150-204-111-01, Revision 01
Power and Grounding
HRE-204 List 1A and List 2A
April 7, 2000
9
P
OWER
AND
G
ROUNDING
The chassis frame ground is connected to pin 27, which is connected to each slot as well as the backplane ground
lug G1, as shown in
. Connect the frame ground lug to the earth ground according to the
grounding recommendations found in Section 9 of Bellcore’s GR-1089-DEC, 1996.
Failure to properly ground the enclosure can cause unsafe voltage levels to occur which
can result in the following adverse situations:
•
a shock hazard to craft personnel who come into contact with the enclosure
•
damage to the installed circuits if the normal discharge path to earth ground of the
enclosure’s secondary surge voltage protection components is missing
•
bit errors due to the inability of the unground enclosure to attenuate the noise inducing
energy from stray EMI fields
•
bit errors due to crosstalk from adjacent communication equipment.
The HRE-204 List 1A and List 2A support mechanics that use pin 27 for the frame (chassis)
ground access.
In certain unusual noise environments, it may be necessary to connect the HRU’s circuit
ground pin 17 to frame ground pin 27 of the card-edge connector to remove bit errors from
the T1 payload.
