Description : An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard ship as a ____________. A. magnetic amplifier B. ship's service alternator C. three-wire DC generator D. saturable core reactor
Last Answer : Answer: B
Description : The speed of the rotor is always somewhat less than the speed of the rotating field. What is the difference called?
Last Answer : Slip.
Description : What determines the number of field poles required to establish a rotating magnetic field in a multiphase motor stator?
Last Answer : The number of phases in the applied voltage.
Description : If the pointer of the synchroscope is rotating in the slow direction when you are preparing to parallel two alternators, the _____________. A. incoming machine is turning faster than the load alternator B ... alternator is ready to split D. incoming machine is beginning to pick up some of the load
Description : The frequency of an AC generator is adjusted by means of the ____________. A. main alternator field rheostat B. exciter field rheostat C. prime mover governor control D. equalizing reactor
Last Answer : Answer: C
Description : What is the main function in the use of a capacitor for starting a single phase motor? A. Reduce radio interference B. Split the phase to establish a rotating magnetic field C. Reduce the phase angle D. Prolong the life of the starting contacts
Description : What is the frequency of the output voltage of an alternator with four poles that is rotated at 3600 rpm?
Last Answer : 120 Hz.
Description : What two factors determine the frequency of the output voltage of an alternator?
Last Answer : Speed of rotation and number of poles.
Description : What are the two methods of connecting the outputs from a three-phase alternator to the load?
Last Answer : Wye and Delta.
Description : In a three-phase alternator, what is the phase relationship between the individual output voltages?
Last Answer : Each phase is displaced 120º from the other two
Description : How many voltage outputs are available from a two-phase three-wire alternator?
Last Answer : Three.
Description : What type of prime mover requires a specially designed high-speed alternator?
Last Answer : Steam turbine.
Description : What is the part of an alternator in which the output voltage is generated?
Last Answer : Armature.
Description : What main advantage does a bridge rectifier have over a conventional full-wave rectifier?
Last Answer : The bridge rectifier can produce twice the voltage with the same size transformer.
Last Answer : The bridge rectifier can produce double the voltage with the same size transformer.
Description : What is the main advantage of using a time-domain reflectometer (tdr) to test a transmission line?
Last Answer : Tdr will indicate the nature of and the distance to or location of any faults.
Description : What is the main advantage of radiotelegraph communications?
Last Answer : Reliability.
Description : What is the main advantage of a series motor?
Last Answer : High torque (turning force) at low speed.
Description : Rotating the plane of polarization of a wavefront by passing it through a ferrite device is called what?
Last Answer : . Faraday rotation.
Description : Which of the two types of deflection coils (fixed or rotating) is used most often?
Last Answer : Fixed.
Description : What is the purpose of rotating the gimbal assembly in a gyro using a mercury erection system?
Last Answer : Applies torque at the proper point for correct precession.
Description : Why is no emf induced in a rotating coil when it passes through the neutral plane?
Last Answer : No flux lines are cut.
Description : Which of the following statements is true concerning the operation of two alternators in parallel? A. The cycles per second of each alternator are the same. B. Both alternator governors must be set ... be the same on each alternator. D. The load must always be divided equally between alternators.
