Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Question
Chapter 37, Problem 9RQ
To determine
The size of the conductor, overload size, circuit breaker size, NEMA and IEC starter sizes, the upper and lower range of the starting current for the motor.
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Check out a sample textbook solutionStudents have asked these similar questions
A 3 kVA motor operates from a 240 V
supply at 50 Hz and has a power
factor of 0.6. Determine the active
power
Select one:
1800 W
Non of the Answers
1900 W
2000 W
The working current has a power of 100 kW and a power factor of 0.50. After a capacitor of 75 KVAR is installed, what does the
power factor become?
A 0.84
B 0.71
C 0.63
D 0.78
E 0.92
The following data were obtained on a 50 kVA 2400/120 V transformer:
Open circuit test, instruments on low voltage side:
Waltmeter reading = 396 Watts
Ammeter reading = 9.65 amperes
Voltmeter reading = 120 Volts
Short circuit test, instruments on high voltage side:
Waltmeter reading = 810 Watts
Ammeter reading = 20.8 amperes
Voltmeter reading = 92 Volts
Find the efficiency when rated kVA is delivered to a load having a power
factor of 0.8 lagging.The following data were obtained on a 50 kVA 2400/120 V transformer :
Open circuit test, instruments on low voltage side:
Waltmeter reading = 396 Watts
Ammeter reading = 9.65 amperes
Voltmeter reading = 120 Volts
Short circuit test, instruments on high voltage side:
Waltmeter reading = 810 Watts
Ammeter reading = 20.8 amperes
Voltmeter reading = 92 Volts
Find the efficiency when rated kVA is delivered to a load having a power
factor of 0.8 lagging.
Chapter 37 Solutions
Understanding Motor Controls
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Similar questions
- A 10 kVA transformer has a primary voltage rating of 240 volts and a secondary voltage rating of 480 volts. The transformer is connected to a circuit protected by a 100 ampere circuit breaker. The secondary is protected by a 25-ampere fuse. Does the primary require separate overcurrent protection?arrow_forwardA 480-volt three-phase load is rated at 34.5 kVA. It is to be supplied with variable three-phase voltage. Because the load is continuous, the transformers ratings are to be increased by 1.25% of the rated load. Three variable autotransformers are used to supply this load. Refer to Table 4-2 and determine the standard size of each transformer that should be used to make this connection.arrow_forwardIf dual-element time delay fuses are to be used as the short circuit protective device, what size fuses should be used to protect the circuit in question #12? Five 5 HP, three-phase motors with NEMA code B are connected to a 240-volt line. The conductors are copper with type THWN insulation. What size conductor should be used to supply all of these motors?arrow_forward
- In a given DC motor, the output power is 20 HP, and the copper losses are 1.1 KW. If the motor is operating at 87 % efficiency, find the converted power and the rotational losses. Select one: a. Pconv = 16.05 KW and Prot = 1.13 KW b. Pconv = 17.15 KW and Prot = 3.11 KW c. Pconv = 14.92 KW and Prot = 1.35 KW d. Nonearrow_forwardThe Subject is Basic Electrical Engineeringarrow_forwardTwo transformers rated at 100 kVA each are connected in an open-delta connection. What is the total output power that can be supplied by this bank?arrow_forward
- what is the smallest gage size copper wire that will limit the conductor voltage drop to 5v when 120 vac is supplied to a 6-A loadarrow_forwardThe input power to a 3-phase load is measured as 6700 watts. If the line voltage and line current to the load are 430 V and 18 A respectively. The power factor of the System is,arrow_forward4. A circuit contains a 20-2 resistor and an inductor with an inductance of 0.093 H. If the circuit has a frequency of 60 Hz, what is the total impedance of the circuit? 5. An R-L series circuit has a power factor of 86%. By how many degrees are the voltage and current out of phase with each other? 6. An R-L series circuit has an apparent power of 230 VA and a true power of 180 W. What is the reactive power? 7. The resistor in an R-L series circuit has a voltage drop of 53 V, and the inductor has a voltage drop of 28 V. What is the applied voltage of the circuit?arrow_forward
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