JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELEMENTS OF ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (October - 2020 - R15)

DC generators are primarily classified based on the method of field excitation:

1. Separately Excited DC Generator: The field winding is energized by an external independent DC source. The generated voltage depends on the field current and speed.
2. Self-Excited DC Generator: The field winding is energized by the current produced by the generator itself. These are further categorized as:
   • Shunt Wound: The field winding is connected in parallel with the armature. It maintains a nearly constant terminal voltage.
   • Series Wound: The field winding is connected in series with the armature. The terminal voltage increases with the load current.
   • Compound Wound: Combines both series and shunt field windings. It can be Cumulative (fluxes assist each other) or Differential (fluxes oppose each other).

To find the current 'i' in a circuit, apply Kirchhoff's Laws or Nodal/Mesh analysis. Assuming the standard circuit configuration for such problems where a voltage source V is connected to a network of resistors R1, R2, and R3:

1. Identify the total equivalent resistance (R_eq) of the network as seen by the source.
2. Apply Ohm's Law:
   i = V / R_eq
3. If the circuit contains multiple loops, use Mesh Analysis by assigning currents I1, I2 to each loop and solving the simultaneous equations:
   ΣV = Σ(I × R)
4. Substitute the known values of resistance and voltage from the figure to calculate the specific value of 'i'.