Apparatus Section 17: Synchronous Machines: Short-circuit Currents of Alternators
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Source Metadata
Section titled “Source Metadata”| Field | Value |
|---|---|
| Source | Theoretical Elements of Electrical Engineering |
| Year | 1915 |
| Section ID | theoretical-elements-electrical-engineering-section-38 |
| Location | lines 10190-10429 |
| Status | candidate |
| Word Count | 1464 |
| Equation Candidates In Section | 0 |
| Figure Candidates In Section | 0 |
| Quote Candidates In Section | 0 |
Opening Source Excerpt
Section titled “Opening Source Excerpt”XVII. Short-circuit Currents of Alternators 31. The short-circuit current of an alternator at full-load excitation usually is from two to five times full-load current, and even less in very large high-speed steam turbine alternators. It is where EQ = nominal generated e.m.f., ZQ = synchronous impe- dance of alternator, representing the combined effect of arma- ture reaction and armature self-inductance. In the first moment after short circuiting, however, the current frequently is many times larger than the permanent short- circuit current, that is, where z = self-inductive impedance of the alternator. That is, in the first moment after short circuiting the poly- phase alternator the armature current is limited only by the arma- ture self-inductance, and not by the armature reaction, and some appreciable time — occasionally several seconds — elapses before the armature reactionSource-Located Theme Snippets
Section titled “Source-Located Theme Snippets”Field language
Section titled “Field language”... ure current is limited only by the arma- ture self-inductance, and not by the armature reaction, and some appreciable time — occasionally several seconds — elapses before the armature reaction becomes effective. At short circuit, the magnetic field flux is greatly reduced by the demagnetizing action of the armature current, and the gen- SYNCHRONOUS MACHINES 161 erated e.m.f. thereby reduced from the nominal value EQ to the virtual value Ez; the latter is consumed by the armature s ...Radiation / light
Section titled “Radiation / light”... simultaneously start from zero in all phases and gradually approach their symmetrical appear- ance, i.e., in a three-phase machine three currents displaced by 120 degrees. Hereby the field current is made pulsating, with nor- mal or synchronous frequency, that is, with the same frequency as the armature current. This full frequency pulsation gradually dies out and the field current becomes constant with a polyphase short circuit, while with a single-phase short circuit it remains 162 EL ...Magnetism
Section titled “Magnetism”... the armature current is limited only by the arma- ture self-inductance, and not by the armature reaction, and some appreciable time — occasionally several seconds — elapses before the armature reaction becomes effective. At short circuit, the magnetic field flux is greatly reduced by the demagnetizing action of the armature current, and the gen- SYNCHRONOUS MACHINES 161 erated e.m.f. thereby reduced from the nominal value EQ to the virtual value Ez; the latter is consumed by the arma ...Waves / transmission lines
Section titled “Waves / transmission lines”... short-circuit current of the machine can be made to decrease somewhat more rapidly by increasing the resistance of the field circuit, that is, wasting exciting power in the field rheostat. In the very first moment the short-circuit current waves are unsymmetrical, as they must simultaneously start from zero in all phases and gradually approach their symmetrical appear- ance, i.e., in a three-phase machine three currents displaced by 120 degrees. Hereby the field current is made pulsa ...Chapter-Local Concept Hits
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Modern Engineering Reading Prompts
Section titled “Modern Engineering Reading Prompts”- Field language: Read for whether field language is mechanical, geometrical, causal, descriptive, or simply a convenient engineering model.
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Ether-Field Interpretive Boundary
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