Polyphase SystemsThe text excels at explaining the shift from single-phase to polyphase power. It demonstrates how three-phase currents create the rotating magnetic field necessary for industrial motor operation.
The polyphase induction motor is the workhorse of industrial applications. Langsdorf breaks down its operation via:
Theory of Alternating-Current Machines by Alexander S. Langsdorf remains a foundational cornerstone in electrical engineering literature. First published by McGraw-Hill, this classic textbook bridges the gap between electromagnetic theory and practical electrical machinery. It provides an rigorous mathematical and physical analysis of alternating current (AC) systems, making it a timeless resource for students, professors, and practicing power engineers. Overview of the Book
Today, his name lives on in a very tangible way. His legacy continues to shape the next generation of engineers through the program at Washington University's McKelvey School of Engineering, which provides 100% tuition for four years to incoming students with exceptional promise. Theory-alternating-current-machines-alexander-langsdorf-pdf
Langsdorf treats the synchronous motor both as a mechanical driver and a power factor correction device.
\beginbmatrix A_ss&A_sr&B_s\ A_rs&A_rr&B_r\ C_s & C_r & 0 \endbmatrix \beginbmatrix i_s\ i_r\ \omega \endbmatrix + \beginbmatrix v_s\ 0\ -T_load/J \endbmatrix ] | | | Solves the linearized equations assuming sinusoidal excitation. Produces classic phasor relationships and the impedance model of an AC machine. | | 8. Harmonic Effects | Analyzes the influence of non‑fundamental space harmonics on torque ripple and iron losses. Provides formulas for harmonic torque and guidelines for winding design to suppress undesired harmonics. | | 9. Efficiency & Losses | Breaks down losses into copper, core, friction, and stray‑load. Introduces the specific electric loading and specific magnetic loading parameters that later become standard design metrics. | | 10. Design Examples | Two illustrative designs: 1. A 3‑phase, 60 Hz, 5 kW synchronous motor. 2. A 3‑phase, 60 Hz, 10 kW squirrel‑cage induction motor. Shows step‑by‑step calculation of dimensions, winding turns, and expected performance. | | 11. Conclusions & Future Work | Summarizes the theoretical contributions and hints at extensions (e.g., non‑linear magnetic material, transient analysis). | | Appendices | A. Derivation of the winding function Fourier series. B. Tables of standard machine constants. C. Sample MATLAB/Fortran code (historical) for numerical solution. |
Though stationary, transformers share the same electromagnetic principles as rotating machinery. Polyphase SystemsThe text excels at explaining the shift
Internet Archive: As an older academic text, digital versions are frequently hosted on the Internet Archive for non-profit lending and research.
(like transformers or synchronous motors) or perhaps analyze the mathematical techniques used in the book?
The text systematically breaks down the operation of machines into several key theoretical pillars: Langsdorf breaks down its operation via: Theory of
Detailed analysis of mutual inductance, core losses (hysteresis and eddy currents), and leakage reactance.
When searching for legal digital copies, academics typically turn to institutional repositories, university library archives, open-content digital libraries (like Internet Archive), or authorized textbook distributors. Final Value Assessment
Langsdorf begins with a rigorous review of alternating current fundamentals, wave shapes, and complex quantities (phasors). He establishes the fundamental laws of magnetic circuits, focusing on: Hysteresis and eddy current losses in core materials.