Class 4 (4th Engineer) MET 📅 Sep 2022

Exam Question

Draw a diagram showing the essential connection of two compound generators A and B coupled to common bus bars for parallel operation. If A is running on the bus bars and supplying all the load, describe the process of bringing B into commission and adjusting it to take its share of the load. (16)

Reference Answer

### **1. Principle of Parallel Operation**
Parallel operation of DC generators is employed on board ships to meet load demands exceeding the capacity of a single generator, and to provide redundancy for enhanced reliability and maintenance flexibility. For **compound wound generators**, a special connection known as an **Equalizer Bar** is essential for stable load sharing. Without it, the inherent characteristics of the series field winding would lead to one generator taking all the load, potentially causing the other to 'motor' (draw current from the bus bars), leading to system instability and blackout.
### **2. Diagram and Essential Connections**
The diagram below illustrates the critical connections for paralleling two compound generators, A and B, onto common bus bars. The key components are:

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