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