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This chapter describes the Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Enhanced router power and cooling systems. It also provides the power, grounding, and cooling requirements for the installation site to help you plan the site facilities for the system. The Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Enhanced Router System Description provides detailed information about these components.
This chapter contains the following sections:
The chassis power system provides power to chassis components and is made up of two power shelves that contain power modules. Each power shelf is connected to a separate and independent power source. Input power enters the power shelves and is processed by the power modules before being distributed to the components in the chassis. At the shelf level, the power system provides 2N redundancy; the PMs themselves provide load-share redundancy.
The Cisco CRS 8-Slot Line Card Chassis Enhanced router can be either DC or AC powered. The AC power system requires single-phase AC input power to power the shelves. If you have 3-phase AC-Delta or AC-Wye at your equipment, a Cisco CRS 3-Phase AC PDU will be required to convert 3-phase AC input power to single-phase AC input power for the power shelf.
Note | In an AC power system, PDU refers to the Cisco CRS 3-phase AC PDU which is required to convert 3-phase AC-Wye or AC-Delta input power to single-phase AC input power for the AC power shelf. For further information, refer to Cisco CRS 3-Phase AC Power Distribution Unit Installation Guide . |
Maximum input power requirements for the Cisco CRS 8-Slot Line Card Chassis Enhanced router are as follows:
Note | If you have a Cisco CRS 3-phase AC PDU installed, three AC PMs are required to be installed in each AC power shelf to maintain a balanced 3-phase power load. |
Note | These power requirements are for a fully loaded chassis with eight PLIMs. A chassis with six or seven PLIMs uses slightly less power. However, it is a good idea to allocate this much power for each chassis to ensure that enough power is available for future system expansion. |
See the Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Enhanced Router System Description for detailed information about how each power system operates and distributes power to components in the chassis.
This section describes the power and grounding requirements you must consider when planning the site facilities for the routing system. In addition, see the DC Power System section or the AC Power Systems section for additional information about the power requirements for your chassis type.
Note | A qualified electrician should review the information in these sections to ensure that the installation site meets these requirements. For larger system configurations, consult a facilities electrical expert to understand the load that the routing system may put on the facility power plant. |
General power and grounding requirements are:
Note | Be sure to review the safety warnings in Regulatory Compliance and Safety Information for the Cisco CRS Carrier Routing System before attempting to install the routing system. |
The chassis allows you to connect the central office ground system or interior equipment ground system to the bonding and grounding receptacles on the router chassis. Six chassis grounding points are provided at the rear (MSC) side of the chassis, as shown in the following figure. Each side of the chassis has one pair of threaded ground studs located on the inside of the chassis and two pairs of grounding receptacles located on the outside of the chassis. These ground points are also called the network equipment building system (NEBS) bonding and grounding points.
Note | These bonding and grounding receptacles satisfy the Telcordia NEBS requirements for bonding and grounding connections. |
1 |
NEBS bonding and grounding points (inside chassis) |
2 |
NEBS bonding and grounding points (outside chassis) |
To connect the chassis to a NEBS-compliant bonding and grounding system at your site, you must have the following:
Caution | The DC Return of the Cisco CRS 8-Slot Line Card Chassis Enhanced router should remain isolated from the system frame and chassis (DC-I: Isolated DC Return). |
For additional information about NEBS, see Cisco CRS Carrier Routing System Regulatory Compliance and Safety Information .
Each DC powered chassis contains two power shelves for 2N redundancy. The power shelves contain the input power connectors. Each shelf can contain up to four DC PMs. The power shelves and DC PMs are field replaceable.
Observe the following guidelines for DC-powered shelves. In addition, be sure to review the requirements described in the Bonding and Grounding Guidelines section.
The following table lists the DC input current and voltage specifications.
Nominal input voltage |
–48 VDC North America–60 VDC European Community(range: –40 VDC to –72 VDC) |
Input line current |
50 A maximum at –48 VDC40 A maximum at –60 VDC60 A maximum at -40 VDC |
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:
Caution | A certified electrician must select the appropriate DC input power cable based on standard electrical practices, such as derating factors, wiring type, operating temperatures, and so on. The electrician must verify that the cable complies with the National Electrical Code (NEC) and local codes and any guidelines in effect at the installation site. At minimum, DC input power cables must be 6-AWG or heavier and rated for 90°C (194°F) temperature or higher. |
Note | Use local electrical codes for clearance requirements when using power lugs to ensure safe operation. |
The following figure shows the DC input power cables connected to the DC power shelf terminal studs.
