Repulsion Motor Question & Answers July 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 Hint 2). 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 Hint 3). 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 Hint 4). What could be the possible cause if a repulsion motor overheats during operation? Insufficient ventilation Overvoltage supply Damaged windings All of the above Hint 5). 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 Hint 6). 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 Hint 7). What is the starting method commonly used for repulsion motors? Rheostatic control Magnetic control Capacitor control Autotransformer control Hint Read 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 Hint 9). Which device is used to limit the starting current in a repulsion motor? Capacitor Rheostat Magnetic starter Overload relay Hint Read 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 Hint 11). 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 Hint 12). 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 Hint 13). Which method is used to stop a repulsion motor? Dynamic braking Plugging Rheostatic braking Reverse voltage braking Hint 14). 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 Hint 15). 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 Hint 16). 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 Hint 17). 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 Hint Read more about Armature 18). Which method of stopping a repulsion motor requires an additional braking resistor? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint 19). 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 Hint 20). Which stopping method can provide rapid deceleration in a repulsion motor? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint 21). 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 Hint 22). Which of the following methods provides the smoothest stopping in a repulsion motor? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint 23). Which stopping method is commonly used in applications requiring rapid and precise stopping? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint 24). Which method of stopping a repulsion motor can result in high mechanical stress? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint 25). In which stopping method does the motor act as a generator and dissipate energy as heat? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint Repulsion Motor MCQ for Quiz 26). Which stopping method requires additional control circuits or devices? Dynamic braking Rheostatic braking Plugging Reverse voltage braking Hint 27). The speed-torque characteristics of a repulsion motor is generally _________________? Linear Non-linear Parabolic Exponential Hint 28). The torque developed by a repulsion motor is proportional to ___________________? Square of the armature current Armature current Square of the speed Speed Hint 29). In a repulsion motor, the maximum torque occurs at _____________? Full load No-load Half-load At any load condition Hint Read more about Load Factor 30). The speed of a repulsion motor at no-load is _________________? Very high Zero Slightly less than synchronous speed Equal to synchronous speed Hint 31). 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 Hint 32). The starting torque of a repulsion motor is _________________? Low High Zero Cannot be determined Hint 33). 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 Hint 34). The power factor of a repulsion motor is typically _________________? Lagging Leading Unity Zero Hint 35). The efficiency of a repulsion motor is generally __________________? High Low Unity Zero Hint 36). 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 Hint 37). 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 Hint 38). The speed regulation of a repulsion motor is ___________________? Good Poor Moderate Cannot be determined Hint 39). The armature windings of a repulsion motor are ___________________? Wound type Squirrel cage type Salient pole type Brushed type Hint 40). The armature and stator windings of a repulsion motor are ___________________? Series-connected Parallel-connected Delta-connected Star-connected Hint 41). The commutation in a repulsion motor is achieved by ___________________? Slip rings Brushes Capacitors Commutator segments Hint 42). The speed-torque characteristics of a repulsion motor are affected by ___________________? Armature resistance Stator resistance Rotor resistance None of the above Hint 43). The repulsion motor finds applications in ___________________? Domestic fans Electric vehicles Industrial pumps All of the above Hint 44). The starting current of a repulsion motor is typically ___________________? Low High Moderate Zero Hint 45). The armature of a repulsion motor consists of ___________________? Wound rotor Squirrel cage rotor Permanent magnet rotor Commutator rotor Hint Read 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 Hint 47). 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 Hint 48). The most common method used for starting a repulsion motor is ___________________? Direct-on-line (DOL) starting Star-delta starting Auto-transformer starting Hint 49). The purpose of centrifugal switches in a repulsion motor is to ___________________? Start the motor Stop the motor Reverse the motor direction Hint Read 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 Hint Repulsion Motor MCQ for Exams 51). Dynamic braking in a repulsion motor is achieved by ___________________? Reversing the armature current Applying mechanical brakes Switching off the power supply Hint 52). The repulsion motor remains an important historical milestone in the field of ___________________? Electrical engineering Computer science Mechanical engineering Civil engineering Hint 53). The repulsion motor is classified as a type of ___________________? DC motor AC motor Brushless motor Stepper motor Hint 54). The repulsion motor was an important innovation during the ___________________? First