ADC 1146963, Техническая практика

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LTPH-TP-1003-02, Issue 2 Power and Grounding
HRE-206 Lists 1 and 2 June 1, 2001 7
T
URN
-U
P
Follow these steps to complete the turn-up procedure:
1 Loosen the 216 HEX security nut on the front cover ( Figure 5 on page 5 ) with a
3
/
8
-inch CAN wrench.
2 Remove the front cover from the chassis to expose the card slots.
3 Insert the cards in the assigned slots and refer to the card’s technical practice for the appropriate turn-up
procedure. (See
“Appendix B - Product Support” on page 18 for obtaining technical practice information.)
If you are using the HRE-206 to locally power one or more HRUs, see “48 Volt Power Options” on page 8 .
P
OWER AND
G
ROUNDING
Pin 27 of every slot is always connected to chassis ground. When a jumper is connected across TB7, pin 1 and pin
27 of each slot are connected together. This attaches both pins to frame (chassis) ground. See
Table 2 below for a
list of units that require pin 1 of each slot to be attached to frame ground for proper fault protection. The enclosure
is shipped without a jumper across TB7.
ADC recommends that the frame ground lug on the outside of the enclosure be connected to earth ground
according to the grounding recommendations found in Section 9 of Bellcore’s GR-1089-DEC 1996.
Table 2. Units Requiring
Jumper Across TB7
Unit Model Number
•
All HRU-412, List xx
• HRU-612, List xx
•
HLU-431, List 1, List 2
• HRU-512, List xx
•
ERU-412, List xx
Failure to properly ground the enclosure can cause unsafe voltage levels to occur which can
result in the following adverse situations:
• 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 ungrounded enclosure to attenuate the noise-inducing
energy from stray Electromagnetic Interference (EMI) fields
• Bit errors due to crosstalk from adjacent communication equipment
In certain unusual noise environments, it may be necessary to connect pin 17 (the HRU’s circuit
ground pin) to frame ground of the card-edge connector to remove bit errors from the DS1
payload.