Understanding Speed Control in Series Motors — Lesson 3

This lesson covers the principles of speed control in series motors, focusing on the control of applied voltage and field current. It explains how series motors are used in traction due to their ability to provide large starting torque. The lesson also discusses the use of multiple DC motors at the start and how they can be connected in series or parallel to control speed. It further delves into the concept of reversing the supply voltage and the impact on the direction of the motor. The lesson concludes with an exploration of the use of AC supply in DC series motors and the conditions under which this is possible.

Video Highlights

00:58 - Discussion on the use of series motors in traction
11:52 - Explanation on why a shunt motor will not work with an AC supply
20:59 - Discussion on the possibility of operating a series motor with an AC supply
26:15 - Discussion on the performance of a series motor when operated from an AC supply
30:23 - Conclusion of the lecture and introduction to the next topics

Key Takeaways

• Series motors are widely used in traction due to their ability to provide large starting torque.
• Multiple DC motors can be connected in series or parallel at the start to control speed.
• Reversing the supply voltage does not change the direction of the motor.
• DC series motors can operate with AC supply, provided the field current and armature current are in the same time phase.
• For a DC series motor to operate from an AC supply, both the stator structure and the armature must be laminated to increase the efficiency of the machine.