| 摘要 |
<p>An engine-driven alternator assembly 50 has an output winding 62 with a relatively high impedance providing an inherent ballasting characteristic, such that the alternator can be used to operate a lamp 24 and limit the current thereto without any separate substantial impedance between the winding and lamp. The lamp may be particularly a high pressure metal halide lamp, or alternatively a high pressure sodium or mercury lamp, a low pressure metal halide or sodium lamp, a fluorescent lamp, or to a limited extent an incandescent lamp. A small modifying ballast may be connected between the alternator and the lamp to provide a desired optimal impedance characteristic. For a discharge lamp, the alternator provides a relatively high starting voltage and a lower sustaining voltage. The alternator-driving engine 58 may be constructed and/or controlled to produce the required voltage droop characteristic of the alternator. The alternator may be a permanent magnet type (Figs.4-7), a switched reluctance type (Figs.15-17), an induction alternator (Figs.18-21) or a synchronous wound type, and may give an output at 200 to 600Hz. The lamp may be operated on direct current by connecting a rectifier (147, Fig.22) between the alternator and the lamp. A plurality of alternator units 56 may have rotors 60 on a common shaft and stator windings 59 supplying respective lamps 24. A mobile lighting tower may have a trailer (12, Figs.1,2) on which the engine and alternator assembly are mounted to supply four metal halide lamps 24 supported by a telescopic boom (20).</p> |
