Description : The simplest method of controlling the terminal voltage of compound-wound DC generator is with a _____________. A. hand-operated field rheostat connected in series with the shunt field circuit B. ... in series with the load D. balance coil diverting neutral current through the shunt field
Last Answer : Answer: A
Description : A DC shunt generator has its field windings connected in _____________. A. series with the series windings B. parallel with the field rheostat C. series with the armature windings D. parallel with the armature windings
Last Answer : Answer: D
Description : Shunt, series, and compound wound motors, are all DC motors designed to operate from _____________. A. constant potential, variable current DC sources B. variable potential, constant current DC ... C. variable potential, variable current DC sources D. constant potential, constant current DC sources
Description : In a compound-wound motor, a portion of the line current flows through the _____________. A. inertial poles B. stator C. shunt field coils D. frame
Last Answer : Answer: C
Description : Which of the methods listed is used to maintain the division of load between two compound-wound, DC generators operating in parallel? A. The shunt fields are interconnected. B. The shunt ... generators are connected in series. D. The equalizer connection parallels the series fields of all machines.
Description : Which of the methods listed is used to maintain equal load sharing between two compound wound DC generators operating in parallel? A. The shunt fields are interconnected. B. The shunt field rheostats ... are connected in series. D. The series fields of both generators are connected in parallel.
Description : An equalizing connection between two compound-wound DC generators when paralleled, serves to _____________. A. reverse the polarity of the incoming generator as the series field weakens B. automatically ... the series field of the incoming generator D. parallel the series fields of the generators
Description : A shunt-wound DC generator is one in which the shunt field windings are in parallel with the _____________. A. commutator B. brushes C. armature D. all of the above
Description : An adjustable resistor, whose resistance can be changed without opening the circuit in which it is connected, is called a _____________. A. bleeder resistor B. rheostat C. bridge D. variable shunt strip
Last Answer : Answer: B
Description : Moving the rheostat handle shown in the illustration, that is used to control a DC generator, towards the 'raise' direction will increase the _____________. EL-0030 A. field resistance B. armature resistance C. armature speed D. line voltage
Description : A series wound DC motor has its armature and field connected in series with a resistor. When the motor is disconnected from its power supply, this motor will exemplify __________. A. the ... the proper connections for an automatic strip heater C. a reversing controller circuit D. dynamic braking
Description : The speed of a wound-rotor induction motor _____________. A. will be fixed by the number of field poles B. can be varied by a rheostat-type control C. can only be synchronous speed at full load D. can only attain synchronous speed at no load
Description : In a series wound motor, the current passing through the field windings is also passing through the _____________. A. armature B. shunt field C. reactance comparator D. laminations
Description : A short in the shunt field of a DC motor is best located by _____________. A. visual inspection of the commutator B. applying AC voltage to each field coil and measuring the voltage drop across ... using a growler and hacksaw blade D. isolating each coil from the others and using a megohmmeter
Description : One method of testing for a reversed shunt field coil in a DC generator or motor is by connecting the field to a direct current source, at reduced field rated voltage, and test for ... placed near each field C. test lamp across adjacent fields D. copper jumper across the interpole connections
Description : An 8 pole lap wound DC shunt generator is supplying 295A to a load. The field current of the generator is 5A. The current per parallel path is: - a) 300A b) 200A c) 150A d) 37.5A
Last Answer : An 8 pole lap wound DC shunt generator is supplying 295A to a load. The field current of the generator is 5A. The current per parallel path is: - 37.5A
Description : The kilowatt load can be adjusted on a paralleled generator by using the _____________. A. field rheostat B. governor control C. automatic voltage regulators D. hand tachometer
Description : In the construction of D.C. motors, parts of both the series and shunt fields are wound on the _____________. A. opposite main pole B. rotor core C. interpole D. same main pole
Description : With the help of neat diagrams,explain the following methods of speed control in DC series motor. i) Field diverter method. ii) Armature diverter method.
Last Answer : (i) Field diverter method: - Resistance connected in parallel with field winding -By adjusting this resistance current can by diverted from field winding -Thus field current decreases and the speed can be ... decreased, the flux must increase and hence speed is decreased than the rated speed.
Description : Which of the following types of DC motors has its field connected in parallel with its armature? A. Counter EMF B. Shunt C. Salient pole D. Series
Description : As compared to shunt and compound DC motors, the series DC motor will have the highest torque because of its comparatively ____________ at the start. (A) Lower armature resistance. (B) Stronger series field. (C) Fewer series turns. (D) Larger armature current.
Last Answer : (D) Larger armature current.
Description : Which of the following statements is true about the illustrated circuit? EL-0030 A. The field rheostat is used for manual voltage control. B. if the generator is flat compounded then the field rheostat ... to act like a series motor and overspeed with the controller in the full raise position.
