Juniper M7i - User Manual

Connecting Power to a DC-Powered M7i Router
Connect DC power to the router by inserting power cables into the field-wiring
terminals on the faceplate of each power supply. Power and grounding cables are
not supplied with the router. For information about the required cable type, see M7i
Chassis Grounding, Connection, and Cable Specifications.
NOTE: The router must be connected to at least two separate external DC power
sources.
CAUTION: There is no standard color coding for DC power cables. The color coding
used by the external DC power source at your site determines the color coding for
the leads on the power cables that attach to the terminal studs on each power supply.
You must ensure that power connections maintain the proper polarity. The power
source cables might be labeled (+) and (–) to indicate their polarity.
To connect DC power to the router (see Figure 1):
1. Verify that there is no power flowing from either external power source, so that
the voltage across the leads of the power cables is 0 V. Ensure that there is no
chance that the cable leads might become active during the procedure.
2. For each power supply, verify that the power switch on the power supply faceplate
is in the OFF (O) position.
3. Connect the grounding cable to a proper earth ground for each external DC
power sources, if it is not already.
4. Verify that a licensed electrician has attached the cable lug provided with the
router to the grounding cable.
5. Using a number 2 Phillips screwdriver, remove the screws next to the grounding
symbol above the power supplies on the chassis rear. Secure the grounding cable
lug to the chosen grounding point by reinstalling and tightening the screws.
6. Verify that a licensed electrician has attached a listed power cable lug to each
power source cable.
7. Loop the power cables through the hook located on the faceplate to the right of
the field-wiring terminals.
8. Depending on the type of power cable lugs used, loosen or remove the screws
on the field-wiring terminals.
9. Insert the power cable lugs into the appropriate field-wiring terminals. Using a
number 1 Phillips screwdriver, turn the screw on each field-wiring terminal
clockwise to secure the power cable lug. Apply between 8 lb-in. (.9 Nm) and 9
lb-in. (1.02 Nm) of torque to each screw.
a. Insert the positive (+) source cable into the return terminal, which is labeled
RTN.
Connecting Power to a DC-Powered M7i Router ■ 1

Summary

Connecting Power to a DC-Powered M7 i Router

Power and Grounding Cable Connection Procedure

Step-by-step instructions for connecting DC power and grounding cables to the router, ensuring proper polarity and secure connections.

Power Supply and Terminal Connections

Details on verifying power switch status, connecting grounding cables, and inserting power cable lugs into field-wiring terminals.

Overview

1. Function Description
2. Usage Features
3. Maintenance Features

This document outlines the procedure for connecting power to a DC-powered M7i router, providing essential steps for safe and correct installation. The M7i router is a networking device that requires external DC power sources to operate. Its primary function is to facilitate network connectivity, and proper power installation is crucial for its reliable performance.

Function Description

The M7i router is designed to be powered by external DC power sources. It features field-wiring terminals on the faceplate of each power supply, into which power cables are inserted. The router is engineered to operate with at least two separate external DC power sources to ensure redundancy and continuous operation. This dual-source requirement enhances the router's reliability, as it can continue functioning even if one power source fails. The power supplies within the router convert the incoming DC power to the appropriate voltage levels required by the internal components. The grounding system is an integral part of the power connection, designed to protect the equipment and personnel from electrical hazards by providing a safe path for fault currents. The router's design emphasizes safety, requiring careful attention to polarity during power cable connections and proper grounding.

Usage Features

The M7i router's power connection process is designed with several usage features to ensure safe and effective installation:

