Alcatel-Lucent 7750 SR-a4, Installation Manual, Page: 100 / 232

Installing, Wiring, and Connecting a –48 VDC PSU
100 7750 SR-a4 and SR-a8 Installation Guide
DC-Input Power Supply Guidelines
If you intend to use DC-input power in the 7750 SR-a chassis, observe the following:
• The 7750 SR-a4 chassis requires a minimum of one PSU to operate, but two are
recommended for redundancy. The 7750 SR-a8 chassis requires a minimum of two
PSUs to operate, but four are recommended for redundancy.
• A fully redundant system operates with two power systems. AC and DC power types
are available in the 7750 SR-a chassis. Ideally, the power sources should be
connected to separate breakers.
• DC-input power connections require copper wire cables.
• DC power cables are not shipped with the 7750 SR-a chassis.
• For DC power connections, a ground connection on the chassis is required.
Grounding cables are not provided.
Wiring the DC Inputs
The –48 VDC PSU has one ground screw and a terminal block with positive and negative
terminals.
Figure 31 shows the –48 VDC PSU. Table 43 describes the components.
Danger:
• Ensure that all power is OFF from the DC circuit. Locate the circuit breaker on the panel
board that serves the DC circuit. Set the circuit breaker to the OFF (O) position.
• When wiring the unit, the ground connection must always be made first and
disconnected last.
• The correct wiring sequence is positive PSU terminal to the power source return
terminal, and negative PSU terminal to the –48V terminal.
• 7750 SR-a systems equipped with DC-input power supplies should be installed in
restricted access areas, such as a dedicated equipment room or an equipment closet,
in accordance with Articles 110-16, 110-17, and 110-18 of the National Electric Code
ANSI/ NFPA 70.
Warning:
• Use a minimum of #8 AWG wire for the –48 VDC and RTN connections.
• Use a minimum of #8 AWG wire for the ground connections.
• A ring lug (approved by an accredited safety agency) and associated approved crimp
tool must be used.
• Consult your local electrical code for more information.