Oldham 700 TP Series, Instruction Manual

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OLCT 700/710 TP
Page 10 of 45 Rev. C.1 OLCT 700/710 TP Instruction Manual
2.7 Field Wiring
Oldham OLCT 700/710 TP solid-state H
2
S detector 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 + (24 VDC), – (0 V), mA (detector signal),
and Modbus™ RS-485 A (+), and B (-). Maximum wire length between detector and 24VDC source is
shown in the Table below. Maximum wire size for termination in the Oldham J-Box accessory is 14 gauge.
Max loop load resistance between green and black wire (analog signal output) is 500 ohms. Minimum loop
load resistance between green and black wire is 100 ohms. This is considers wire diameter, wire length,
max operating temperature and selected termination resistor.
Table 2: Wire Gauge vs. Distance
AWG Wire Dia. Cross Section Meters/Feet
Over-Current
Protection
22 0,65 mm 0,32 mm² 700/2080 3A
20 0,8 mm 0,5 mm² 1120/3350 5A
18 1,0 mm 0,8 mm² 1750/5250 7A
16 1,3 mm 1,3 mm² 2800/8400 10A
14 1,6 mm 2 mm² 4480/13440 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 or tray
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.
2.7.1 Cable Preparation
NOTE : It is essential that the instructions provided by the manufacturer of the cable gland are
followed and the braid is correctly connected.
1 - Remove the rubber pot and the two metal washers
(A)
2 - Arrange the cable as shown in the picture