Pro-face LT series, Hardware Manual

Page: 39 / 143

LT-4201TM/4301TM Hardware Manual
39
Grounding the System
Overview
To minimize the effects of electromagnetic interference, cables carrying the fast
Input/Output, analog Input/Output, and Serial communication signals must be
shielded.
1
To avoid damage to the shielded cable when there is a short circuit in the power
line, set up a multi-point frame ground (FG) each with the same electric potential.
The use of shielded cables requires compliance with the following wiring rules:
z
When there is no protective earth ground, you can use metal conduit or cable duct
shield as a part of the protective earth ground. The functional ground (FE) shield
must attenuate electromagnetic interference and must be shielded the length of
the cable. If the purpose is for both functional and protective grounding, as is
often the case for communication cables, the cable must have continuous
shielding.
z
Wherever possible, keep cables carrying one type of signal separate from the
cables carrying other types of signals or power.
Protective Earth Ground on the Backplane
For protective grounding, connect braided copper cable (that can withstand the
maximum voltage/current allowed by the system) to the conductive backplane.
Functional Ground on the DIN Rail
The DIN rail for your LT is common with the functional ground plane and must be
mounted on a conductive backplane.
WARNING
IMPROPER GROUNDING CAN CAUSE UNINTENDED EQUIPMENT OPERA
TION
z
Use cables with insulated shielded jackets for analog Input/Output, fast
Input/Output and communication signals.
z
Ground shielded cables for analog Input/Output, fast Input/Output and
communication signals at a single point
1
.
z
Always comply with local wiring requirements regarding grounding of shielded
cable.
Failure to follow these instructions can result in death, serious injury, or
equipment damage.
WARNING
UNINTENDED EQUIPMENT OPERATION
When connecting DIN rails, connect the DIN rails to functional ground (FE).
Failure to follow these instructions can result in death, serious injury, or
equipment damage.