Wave transmission lines and networks – Automatically controlled systems – With control of equalizer and/or delay network
Patent
1974-09-09
1976-08-03
Miller, J D
Wave transmission lines and networks
Automatically controlled systems
With control of equalizer and/or delay network
317 15, 317 31, 333 79, H02H 720, H02H 320
Patent
active
039731707
ABSTRACT:
A data communication system for an industrial plant includes a plurality of communication stations which are interconnected by a coaxial cable that is required to pass through one or more hazardous areas. The communication stations are energized from a source of alternating voltage of commercial frequency and are arranged to transmit over and to receive from said cable communicating signals that have frequencies which are substantially higher and that have an energy level which is substantially lower than that of the frequency and energy level, respectively, of the power source. Each of said stations is coupled to the cable by an individually associated intrinsic safety barrier each of which includes an iron core transformer. Each transformer includes a primary winding connected in circuit with the associated station and an inductively coupled secondary winding that is connected between the sheath and the internal conductor of the cable. Resistors and fuses are included in the transformer primary winding circuit to interrupt the latter upon an apparatus failure or other occurrence that results in direct application of the power source voltage to the primary winding.
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"Line-Sharing Systems for Plant Monitoring and Control"; Aronson; Jan. 1971, pp. 68-69.
Bodenstein George E.
Burton Lockwood D.
Honeywell Inc.
Marhoefer Laurence J.
Miller J D
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