Aramco Aramco QM21_GnratrMotr PDF Aramco Aramco QM21_GnratrMotr PDF Questions Available Here at: https://www.certification-exam.com/en/dumps/aramco-exam/qm21_gnratrmotr- dumps/quiz.html Enrolling now you will get access to 383 questions in a unique set of Aramco QM21_GnratrMotr Question 1 What is the primary purpose of using a star-delta starter for a three-phase induction motor? Options: A. To increase starting torque above full-load torque B. To reduce starting current during motor startup C. To provide automatic speed control D. To reverse the direction of motor rotation Answer: B Explanation: A star-delta starter is mainly used to reduce the starting current of a three-phase induction motor by initially connecting the stator windings in star configuration, which lowers the voltage across each winding. This reduces current and torque during startup. Option A is incorrect because starting torque is reduced, not increased. Option C is incorrect because star-delta starting does not provide speed control. Option D is incorrect because direction reversal requires changing phase sequence, not star-delta switching. Question 2 What is the basic principle by which an electric motor operates? Options: A. Conversion of mechanical energy into electrical energy by electromagnetic induction B. Conversion of electrical energy into mechanical energy through electromagnetic force C. Storage of electrical energy in magnetic domains Aramco Aramco QM21_GnratrMotr PDF https://www.certification-exam.com/ D. Reduction of resistance by increasing temperature Answer: B Explanation: An electric motor works by converting electrical energy into mechanical energy through electromagnetic force acting on current-carrying conductors in a magnetic field. Option A describes a generator, not a motor. Option C is unrelated to the operating principle of motors. Option D is incorrect because increasing temperature usually increases resistance in conductors. Question 3 Why does a DC motor require a commutator? Options: A. To maintain unidirectional torque by reversing armature current appropriately B. To reduce the supply frequency to zero C. To increase insulation resistance in the winding D. To synchronize rotor speed with stator frequency Answer: A Explanation: A commutator in a DC motor reverses the current in the armature conductors at the proper time so that torque remains in one direction. Option B is incorrect because DC supply already has zero frequency. Option C is incorrect because the commutator does not serve to increase insulation resistance. Option D is incorrect because synchronization with stator frequency is relevant to AC synchronous machines, not DC motors. Question 4 What is the main purpose of the excitation system in a synchronous generator? Options: A. To supply DC current to the rotor field winding B. To provide lubrication to the rotor bearings C. To synchronize generator speed with load torque D. To reduce stator copper losses directly Answer: A Explanation: The excitation system supplies DC current to the rotor field winding to establish the magnetic field required Aramco Aramco QM21_GnratrMotr PDF https://www.certification-exam.com/ for voltage generation in a synchronous generator. Option B is incorrect because lubrication is a mechanical support function. Option C is incorrect because synchronization involves matching conditions before connection, not simply load torque. Option D is incorrect because excitation does not directly reduce stator copper losses. Question 5 What is the primary purpose of an ammeter in an electrical circuit? Options: A. To measure voltage across components B. To measure current flowing through a circuit C. To measure resistance of a conductor D. To measure power factor Answer: B Explanation: An ammeter is designed to measure electric current and is connected in series with the circuit. Question 6 What is the main difference between a single-phase system and a three-phase system? Options: A. A single-phase system uses one alternating voltage waveform, while a three-phase system uses three alternating voltage waveforms separated by 120 degrees B. A single-phase system uses direct current, while a three-phase system uses alternating current C. A single-phase system always has higher power than a three-phase system D. A three-phase system can only be used for lighting loads Answer: A Explanation: A single-phase system has one AC waveform, while a three-phase system has three AC waveforms shifted by 120 degrees. Question 7 What is the primary purpose of Electrical Safety and Lockout/Tagout procedures? Options: Aramco Aramco QM21_GnratrMotr PDF https://www.certification-exam.com/ A. To speed up equipment startup after maintenance B. To prevent unexpected energization or release of stored energy C. To reduce the number of tools needed for repairs D. To improve production output during maintenance Answer: B Explanation: Lockout/Tagout is used to control hazardous energy and prevent accidental startup or energization while work is being performed. Question 8 What is the primary purpose of preventive maintenance for a generator motor? Options: A. To correct failures after they occur B. To reduce the likelihood of unexpected breakdowns C. To increase operating voltage D. To eliminate the need for inspections Answer: B Explanation: Preventive maintenance is designed to detect wear, degradation, or abnormal conditions before they lead to failure. Question 9 What is the primary purpose of a technical schematic in generator-motor documentation? Options: A. To show the exact physical appearance of the equipment B. To represent the functional relationships between components using symbols and lines C. To provide a maintenance schedule D. To list spare parts only Answer: B Explanation: A schematic focuses on function and connection logic, not on physical appearance. Aramco Aramco QM21_GnratrMotr PDF https://www.certification-exam.com/ Question 10 What is the primary function of a transformer in motor and generator systems? Options: A. To change AC voltage levels while keeping frequency the same B. To convert AC into DC C. To increase mechanical torque D. To reduce motor speed directly Answer: A Explanation: A transformer is used to step voltage up or down in AC systems without changing frequency, which is essential in motor and generator power distribution. Would you like to see more? Don't miss our Aramco QM21_GnratrMotr PDF file at: https://www.certification-exam.com/en/pdf/aramco-pdf/qm21_gnratrmotr-pdf/ Aramco Aramco QM21_GnratrMotr PDF https://www.certification-exam.com/