Industrial Revolution Second Industrial Revolution Information Age Digital Revolution Hint Read more about AC motor 55). The development of the repulsion motor contributed to advancements in ___________________? Electromechanical devices Telecommunications Digital computing Power electronics Hint 56). The repulsion motor can provide ___________________? Variable speed control High efficiency Bidirectional rotation Low starting torque Hint 57). The repulsion motor was an important stepping stone towards the development of ___________________? Linear motors Three-phase induction motors Switched reluctance motors Brushless servo motors Hint 58). The development of the repulsion motor was significant in the advancement of ___________________? AC power distribution DC power distribution Electric lighting systems Electric heating systems Hint 59). Which of the following is a characteristic feature of repulsion motors? High efficiency Rotor with permanent magnets Commutator and brushes No speed control Hint 60). Which motor type is known for its simplicity and ruggedness? Induction motor Synchronous motor Repulsion motor Brushless DC motor Hint 61). 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 Hint 62). Which motor type exhibits self-starting capability without the need for additional starting mechanisms? Repulsion motor Permanent magnet motor Universal motor Stepper motor Hint 63). Which motor type is commonly used in ceiling fans and air conditioning units? Induction motor Synchronous motor Repulsion motor Brushless DC motor Hint 64). Which motor type offers precise speed control with a wide range of operating speeds? Repulsion motor Permanent magnet motor Stepper motor Synchronous motor Hint 65). Which motor type requires slip rings and brushes for rotor power supply? Synchronous motor Induction motor Repulsion motor Brushless DC motor Hint 66). Which motor type provides a constant speed regardless of the load? Induction motor Repulsion motor Synchronous motor Brushless DC motor Hint 67). Which motor type is suitable for applications requiring high torque at low speeds? Repulsion motor Permanent magnet motor Induction motor Brushless DC motor Hint Read 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 Hint 69). Which motor type does not require external brushes for operation? Repulsion motor Permanent magnet motor Synchronous motor Universal motor Hint 70). Which motor type is commonly used in electric vehicles and robotics? Induction motor Repulsion motor Brushless DC motor Stepper motor Hint 71). Which motor type is best suited for constant-speed applications? Repulsion motor Induction motor Synchronous motor Brushless DC motor Hint 72). Which motor type does not require a separate field winding for operation? Repulsion motor Induction motor Synchronous motor Universal motor Hint 73). Which motor type exhibits good speed regulation even under varying loads? Repulsion motor Induction motor Synchronous motor Stepper motor Hint 74). Which motor type is most suitable for applications requiring precise positioning and control? Repulsion motor Permanent magnet motor Stepper motor Brushless DC motor Hint 75). Which motor type is commonly used in pumps, compressors, and conveyor belts? Repulsion motor Synchronous motor Induction motor Brushless DC motor Hint Repulsion Motor Questions for Interviews 76). Which motor type requires periodic maintenance of brushes and commutator? Repulsion motor Permanent magnet motor Synchronous motor Brushless DC motor Hint 77). Which motor type is most suitable for high-speed applications? Repulsion motor Permanent magnet motor Induction motor Brushless DC motor Hint 78). Which motor type is commonly used in clocks, timers, and record players? Repulsion motor Synchronous motor Universal motor Stepper motor Hint 79). Which motor type offers the highest efficiency among the options listed? Repulsion motor Induction motor Synchronous motor Brushless DC motor Hint 80). 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 Hint 81). Which type of motor is the RSIR motor typically used in? Air compressors Electric vehicles HVAC systems Washing machines Hint 82). 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 Hint 83). Which component provides the necessary starting torque in an RSIR motor? Centrifugal switch Rotor Stator Starting winding Hint 84). 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 Hint 85). Which type of rotor is typically used in an RSIR motor? Squirrel cage rotor Wound rotor Induction rotor Hint 86). What is the main advantage of using an RSIR motor? High efficiency Variable speed control Low cost High power factor Hint 87). 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. Hint 88). Which motor type is commonly used as the main power motor in an RSIR motor? Synchronous motor Induction motor DC motor Universal motor Hint 89). 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 Hint 90). 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. Hint 91). 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 Hint 92). 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 Hint 93). What is the typical speed range of an RSIR motor? Fixed speed Variable speed High speed Low speed Hint 94). 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 Hint 95). 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 Hint 96). What is the power factor of an RSIR motor? Leading power factor Lagging power factor Unity power factor Power factor cannot be determined Hint 97). 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. Hint 98). 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. Hint 99). Who is credited with inventing the Repulsion-Start Induction Run (RSIR) motor? Nikola Tesla Thomas Edison Charles Francis Dalziel Michael Faraday Hint 100). In what decade was the Repulsion-Start Induction Run (RSIR) motor first introduced? 1890s 1910s 1940s 1970s Hint For More MCQs Slip Ring Motor MCQs Three Phase Induction Motor MCQs Switched Reluctance Motor MCQs Reluctance Motor MCQs Induction Motor MCQs Time's up
