UPSC IES/ESE (Engineering Services) Electrical Machines, Power Systems and Power Electronics Syllabus

Electrical Machines, Power Systems and Power Electronics syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Electrical Machines, Power Systems and Power Electronics in UPSC IES/ESE (Engineering Services), not a summary of it.

1. 1

   Electromagnetic Theory and Circuit Fundamentals

   4 topics

   • Electrostatics, magnetostatics and Maxwell's equations
   • Network theorems and transient analysis
   • AC circuits, resonance and three-phase systems
   • Two-port networks and filters
2. 2

   DC Machines and Transformers

   4 topics

   • Construction, EMF and torque equations of DC machines
   • DC motor characteristics, starting and speed control
   • Single-phase and three-phase transformers
     • Equivalent circuit and efficiency
     • Auto-transformers and parallel operation
   • Testing and losses in machines
3. 3

   Induction and Synchronous Machines

   4 topics

   • Three-phase induction motor principle and characteristics
   • Starting, speed control and braking of induction motors
   • Synchronous generators and voltage regulation
   • Synchronous motors and power factor control
4. 4

   Power System Generation and Transmission

   4 topics

   • Generation and economics of power systems
   • Transmission line parameters and performance
     • Short, medium and long lines
     • Corona and insulators
   • Distribution systems and cables
   • Load flow and power system stability
5. 5

   Switchgear, Protection and Fault Analysis

   4 topics

   • Symmetrical and unsymmetrical fault analysis
   • Circuit breakers and protective relays
   • Protection schemes for lines, transformers and generators
   • Insulation coordination and overvoltage protection
6. 6

   Power Electronics and Drives

   4 topics

   • Power semiconductor devices and characteristics
   • Rectifiers, choppers and inverters
     • Controlled rectifiers
     • PWM inverters
   • AC and DC drives
   • FACTS devices and HVDC basics

Electrical Machines, Power Systems and Power Electronics flashcards for UPSC IES/ESE (Engineering Services)

23 of 60 cards from the Electrical Machines, Power Systems and Power Electronics deck — real questions with worked answers.

1. State the differential (point) form of Gauss's law for electric fields.

   $\nabla \cdot \vec{D} = \rho_v$, where $\vec{D}$ is the electric flux density and $\rho_v$ is the volume charge density. Equivalently $\nabla \cdot \vec{E} = \dfrac{\rho_v}{\varepsilon}$.

2. Write Maxwell's four equations in differential form for time-varying fields.

   $\nabla \cdot \vec{D} = \rho_v$, $\nabla \cdot \vec{B} = 0$, $\nabla \times \vec{E} = -\dfrac{\partial \vec{B}}{\partial t}$, $\nabla \times \vec{H} = \vec{J} + \dfrac{\partial \vec{D}}{\partial t}$.

3. What term did Maxwell add to Ampère's law and what is its expression?

   The displacement current density $\vec{J_d} = \dfrac{\partial \vec{D}}{\partial t}$. It accounts for time-varying electric fields (e.g. in a capacitor) and makes the equations consistent with charge continuity.

4. State Coulomb's law for the force between two point charges in vacuum.

   $\vec{F} = \dfrac{1}{4\pi\varepsilon_0}\dfrac{q_1 q_2}{r^{2}}\,\hat{r}$, with $\varepsilon_0 = 8.854\times10^{-12}\ \text{F/m}$.

5. Give the capacitance of a parallel-plate capacitor and the energy stored in it.

   $C = \dfrac{\varepsilon A}{d}$ and stored energy $W = \dfrac{1}{2}CV^{2} = \dfrac{1}{2}\dfrac{Q^{2}}{C}$.

6. State the Biot–Savart law for the magnetic field due to a current element.

   $d\vec{B} = \dfrac{\mu_0 I\,d\vec{l} \times \hat{r}}{4\pi r^{2}}$.

7. What is the magnetic field inside a long solenoid, and the energy stored in an inductor?

   $B = \mu_0 n I$ (n = turns per metre). Energy stored in an inductor: $W = \dfrac{1}{2}L I^{2}$.

