Electrical Machines - II | EveryEng

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Electrical Machines - II

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714 min

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Electrical Engineering

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Why enroll

This course builds a strong conceptual foundation in electrical rotating machines essential for power and industrial applications. It helps students understand machine operation clearly and develop problem-solving skills needed for academics, competitive exams, and core engineering roles.

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Is this course for you?

You should take this if

You work in Automotive
You're a Electrical Engineering professional
You have 3+ years of hands-on experience in this field
You want to build skills in Engineering & Design, Project Management

You should skip if

You're new to this field with no prior experience
You need a different specialisation outside Electrical Engineering
You need live interaction with an instructor

Course details

The course begins by explaining the basic principles governing the operation of different types of electrical rotating machines. It covers the conditions required for steady production of electromagnetic torque (Te) and explains both motoring and generating modes of operation. The primary focus is on three-phase induction machines, single-phase induction motors, and synchronous machines. A sound understanding of distributed windings is essential to grasp the working of rotating machines; therefore, a few lectures are dedicated to this topic. The concepts of electrical and mechanical angles are explained in detail, along with the nature of magnetic flux distribution in the air-gap of rotating machines. A clear understanding of the rotating magnetic field is emphasized as it is fundamental to the operation of induction and synchronous machines. For each machine, the equivalent circuit is derived and used to obtain torque expressions. Topics such as starting, speed control, and electrical braking of motors are discussed. While the main emphasis is on steady-state performance analysis, important transient conditions are also introduced. The course encourages students to develop a logical and efficient approach to solving numerical problems.

Source: NPTEL IIT Kharagpur [Youtube Channel]

Course suitable for

Key topics covered

Relationship of inductances in a transformer
Derivation of equivalent circuit from circuit KVL equations
Co-efficient of coupling and energy stored in coupled coils
Single conductor generator and motor: concept and principle
Analysis of single conductor generator and motor
Analysis of single conductor generator and motor (continued)
Flux density distribution in space and nature of induced EMF
Flux density distribution in space and nature of induced EMF (continued)
Transition from linear machine to rotating machine
From linear to rotating machine (continued)
Basic underlying principle of operation of rotating machines
Basic underlying principle of operation of rotating machines (continued)
Flux density distribution along the air-gap
Flux density distribution along the air-gap (continued)
Induced voltage in a coil in a rotating machine
Induced voltage in a coil in a rotating machine (continued)
Induced voltage in a coil in a rotating machine (continued – I)
Induced voltage due to fundamental and harmonic components of flux density distribution
Resultant voltage of distributed coils connected in series
Distribution factor
Pitch factor and winding factor
Selection of short-pitch angle (ϵ)
Introduction to double-layer three-phase winding

Course content

The course is readily available, allowing learners to start and complete it at their own pace.

25 lectures11 hr 54 min

Opportunities that await you!

Skills & tools you'll gain

Engineering & Design

Project Management

Research & Developmnet

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Questions and Answers

Q: You're closing a DFMEA on a conveyor drive and need to select an induction motor rotor class. Duty is frequent start-stop, 6 starts/hour, high inertia load, ambient 50°C. The purchasing team asks you to confirm after searching 'induction motor rotor selection high inertia frequent starts'. Which rotor choice keeps thermal margin without blowing line current limits?

A: Pick the wrong rotor and you cook the rotor bars during commissioning, then fail the thermal endurance test before SOP. Design D trades efficiency for high starting torque at lower starting current, which protects the rotor under repeated acceleration. Design B looks safe on paper but stalls longer under inertia, stacking I²t. Double-cage helps starting but is still thermally stressed with frequent starts. A wound rotor shorted after start loses the benefit that justifies its complexity.

Q: A synchronous motor is rated 3 MW, 11 kV, 0.9 pf leading, 50 Hz. You're checking excitation current margin after a vendor update and you search 'synchronous motor line current calculation 11 kV 3 MW'. What is the approximate line current at rated load?

Q: During a design review you need a quick estimate of slip for a 4-pole induction motor delivering rated torque at 50 Hz. You type 'typical induction motor slip at full load 4 pole'. What's the defensible order-of-magnitude slip?

Q: A traction motor operates near coastal roads with salt spray and high humidity. You're asked to sign off insulation class and you search 'motor insulation failure salt spray humidity'. What degradation mechanism dominates and drives the correct insulation choice?