Magnetic Fields in AC Machines — Lesson 4

This lesson covers the role of commutator rings and segments in DC machines, and the impact of mechanical displacement in AC machines. It further discusses the concept of rotating magnetic fields, their symmetry, and the effect of current excitation on these fields. The lesson uses illustrative examples to explain how the magnitude and direction of the resultant magnetic field vector changes with respect to time in both types of machines.

Video Highlights

00:00 - Magnetic fields in DC and induction machines
02:51 - Impact of current excitation on magnetic fields
06:00 - Examination of the resultant flux direction
23:49 - Drawing resultant flux vector on XY plot

Key Takeaways

- In DC machines, there is a rotating magnetic field, but it is not symmetrical.
- AC machines like induction machines and synchronous machines with a single coil and AC supply do not have a rotating magnetic field.
- The magnitude and direction of the resultant magnetic field vector change with respect to time in both DC and AC machines.
- The mechanical displacement of coils in AC machines plays a significant role in the operation of the magnetic field.