Cisco CRS-1 - Manual (Page 25)

2-5
Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Site Planning Guide
OL-5802-09
Chapter 2 Power and Cooling
DC Power Systems
DC Power Systems
The Cisco CRS 8-slot line card chassis can be configured with either a fixed or modular configuration
DC-input power subsystem. The chassis power system provides the necessary power for chassis
components. Site power requirements differ, depending on the source voltage used.
Each DC powered chassis contains either two fixed configuration PDUs or two modular configuration
power shelves for 2N redundancy. A fixed configuration DC PDU connects to a DC PEM, while a
modular configuration DC power shelf connects to up to four DC PMs.
Fixed Configuration DC Power Requirements
A fixed configuration DC-powered LCC contains two DC-input PDUs and two DC PEMs. Each DC PDU
is connected to three DC power inputs and contains a single 7500-watt DC PEM that is field replaceable.
Input DC power enters the PDU and is passed to the PEM, which provides power to the components in
the chassis. Each PEM has its own circuit breaker.
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 8,000 watts (8.0 kW) of DC input power when
the chassis is fully loaded.
• Each DC PDU requires three DC input feeds of –48/–60 VDC (nominal). The PDU accepts input
DC power in the range –40.5 to –75 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 PDU should be connected to three –48/–60 VDC inputs from the central office “A” power
bus.
– The other PDU should be connected to three –48/–60 VDC inputs from the “B” power bus.
• Required input current is as follows:
– 56 amps at nominal input voltage (–48/–60 VDC).
– 66 amps at low input voltage (–40.5 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.
• A DC-powered system should be installed in a restricted access area in accordance with the
National Electric Code, ANSI/NFPA 70.
• All components in the area where DC input power is accessible must be properly insulated.
• A readily accessible two-pole disconnect device must be incorporated in the fixed wiring, unless it
is possible to rely on the identification of the power return conductor that is earth-grounded in the
DC power system.