Common Systems Connection Standards AT&T Services, Inc
Date: August 31, 2007 ATT-TP-76450, Issue 9
Copyright ©2004 – 2006, AT&T Knowledge Ventures
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Page 6
2.1.3 Battery Return Conductor
2.1.3.1 Each power feeder shall have its own battery return conductor. This design concept
shall also carry through directly to each piece of equipment.
2.1.3.2 Equipment configured with the battery return and chassis ground bonded together shall
not be deployed in the network.
2.1.3.3 Battery return and current path information must be provided in the supplier's response
documentation to be in compliance with this item. List 1, 1X, 2 and 2X drains shall be provided
in the documentation.
Drain Definitions
Defined below are the four drain categories used in this document.
• List 1 Drain:
Represents the average busy-hour current required at normal operating voltages at
operating conditions as provided by the equipment manufacturer. List 1 current
drains are used to size batteries and rectifiers. The cumulative List 1 current drain is
the current consumed on both the A and B supplies.
• List 1X Drain
The amperage that will flow in one side of
a dual powered circuit when the other supply circuit has failed and the
power plant feeding the remaining circuit is at it’s nominal operating
voltage (float voltage).
• List 2 Drain:
Representing the peak current required to operate equipment at –42.64 vDC. This
value is based on manufacturer-supplied data, and calculated to the AT&T minimum -
42.64 vDC design level and equipment configuration.
• List 2X Drain
The amperage that will flow in one side of a dual powered circuit if the other supply
circuit is failed and the power plant feeding the remaining circuit is at 42.64 volts or
the total wattage divided by 42.64volts.
2.1.4 Architecture Integration
Any equipment that requires more than a 70 amp fuse ( 56 amp load of List 2X ) may
necessitate special accommodations.
2.2 POWER TERMINATIONS AT THE NETWORK ELEMENT
