Repulsion Motor Question & AnswersJuly 14, 2023 By Wat Electrical This article lists 100 Repulsion Motor MCQs for engineering students. All the Repulsion Motor Questions & Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of Repulsion Motor. A repulsion motor, also known as a repulsion-induction motor, is an electric motor that operates based on the principle of repulsion between like magnetic poles. It is a type of single-phase AC motor that is commonly used in various applications requiring high starting torque. The construction of a repulsion motor is similar to that of a DC motor, consisting of a stator (stationary part) and a rotor (rotating part). The stator includes a laminated iron core with evenly spaced windings. These windings are connected to a commutator, which is a segmented cylindrical structure.The rotor of a repulsion motor is also a laminated iron core, but it has a different winding arrangement compared to the stator. The rotor windings are shorted together at the ends, forming a closed loop. The windings are typically distributed on the rotor surface in a semi-circular or skewed pattern.Repulsion motors offer several advantages, including high starting torque, smooth acceleration, and good speed regulation. They are commonly used in applications requiring high starting torque, such as heavy machinery, compressors, hoists, and pumps. 1). What is the primary purpose of regular maintenance for a repulsion motor? Increasing motor efficiency Extending motor lifespan Ensuring motor safety All of the above None Hint2). Which of the following maintenance practices is essential for repulsion motors? Lubricating the bearings regularly Cleaning the motor windings with water Overloading the motor to test its limits Ignoring preventive maintenance altogether None Hint3). What is a common issue that can occur in a repulsion motor? Excessive noise during operation Overheating of the motor Reduced motor speed All of the above None Hint4). What could be the possible cause if a repulsion motor overheats during operation? Insufficient ventilation Overvoltage supply Damaged windings All of the above None Hint5). What is the recommended course of action if a repulsion motor produces excessive noise? Continue using the motor, as the noise is normal Increase the load on the motor Inspect and repair any loose or worn-out components Replace the motor immediately None Hint6). How can you troubleshoot a repulsion motor that fails to start? Increase the applied voltage Check the starting switch contacts for proper functioning Reduce the load on the motor Replace the motor with a new one None Hint7). What is the starting method commonly used for repulsion motors? Rheostatic control Magnetic control Capacitor control Autotransformer control None HintRead more about Autotransformer 8). In the autotransformer starting method, which taps are used during the starting period? High voltage taps Low voltage taps Medium voltage taps All taps simultaneously None Hint9). Which device is used to limit the starting current in a repulsion motor? Capacitor Rheostat Magnetic starter Overload relay None HintRead more about Rheostat 10). Why is a starting resistance used in a repulsion motor? To reduce voltage To reduce torque To limit starting current To increase efficiency None Hint11). How is the starting resistance gradually reduced during the starting period? Automatically by a timer Manually by an operator By a centrifugal switch By a magnetic contactor None Hint12). What is the purpose of the centrifugal switch in a repulsion motor? To control the starting current To change the direction of rotation To control the speed during operation To disconnect the starting resistance None Hint13). Which method is used to stop a repulsion motor? Dynamic braking Plugging Rheostatic braking Reverse voltage braking None Hint14). How does plugging stop a repulsion motor? By applying a reverse voltage By short-circuiting the armature By reducing the supply voltage By increasing the rotor resistance None Hint15). Which of the following is a disadvantage of the plugging method? High torque during braking Excessive heat generation Slow deceleration rate High cost of implementation None Hint16). What is the purpose of dynamic braking in a repulsion motor? To reduce starting current To increase the motor’s torque To bring the motor to a quick stop To improve the motor’s efficiency None Hint17). How does dynamic braking work in a repulsion motor? By short-circuiting the armature By short-circuiting the armature By reducing the supply voltage By increasing the rotor resistance None HintRead more about Armature18). Which method of stopping a repulsion motor requires an additional braking resistor? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None Hint19). What is the function of the braking resistor in rheostatic braking? To increase the braking torque To limit the braking current To limit the braking current To reverse the motor’s direction None Hint20). Which stopping method can provide rapid deceleration in a repulsion motor? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None Hint21). In reverse voltage braking, what happens to the supply voltage during stopping? It is reduced gradually It is increased gradually It is applied intermittently It is abruptly reversed None Hint22). Which of the following methods provides the smoothest stopping in a repulsion motor? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None Hint23). Which stopping method is commonly used in applications requiring rapid and precise stopping? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None Hint24). Which method of stopping a repulsion motor can result in high mechanical stress? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None Hint25). In which stopping method does the motor act as a generator and dissipate energy as heat? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None HintRepulsion Motor MCQ for Quiz 26). Which stopping method requires additional control circuits or devices? Dynamic braking Rheostatic braking Plugging Reverse voltage braking None Hint27). The speed-torque characteristics of a repulsion motor is generally _________________? Linear Non-linear Parabolic Exponential None Hint28). The torque developed by a repulsion motor is proportional to ___________________? Square of the armature current Armature current Square of the speed Speed None Hint29). In a repulsion motor, the maximum torque occurs at _____________? Full load No-load Half-load At any load condition None HintRead more about Load Factor30). The speed of a repulsion motor at no-load is _________________? Very high Zero Slightly less than synchronous speed Equal to synchronous speed None Hint31). The speed-torque characteristics of a repulsion motor can be improved by _________________? Increasing the number of stator windings Increasing the number of rotor windings Increasing the rotor resistance Increasing the rotor inductance None Hint32). The starting torque of a repulsion motor is _________________? Low High Zero Cannot be determined None Hint33). In a repulsion motor, the speed can be controlled by _________________? Varying the armature voltage Varying the armature resistance Varying the rotor resistance Varying the rotor inductance None Hint34). The power factor of a repulsion motor is typically _________________? Lagging Leading Unity Zero None Hint35). The efficiency of a repulsion motor is generally __________________? High Low Unity Zero None Hint36). The armature current of a repulsion motor is typically controlled by ___________________? Varying the stator voltage Varying the rotor voltage Varying the stator resistance Varying the rotor resistance None Hint37). A repulsion motor can be used in applications requiring ___________________? High speed and low torque Low speed and high torque High speed and high torque Low speed and low torque None Hint38). The speed regulation of a repulsion motor is ___________________? Good Poor Moderate Cannot be determined None Hint39). The armature windings of a repulsion motor are ___________________? Wound type Squirrel cage type Salient pole type Brushed type None Hint40). The armature and stator windings of a repulsion motor are ___________________? Series-connected Parallel-connected Delta-connected Star-connected None Hint41). The commutation in a repulsion motor is achieved by ___________________? Slip rings Brushes Capacitors Commutator segments None Hint42). The speed-torque characteristics of a repulsion motor are affected by ___________________? Armature resistance Stator resistance Rotor resistance None of the above None Hint43). The repulsion motor finds applications in ___________________? Domestic fans Electric vehicles Industrial pumps All of the above None Hint44). The starting current of a repulsion motor is typically ___________________? Low High Moderate Zero None Hint45). The armature of a repulsion motor consists of ___________________? Wound rotor Squirrel cage rotor Permanent magnet rotor Commutator rotor None HintRead more about Commutator 46). The direction of rotation of a repulsion motor can be reversed by ___________________? Reversing the armature current Reversing the stator current Reversing the rotor current Reversing the field windings None Hint47). The starting torque of a repulsion motor can be increased by ___________________? Decreasing the rotor resistance Increasing the rotor resistance Decreasing the stator resistance Increasing the stator resistance None Hint48). The