Operating instructions

AMC-DTR Sensor Transmitter User Manual
8
4.6.2 3-Wire 4-20mA Mode Installation
Description:
3-wire sourcing transmitters require an additional dedicated 24 VDC wire. The 4-20mA loop
current is then delivered, or sourced, from the transmitter output and the receiver device must
not provide 24 VDC from its input terminal. When the AMC-DTR is equipped with the bottom
DTR-10-0233 I/O Power Supply board shown in Figure 6, the 2-wire 4-20mA output is disabled
and one of the DTR-10-0233’s 3-wire outputs must be used. TB2 terminal 2 is for ECHEM toxic
/ oxygen 3-wire 4-20mA output signals and TB2 terminal 3 is for Catalytic bead 3-wire 4-20mA
output signals. See Figure 6 below.
Instructions:
Unscrew the cover on the AMC-DTR explosion-proof enclosure. Loosen the 2 thumbscrews
holding the display assembly in place and remove it. A small ribbon cable is attached with
sufficient length to allow access to the I/O PCB mounted in the bottom of the enclosure (Figure
6). Power and signal connections are to TB2 where 24 VDC, Signal and Common wires must
be connected. A blocking diode protects the AMC-DTR if polarity of the power supply is
reversed but it will not operate. Reassemble the AMC-DTR. Follow the procedures and
recommendations in the receiver and power supply manuals to complete the installation. Be
sure the AMC-DTR enclosure and conduit are properly grounded. Apply power and the AMC-
DTR should function. Proceed to section 5.
Figure 6: DTR-10-0233 I/O Power Supply / 3-Wire 4-20mA Assembly