ATI Technologies A12-17, Руководство по эксплуатации и обслуживанию

Страница: 6 / 32

A 12-17 Combustible Gas Transmitter
O & M Manual
Rev-H, 7/15
- 6 -
Model A12-17 transmitters are available with a unique sensor verification system called Auto-Test.
This option consists of a miniature gas generator incorporated into the explosion-proof sensor assembly
which automatically generates a combustible gas every 24 hours. The gas generator function is
controlled by the microcontroller in the transmitter electronics. When activated, the generator will provide
a true gas test of the combustible gas sensing element, and will automatically alert operators to sensor
problems that might develop due to sensor poisoning or coating. Figure 1 shows both a standard sensor
and a sensor equipped with the Auto-Test generator.
The Auto-Test feature provides daily verification of sensor response. While it is not intended to
replace calibration, the automatic sensor test greatly reduces the amount of manual testing required to
assure that the gas detection system is functioning properly. Should a sensor fail to respond to the gas
test, the 4-20 mA signal from the transmitter is locked at 3 mA, providing a trouble signal to any receiving
equipment.
A typical installation for the A12-17 is shown in Figure 2 below. It is shown connected to ATI’s series
B14 single channel receiver, but the transmitter may be used directly with PLC, DCS, or computer
monitoring systems without the use of a special receiver.
4-20mA OUTPUT
(3) SPDT, 10A, ALARM RELAYS
(1) SPDT, 10A, TROUBLE RELAY
3 COND. 20 AWG UNSHIELDED OR SHIELDED CABLE
POWER, 85-255 VAC or VDC
A12-17 TRANSMITTER
C28-17 GAS SENSOR WITH AUTO-TEST
(SHOWN WITH SPLASH GUARD)
Figure 2 - Typical System Diagram