Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Textbook Question
Chapter 42, Problem 6SQ
What influence do both of the polarized field frequency relay (PFR) coils exert on the normally closed contact?
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Q2/ Design a 4-pole wave winding for an armature with 21 slots. Assume single turn coils and
two conductors per slot.
(35 mark)
What is the difference between a fuse and a relay ?
What is the difference between an overcurrent relay and current differential relay ?
Which of the statement is true?
A Normally closed (NC) relay contact is open when the relay coil is de – energized. It opens when the coil
energizes, but returns to closed position when the coil de – energizes.
O b. When a relay contact is normally open (NO), there is an open contact when the relay is energized.
O c. A NO relay contact is open when the relay coil is de – energized. It closes when the coil energizes but
returns to open position when the coil de – energizes.
d.
When a relay contact is Normally Closed (NC), there is a closed contact when the relay is energized.
Chapter 42 Solutions
Electric Motor Control
Ch. 42 - What are the two basic methods of automatically...Ch. 42 - What is an out-of-step relay?Ch. 42 - Why is an out-of-step relay used on automatic...Ch. 42 - Under what conditions will the out-of-step relay...Ch. 42 - What is the last control contact that closes on a...Ch. 42 - What influence do both of the polarized field...Ch. 42 - Prob. 7SQCh. 42 - Approximately how much time (in terms of...Ch. 42 - How does the AC coil of the PFR receive the...Ch. 42 - Why is a control relay (CR1) used in Figure 426?...
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- The preferred method for applying the field excitation voltage uses a field relay which operates on the principle of A. speed application. B. time application.C. angle application. D. thermal application.arrow_forward40 The armature, frame, and core of a 12-V DC control relay are made of sheet steel. The average length of the magnetic circuit is 12 cm when the relay is energized, and the average cross section of the magnetic circuit is 0.60 cm?. The coil is wound with 250 turns and carries 50 mA. Determine a. The flux density B in the magnetic circult of the relay when the coil is energized. b. The force F exerted on the armature to close it when the col is energized.arrow_forwardHow does the AC coil of the PFR receive the induced field current without receiving the full field current strength?arrow_forward
- What is the commutator pitch of a 4-pole, duplex wave-wound armature having 120 commutator bars?arrow_forwardExplain the following armature winding terminologies (i)commutator Pitch (ii)Coil Side (iii)Pole Pitcharrow_forwardB: Relay is consist two circuits, what they are? And determine whether the next relay is normally open or normally closed. 3arrow_forward
- For the design we assuming following parameters 1) winding : Lap 2) simplex 3) Number of slots : 16 , single turn coil with 2 conductors per slot 4) Number of poles = 4arrow_forwardAssume that HOA SW 120 has been set in the AUTO position. List four ways by which coil CR-8 could be energized.arrow_forwardWhat is the difference between a balanced voltage relay and a Translay relay ?arrow_forward
- A four-pole lap-wound DC machine armature has 54 slots with single-turn coils. How many armature conductors are required if there are two coil sides per slot?arrow_forwardDeterming the front pitch, back pitch, and average pitch of the armature winding. 12 poles 100 slots 2 conductors/slot 100 commutator segment progressive, simplexarrow_forward1) Calculate the coil pitches and indicate the slots into which the first coil should be place for the following armature windings a. 36 slots , 4 poles b. 57 slots , 4 poles c. 76 slots , six poles d. 132 slots , eight poles e. 270 slots , 10 polesarrow_forward
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