 A, yellow phase 50 A and blue phase 60 A. If the supply is 400 V, three-phase, four-wire, calculate the current in the neutral and the total active power. Draw a phasor diagram for phase and line quantities. Assume that, relative to the current in the red phase, the current in the yellow phase lags by 120° and that in the blue phase leads by 120°.arrow_forwardFundimentals of Energy Systems Q8arrow_forward
- Two wattmeters are used to measure power in a three phase, three-wire network. Show by means of connection and complexor (phasor) diagrams that the sum of the wattmeter readings will measure the total active power. Two such wattmeters read 120 W and 50 W when connected to measure the active power taken by a balanced three-phase load. Find the power factor of the load. If one wattmeter tends to read in the reverse direction, explain what changes may have occurred in the circuit ANS: 0.815arrow_forwardFundimentals of Energy Systems Q7arrow_forwardFundimentals of Energy Systems Q6arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
