Det-Tronics R8471NH34001,2,3 Single Channel Gas Controller, NH3 - Manual (Page 6)

95-8529 1.1 4
SYSTEM OPERATION
SENSOR
The sensor consists of a housing and a field
replaceable electrochemical sensor cell. The sensor
output is a 4 to 20 ma signal that corresponds to gas
levels from 0 to 100% full scale.
The C7067E Sensor (Cl
2
) is intrinsically safe (when
used with an approved intrinsically safe barrier) and
is designed for use in Class I, Division 1, Groups A, B,
C and D locations.
The explosion proof C7068E (SO
2
) and C7069E (NO
2
)
Sensors are designed for use in Class I, Division 1,
Groups C and D locations.
CONTROLLER
Faceplate Description
The controller faceplate provides LEDs for identifying
system status conditions, a digital display and bar
graph display for indicating the sensor input, and
pushbuttons for programming, calibrating and
resetting the system. See Figure 4 for the location of
indicators and pushbuttons.
1. Digital Display - The digital display provides a
continuous reading in ppm of the sensor input in
both the Normal and Calibrate modes. In the event
of a fault, it identifies the nature of the fault using
an alpha-numeric code. In other operating modes
it shows the alarm setpoints and programmed
calibration gas time (the length of time that the
gas is applied to the sensor during calibration).
A negative zero drift condition is indicated by a
minus (-) sign in the left hand digit. Since the digital
display is always lit when power is applied, it also
functions as a power indicator (except during the
power-up time delay, when the Fault LED is on and
the digital display is off).
2. Bar Graph Display - The 20 segment bar graph
display corresponds to the sensor input.
NOTE
The alarm LEDs flash when the setpoint is
reached or exceeded and are on steady (until
reset) when the gas level drops below the
setpoint.
3. High Alarm LED - Flashes in response to a sensor
signal that exceeds the high setpoint.
4. Auxiliary Alarm LED - Flashes in response to a
sensor signal that exceeds the auxiliary setpoint.
5. Low Alarm LED - Flashes in response to a sensor
signal that exceeds the low setpoint.
6. CAL LED - Illuminated while the controller is in the
calibrate mode.
7. FAULT LED - Flashes upon detection of a system
fault and is on steady during the power-up time
delay.
8. RESET Pushbutton - Used for various system
programming and calibration functions as well as
for resetting the controller.
9. SET Pushbutton - Used for various system
programming and calibration functions.
FAULT LED
CAL LED
BAR GRAPH
DIGITAL DISPLAY
AUXILIARY LED
HIGH LED
RESET
PUSHBUTTON
SET
PUSHBUTTON
LOW LED
A1429
1
2
3
9
5
6
7
8
4
Figure 4—Controller Front Panel