(19)
(11) EP 0 967 585 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
10.01.2001 Bulletin 2001/02

(43) Date of publication A2:
29.12.1999 Bulletin 1999/52

(21) Application number: 99304994.9

(22) Date of filing: 25.06.1999
(51) International Patent Classification (IPC)7: G08B 25/04, G08B 26/00
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 27.06.1998 GB 9813883

(71) Applicant: PROTEC FIRE DETECTION PLC
Nelson, Lancashire BB9 6RT (GB)

(72) Inventor:
  • Priest, Eric
    Churchl.Way, Nelson, Lancashire BB9 6RT (GB)

(74) Representative: Robinson, Ian Michael 
Appleyard Lees, 15 Clare Road
Halifax HX1 2HY
Halifax HX1 2HY (GB)

   


(54) Alarm apparatus


(57) An alarm apparatus using a single pair of signal wires (20) coupled to detector units (30) and alarm output units (40). Voltage on the signal wires (20) is reversed to indicate an alarm condition and periodically dipped to a third voltage level to decouple the alarm output units (40) enabling the detector units (30) to be monitored in the alarm state.






Search report