Loss Calculations in Induction Machines - II — Lesson 2

This lesson covers the intricate process of calculating losses in an induction machine. It delves into the mechanical losses, including bearing and windage losses, and how they are influenced by factors such as shaft speed, bearing type, and properties of lubricants. The lesson also explains how to calculate bearing losses using a specific equation and the factors that contribute to windage losses. It further discusses stray load losses and how they are calculated based on the machine's rating. The lesson concludes with the calculation of the machine's efficiency, output power, and torque, as well as the power and torque density of the induction machine.

Video Highlights

00:00 - Introduction
00:18 - Explanation of mechanical losses
01:52 - Calculation of bearing losses
03:07 - Discussion on windage losses
07:49 - Calculation of stray load losses
11:58 - Calculation of machine's efficiency and output power
12:36 - Calculation of power and torque developed by the machine
15:35 - Calculation of mass, torque and power density of the machine

Key Takeaways

- Mechanical losses in an induction machine are a result of bearing friction losses and windage losses of the rotating rotor.
- Bearing losses depend on the shaft speed, bearing type, properties of lubricants, and the load acting on the bearing.
- Windage losses are a consequence of friction between the rotating surface and the surrounding air.
- Stray load losses are the losses caused by load currents and their spatial harmonics in the windings, laminations, or frame, which are not considered during other loss component calculations.
- The efficiency of the machine is calculated by dividing the output power by the sum of the output power and losses.