Understanding Universal Motors Operation — Lesson 4

This lesson covers the operation and characteristics of universal motors. It explains why these motors are termed 'universal', as they can operate from both AC and DC supply. The lesson further elaborates on the concept of unidirectional torque produced by these motors, even when the current reverses. It also highlights the importance of laminating the stator in a series motor for efficient operation from both AC and DC supply. For instance, if a DC series motor designed for DC supply is energized with AC supply, the core losses will be high on the stator, hence the need for lamination.

Video Highlights

00:15 - Explanation of the torque production in the universal motor
01:52 - Introduction to testing on DC machines
04:34 - Discussion on the calculation of efficiency in DC machines
08:53 - Explanation of the Swinburne Test for estimating rotational loss
15:27 - Introduction to the Hopkinson test for DC machines

Key Takeaways

• Universal motors can operate from both AC and DC supply.
• Unidirectional torque is produced in universal motors even when the current reverses.
• If a DC series motor designed for DC supply is energized with AC supply, the core losses will be high on the stator.
• To operate a series motor from both AC and DC supply, the stator ions should be laminated apart from the armature.