Detcon 400FB - Manual (Page 5)

Detcon Model 1/2/400FB Gas Detection System PG.5
HIGH LO
W SP
AN ZER
O
ALARM ADJUSTMENTS
CAUTION:
LCD ADJUSTMENTS
ARE FACTORY SET
CHANNEL 4
F4
CHANNEL 3
F3
CHANNEL 2
F2
CHANNEL 1
F1
LOW
ALARM
HIGH
ALARM
NO
NC
C
GND
NO
NC
C
GND
+V
COM MA SW1 +V
COM MA SW1 +V
COM MA SW1 +V
COM MA SW1
❏
1.10 START UP
Upon completion of all field wiring, apply
12 vdc (or optional 117 VAC) to the power
cable. Note that the LDC indicator
illuminates. Varying readings may occur
during sensor warm-up. Refer to section
3.0 for additional sensor start-up detail.
01.
02.
03.
04.
NOTE: Refer to figure 4 for location of alarm set potentiometers.
To set the alarms you will apply a gas sample to the sensor on channel #1 and then adjust
the signal on that sensor with the "COARSE" span potentiometer until the reading on the
LCD display is equal to the point at which you want the alarm to fire. (See section 3.0 for
more detail on Detcon sensor assemblies).
NOTE: This procedure only needs to be done once and may be done off location in advance if
desired. This procedure will require that the sensor on channel 1 be recalibrated as
instructed in section 3.0 of this manual. Each time the alarms are changed using this
method be sure to recalibrate the sensor being used.
For example, if you want to set the low alarm at 10 ppm and the high alarm at 20 ppm follow
the steps below.
Apply a gas sample to the sensor at channel 1 and turn its "COARSE" span potentiometer
until the LCD display reads 10.
Turn the "Alarm Set Low" potentiometer (located on back of the controller circuit board) until
the low alarm LED on the front panel illuminates. If you have the strobe option, the strobe
will also activate.
Adjust the signal input (via Coarse potentiometer on sensor #1) above and below the low
alarm set point to verify the exact firing point and make any further adjustments as
neccessary.
Next, repeat the same procedure for the High alarm (first set the LCD display to 20).
Alarm set is complete. Both Low and High alarms may be independently set over the range
from 0-100 ppm. The alarm set points are common to all sensors connected to the enclosure.
NOTE: Alarms may be set without interfering with the Coarse potentiometer (on sensor
transmitter) by applying an appropriate gas sample and adjusting the Low and High alarm
potentiometers as the gas concentration passes the desired alarm set point as seen on the
LCD indicator. This method will not interfere with calibration but may be more tedius to
perform.
❏
1.11 SETTING ALARMS
Fig. 4
Controller Circuit Board
Connector side view