We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
7,000
1.6 2.0 2.4 2.8
Fig. 1. Speed calibration curves for 16mm Fastax Cameras.
most difficult of which was perhaps that of providing sufficient illumination. When the breaker contacts part, an arc is formed which, in this case, would have a duration of 0.06 to 0.07 sec. This arc would be maintained by a recovery voltage of approximately 133,000 v at a current density of 6000 amp. Needless to say, the luminosity of this arc would be extremely high and as it was desired to obtain a recognizable picture of the contacts and their supporting structure prior to arc initiation and after extinction, the problem of obtaining sufficient illumination on these areas was, to say the least, difficult. As anti-aircraft type of searchlights were not available at that time, the illumination used consisted of one narrow-beam 2-kw airport ceiling indicator plus 26 kw of semi-focusing incandescent floodlights concentrated as
much as possible on an area approximately 6 ft in diameter. Incident light thus obtained was approximately 15,000 ft-c.
The results obtained, while permitting fairly satisfactory observation of breaker operation, were not ideal from an exposure standpoint. Considerable manipulation in development of the negative and printing of the positive was required in order to prevent the breaker areas from disappearing completely. As a result, the self-luminous portions which include the actual conducting portions of the arc and surrounding volume of hot gasses blocked up pretty badly.
Recording of HighVoltage Electrical Arc Phenomena
This first use of the high-speed camera led us to believe that it might be a useful tool in investigating the behavior of
676
June 1953 Journal of the SMPTE Vol. 60