most common method used for starting a repulsion motor is ___________________? Direct-on-line (DOL) starting Star-delta starting Auto-transformer starting None Hint49). The purpose of centrifugal switches in a repulsion motor is to ___________________? Start the motor Stop the motor Reverse the motor direction None HintRead more about Centrifugal Switches 50). The speed of a repulsion motor during the starting period is typically ___________________? Very high Zero Slightly less than synchronous speed Equal to synchronous speed None HintRepulsion Motor MCQ for Exams51). Dynamic braking in a repulsion motor is achieved by ___________________? Reversing the armature current Applying mechanical brakes Switching off the power supply None Hint52). The repulsion motor remains an important historical milestone in the field of ___________________? Electrical engineering Computer science Mechanical engineering Civil engineering None Hint53). The repulsion motor is classified as a type of ___________________? DC motor AC motor Brushless motor Stepper motor None Hint54). The repulsion motor was an important innovation during the ___________________? First Industrial Revolution Second Industrial Revolution Information Age Digital Revolution None HintRead more about AC motor55). The development of the repulsion motor contributed to advancements in ___________________? Electromechanical devices Telecommunications Digital computing Power electronics None Hint56). The repulsion motor can provide ___________________? Variable speed control High efficiency Bidirectional rotation Low starting torque None Hint57). The repulsion motor was an important stepping stone towards the development of ___________________? Linear motors Three-phase induction motors Switched reluctance motors Brushless servo motors None Hint58). The development of the repulsion motor was significant in the advancement of ___________________? AC power distribution DC power distribution Electric lighting systems Electric heating systems None Hint59). Which of the following is a characteristic feature of repulsion motors? High efficiency Rotor with permanent magnets Commutator and brushes No speed control None Hint60). Which motor type is known for its simplicity and ruggedness? Induction motor Synchronous motor Repulsion motor Brushless DC motor None Hint61). In a repulsion motor, the stator winding is connected to which type of power supply? AC power supply DC power supply Variable frequency power supply Three-phase power supply None Hint62). Which motor type exhibits self-starting capability without the need for additional starting mechanisms? Repulsion motor Permanent magnet motor Universal motor Stepper motor None Hint63). Which motor type is commonly used in ceiling fans and air conditioning units? Induction motor Synchronous motor Repulsion motor Brushless DC motor None Hint64). Which motor type offers precise speed control with a wide range of operating speeds? Repulsion motor Permanent magnet motor Stepper motor Synchronous motor None Hint65). Which motor type requires slip rings and brushes for rotor power supply? Synchronous motor Induction motor Repulsion motor Brushless DC motor None Hint66). Which motor type provides a constant speed regardless of the load? Induction motor Repulsion motor Synchronous motor Brushless DC motor None Hint67). Which motor type is suitable for applications requiring high torque at low speeds? Repulsion motor Permanent magnet motor Induction motor Brushless DC motor None HintRead more about Permanent magnet motor 68). Which motor type is known for its high starting torque? Induction motor Repulsion motor Synchronous motor Brushless DC motor None Hint69). Which motor type does not require external brushes for operation? Repulsion motor Permanent magnet motor Synchronous motor Universal motor None Hint70). Which motor type is commonly used in electric vehicles and robotics? Induction motor Repulsion motor Brushless DC motor Stepper motor None Hint71). Which motor type is best suited for constant-speed applications? Repulsion motor Induction motor Synchronous motor Brushless DC motor None Hint72). Which motor type does not require a separate field winding for operation? Repulsion motor Induction motor Synchronous motor Universal motor None Hint73). Which motor type exhibits good speed regulation even under varying loads? Repulsion motor Induction motor Synchronous motor Stepper motor None Hint74). Which motor type is most suitable for applications requiring precise positioning and control? Repulsion motor Permanent magnet motor Stepper motor Brushless DC motor None Hint75). Which motor type is commonly used in pumps, compressors, and conveyor belts? Repulsion motor Synchronous motor Induction motor Brushless DC motor