Detcon 971-071170-LRY - Manual (Page 4)

7. If applicable, connect alarm devices. Discreet alarm relay contacts are provided for three alarms: Fault,
Low and High. The contacts consist of common and choice of normally open or normally closed. Contact
output selections are jumper programmable on the sensor connector board. See the sensor manual for con-
tact ratings and other information.
8. If applicable, connect flow fault alarm wiring. Two sets of form C contacts (common, normally open and
normally closed) are provided. Relay contacts are rated 1 amp at 30VDC/.24 amp at 125VDC.
9. If applicable, connect RS-485 wiring.
The RS-485 requires 24 gauge, two conductor, shielded, twisted pair
cable between sensor and host PC. Use Belden part number 9841. Two sets of terminals are located on the
connector board to facilitate serial loop wiring from sensor to sensor. Wiring designators are +, –, and shield.
1.2 START UP
Upon completion of all tubing connections and field wiring turn on the power switch located on the enclo-
sure door. Note that the power lamp illuminates. If applicable, note that the sensor LCD indicator activates.
Varying readings may occur during sensor warm-up. Allow approximately 1 hour to stabilize (24 hours is best).
Also note air flow through the flow meter. Adjust the flow meter as necessary so that it falls between 500
and 1000 ml/m (milli liters per minute).
Assure that all field tubing connections are secure by obstructing the end of the sample line and observ-
ing that the flow meter decreases to “0” flow.
1.3 FLOW FAULT/LIQUID LEVEL DETECTION
Flow fault and liquid level detection consists of a circuit board assembly located on the motherboard.
Features of the circuit include a door mounted flow fault/liquid level indicator lamp.
Detcon Model 971-071170-LRY Gas Detection System PG.4
COM
NO
NC
Flow Fault
Liquid Level
Detection
Circuit
PT1
User Available
Dry Contacts
Flow fault adjust potentiometer
Fault indicator LED
P7 P8
mA C NO/NC C NO/NC C NO/NC
SENSOR #1 FAULT
ALARM CONTACTS #1
ALARM 1 ALARM 2
ALARM DRY
CONTACTS
COM
NO/NC
COM COM
NO/NC NO/NC
FLT ALM 1 ALM 2
mA
4-20mA
Wire alarms and the 4-20mA output
signal to the plug-type connectors.
P10 P11
mA C NO/NC C NO/NC C NO/NC
SENSOR #2 FAULT
ALARM CONTACTS #2
ALARM 1 ALARM 2
ALARM DRY
CONTACTS
COM
NO/NC
COM COM
NO/NC NO/NC
FLT ALM 1 ALM 2
mA
4-20mA
P6 P5
L1 L2 GND
117 VAC
IN
24 VDC
IN
Battery
Backup
Wire 117 VAC & optional 24 VDC
backup to the lugless connectors.
P9
Shld
SENSOR #1
RS-485
RS-485
P12
Shld
SENSOR #2
RS-485
RS-485