Description : A 8-pole, DC generator has a simplex wave-wound armature containing 32 coils of 6 turns each. Its flux per pole is 0.06 Wb. The machine is running at 250 rpm. The induced armature voltage is (A) 96 V (B) 192 V (C) 384 V (D) 768 V
Last Answer : A 8-pole, DC generator has a simplex wave-wound armature containing 32 coils of 6 turns each. Its flux per pole is 0.06 Wb. The machine is running at 250 rpm. The induced armature voltage is 384 V
Description : What is the difference between resistor, rheostat and potential divider?
Last Answer : Resistor: a fixed resistance connected permanently in the circuit for limiting the current to definite value is called the resistor. Rheostat: a variable resistance by sliding contacts on it the current can ... : when a resistance is used to develop a voltage drop it is called a potential divider.
Description : The electrical diagram shown in the illustration represents a ___________. EL-0054 A. series-wound motor B. shunt-wound motor C. compound-wound motor D. flat-compounded motor
Description : When the series field relay "FR" of the winch circuit shown in the illustration is energized during dynamic braking the _______________. EL-0102 A. shunt Field Relay "FR-B.O." is de-energized and contacts ... . shunt Field Relay "FR-B.O." opposes the series coil's flux and sets the mechanical brake
Description : Which of the terms listed best describes a compound-wound DC generator having a higher voltage at no load than at full load? A. Flat compounded B. Over compounded C. Under compounded D. Terminal compounded
Description : A synchronous motor maintains synchronism with the rotating field because _____________. A. field strength varies directly with rotor slip B. DC current applied to the rotor coils causes the rotor ... the flux created by the excitation current D. the stator flux rotates in the opposite direction
Description : If a unloaded shunt motor's field were weakened by rheostat resistance or by an open circuit, the motor would _________. A. overspeed due to reduced CEMF B. stop because of low flux C. continue to run at base speed D. slow down and overheat
Description : The frequency of an AC generator is controlled by the _____________. A. rheostat B. governor C. exciter D. capacitor
Description : When starting a DC propulsion motor the variable rheostat must FIRST be turned ____________. A. all the way to the run position then quickly back to slow B. to the slow position then gradually moved to full speed C. to the mid position D. quickly to the run position
Description : To limit the current flow through a DC voltmeter to as low a value as possible, the moving coil circuit is provided with a/an _____________. A. high series resistance B. high parallel resistance C. series inductor D. external shunt
Description : If a DC motor runs hot, the cause may be _____________. A. high mica condition B. low ambient temperature C. clogged ventilation ducts D. an open in the shunt field
Description : Which of the listed electrical devices is represented by the symbol shown in the illustration? EL-0055 A. Fixed resistance resistor B. Coil with magnetic core C. DC motor or generator shunt field D. Transformer
Description : Current measuring instruments must always be connected in _____________. A. series with a circuit B. parallel with a circuit C. series-parallel with a circuit D. delta with the shunt
Description : A booster is a (a) series wound generator (b) shunt wound generator (c) synchronous generator (d) none of the above
Last Answer : (a) series wound generator
Description : The shunt of a DC ammeter should be connected in __________. A. series with the load and in parallel with the meter movement B. parallel with the load and in series with the meter movement C. ... and in parallel with the meter movement D. series with the load and in series with the meter movement
Description : Air gap readings should be taken periodicly on electrical generation equipment to __________. A. determine the amount of varnish that can be applied to correct insulation problems B. determine the ... field coil bolts and correct lateral adjustment of the field coils D. increase machine efficiency
Description : Which of the following operating characteristics for DC motors is considered to give high starting torque? A. series B. shunt C. cumulative-compound D. differential-compound
Description : A 4 pole lap wound dc shunt motor rotates at the speed of 1500 rpm, has a flux of 0.4 mWb and the total number of conductors are 1000. What is the value of emf? (A) 100 Volts. (B) 0.1 Volts. (C) 1 Volts. (D) 10 Volts.
Last Answer : Ans: D Given N = 1500 rpm, Φ = 0.4 mWb, Z = 1000, P = 4, & A= 4 Therefore, Eb = NΦPZ / 60 A = 1500 x 0.4 x 4 x 1000 x 10^-3 / 60 x 4 = 60/6 = 10 volts
Description : A motor which can conveniently be operated at lagging as well as leading power factors is the (A) squirrel cage induction motor. (B) wound rotor induction motor. (C) synchronous motor. (D) DC shunt motor.
Last Answer : (C) synchronous motor.
Description : The KW load is evenly distributed between two alternators just placed in parallel by adjusting _____________. A. a balance coil B. the governor settings C. the field excitation D. a rheostat
Description : If two AC generators have just been placed in parallel, the true power load is initially distributed evenly by _____________. A. a balance coil B. changing field excitation C. adjusting the governor control settings D. a rheostat
Description : You are attempting to parallel two AC generators and the synchroscope pointer is revolving slowly in the fast direction. You should _____________. A. use the governor control switch to adjust the incoming ... the 0° position D. use the field rheostat to adjust the speed of the incoming machine
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 : 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 : 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
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
Description : A motor using a rheostat in the motor circuit to vary the speed is called a ____________. A. squirrel-cage induction motor B. regenerative braking motor C. wound-rotor induction motor D. synchronous motor