Det-Tronics C7051B, C UV Flame Detector - Manual (Page 10)

The basic operation of the Automatic oi program
involves selecting and illuminating a UV test lamp, sens-
ing a return signal from the detector, turning off the UV
test lamp, sensing the termination of the return signal,
and selecting and illuminating the next UV test lamp. In
the R7404 nuclear surveillance system, all detector mod-
ules (both surveillance and fire protection) are continual-
ly checked by the microprocessor programs of the con-
troller.
AUTOMATIC FAULT IDENTIFICATION
In the event of a system malfunction, the microprocessor
branches to an automatic fault identification program.
This feature operates much the same as on previous
generations of Det-Tronics equipment. When a fault
occurs, the (normally energized) solid state fault output
is de-energized, the FAULT LED is illuminated and the
STATUS and ZONE displays are activated to identify the
fault code and (when applicable) the number of the
affected zone. Because there is only one detector mod-
ule per zone, the DETECTOR display will show “0” when-
ever a status change is identified. When a non-fault sta-
tus indication such as “fire” (6-status) occurs, the fault
output remains energized, and the FAULT LED is not
turned on, but the STATUS and ZONE displays are acti-
vated to indicate the status code and number of the
affected zone.
Depending on the zone affected, the 3-status can have
one of two meanings. If the STATUS display shows “3”
and the ZONE display indicates zones 1 to 4, the count
rate of the sensor tube affected has exceeded 50 per-
cent of the controller’s sensitivity setting. If this occurs, a
separate “LOW LEVEL ALARM” output is activated (ter-
minal 39), but the FAULT output is not activated.
If the STATUS display shows “3” and the ZONE display
indicates zones 5 to 8, the blinded surveillance detector
indicated may be in a “runaway” state, uncontrollably
generating counts. This can be checked by using the
count mode test of the controller as described in the
“Checkout” section. If the sensor tube in the blinded
detector module is in a “runaway” state, it and its coun-
terpart in the fire detector module must be replaced.
Tables 1 and 5 provide an explanation of the STATUS
codes of the nuclear surveillance controller.
TEST MODE
Although the automatic optical integrity and fault identifi-
cation features provide continuous monitoring of most of
the system circuitry, a microprocessor controlled test
mode provides a means to positively determine that the
system is operational. The controller is placed in the test
mode by turning the keylock switch to the TEST position.
When the controller is placed in the test mode, the fol-
lowing occurs:
1. Fault output is de-energized and the FAULT LED is
illuminated.
2. Outputs inhibited output (see “Installation” section)
is energized and the INHIBIT LED is illuminated,
indicating that all other outputs are disabled.
3. SYSTEM STATUS display shows a “1”.
4. DETECTOR display shows a “0”.
5. ZONE display indicates the number of the highest
numbered zone.
In the test mode, the SELECT and TEST buttons are
enabled. Pressing the SELECT button causes the micro-
processor to step to the next lower zone, allowing anoth-
er detector to be selected for testing. When the TEST
button is depressed, the UV test lamp of the detector
under test is turned on. After the pre-selected time
delay, the ZONE LED that corresponds to the detector
under test will blink. Because the controller outputs are
inhibited, the data bus or corresponding zone output will
not be energized.
COUNT TEST MODE
The count test is a means of determining the response of
each detector in the system. To enter the count test
mode:
1. Place the keylock switch in the TEST position.
8
UV DETECTOR
UV TEST LAMP
OPTICAL SHIELD
VIEWING WINDOW
SNAP-IN oi RING
UV SENSOR
C784
Figure 5—Fire Detector Module with Oi