• Dual Power Source Requirement: The router mandates connection to at least two separate external DC power sources. This feature is critical for maintaining network uptime, as it provides power redundancy. If one power source experiences an interruption or failure, the other source can continue to power the router, preventing service disruption. This is a key operational feature for mission-critical networking environments.
• Field-Wiring Terminals: The power supplies are equipped with field-wiring terminals, which are designed for direct connection of power cables. This allows for flexible installation, as the cables can be cut to the required length and fitted with appropriate lugs on-site. The terminals are designed to securely hold the power cable lugs, ensuring a stable electrical connection.
• Power Switch: Each power supply on the router faceplate includes a power switch, clearly marked with OFF (O) position. This switch allows for safe disconnection of power to individual power supplies during installation or maintenance, without affecting the other power supply or requiring a complete shutdown of the router. This feature enhances safety and simplifies troubleshooting.
• Grounding Point: The chassis rear of the router features a designated grounding point, identifiable by a grounding symbol. This point is crucial for connecting the grounding cable, which provides a protective earth ground. Proper grounding is a fundamental safety feature, preventing electrical shock and protecting the router from power surges.
• Cable Management Hook: A hook is located on the faceplate, to the right of the field-wiring terminals. This hook serves as a cable management feature, allowing power cables to be looped through it. This helps in organizing the cables, preventing them from dangling loosely, which could lead to accidental disconnections or tripping hazards. It contributes to a neater and safer installation environment.
• Polarity Awareness: The router's power connection system emphasizes strict adherence to polarity. The input terminal is labeled "-48V" for the negative source cable, and the return terminal is labeled "RTN" for the positive source cable. This clear labeling, combined with the caution about non-standard color coding, highlights the importance of correct polarity for the router's operation and to prevent damage.
• Visual Verification: The installation process includes a step for visual verification of the cabling. This ensures that the DC source power cabling and grounding cabling are correctly routed, not touching or blocking access to router components, and not creating tripping hazards. This step is a practical usage feature that promotes a safe and organized installation.

Maintenance Features

The design of the M7i router's power system also incorporates features that facilitate maintenance and ensure long-term reliability:

• Modular Power Supplies: While not explicitly detailed as "modular," the presence of individual power switches for each power supply suggests a modular approach to power management. This allows for isolated maintenance or replacement of a single power supply without impacting the operation of the entire router, assuming the other power supply is functional. This significantly reduces downtime during maintenance activities.
• Accessible Terminals: The field-wiring terminals are designed to be easily accessible on the faceplate. This allows for straightforward connection and disconnection of power cables using standard tools (e.g., Phillips screwdrivers). Easy access simplifies routine checks, cable replacements, or troubleshooting of power connections.
• Tool Requirements: The document specifies the use of standard tools like a number 2 Phillips screwdriver for removing grounding screws and a number 1 Phillips screwdriver for securing power cable lugs. This reliance on common tools simplifies maintenance, as specialized equipment is not required.
• Torque Specifications: Specific torque values (8 lb-in. to 9 lb-in. or .9 Nm to 1.02 Nm) are provided for tightening the screws on the field-wiring terminals. Adhering to these specifications is a crucial maintenance practice. It ensures a secure electrical connection, preventing loose connections that could lead to intermittent power, arcing, or overheating. Proper torque also prevents over-tightening, which could damage the terminals or cables.
• Clear Labeling: The power terminals are clearly labeled "-48V" and "RTN." This clear labeling is a significant maintenance feature, as it helps technicians quickly identify the correct connection points for positive and negative source cables, reducing the risk of polarity errors during re-connection or troubleshooting.
• Pre-installation Verification Steps: The maintenance process is implicitly supported by the pre-installation verification steps. For instance, verifying that no power is flowing from external sources and that power switches are in the OFF position before commencing work are critical safety procedures that also apply to maintenance scenarios. These steps ensure a safe working environment for technicians.
• Grounding Cable Lug Attachment: The requirement for a licensed electrician to attach the cable lug to the grounding cable ensures that this critical safety component is installed correctly and securely. This contributes to the long-term reliability and safety of the grounding system, reducing the need for frequent maintenance related to grounding issues. Similarly, the requirement for listed power cable lugs on power source cables ensures robust and safe power connections.
• Emphasis on Professional Installation: The repeated mention of a "licensed electrician" for certain steps (attaching cable lugs) underscores the importance of professional expertise in the initial setup. This ensures that the power infrastructure is correctly and safely established from the outset, minimizing future maintenance issues stemming from improper installation.
• Documentation for Troubleshooting: The detailed, step-by-step instructions in the manual serve as a valuable resource for troubleshooting power-related issues. Technicians can refer to these steps to verify connections, polarity, and grounding, aiding in the quick diagnosis and resolution of problems.

Juniper M7i Specifications

General

Platform	M7i
Product Type	Router
Max Number of Interfaces	16
Power Supply	AC or DC
Operating Temperature	32 to 104°F (0 to 40°C)
Operating System	JUNOS
Interfaces	Gigabit Ethernet
Routing Protocol	BGP, OSPF, IS-IS, RIP
Cooling	Fan
Memory	256 MB SDRAM