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Electrical Machines

Electrical Machines for GATE Electrical Engineering, one topic per lesson: the theory in plain words, the formulas, a solved example, and GATE-style questions (MCQ, MSQ and NAT) whose numerical answers are recomputed by a program when the site is built.

Start the first lesson

1Transformers

  1. Magnetic Circuits and Single-Phase TransformersMagnetic circuits and reluctance, EMF equation of a transformer, equivalent circuit, open and short-circuit tests, voltage regulation, losses, efficiency and condition for maximum efficiency.
  2. Three-Phase Transformers and AutotransformersThree-phase transformer connections and phase shifts, vector groups, autotransformer copper saving and power transfer, parallel operation and load sharing, and per-unit impedance.

2DC Machines

  1. DC Machines: Generators and MotorsEMF and torque equations, lap and wave windings, types of excitation, armature reaction and commutation, generator characteristics, motor speed and torque, speed control, starting and losses.

3AC Machines

  1. Three-Phase and Single-Phase Induction MotorsRotating magnetic field, synchronous speed and slip, equivalent circuit and power flow, torque-slip characteristic, maximum and starting torque, starting methods, speed control and single-phase motors.
  2. Synchronous Generators and MotorsEMF equation with winding factors, synchronous reactance, phasor diagram, voltage regulation methods, power-angle characteristic, parallel operation and synchronisation, V-curves and synchronous motor starting.