-30-
Section 10 - Dual Redundancy
Discovery Conventional Mode and the Hardware Fire Detection Circuit (HWFD)
Loop powered Sounders, Beacons or Output module attached to the faulty loop WILL NOT operate.
All addressable loop devices communicate with the Loop cards, ED722 and ED726, using the Apollo S90, XP95
or Discovery protocol. If this communication fails (due to microprocessor failure etc.) most panels would have a
total loss of Alarm detection, a very dangerous situation. The ED700A and ED816A have Dual Redundancy, a
secondary method of Fire and Gas Detection, built in to each ED722 and ED726 module when used with
Discovery detectors and EDL’s Gas Detector Interface Units. In the event of communications failure, between
the detectors and the control panel, the detectors can still respond to a Fire or Gas alarm but cannot give the
location details.
For communications to have failed some hardware / software failure must have occurred. It is likely many fault
messages will be displayed depending upon what has failed and an
.
It is impossible to say how much of the system will still function without knowing the exact problem. The
minimum being that the Sounder 1 circuit and the alarm relays operate. If the ED722 / ED726 Loop card
microprocessor is still functioning correctly the following will occur in the event of a Fire or Gas Alarm:
the alarm lamps, buzzers and relays will operate and the following screen will be displayed:
If
internal system communications are functioning the EVAC command will also be given, operating the Immediate
Fire / Gas alarm relay, the pre-alarm relay and Sounders 2 and 3. All sounders connected to fully functional
loops will also operate.
Pressing “MUTE” will silence all sounders. Removing the detector in alarm and pressing the “RESET” buttons
on both the ED816A I/O (see page 29) and ED816A Display will reset the system. If the detector in alarm
cannot be removed ensure it is clear of smoke, heat etc. and then the ED816A should be turned off for a few
seconds and then turned on.
If Sounder 1 does not silence and the Immediate alarm relay, delayed alarm relay, pre-alarm relay and the fault
relays do not return to the normal state this indicates either loop card removal, loop card microprocessor failure
or I/O module failure.
Engineer should be called immediately
10:51 05/06/08
ELECTRONIC DEVICES
NO OF DETECTORS IN ALARM:
1
IN
0 ZONES
10:50 05/06/08 CONV MODE ALARM
FIRE ON LOOP 1
PRE ALARMS
0 FAULTS
0
ISOL ZONES
0
ED816A Addressable Fire and gas detection Installation manual 8-9-08 Rev-a
