DC Motors Quiz Set 1 in English Posted on June 10, 2020September 8, 2020 by Surendra 0% 1 Created by Surendra DC Motors Quiz in English Set 1 All Important Question Answers for Electrician Related Exams 1 / 25 In case of D.C. shunt motors the speed is dependent on back e.m.f. only because back e.m.f. is equal to armature drop flux is practically constant in D:C. shunt motors flux is proportional to armature current armature drop is negligible 2 / 25 Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ? Fleming’s left-hand rule Lenz’s law Coloumb’s law Faraday’s law 3 / 25 Starters are used with D.C. motors because these motors are not self-starting back e.m.f. of these motors is zero initially to restrict armature current as there is no back e.m.f. while starting these motors have high starting torque 4 / 25 A three point starter is considered suitable for shunt as well as compound motors shunt compound and series motors all D.C. motors shunt motors 5 / 25 Which of the following motor is preferred for operation in highly explosive atmosphere ? Air motor Shunt motor Battery operated motor Series motor 6 / 25 can be obtained by decreasing the armature current increasing the armature current decreasing the field current increasing the field current 7 / 25 In a D.C. shunt motor speed is independent of armature current proportional to the square of the current inversely proportional to the armature current directly proportional to the armature current 8 / 25 What will happen if the back e.m.f. of a D.C. motor vanishes suddenly? The motor will stop The armature may burn The motor will run noisy The motor will continue to run 9 / 25 These days D.C. motors are widely used in air compressors machine shops pumping sets electric traction 10 / 25 When two D.C. series motors are connected in parallel the resultant speed is more than the normal speed loss than the normal speed normal speed zero 11 / 25 A direct on line starter is used: for starting motors up to 15 H.P. up to 20 H.P. up to 5 H.P. up to 10 H.P. 12 / 25 In which of the following applications D.C. series motor is invariably tried? Starter for a car Fan motor Drive for a water pump Motor operation in A.C. or D.C. 13 / 25 If a D.C. motor is connected across the A.C. supply it will burn due to heat produced in the field winding by .eddy currents run at normal speed run at lower speed not run 14 / 25 A D.C. series motor is that which can be started easily without load has a poor torque has its field winding consisting of thick wire and less turns has almost constant speed 15 / 25 In case the back e.m.f. and the speed of a D.C. motor are doubled the torque developed by the motor will remain unchanged be doubled reduce to one-fourth value increase four folds 16 / 25 Sparking is discouraged in a D.C. motor because it increases the input power con-sumption both and commutator gets damaged none of the above 17 / 25 Usually wide and sensitive speed control is desired in case of elevators colliery winders centrifugal pumps steel rolling mills 18 / 25 Which of the following method of speed control of D.C. machine will offer minimum efficiency ? Armature control method Field control method All above methods Voltage control method 19 / 25 If the speed of a D.C. shunt motor is increased the back e.m.f. of the motor will become zero remain same decrease increase 20 / 25 The ratio of starting torque to full-load torque is least in case of shunt motors none of the above compound motors series motors 21 / 25 Speed control by Ward Leonard method gives uniform speed variation in one direction in both directions below normal speed only above normal speed only. 22 / 25 Which of the following motors one will choose to drive the rotary compressor ? Synchronous motor Universal motor D.C. series motor D.C. shunt motor 23 / 25 Three point starter can be used for compound motor only shunt motor only series motor only both shunt and compound motor 24 / 25 In D.C. machines fractional pitch winding is used to increase the generated e.m.f. to reduce the sparking to reduce copper losses to improve cooling 25 / 25 Sparking at the commutator of a D.C. motor may result in all of the above damage to commutator segments damage to commutator insulation increased power consumption कृपया सही सूचना भरें ताकि सर्टिफिकेट ईमेल पर भेजा जा सकें। Your score is LinkedIn Facebook Twitter 0% Restart quiz आपको यह क्विज अच्छी लगी तो 5 स्टार रेटिंग जरुर दें । Send feedback
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