Communications: electrical – Condition responsive indicating system – With particular system function
Patent
1987-06-11
1988-07-05
Levy, Stewart J.
Communications: electrical
Condition responsive indicating system
With particular system function
G08B 2100
Patent
active
047557974
ABSTRACT:
A fire alarm apparatus includes a fire receiver, a pair of transmission lines extending from the fire receiver, a series of nonpolar fire detectors connected to the transmission lines, and a terminating unit, connected to the end terminals of the transmission lines, the terminating unit having an impedance element including a polar element. Each fire detector includes polarity inverting circuitry which includes a limit switch, arranged at a socket portion of the detector, and having a switch lever which is actuated by the detector body engaging with the socket portion; and diodes for inverting the polarity of the pair of transmission lines in synchronism with actuation of the switch lever. The polarity of the transmission lines after a detector is inverted when a detector body is detached from that detector.
REFERENCES:
patent: 4369435 (1983-01-01), Adachi et al.
Levy Stewart J.
Nittan Co., Ltd.
Roskos Joseph W.
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