Acromag DT236-0600, Руководство пользователя, Страница: 12 / 40

Model DT23x-0600 Dual Two-Wire DC I/V Input Transmitters
Acromag, Inc. Tel: 248-295-0880 - 12 -
http://www.acromag.com
- 12 - https://www.acromag.com
Output/Power
Connections
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This model includes an extra termination screw marked “C” at each output intended
to provide a convenient tie- point for a “sourcing” wiring variation as shown below.
The C terminals do not connect to the internal circuit but is used to simply join
wired connections. Use of this terminal in your wiring scheme allows you to
connect external power local to the transmitter and form a “sourcing” or active
entity from this “sinking” or passive output as shown below.
Earth Ground Connections
IMPORTANT: A USB isolator is
recommended when configuring
or calibrating a unit to avoid the
ground loop that occurs if your
input signal is also earth grounded
(A PC commonly ties earth ground
to its USB port signal and shield
ground, which is held in common
to the input circuit ground of this
transmitter).
The unit housing is plastic and does not require an earth ground connection to
itself.
If the module is mounted in a metal housing, an earth ground wire
connection to that metal ho using’s ground terminal (green screw) is usually
required using suitable wire per applicable codes. As a rule of good practice,
isolated circuits are normally earth grounded at only one point. Circuits wired to
isolated analog inputs should be earth grounded as reflected in their input
connection diagram. See the Electrical Connections Drawing for Output/Power
connections and note the traditional position of earth ground for a two-wire output
current loop--earth ground is normally applied at the output loop power supply
minus terminal and held in common with the loop load or loop receiver minus
terminal (not the transmitter output terminal). These type II transmitter output
terminals have a
“ floating ” connection relative to earth ground and their potential
varies with the voltage drop in the load and connection wire. Ground connections
noted are recommended for best results and help protect the unit and its isolated
circuitry by giving it a low impedance path to ground for shunting destructive
transient energy away from sensitive module circuitry. Respect the traditional
position of earth ground in a two-wire current loop and avoid inadvertent
connections to earth ground at other points in the same loop, which would drive
ground loops and negatively affect operation.