A
12-17 Combustible Gas Transmitter
O & M Manual
Rev-H, 7/15
- 23 -
When the test sequence is activated, the 4-20 mA output will be locked at the value being transmitted
before the sequence began, normally close to 4.0 mA. If you observe the LCD, you will see the gas
concentration begin to increase as gas is evolved from the generator. When the display reaches 5%
above the start value, a PASS message will flash on the display, indicating that the sensor passed the
test. At this point the AUTO TEST flag will stop flashing and go to steady on. This indicates that the
Auto-Test was successful but that the 4-20 mA output is still locked. The output will stay locked for the
next 2 minutes to allow the sensor to recover to zero. In addition, it will remain partially locked for an
additional 8 minutes to insure complete sensor recovery before again activating the output. However, if
the measured gas concentration goes above 50% of range during the second 8 minute inhibit period, the
output lock is released and any receivers connected to the transmitter will indicate high gas levels.
ANALOG OUTPUT SIMULATION
The A12-17 transmitter provides the ability to simulate 4 different current output values in order to test
the complete detection system. The output may be set to values of 4.0, 12.0, and 20.0, and may also be
set to the “Trouble” value of 3.0 mA.
From the NORMAL display, activate the MODE control twice and the display will read “tESt”.
Activate the ENTER control. The display will change to “SEnS” and the TEST flag will be displayed near
the top of the display. Activate the MODE control once and the display will change to tESt and the mA
flag will be on. Activate the ENTER control once and the display will indicate 4 mA. The current output
from the transmitter will now be locked on 4 mA. Use the UP or DOWN control to change the output to 12
mA, 20 mA, or “trbl” as desired. When “trbl” is displayed, the output will go to 3 mA, which is the output
value used to indicate “Trouble” with the transmitter. The output current from the transmitter will change
to the value shown on the display.
CAUTION: Simulation of 12 or 20 mA, or trb1 (3mA) outputs may cause receiving devices to
activate alarms and/or control devices. Never simulate these outputs without
inhibiting alarm receivers or notifying operating personnel that a system test is in
progress.
To escape the output simulation mode, activate the ENTER control once.