Note | In the DC power system, the power wire connectors have a torque value of 20 in-lb (2.26 N-m). |
The chassis power system provides the necessary power for chassis components. Site power requirements differ, depending on the input source voltage available, i.e. single-phase AC, AC Delta or AC Wye.
Each AC powered chassis contains two AC power shelves for 2N redundancy. The power shelves contain the input power connectors. Each AC power shelf can contain up to three AC PMs. The power shelves and AC PMs are field replaceable.
In addition to the requirements in the Bonding and Grounding Guidelines section, AC input power requirements are as follows:
Note | If you have a Cisco CRS 3-phase AC PDU installed, three AC PMs are required to be installed in each AC power shelf to maintain a balanced 3-phase power load. |
For detailed AC power specifications, see the Line Card Chassis Specifications section.
The AC power shelf is shipped with AC power cords when the AC PDU is not ordered. Each AC power shelf accepts up to three power cords. Each AC power cord is 4.25 m in length and different plug types (pre-attached) are available, depending on the locale. AC power cords are available for the following locales:
The following table lists the single-phase AC-input cord power options and Cisco product numbers for the Cisco CRS 8-Slot Line Card Chassis Enhanced router with AC power shelves installed. The table also references power cord illustrations.
Locale |
Cisco Product Number |
Plug Rating |
Reference Illustration |
---|---|---|---|
North America |
CRS-AC-CAB-NA(=) |
20 A/250 VAC |
|
Europe |
CRS-AC-CAB-EU(=) |
16 A/250 VAC |
|
United Kingdom |
CRS-AC-CAB-UK(=) |
13 A/250 VAC |
|
Italy |
CRS-AC-CAB-IT(=) |
16 A/250 VAC |
|
Australia |
CRS-AC-CAB-AU(=) |
15 A/250 VAC |
Note | The BS-1363 standard rates cord sets up to a maximum of 13 A, 250 VAC for the C-21 plug. Therefore, the building circuit breaker must be 13 A maximum. Installation of the Cisco CRS 8-slot line card chassis must follow national and local electrical codes. |
Note | The AS 3112 standard rates cord sets up to a maximum of 15 A, 250 VAC for the C-21 plug. Therefore the building circuit breaker must be 15 A maximum. Installation of the Cisco CRS 8-slot line card chassis must follow national and local electrical codes. |
If you have 3-phase AC Delta or AC Wye input power at your equipment, a Cisco CRS 3-phase AC PDU will be required to convert 3-phase AC Delta or AC Wye input power to single-phase AC input power that connects directly to the rear of the AC power shelf. The Cisco CRS PDU includes either an AC Delta or AC Wye power interface, and has power input and power output cords entering and exiting the box.
There are two versions of the Cisco CRS 3-Phase AC PDU available for the Cisco CRS8-Slot Line Card Chassis Enhanced router:
In addition to the requirements in the General Power and Grounding Requirements section, AC input power requirements are as follows:
For detailed Cisco CRS Power Distribution Unit AC power specifications, see the Cisco CRS 3-Phase AC Power Distribution Unit Installation Guide.
The Cisco CRS 8-Slot Line Card Chassis Enhanced router has two fan trays, with four fans each, that cool the chassis card cages. Cool air flows in at the bottom front of the chassis and flows through the chassis card cages and through the fans in the fan trays before being exhausted through the bottom rear of the chassis, as shown in the following figure.
A replaceable air filter is located on the front of the chassis below the PLIM card cage. How often you should replace the air filters depends on the facility environment.
In a dirty environment, or when you start getting frequent temperature alarms, you should always check the intake grills for debris, and then check the air filters to see if they need to be replaced.
Note | We recommend that you check the air filters once a month. Replace a filter when you notice a significant amount of dust. |
The Cisco CRS 8-Slot Line Card Chassis Enhanced router airflow volumes are as follows:
The Cisco CRS 8-Slot Line Card Chassis Enhanced router dissipates considerable power that generates much heat. In large configurations, additional air cooling is required to maintain correct operating temperatures. The room air must be cooled by external cooling units that are installed as part of the routing system.
Heat dissipation and external cooling requirements for the Cisco CRS 8-Slot Line Card Chassis Enhanced router are as follows:
To ensure that the site provides the proper air circulation for the system: