Det-Tronics C7051B, C UV Flame Detector - Manual (Page 8)

2. The alarm output is energized (solid state - open
collector). The alarm is activated when any zone
detects a fire.
3. The ZONE display shows the number of the first
responding zone. The DETECTOR display is
blank.
4. The SYSTEM STATUS display shows a “6”, indicat-
ing fire.
5. If the voting criteria (see below) have been satis-
fied, the fire logic output is energized and the fire
logic LEDs are illuminated.
NOTE
When the UV signal (count rate) falls below the
sensitivity threshold, the zone and fire logic out-
puts are de-activated and their corresponding
LEDs are turned on (steady state). If the latching
option (see below) has been selected, the outputs
will remain activated and their corresponding
LEDs will continue to blink. The alarm output is a
latching output and will remain activated after the
UV signal has been removed.
CONTROLLER SENSITIVITY AND TIME DELAY
The R7404 Controller can be programmed to respond
only when a specific level of UV radiation has been
exceeded, and to require that the duration of the radia-
tion is greater than a desired time period (see also:
“Installation” section). Selection of controller sensitivity
and the time delay to be used in a given application is
dependent on the level of hazard present, and the action
to be taken in the event of a fire. The programmable
sensitivity and time delay of the R7404 system allow it to
meet the requirements of virtually any application.
Sensitivity is field programmable (in increments of 8 cps)
over a range of 8 through 120 counts per second. The
maximum response distance (highest sensitivity) is
achieved at an eight cps sensitivity setting. For applica-
tions involving high background UV radiation potential,
the system can be desensitized by increasing the count
rate required to actuate it. The 120 cps setting (minimum
sensitivity) results in the minimum response distance.
The fire response output signals can be delayed (in
quarter second intervals) over a range of 0.5 to 8.25 sec-
onds.
Although there is one delay setting for the entire con-
troller, the response of each zone output is affected by
the time delay individually. For example: If zone one
detects a fire, the zone one output will be activated pro-
vided UV radiation is continuously detected for the pre-
selected time delay. If zone three detects a fire at a later
time, the microprocessor will again require that UV is
detected continuously for the time delay period before
activating the zone three output.
NOTE
Setting the controller at maximum sensitivity and
minimum delay may increase the possibility of
false system actuation. Consult Detector
Electronics’ Customer Service Department if such
a setting is desired.
CONTROLLER - FIRE LOGIC “VOTING”
“Fire Logic” is activated when a preset number of zones
sense UV radiation (see “Installation” section). Up to
four zones can “vote” together. Specifically, the con-
troller can be programmed so that one, two, three or four
of zones 1 to 4 detect fire before activating the fire logic
output. Unless the controller is programmed for latching
outputs (see below), voting criteria can be satisfied only
by simultaneously activated zones. Figure 4 is a brief
flow chart of fire logic selection and voting.
The external data bus is used to connect up to four con-
trollers so that up to 16 detectors can vote together.
The Det-Tronics “voting” principle allows combinations of
detectors to fulfill voting requirements and represents the
best balance between reliability of fire detection and
freedom from false actuation due to individual detector
malfunction.
CONTROLLER - LATCHING OUTPUTS
The controller can be field-programmed to have latching
or non-latching outputs (see “Installation” section). If the
controller is programmed for latching outputs, all
responding zone and fire logic outputs will remain acti-
vated (6-status) until manually reset. If the controller is
programmed for non-latching outputs, all activated
zones and fire logic outputs will be deactivated and their
respective LEDs will be illuminated (steady state) after
UV radiation has been removed. The alarm output is
latching and, once activated, will remain so until manual-
ly reset (via the TEST/ACCEPT button or the External
Accept input). When the controller is programmed for
latching outputs, the fire logic (voting) criteria can be sat-
isfied by detector zones that are latched on. In this case,
simultaneous detection of fire is not required to satisfy
voting criteria.
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