Winding Table of 120 degree Phase Spread Coils and Group Connection — Lesson 2

This lesson covers the concept of 120-degree phase spread winding in electrical machines. It explains how to handle different numbers of poles and slots, using an example of a machine with 24 slots and 4 poles. The lesson further elaborates on how to distribute the winding for different phases (R, Y, and B) over a pair of poles. It also discusses the creation of a winding table and the importance of correct polarity when connecting the coils. The lesson concludes with an explanation of how a rotating magnetic field is produced by a stationary polyphase balanced winding when excited by a balanced three-phase current.

Video Highlights

00:24 - Example of a machine with 24 slots and 4 poles
03:08 - Creation of a winding table
10:51 - Importance of correct polarity when connecting the coils
19:58 - Production of a rotating magnetic field by a stationary polyphase balanced winding

Key Takeaways

- In a 120-degree phase spread winding, the number of group of coils equals the number of pair of poles.
- The polarity of the voltages in the winding is crucial. Incorrect connection can lead to internal short-circuits.
- The winding can be connected in series for high-voltage machines or in parallel for low-voltage, high-current machines.
- A balanced three-phase winding, when excited by a balanced three-phase current, produces a rotating magnetic field.