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