Understanding DC Motors: Start, Control, Braking — Lesson 2

This lesson covers the fundamental aspects of DC motors, particularly shunt and separately excited motors. The three main areas of focus are the starting of the machine, speed control, and electrical braking. The lesson explains the role of a starter in protecting the machine from high current drawn at the start due to the absence of back EMF. It also discusses the use of an electromagnet in case of overload or under voltage situations. The lesson concludes with a study of speed control aspects of DC shunt and separately excited motors.

Video Highlights

02:16 - Explanation of why DC motors were popular for Pit control of the machine in the past
14:01 - Discussion on how the speed of the machine changes from no load to full load and the concept of speed regulation
31:14 - Discussion on how the machine operates at different speeds while supplying the same load torque by controlling the armature resistance
34:43 -Explanation of why the armature resistance control method is not efficient due to the extra power loss in the external resistance

Key Takeaways

• DC motors, particularly shunt and separately excited motors, have three main aspects - starting, speed control, and electrical braking.
• A starter is used in DC motors to protect the machine from high current drawn at the start due to the absence of back EMF.
• An electromagnet is used in DC motors to handle overload or under voltage situations.
• The speed control of DC shunt and separately excited motors is a crucial aspect of their operation.