Cisco CRS-1 - Manual (Page 29)

2-9
Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Site Planning Guide
OL-5802-09
Chapter 2 Power and Cooling
DC Power Systems
• 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.
Modular Configuration DC Input Power Cables
Each power shelf contains four pairs of double-stud terminals (RTN, –48V/–60V) for connecting DC
input power. To provide 2N power redundancy, one power shelf should be connected to the central office
“A” power bus and the other power shelf should be connected to the “B” power bus.
The requirements for the DC input power connections are as follows:
• For DC input power cables, select the appropriate wire gauge based on the National Electrical Code
(NEC) and local codes for –48 VDC (nominal), 50 A DC input voltage, or –60 VDC (nominal), 40 A
DC input voltage. Up to four pairs of cable leads, source DC (–) and source DC return (+), are
required for each power shelf, depending on the number of DC PMs installed. These cables are
available from any commercial cable vendor. All input power cables for the chassis should have the
same wire gauge and cable lengths should match within 10 percent of deviation.
• Each DC input power cable is terminated at the power shelf by a cable lug. The power supply
terminal block lug opening width is 0.625 inch (15.8 mm). The terminal posts are centered 0.625
inches (15.88 mm) apart and are M6-threaded. We recommend that you use an appropriately sized
180-degree angle (straight) industry standard dual-hole, standard barrel compression lug, as shown
in
Figure 2-5 , or an appropriately sized 45-degree angle industry standard 2-hole, standard barrel
compression lug, as shown in Figure 2-6 .
Figure 2-5 180 Degree (Straight) DC Input Power Cable Lug
Crimp area
25527
2.24
0.48
0.08
0.25 0.37 0.63
End View
Ø 0.267
2 holes
All measurements in inches