Cisco CRS-1 - Manual (Page 28)

2-8
Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Site Planning Guide
OL-5802-09
Chapter 2 Power and Cooling
DC Power Systems
Note When wiring the fixed configuration DC PDU, be sure to attach the ground wire first (shown above on
the far left side of PDU). When removing the wiring, be sure to remove the ground wire last.
Note In the fixed configuration DC power system, power wires have a 20 in.-lb (2.26 N-m) torque value and
ground wires have a 30 in.-lb (3.39 N-m) torque value. The PDU mounting screws have a 9 in.-lb (1.04
N-m) torque value.
The color coding of the DC input power cable leads depends on the color coding of the site DC power
source. Typically, green or green and yellow indicates that the cable is a ground cable. Because there is
no color code standard for the source DC wiring, you must ensure that the power cables are connected
to the PDU terminal studs in the proper positive (+) and negative (–) polarity.
Caution Although reverse polarity should not damage the DC power system, you should correct a reverse polarity
condition immediately.
Modular Configuration DC Power Requirements
A modular configuration DC-powered LCC contains two DC power shelves. Each modular configuration
DC power shelf is connected to up to four DC power inputs and contains up to four DC PMs that are
field replaceable.
In addition to the requirements described in the “General Power and Grounding Requirements” section
on page 2-2 , DC input power requirements are as follows:
• A DC-powered chassis requires up to a maximum of 9,500 watts of DC input power when the chassis
is fully loaded.
• Each modular configuration DC power shelf requires up to four DC input feeds of either
–48 VDC (nominal), 50 A or –60 VDC (nominal), 40 A. The power shelf accepts input DC power
in the range –40 to –72 VDC.
• A DC-powered chassis requires access to the “A” and “B” power buses at the central office (CO).
This dual connectivity provides 2N power redundancy in case a power source fails.
– One power shelf should be connected to up to four –48/–60 VDC inputs from the central office
“A” power bus, depending on the number of DC PMs installed.
– The other power shelf should be connected to up to four –48/–60 VDC inputs from the “B”
power bus, depending on the number of DC PMs installed.
• Required input current is as follows:
– 50 amps at –48 VDC nominal input voltage.
– 40 amps at –60 VDC nominal input voltage
– 60 amps at low input voltage (–40 VDC).
• All power connection wiring must conform to the rules and regulations in the National Electrical
Code (NEC) and any local codes. In addition, make sure that the wiring conforms to any internal
requirements at the installation site.
• Each DC power source must comply with the safety extra-low voltage (SELV) requirements in
UL 60950-1, CSA-C22.2 No. 60950-1, EN60950-1, AS/NZS 60950, and IEC60950-1.