Color Coding Of The Source Dc Power Cable; Dc Cable Polarity Labels; Wiring Block On The Pim - Cisco CRS-1 System Description

Chapter 2 Chassis Power System

Color Coding of the Source DC Power Cable

The color coding of the source DC 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 no color
code standard exists for the source DC wiring, you must ensure that the power cables are connected to
the DC-input power shelf terminal studs in the proper positive (+) polarity and negative (–) polarity.

DC Cable Polarity Labels

Sometimes, the source DC cable leads might have a positive (+) or a negative (–) label. This label is a
relatively safe indication of the polarity, but you must verify the polarity by measuring the voltage
between the DC cable leads. When making the measurement, the positive (+) lead and the negative (–)
lead must always match the (+) and (–) labels on the power shelf.
The DC-input power supplies contain circuitry to prevent damage due to reverse polarity, but you should
Caution
correct a reverse-polarity condition immediately.
Table 2-3
Nominal input voltage
Input line current
Inrush current
When wiring the DC power shelf, be sure to attach the ground wire first. When removing the wiring, be
Note
sure to remove the ground wire last. The ground wire must be attached with a torque value of 30 in-lb.
The power cables should also be attached with a torque value of 30 in-lb.

Wiring Block on the PIM

Each wiring block on the power input module (PIM) contains four sets of terminals, two positive and
two negative (see
wiring block and is secured by a screw to a torque value of 50 in.-lb.
You must remove the block cover before you work with the wires.
OL-10805-10
DC Input Current and Voltage Information
Supports –48 VDC and –60 VDC systems
(range: –40 to –72 VDC)
The turn-on voltage of the DC power supplies
Note
is –43.5 +/- 0.5 VDC. When a power supply is
powered on, it continues to operate down to an
input voltage of –40 VDC.
50-A maximum at –48 VDC
40-A maximum at –60 VDC
60-A peak at –75 VDC
(maximum for 1 ms)
Figure 2-6). Each wiring block is covered by a plastic block cover that snaps onto the
Cisco CRS Carrier Routing System 4-Slot Line Card Chassis System Description
DC Power System
2-9