8. State Thévenin's theorem.

   Any linear two-terminal network can be replaced by a single voltage source $V_{th}$ (open-circuit voltage) in series with a resistance $R_{th}$ (resistance seen from the terminals with all independent sources deactivated).

9. State the Maximum Power Transfer theorem for a DC source with internal resistance.

   Maximum power is delivered to the load when $R_L = R_{th}$ (source internal resistance). The maximum power is $P_{max} = \dfrac{V_{th}^{2}}{4R_{th}}$, with efficiency $50\%$.

10. For a source-free series RL circuit, write the current transient response.

    $i(t) = I_0\,e^{-t/\tau}$ with time constant $\tau = \dfrac{L}{R}$.

11. For a source-free series RC circuit, write the capacitor voltage transient and time constant.

    $v_C(t) = V_0\,e^{-t/\tau}$ with $\tau = RC$.

12. State the condition (in terms of damping) for an RLC circuit to be critically damped.

    Critical damping occurs when $\zeta = 1$, i.e. $R = 2\sqrt{\dfrac{L}{C}}$ for a series RLC circuit, where $\alpha = \dfrac{R}{2L} = \omega_0 = \dfrac{1}{\sqrt{LC}}$.

13. State Superposition theorem and its limitation.

    In a linear network the response due to multiple independent sources equals the sum of responses due to each source acting alone (others deactivated). Limitation: it does not apply to power (a nonlinear quantity).

14. Give the resonant frequency and quality factor of a series RLC circuit.

    Resonant frequency $f_0 = \dfrac{1}{2\pi\sqrt{LC}}$. Quality factor $Q = \dfrac{\omega_0 L}{R} = \dfrac{1}{R}\sqrt{\dfrac{L}{C}}$.

15. At series resonance, what are the impedance, current and power factor?

    Impedance is minimum and purely resistive ($Z = R$), current is maximum ($I = V/R$), and power factor is unity. $X_L = X_C$.

16. Relate bandwidth, resonant frequency and Q-factor for a resonant circuit.

    $\text{BW} = f_2 - f_1 = \dfrac{f_0}{Q}$, where $f_1$ and $f_2$ are the half-power frequencies.

17. Define average (real), reactive and apparent power, and power factor in AC circuits.

    Real $P = VI\cos\phi$ (W), reactive $Q = VI\sin\phi$ (VAR), apparent $S = VI$ (VA), with $S^{2} = P^{2}+Q^{2}$ and power factor $= \cos\phi = \dfrac{P}{S}$.

18. In a balanced three-phase star (Y) connection, relate line and phase voltages/currents.

    $V_L = \sqrt{3}\,V_{ph}$ and $I_L = I_{ph}$.

19. In a balanced three-phase delta ($\Delta$) connection, relate line and phase voltages/currents.

    $V_L = V_{ph}$ and $I_L = \sqrt{3}\,I_{ph}$.

20. Give the total power in a balanced three-phase system in terms of line quantities.

    $P = \sqrt{3}\,V_L I_L \cos\phi$ (same expression for both star and delta when using line values).

21. Define the ABCD (transmission) parameters of a two-port network.

    $\begin{pmatrix}V_1\\I_1\end{pmatrix} = \begin{pmatrix}A & B\\C & D\end{pmatrix}\begin{pmatrix}V_2\\-I_2\end{pmatrix}$. For a reciprocal network $AD-BC=1$; for a symmetrical network $A=D$.

22. State the reciprocity and symmetry conditions for Z-parameters of a two-port.

    Reciprocity: $Z_{12}=Z_{21}$. Symmetry: $Z_{11}=Z_{22}$.

23. Define cutoff frequency of a filter and name the four basic ideal filter types.

    Cutoff frequency $f_c$ is the half-power ($-3$ dB) frequency separating passband from stopband. Types: low-pass, high-pass, band-pass, band-stop (band-reject).

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