Siemens SIMATIC TI555 - Grounding the Controller; Grounding the Cabinet or Rack; Ground Connections; Figure 2-9 Grounding the TI545;TI555 Controller

2-14
Pre-installation Guidelines TI545/TI555 System Manual
Power System Grounding (continued)
When installing the controller , ensure that noise is minimized by following
these guidelines. Use the ground connection (Figure 2-9) to attach one end
of a ground wire; attach the other end to a nearby grounding rod that meets
all electrical specifications required for an earth ground. Use the shortest
possible length of #8-gauge copper wire, or equivalent braided cable to make
the connection.
G
G
Figure 2-9 Gr ounding the TI545/TI555 Contr oller
If the controller is mounted in a cabinet or rack, use the same grounding
procedure. Ensure that a good cabinet or rack ground connection is achieved
by removing existing paint and attaching a #8-gauge copper wire (or
equivalent) using a bolt, washers, and nut as necessary . Y ou can attach the
other end of the wire to the same ground rod used to ground the controller .
Use particular care when establishing the ground connections. The
following techniques will help to establish good electrical connections and
decrease noise interference:
• T erminate grounding braid and green wires at both ends with copper
eye lugs to provide a good contact surface. Lugs should be crimped and
soldered.
• Use #10 copper bolts (or equivalent) for those fasteners providing
electrical connections to the single-point ground. This applies to
device-mounting bolts and braid termination bolts for subpanel and
user -supplied single points. T apped holes for these fasteners are better
than nut-bolt arrangements.
• Paints, coatings, and corrosion can prevent good electrical contact at
ground points. Remove these impediments in the area of contact and
use external toothed lock washers (star washers) to ensure good
continuity and low impedance. This practice should be used for all
terminations — lug to subpanel, device to lug, device to subpanel,
subpanel to conduit, etc. Examples of ground connections are shown in
Figure 2-10.
Gr ounding the
Controller
Gr ounding the
Cabinet or Rack
Ground
Connections