None HintRepulsion Motor Questions for Interviews76). Which motor type requires periodic maintenance of brushes and commutator? Repulsion motor Permanent magnet motor Synchronous motor Brushless DC motor None Hint77). Which motor type is most suitable for high-speed applications? Repulsion motor Permanent magnet motor Induction motor Brushless DC motor None Hint78). Which motor type is commonly used in clocks, timers, and record players? Repulsion motor Synchronous motor Universal motor Stepper motor None Hint79). Which motor type offers the highest efficiency among the options listed? Repulsion motor Induction motor Synchronous motor Brushless DC motor None Hint80). What is the purpose of the repulsion-start mechanism in an RSIR motor? To provide high starting torque To provide precise speed control To improve efficiency To reduce maintenance requirements None Hint81). Which type of motor is the RSIR motor typically used in? Air compressors Electric vehicles HVAC systems Washing machines None Hint82). In an RSIR motor, what is the function of the starting winding? To provide the main power for the motor To provide the motor’s braking capability To initiate the motor’s rotation To regulate the motor’s speed None Hint83). Which component provides the necessary starting torque in an RSIR motor? Centrifugal switch Rotor Stator Starting winding None Hint84). What happens to the starting winding in an RSIR motor once the motor reaches a certain speed? It disconnects from the power supply. It becomes a part of the main winding. It reverses the direction of current flow It increases its resistance None Hint85). Which type of rotor is typically used in an RSIR motor? Squirrel cage rotor Wound rotor Induction rotor None Hint86). What is the main advantage of using an RSIR motor? High efficiency Variable speed control Low cost High power factor None Hint87). How does the RSIR motor differ from a standard repulsion motor? RSIR motors have multiple starting windings. RSIR motors have a different commutation mechanism. RSIR motors have higher starting torque. RSIR motors are more expensive. None Hint88). Which motor type is commonly used as the main power motor in an RSIR motor? Synchronous motor Induction motor DC motor Universal motor None Hint89). What is the role of the centrifugal switch in an RSIR motor? To control the motor’s speed To reverse the motor’s direction To regulate the motor’s torque To disconnect the starting winding None Hint90). Which winding has a higher resistance in an RSIR motor? Starting winding Main winding Both windings have equal resistance. Resistance is not a factor in RSIR motors. None Hint91). What is the effect of the higher resistance in the starting winding of an RSIR motor? It provides higher torque during starting It reduces the motor’s overall efficiency It increases the motor’s power factor It improves the motor’s speed control None Hint92). What happens if the centrifugal switch fails in an RSIR motor? The motor will not start. The motor will run at a lower speed The motor will overheat The motor will reverse its direction None Hint93). What is the typical speed range of an RSIR motor? Fixed speed Variable speed High speed Low speed None Hint94). How is the speed of an RSIR motor controlled? By adjusting the voltage applied to the motor By changing the number of poles in the motor By using an external speed controller By changing the resistance in the starting winding None Hint95). Which motor type provides better speed control: RSIR motor or variable frequency drive (VFD) motor? RSIR motor VFD motor Both provide the same level of speed control It depends on the specific application None Hint96). What is the power factor of an RSIR motor? Leading power factor Lagging power factor Unity power factor Power factor cannot be determined None Hint97). Which of the following statements is true regarding the efficiency of an RSIR motor? RSIR motors are highly efficient. RSIR motors are less efficient compared to other motor types. Efficiency depends on the specific application. Efficiency cannot be determined. None Hint98). Can an RSIR motor be used for continuous duty applications? Yes, it can operate continuously. No, it is only suitable for intermittent duty. It depends on the specific motor design. Continuous duty is not applicable to RSIR motors. None Hint99). Who is credited with inventing the Repulsion-Start Induction Run (RSIR) motor? Nikola Tesla Thomas Edison Charles Francis Dalziel Michael Faraday None Hint100). In what decade was the Repulsion-Start Induction Run (RSIR) motor first introduced? 1890s 1910s 1940s 1970s None HintFor More MCQsSlip Ring Motor MCQsThree Phase Induction Motor MCQsSwitched Reluctance Motor MCQsReluctance Motor MCQsInduction Motor MCQs Time's up
