Wiring; Figure 4-7 Example Of Connections To A 120Vac Amc-1Db1-3Xxxx Digital Monitor - AMC -UT M-400 Series User Manual

AMC-UTx-M-xx-400 Series Digital Transmitter

4.3 WIRING

•
The AMC-UTx Digital Transmitter employs a four wire plus shield system which has two
main wiring systems: the monitor communication (two wires) and power supply wiring (two
wires).
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A two conductor, 20-24 AWG shielded cable is used to connect the RS-485 signals from
the AMC-UTx Digital Transmitter to the monitor. The cable characteristics required are an
impedance of 120 ohms and a low capacitance: ~13pf/ft conductor to conductor and ~
23pf/ft conductor to shield.
•
For best signal transmission and maximum noise rejection, it is recommended to connect
the cable shields to chassis ground at the monitor. The shield is wired to the T-connector
at each transmitter, to maintain end to end continuity.
•
A two conductor 12-18 AWG cable is recommended to connect the power from the
Transmitter to the DC power source. The selected cable must meet application and/or
local regulatory requirements.
•
Wire gauge will affect maximum distance between transmitters and power supply. Thicker
wire required for greater distance.
•
For wiring taps the derivations must be short (never more than 20m
used with n derivations, the sum of all taps must not exceed a maximum of 40m

Figure 4-7 Example of connections to a 120VAC AMC-1DB1-3XXXX Digital Monitor

•
Route cabling away from AC power cabling and any source of electro-magnetic
interference (EMI) or radio frequency interference (RFI) such as power transformers,
electric motors, etc.
•
EMT (Electrical Metal Tube) conduit also adds an added degree of electrical shielding
against EMI (Electro-Magnetic Interference) from devices such as RF (i.e. radio)
sources.
•
Cabling should enter the sensors and monitors from the bottom to ensure best protection
against water damage due to water inside the conduit from condensation or leaks.
•
Ensure that there are no short or open circuits in the sensor cabling.
•
Verify that the communication cabling is voltage free prior to connecting the cabling to
either the AMC-UTx Digital Transmitter or the monitor.
•
All Shield wires must be dress with insulating material to prevent them from shorting with
other wires.
The next pages are example of electrical wiring diagrams for an application where the monitor
supplies both power and communication.
Warning:
Installing monitor communication without shield will produce unreliable system wide
failure. Armstrong Monitoring Corporation will not support this type of installation.
24
If multiple taps are
).
See
.