Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR

USCG Marine Electrical Systems (Set 1)

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Question 1 of 30

Which of the following statements is true concerning the operating characteristics of a basic squirrel-cage induction motor?

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30 MCQs

#1 Which of the following statements is true concerning the operating characteristics of a basic squirrel-cage induction motor? #2 How is the speed of a squirrel-cage induction motor determined? #3 In a three-phase, squirrel-cage type, and induction motor, how is the primary rotating magnetic field established? #4 Which of the illustrated motors has a totally enclosed, fan-cooled (TEFC) motor enclosure? Illustration EL-0001 #5 Which of the pictured motors is a square core shaded pole motor used to drive very small electrical loads and is non-reversible. Illustration EL-0208 #6 One item listed on the name plate of a cargo pump motor is 'degrees centigrade rise.' What does the number stamped for this item represent? #7 How is the full-load (rated) torque of an induction motor defined? #8 What type of motor is illustrated by the schematic of figure "B" of the illustration and what type of starting relay is used? EL-0209 #9 With respect to electrical enclosure types, how may an electric motor be designed and constructed? #10 What will be the impact of reduced voltage applied to an AC induction motor during the starting period? #11 In general, what type of starter would be used to connect polyphase induction motors to full line voltage at the instant of start-up? #12 How is the difference between the synchronous speed of a three phase induction motor and its operating speed correctly expressed? #13 Assuming that the 3-phase power source has a phase sequence of A-B-C and that the motor is connected as shown in figure "A", if the motor has a counterclockwise (CCW) rotation, what statement is true concerning the motors connected as shown in the other figures? Illustration EL-0156 #14 Auto-transformer starters, sometimes called starting compensators, are sometimes used with larger polyphase induction motors. What function do they perform? #15 As shown in the two-speed single winding three phase motor connection diagrams illustrated in figure "B", what is the connection scheme associated with low speed operation? Illustration EL-0118 #16 The torque-speed and current-speed curves for a three-phase induction motor with a squirrel cage rotor are shown in figures "A" and "B" of the illustration. Which of the following statements is true concerning the depicted curves? Illustration EL-0056 #17 Which of the following statements describes what will occur if the motor torque-speed and current-speed curves shown in the illustration is required to carry 150% of full load? Illustration EL-0056 #18 According to the sample sheet of a typical "List of Motors and Controls" as shown in the illustration, which of the following motor applications features a means of keeping the motor windings warm and dry when the motor is idle? Illustration EL-0204 #19 Which of the pictured motors within the split phase family of single phase induction motors represents a capacitor start, induction run motor? Illustration EL-0146 #20 What is the main function in the use of a capacitor for starting a single phase motor? #21 Within the split phase family of single phase motors, what are the operational characteristics of the motor shown in figure "B" of the illustration? Illustration EL-0207 #22 As shown in figures "A", "B", "C", and "D" of the illustration, what is the usual means by which the rotation direction of the motor is reversed? Illustration EL-0207 #23 What are the operational characteristics of the split phase motor shown in figure "B" of the illustration? Illustration EL-0215 #24 Of the following listed single-phase induction motors, which has the highest starting torque? #25 What is the main purpose of the auxiliary winding on a split-phase, single-phase motor? #26 What type of rotor is used in the split-phase family of single-phase motors? #27 Which statement is true concerning a split-phase induction motor? #28 A shaded-pole motor is a specific type of motor included in what class of motor? #29 Universal motors will operate on AC or DC current. In what application is this type of motor generally? #30 An increase in which of the listed conditions will increase the speed of a synchronous electric motor?

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