Electrical Transformers and Rotating Machines
4th Edition
ISBN: 9781305494817
Author: Stephen L. Herman
Publisher: Cengage Learning
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Textbook Question
Chapter 7, Problem 9RQ
An alternator with a line voltage of 2400 V supplies a delta-connected load. The line current supplied to the load is 40 A. Assuming the load is a balanced three-phase load, what is the impedance of each phase?
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Chapter 7 Solutions
Electrical Transformers and Rotating Machines
Ch. 7 - Prob. 1RQCh. 7 - Prob. 2RQCh. 7 - A wye-connected load has a voltage of 480 V...Ch. 7 - A wye-connected load has a phase current of 25 A....Ch. 7 - Prob. 5RQCh. 7 - A delta connection has 30 A of current flowing...Ch. 7 - A three-phase load has a phase voltage of 240 V...Ch. 7 - If the load in question 7 is connected in a wye,...Ch. 7 - An alternator with a line voltage of 2400 V...Ch. 7 - Prob. 10RQ
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- A load impedance of 52 Ω is connected to the secondary winding of the transformer in question 3. How much current will flow in the secondary?arrow_forwardIf the secondary of the transformer in question 5 supplies a current of 9.6 amperes to a load, what is the primary current? (Disregard excitation current.)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_forward
- 4. 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_forwardWhat is the peak voltage of a 120V RMS AC voltage?arrow_forwardThe 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.arrow_forward
- A three-phase transformer connection has a delta-connected primary and a wye-connected secondary. The center tap of the wye is used as a neutral conductor. If the line-to-line voltage is 480 volts, what is the voltage between any one phase conductor and the neutral conductor?arrow_forwardAn open-delta three-phase transformer system has one transformer center-tapped to provide a neutral for single-phase voltages. If the voltage from line to center tap is 277 volts, what is the high-leg voltage?arrow_forwardA 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_forward
- Please help me solve this questionarrow_forwardExample 7-3. A 460-V, 25-hp. 60-Hz, four-pole, Y-connected induction motor has the following impedances in ohms per phase referred to the stator circuit: - 0.641n X,-1.106 N R2 - 0.332 N X2 = 0.464 XM - 26.3 N The total rotational losses are 1100 W and are assumed to be constant. The core loss is lumped in with the rotational losses. For a rotor slip of 2.2 percent at the rated voltage and rated frequency, find the motor's (a) Speed (b) Stator current (c) Povwer factor (d) Peony and Pout (e) Tiad and Toad Efficiencyarrow_forwardFind the value of the currents I1 and 12. 100 ohm 5V 5V 100 ohm 12 O a. 1=-0.3A, 12=-0.1A O b. 11=0.3A, 12=0.1A Oc. 11=0.05A, 12=0.1A O d. 11=0.1A, 12=0.2Aarrow_forward
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