Last Answer : Answer: A
Description : An open occurring within the field rheostat of an AC generator can be detected by short circuiting its terminals and observing a ____________. A. negative deflection of the wattmeter pointer B. ... of the wattmeter pointer C. buildup of alternator voltage D. low, but constant alternator voltage
Description : If field excitation is suddenly lost to an alternator operating in parallel, that alternator will _____________. A. supply excessive current to the bus B. operate at the same load, but with reduced voltage C. lose its load and tend to overspeed D. become overloaded and slow down
Description : A change in field excitation of an alternator operating in parallel will cause a change in its _____________. A. alternator frequency B. kilowatt load C. voltage output D. all of the above
Description : Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator ... rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field
Last Answer : Answer: D
Description : The standard method of controlling the output voltage of a 440 volt, 60 Hz, AC generator is accomplished by adjusting the ____________. A. prime mover speed droop B. number of poles C. alternator field excitation D. load on the alternator
Description : The cycles per second developed by the alternator aboard your vessel is determined by _____________. A. the speed of the engine driving the alternator B. the resistance applied to the field rheostat C. the synchronous speed of induction D. the adjustments made to the voltage regulator
Description : The division of kilowatt load between two paralleled alternators is determined by the _____________. A. amount of field excitation of the leading machine B. load-speed characteristics of the governors C. amount of field excitation to the lagging machine D. type of alternator
Description : The division of kilowatt load between two paralleled alternators is determined by the _____________. A. amount of field excitation to the leading machine B. load-speed characteristics of the governors C. amount of field excitation to the lagging machine D. number of field poles per alternator
Description : The output voltage of a three-phase alternator is regulated by the _____________. A. AC voltage to the armature B. AC voltage to the field C. DC voltage to the armature D. DC voltage to the field
Description : A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a terminal voltage of 2000 V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200 A is (A) 1 V (B) 10 V (C) 100 V (D) 1000 V
Last Answer : 800
Description : What is the main advantage of transplantation method in rice cultivation? (a) This method ensures maximum utilization of land (b) It is helpful in achieving an economical use of water and a higher ... helps in early harvesting (d) The draining of water from the field before harvesting is made easy
Last Answer : Ans: (b)
Description : A charged particle is rotating in uniform circular motion in a uniform magnetic field . Let r= radius of circule, v= speed of particle k = kinetic ene
Last Answer : A charged particle is rotating in uniform circular motion in a uniform magnetic field . Let r ... angular speed. then match the following two columns.
Description : There is a ring of radius r having linear charge density `lambda` and rotating with a uniform angular velocity `omega.` the magnetic field produced by
Last Answer : There is a ring of radius r having linear charge density `lambda` and rotating with a uniform angular velocity ` ... D. `(mu_(0)lambda)/(2omega^(2))`
Description : Assertion A charged particle is rotating in a circle. Then magnetic field (B) at centre of circle and magnetic moment (M) produced by motion of charge
Last Answer : Assertion A charged particle is rotating in a circle. Then magnetic field (B) at centre of circle and ... M and B are always parallel to each other.
Description : Assertion A charged particle is rotating in a circular path in uniform magnetic field. Then, plane of circle is perpendicular to the magnetic field. R
Last Answer : Assertion A charged particle is rotating in a circular path in uniform magnetic field. Then, plane of ... . If Assertion is false but Reason is true.
Description : Assertion If a charged particle enters from outside in uniform magnetic field, then it will keep on rotating in a circular path. Reson Magnetic force
Last Answer : Assertion If a charged particle enters from outside in uniform magnetic field, then it will keep on ... . If Assertion is false but Reason is true.
Description : What does a Rotating magnetic field do?
Last Answer : Rotating magnetic field induces the voltage in the statorwinding under which the rotor is rotating. refer Faraday's law.
Description : The most common type of AC service generator found aboard ship is the stationary _____________. A. electromagnetic field, revolving armature type B. electromagnetic field, oscillatory armature type C. armature, oscillatory electromagnet field type D. armature, rotating electromagnetic field type
Description : If an AC generator experiences voltage failure, the cause may be _____________. A. an open in the field circuit B. the brushes shifting out of the neutral plane C. excessive locked-rotor current D. a rotating slip ring
Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.
Description : The most practical way to control the voltage output of an AC generator is to vary the _____________. A. number of windings B. speed of the rotating field C. strength of the rotating magnetic field D. power factor of the load
Description : In a three-phase, squirrel-cage type, induction motor the rotating magnetic field is established by the _____________. A. current induced in the rotor windings B. application of a three-phase voltage ... caused by the induced current in the squirrel-cage bars with the magnetic field of the stator
Description : The synchronous speed of an induction motor is the ________. A. speed at which the rotor turns B. speed of the rotating field C. frequency of the rotor current D. slip in per cent of rotor RPM
Description : The rotor of a synchronous motor operates in synchronism with the rotating field because ______________. A. of the amortisseur windings B. the rotor is magnetically locked into step with the ... field strength varies directly with rotor slip D. the stator flux rotates in the opposite direction
Description : Regarding an induction motor, the power developed by the rotor automatically adjusts itself to the _____________. A. power required to drive the load B. speed required to drive the load C. current flow in the motor stator D. torque developed by the rotating field
Description : The direction of rotation of an induction motor is ________. A. opposite the rotating field direction B. the same as the direction of the rotating field C. determined by the number of poles D. determined by the staggering of the brushes
Description : What will be the phase angle relationship of a six-pole, three-phase, rotating field generator? A. 60° B. 120° C. 180° D. 360°