EP 0011461 A1 19800528 - An improved fire detection system.
Title (en)
An improved fire detection system.
Title (de)
Ein verbessertes Feuerdetektionssystem.
Title (fr)
Système perfectionné de détection du feu.
Publication
Application
Priority
GB 7843944 A 19781110
Abstract (en)
A monitoring system for detecting fire or other elevated temperature conditions in a plurality of discrete zones Z1, Z2, Z3, etc. comprises a loop box 1 which has two pairs of terminals A and B to each of which is connected one end of a pair of conductors of a linear temperature detector cable passing through each of the discrete zones. Adjacent zones are sectionalised by zone boxes 9, each of which comprises a pair of balanced resistors, one resistor connected in series in one conductor of the loop and the other resistor being connected in series in the other conductor. The loop box 1 has a constant current generator 2 which can be connected via an electronic switch 3 to either the A or B end of the loop 4; an electronic switch 5 which connects one of two fixed resistors 6 directly across the two conductors of the loop at the opposite end to that to which the generator 2 is connected; and an electronic switch 7 which connects a voltage measuring circuit 8 onto the terminals of the loop to which the generator 2 is connected. Electronic switches 3, 5 and 7 are operated by control circuits 10 whose output signals are fed to a display device 11, which shows if the system is operating normally, identifies the nature of any abnormalities and indicates any discrete zone in which there is a short circuit caused by a fire, and to external alarms.
IPC 1-7
IPC 8 full level
G08B 17/06 (2006.01); G08B 25/01 (2006.01); G08B 25/04 (2006.01)
CPC (source: EP)
G08B 17/06 (2013.01); G08B 25/018 (2013.01); G08B 25/045 (2013.01)
Citation (search report)
- US 3277457 A 19661004 - LEON HERMAN
- GB 811169 A 19590402 - OLOF INGEMAR HARALD EKMAN
- FR 2205664 A1 19740531 - EURATOM [LU]
- GB 1266424 A 19720308
- US 2452942 A 19481102 - LORD KENNETH M, et al
Designated contracting state (EPC)
BE DE FR IT NL SE
DOCDB simple family (publication)
DOCDB simple family (application)
EP 79302527 A 19791112