Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Question
Chapter 46, Problem 8SQ
To determine
Explain the use made of double break contacts or the contacts connected in series such as FA relay contacts across the rheostat and contact M in the armature circuit in Figure 46-4.
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List the probable causes if the armature dos notable release after the magnetic starter is de - energized .
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Chapter 46 Solutions
Electric Motor Control
Ch. 46 - Prob. 1SQCh. 46 - What physical characteristic distinguishes between...Ch. 46 - Prob. 3SQCh. 46 - What protection is available from excessive...Ch. 46 - How does a field accelerating relay prevent...Ch. 46 - Prob. 6SQCh. 46 - How may more steps of acceleration be added to a...Ch. 46 - Prob. 8SQ
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- What is the function of the shunt field rheostat?arrow_forwardWhat is the difference bewteen a grounded control system And a floating control system?arrow_forwardWhile discussing armature testing: Technician A says to test for shorts, place the ohmmeter leads on a commutator segment and armature shaft. Technician B says that continuity should exist between the commutator and the armature shaft. Who is correct?arrow_forward
- Completely solve and box/highlight/bold the final answers. WRITE LEGIBLY OR TYPEWRITE THE SOLUTIONS. A 60 kW, 230 volts shunt generator has an equivalent armature resistance of 0.3 ohms, and shunt field resistance of 60 ohms. Calculate: a. armature current and induce voltage b. generated power and total power lossarrow_forwardExplain with the aid of a drawing or hand sketch how a bimetallic overload relay operates?arrow_forwardIf all of the control circuits are ACand DC is not availablewhat will be the result of energizing all of the contactor coils?arrow_forward
- What happens when the holding coil gets the supply in the magnetic controller?arrow_forward1. Which NEC table is used to determine the full-load current of a torque motor? 2. What is the rated full-load current of a ¾-horsepower, 208-volt single-phase motor 3. What are the minimum allowable ampacities of the phase conductors and the neutral conductor that are to supply a 2-phase, 3-wire, 230-volt, 30-horsepower motor 4. . What is the full-load current of a 230-volt, 3-phase, 125-horsepower synchronous motor when it is operated at an 80% power factor?arrow_forwardIn Figure 482, what is the purpose of normally closed contact F?arrow_forward
- A 6 pole dc armature has Simplex lap connected 720 conductors, 3 turns per coil and 4 coil sides per slot. Determine the number of slots in the armature and state whether equalizers can be employed or not ?arrow_forwardA selector switch and two - wire pilot device cannot be used to control a large motor directly but rather must be connected to a magnetic starter. Why this is true.?arrow_forwardHow does a field accelerating relay prevent current excess that may occur because of adjusting the rheostat to change speeds?arrow_forward
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