Theory-alternating-current-machines-alexander-langsdorf-pdf -
Report: Theory of Alternating Current Machinery by Alexander S. Langsdorf
4. Why Study the "Old" Text?
In an era dominated by Finite Element Analysis (FEA) software, why do engineers still seek out Langsdorf? Theory-alternating-current-machines-alexander-langsdorf-pdf
Used Bookstores: Hardcover copies are prized by collectors for their high-quality technical illustrations. Report: Theory of Alternating Current Machinery by Alexander
- Electric Machinery by Fitzgerald, Kingsley, Umans (the 6th+ editions are good, but the 4th edition is closest to Langsdorf’s style).
- Analysis of Electric Machinery by Krause, Wasynczuk, Sudhoff (for the state-space/modern control perspective).
- Equivalent Circuit: A simplified circuit representation of an AC machine, used to analyze performance and predict behavior.
- Power Flow: The flow of power through an AC machine, including input power, output power, and losses.
- Synchronous Generator: Detailed analysis of armature reaction (the effect of armature current on the main field flux). Langsdorf distinguishes between the effects of wattless current (distortion) and power current (cross-magnetization).
- Synchronous Motor: Discussion of the "V-Curves" (relationship between field excitation and armature current). He explains how varying DC field excitation affects the power factor of the motor—a critical concept for power system stability.
- Two-Reaction Theory: Later editions incorporate the "Blondel Two-Reaction Theory" (direct and quadrature axis), which is essential for analyzing salient-pole machines.
- Topics: Ideal vs. practical transformers, core losses, copper losses, voltage regulation, and efficiency.
- Method: He derives the exact equivalent circuit, showing how resistances and reactances can be referred from one side of the transformer to the other.
- Significance: His treatment of transformer vector diagrams (phasor diagrams) is considered one of the clearest explanations in vintage literature for understanding the phase relationships between flux, voltage, and current.