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Xedge Chassis Systems
Ground Connections
A shorting bar located on the rear of the Xedge 6280 chassis provide for the connection, separation,
or isolation of frame and signal grounds as required (connection is the default).
It is common practice to connect chassis and signal ground together (this is the default selection).
Signal ground is the 0 V reference for the digital circuits contained in the chassis and the reference
for unbalanced data interfaces such as EIA/TIA-232-E and RS-423. Connecting grounds helps
prevent AC power line noise, but a large ground current can flow in the shield and the exchanged
signals grounds of a cable (i.e., signal grounds that are in the cable) if it is connected between
equipment grounds that have different potentials.
To avoid this problem:
•
Check that the potential difference between grounds is less than 0.25 V RMS.
•
Break the continuity of the shield in the middle of a long cable run.
•
Connect the shield to ground at only one end.
•
Separate the signal and chassis grounds.
•
Isolate the signal and chassis grounds with a 100-ohm, 1 watt resistor (this limits the current in
the signal ground leads and helps prevent AC power line noise).
Some local electrical codes and equipment manufacturers require separation of signal and chassis
grounds. In this case, you have to separate the grounds and connect the frame ground to a ground
connection at the site.
Grounding Options
The following describes how to implement the various grounding options.
To connect frame and signal grounds:
1. Loosen both ground screws.
2. Slide the shorting bar fully to the left.
3. Tighten both ground screws.
To separate frame and signal grounds:
1. Loosen both ground screws.
2. Slide the shorting bar fully to the right.
3. Tighten both ground screws.
4. Connect the frame ground to a ground connection at the site.
To isolate frame and signal grounds:
1. Loosen both ground screws.
2. Slide the shorting bar fully to the right.
3. Connect a 100-ohm, 1-W resistor between the ground screws.
4. Tighten both ground screws.
2-26
Xedge 6000 Hardware
Installation & Setup Guide
Xedge 6280 Chassis
032R440-000
Issue 17
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