Electrical Machines
- What is the working principle of a DC motor and how does Fleming's left-hand rule apply? In one line A DC motor works because a current-carrying conductor placed in a magnetic field experiences a force F = BIl , and the commutato... 1
- What is back EMF in a DC motor and why is it important for the motor's operation? In one line Back EMF is the voltage generated in the rotating armature of a DC motor that opposes the supply voltage; it automatically contr... 1
- What are the main parts of a DC motor and what is the function of each part? In one line A DC motor consists of a stationary field system (yoke, poles, field winding) and a rotating armature (armature core, winding, c... 1
- How does a three-phase supply create a rotating magnetic field in an induction motor stator? In one line When a balanced three-phase current flows in three stator windings placed 120° apart in space, the combined flux has constant ma... 1
- What are the types of DC motors and where are shunt, series and compound motors used? In one line DC motors are classified by how the field winding is connected to the armature: separately excited and self-excited (shunt, seri... 1
- How does a three-phase induction motor work, and what is slip? In one line The rotating stator field cuts the rotor conductors, induces currents in them, and the resulting force drags the rotor along in... 1
- How is a three-phase induction motor constructed, and how do squirrel-cage and slip-ring rotors compare? In one line A three-phase induction motor has a stator with a distributed three-phase winding in a laminated slotted core, and a rotor that... 1
- Where are BLDC motors used, and what are their advantages and limitations? In one line BLDC motors are used wherever high efficiency, long life, quiet operation and precise speed control matter, such as fans, electr... 1
- Why is a single-phase induction motor not self-starting, according to double revolving field theory? In one line A single-phase winding produces a pulsating (not rotating) flux, which can be split into two equal fields rotating in opposite d... 1
- What are the types of single-phase induction motors and where is each type used? In one line Single-phase induction motors are named by how they create starting torque: split-phase, capacitor-start, capacitor-start capaci... 1
- What is a BLDC motor and how does electronic commutation replace brushes? In one line A brushless DC (BLDC) motor has permanent magnets on the rotor and windings on the stator, and an electronic controller switches... 1
- Explain the concept of back emf in a DC motor. When the armature of a DC motor rotates in the magnetic field, its conductors cut the flux, so an EMF is induced in them (generator action,... 1
- Explain the working principle of three phase induction motor and mention its types. Working principle of a three-phase induction motor: Rotating magnetic field: the stator carries a three-phase winding displaced by 120° in s... 1
- Explain the working principle of Brushless DC Motor. Brushless DC (BLDC) motor: a DC-supplied motor in which mechanical commutator and brushes are replaced by electronic commutation. Constructi... 1
- Compare single-phase and three-phase induction motors. PointSingle-phase induction motorThree-phase induction motor Supply1-phase AC3-phase AC Field producedPulsating field (two counter-rotating... 1
- Explain the construction and working principle of a BLDC motor. Brushless DC (BLDC) motor: a DC-supplied motor in which mechanical commutator and brushes are replaced by electronic commutation. Constructi... 1
- Draw the construction of a DC Motor and label its parts. What are the types of DC Motor? Yoke (outer frame) +---------------------------+ | N pole core + field coil | | \_pole shoe_/ | | .-----------------. | | / armature core \... 1
- State the function of each constructional part of a DC motor. PartFunction Yoke (frame)Outer cast-iron/steel frame; gives mechanical support and protection, and carries the magnetic flux (return path) b... 1
- Explain the working principle of three phase induction motor. Working principle of a three-phase induction motor: Rotating magnetic field: the stator carries a three-phase winding displaced by 120° in s... 1
- Write short note on any one: (i) Single phase induction motor (ii) BLDC motor. (Answering option (ii); a note on (i) is also given briefly.) Brushless DC (BLDC) motor: a DC-supplied motor in which mechanical commutator... 1