D12
EX-IR
Gas Transmitter with IR Smart Sensor
Dec 2019 ( 85-0004 Rev A)
17
Power Supply Board
Electrical connections are made to the Power Supply Board at terminal blocks TB1 and TB2. The 4-
20mA current loop, optional digital communications, and remote alarm reset, are connected at TB1, and
connections to the three optional relays are made at TB2. The transmitter may be powered from a 3-wire
(ANSI/ISA Type III) or 4-wire (ANSI/ISA Type IV) connection. The transmitter cannot operate from a
2-wire, loop power (ANSI/ISA Type II) connection. It is recommended to power the transmitter,
controls, and indicators from separate, uninterruptable supplies.
The transmitter cannot operate from a 2-wire, loop power
(ANSI/ISA Type II) connection.
The transmitter requires
primary power in the range of
12 to 30 VDC applied to pins 7
and 8 on TB1. Current loop
operation requires power in the
same range on pin 5 (mA+),
from which the transmitter
sources a positive, 4-20mA
output on pin 6 (mA-).
Figure 8.
“
Power Supply
”
board
connections.
In 3-wire mode, the transmitter
requires a maximum of 250
mA, with all relays active.
Power supplies operating
multiple units should be sized
for twice the calculated current
requirement to allow for inrush
current during startup.
The transmitter housing has limited space for wire. Use the smallest gauge wire available that is
compatible with electrical code and current requirements. When powering a group of transmitters from
the same supply, 12 AWG wire is recommended for long runs, with smaller (higher gauge) wire drops to
each transmitter. The temperature rating of the wiring must be rated the same as, or higher than, the
transmitter.
Wiring must be rated for at least 60°C
Internal relays are best used as pilot relays if heavy load switching is desired. Use suitable arc
suppression devices across loads switched through internal relays.
If the
Remote Reset
input is used, install a momentary switch between TB1-4 and TB1-6.
The transmitter housing may be grounded through explosion proof conduit. In the absence of such
conduit, use a suitable grounding strap to bond the transmitter’s housing to earth ground.
TB2 (Optional Relay Connections)
T
B1
(8) +12 to 30 VDC
(7) Ground
(6) mA(-) Output
(5) mA(+) Supply
(4) Remote Reset
(3) Ground
(2) RS232(RX)/485(B)
(1) RS232(TX)/485(A)
