Fireray 2000 - System Description; Smoke Detection; Auto Reset Configuration; Automatic Gain Control (AGC)

FIRERAY 2000
01B-05-S1
02 1/01
PAGE 2 of 5
Table 2 gives the meaning of the LED indications on the PCB in the Control Box - see Fig 1.
* When the received signal level changes, either an increase or decrease by more than 10%, the corresponding Signal High
(LED 2) or the Signal Low (LED 3) will come ON and an AGC change is requested.
If this request is continuous in each time period (9 hours in increase and about 2 minutes to decrease) the AGC responds
automatically by changing the receiver gain in order to bring the received signal level back to the nominal required level. Only
one stage gain (10%) is affected.
When 15 stages of the AGC gain have been used, ie, the gain increased, the fault relay is turned on then off at a rate of one
per 2 seconds (0.5Hz). The fire alarm will have no further levels of gain compensation available and must not be used.
Note: If maximum AGC gain is reached the alarm will not be reliable and must not be used.
If the signal is reduced any further then the alarm will be signalled.
Check any causes of reaching the AGC limit, such as dirty transmitter or detector round glass area or misalignment.
Clean the glasses thoroughly and check alignment.
LED INDICATION
MEANING OF INDICATION ACTION
Fire Alarm
front panel (RED)
When ON smoke present for 5 seconds.
(40% to 93% obscuration of IR beam).
Wait for conditions to clear and reset the unit by
switching OFF/ON/OFF on Test/Reset switch
Both Signal High and
Signal Low lit
Normal for initial calibration state, both LEDs
should switch off within 45 seconds.
Signal High
(GREEN)
Increase of about 10% of signal input (by AGC) Ensure that the AGC will reduce the gain to bring
down the signal down to the nominal level
Signal Low
(GREEN)
Loss of about 10% of signal input Ensure that in normal operation the AGC will
increase the gain to bring the signal up to nominal
Fault
(YELLOW)
1 ON when maximum Gain is reached No more levels of compensation are available*
2 ON when Reset switch is ON Ensure Test/ Reset switch is in Test position when
returning the detector to normal operation
3 ON if the Both Signal High and Signal Low
fail to extinguish after the 45 second calibration
period.
Faulty unit
Table 2 LED Indication (Circuit Board in Control Box)