Class 4 (4th Engineer) MET 📅 Feb 2026

Exam Question

(a) Describe the basic principles a self-excited generator. (6)

(b) The armature resistance of a 200 V, shunt motor is 0.4 ohms and the no-load armature current is 2A. When fully loaded and taking an armature current of 50 A, the speed is 1200 rev/min. Find the no-load speed and state the assumption made in the calculation. (10)

Reference Answer

### (a) Basic Principles of a Self-Excited Generator (6 Marks)
#### 1. Fundamental Principle
A self-excited DC generator utilizes its own armature output current to energize its field windings, thereby creating the magnetic field necessary for electricity generation. This is distinct from a separately excited generator, which requires an independent external DC source for field excitation. The entire process relies on the phenomenon of **residual magnetism** within the generator's field poles.
#### 2. Voltage Build-Up Process

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