Fire alarm system
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
May 21, 1991
Issued Date -
N/A
app pub date -
Oct 2, 1990
filing date -
Nov 30, 1987
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
In a fire alarm system including a plurality of addressable detectors connected to a main circuit extended from a central receiving unit, any alarming detector is discriminated and indicated in accordance with its address on the receiving unit side. In this system, one of the addressable detectors is assigned as a group master detector to each of areas under surveillance and the other detectors within the same area under surveillance have no addressing function. The unaddressable detectors are dependently connected to the group addressable detector within the same area under surveillance. Each of the addressable detectors includes a current limiting circuit which upon alarming limits the amount of current supplied to the main circuit to which the addressable detector is connected, and a changeover circuit for changing over the limited current value by the current limiting circuit to a lower value in response to an address-designated control signal supplied from the receiving unit when the number of alarming detectors exceeds a predetermined number.
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