Detcon TP-700 - Manual (Page 13)

Model TP-700
TP-700 Instruction Manual Rev. 3.5 Page 9 of 38
NOTE: A conduit seal is typically required to be located within 18" of the J-Box and Sensor
Assembly. Crouse Hinds type EYS2, EYD2 or equivalent are suitable for this purpose.
NOTE: The Detcon Warranty does not cover water damage resulting from water leaking into
the enclosure. However, since the electronics are 100% epoxy encapsulated, only the wire
terminations could get wet. Moisture could cause abnormal operation and possibly corrosion
to the terminal connections, but permanent damage to the sensor would not be expected.
NOTE: Any unused ports should be blocked with suitable ¾” male NPT plugs. Detcon
Supplies one ¾” NPT male plug with their accessory J-box enclosures. If connections are
other than ¾” NPT, use an appropriate male plug of like construction material.
2.6 Field Wiring
Detcon Model TP-700 solid-state H
2
S sensor assemblies require three conductor connections between power
supplies and host electronic controller’s 4-20mA output, and 2 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 below.
Maximum wire size for termination in the Detcon J-Box accessory is 14 gauge.
Table 2 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