Industrial Motor Control
7th Edition
ISBN: 9781133691808
Author: Stephen Herman
Publisher: Cengage Learning
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Question
Chapter 12, Problem 1RQ
To determine
The average amount of current flowing in two remaining phases.
Expert Solution & Answer
Explanation of Solution
Given:
The name plate current of three-phase motor is 56 A.
Calculation:
A failure phase occurs when power is lost from a three-phase motor power supply line. The motor is still running, but it draws excessive current. This phenomenon is known as Single phasing. Single phasing causes a current increase of 173% in average of both phases which remain energized in a three-phase motor.
Calculate the current flowing in two remaining phases:
Thus, the average amount of current flowing in two remaining phases is
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This is an old practice exam question.
Steam enters the high-pressure turbine of a steam power plant that operates on the ideal reheat Rankine cycle at 700 psia and 900°F and leaves as saturated vapor. Steam is then reheated to 800°F before it expands to a pressure of 1 psia. Heat is transferred to the steam in the boiler at a rate of 6 × 104 Btu/s. Steam is cooled in the condenser by the cooling water from a nearby river, which enters the condenser at 45°F. Use steam tables.
NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part.
Determine the pressure at which reheating takes place. Use steam tables.
Find:
The reheat pressure is psia. (P4)Find thermal efficiencyFind m dot
Air at T1 = 24°C, p1 = 1 bar, 50% relative humidity enters an insulated chamber operating at steady state with a mass flow rate of 3 kg/min and mixes with a saturated moist air stream entering at T2 = 7°C, p2 = 1 bar. A single mixed stream exits at T3 = 17°C, p3 = 1 bar. Neglect kinetic and potential energy effects
Determine mass flow rate of the moist air entering at state 2, in kg/min
Determine the relative humidity of the exiting stream.
Determine the rate of entropy production, in kJ/min.K
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Industrial Motor Control
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