Detcon PI-700 0-500ppb - Manual (Page 11)

Model PI-700 0-500ppb
PI-700 0-500ppb Instruction Manual Rev. 0.0 Page 7 of 53
2.5 Electrical Installation
The Sensor Assembly should be installed in accordance with local electrical codes. The sensor assemblies are
designed for Class I, Division 1, Groups B, C, & D area classifications, and for ATEX Class I, Zone 1, Group
IIC area classifications.
Proper electrical installation of the gas sensor is critical for conformance to Electrical Codes. Refer to Figure
8 for proper electrical installation.
2.6 Field Wiring
Detcon Model PI-700 toxic gas sensors assemblies require three conductor connections between power
supplies and host electronic controller’s 4-20mA output, and two conductor connections for the Modbus™ RS-
485 serial interface. Wiring designations are + (DC), – (DC), mA (sensor signal), and Modbus™ RS-485 A
(+), and B(-). Maximum wire length between sensor and 24VDC source is shown in the Table 1 below.
Maximum wire size for termination in the Detcon J-Box accessory is 14 gauge.
Table 1 Wire Gauge vs. Distance
AWG Wire Dia. Meters Feet
Over-Current
Protection
22 0.723mm 700 2080 3A
20 0.812mm 1120 3350 5A
18 1.024mm 1750 5250 7A
16 1.291mm 2800 8400 10A
14 1.628mm 4480 13,440 20A
NOTE 1: Wiring table is based on stranded tinned copper wire and is designed to serve as a
reference only.
NOTE 2: Shielded cable is required for installations where cable trays or conduit runs include
high voltage lines or other possible sources of induced interference. Separate conduit runs are
highly recommended in these cases.
NOTE 3: The supply of power should be from an isolated source with over-current protection
as stipulated in table.
Terminal Connections
CAUTION: Do not apply System power to the sensor until all wiring is properly terminated. Refer
to Section 2.7 Initial Start Up