Table Of Contents
Quick Start Guide
Cisco DC Isolation Power Shelf Installation Guide
Revised: October 6, 2006, OL-11503-01
The DC Isolation Power Shelf provides power isolation for Cisco MGX 8800/8900 series switches. Each DC Isolation Power Shelf supports four power supply modules, for a maximum output power of 4,800W. The number of power supply modules installed in the DC Isolation Power Shelf depends on the power requirements of the Cisco MGX 8800/8900 series switch. Typically, you install either two or four supplies.
The DC Isolation Power Shelf has four independent DC inputs: (A1, B1, A2, B2), one for each power supply module. DC inputs A1 and A2 are powered from one facility power source, and B1 and B2 are powered from a different facility power source. To provide continuous power if source A or source B fails, DC outputs from slots A1 and B1 are connected in parallel, and DC outputs from slots A2 and B2 are connected in parallel. The two groups (A1, B1) and (A2, B2) are independent, but share the same common return (OV) from the converter shelf.
Four breakers on the rear of the DC Isolation Power Shelf independently control power to the four output terminals. The input circuits do not have breakers. Each power supply module has its own power switch, so DC power is present at the output only when the power supply module and corresponding breaker are both switched on.
2 Preparing to Install the DC Isolation Power Shelf
Carefully unpack the following DC Isolation Power Shelf components:
•DC Isolation Power Shelf (700-24113-01)
•DC-DC Power Modules (341-0124-XX)
•DC Isolation Power Shelf installation kit (ISLPWR-INSTALL-KIT)
Includes terminal lugs for 2,4, and 6 gauge wire, static strap, and this guide
•Midmounting rack kit
–19 in midmounting kit (ISLPWR-MNT19-4RU=)
–23 in midmounting kit (ISLPWR-MNT23-4RU=)
•Output DC power cables (2 or 4 required). Choose a length that corresponds to the mounting location:
–15 in. power cable (CAB-ISLPWR-15=)
–5 foot power cable (CAB-ISLPWR-60=)
–8 foot power cable (CAB-ISLPWR-96=)
The following tools and stock are required for installation:
•Crimp tool for #2, #4, or #6 terminal lugs
•Torque wrench for tightening terminal nuts
•Metric socket set
•#2, #4, or #6 AWG wire for input DC circuits
3 Installing the DC Isolation Power Shelf
Install the DC Isolation Power Shelf in the same rack as the equipment that it powers, as follows:
•Immediately below the Power Entry Module (PEM) of a Cisco MGX 8800/8900 series switch.
This option uses the 15-inch power cable (CAB-ISLPWR-15=).
•Immediately above the Cisco MGX 8800/8900 series switch.
This option uses the 5-foot power cable (CAB-ISLPWR-60=).
•At the top of the rack above two Cisco MGX 8800 series switches.
This option uses use the 8-foot power cable (CAB-ISLPWR-96=).
When you install the DC Isolation Power Shelf in a 19-inch rack, adhere to the following guidelines:
•Open-rack configuration—Midmount the DC Isolation Power Shelf in the rack using the 19-inch midmounting kit (ISLPWR-MNT19-4RU=).
•Cisco cabinet configuration—Front-mount the DC Isolation Power Shelf in the cabinet using the attached front flanges, and support it at the rear using rear mounting bracket.
When you install the DC Isolation Power Shelf in a 23-inch rack, midmount the DC Isolation Power Shelf using the 23-inch midmounting kit (ISLPWR-MNT23-4RU=).
Figure 1 Open-rack Mounting Brackets
To install the DC Isolation Power Shelf in a rack, follow these steps:
Step 1 Remove blank covers from the front panel of the converter shelf, if present. To remove covers, loosen the two screws at the top, slide out the bottom, and then remove the panel.
Step 2 Before mounting the DC Isolation Power Shelf in an open rack, install either the 19 or 24-inch midmounting brackets on the sides using 10-32 screws and washers. Figure 2 shows the 23-inch midmounting bracket installation and Figure 3 shows the 19-inch midmounting bracket installation.
Figure 2 23-inch Midmounting Bracket Installation
Figure 3 19-inch Midmounting Bracket Installation
Step 3 Position the DC Isolation Power Shelf in the rack and secure the shelf using rack mounting hardware. Because of its size and weight, two or three people are required for this task.
For a Cisco cabinet, secure the front flange of the DC Isolation Power Shelf to the front of the cabinet and the rear flange to the rear of the cabinet. For an open rack, secure the midmounting brackets to the rack (see Figure 4).
Figure 4 DC Isolation Power Shelf Mounting Positions
Opening for power module (or blank faceplate)
Midmounting position (19 or 23 in)
Rear flange (not shown)
Midmounting position (19 in)
4 Connecting the Chassis Ground
To connect the power source ground to the DC Isolation Power Shelf, follow these steps:
Step 1 On the rear panel, remove the large plastic covers over the input terminals and set them aside (see Figure 5). Each cover is attached by three phillips screws.
Figure 5 Input Terminal Plastic Cover Removal
Attachment screw (captive)
Attachment screw (captive)
Attachment screw (captive)
Right plastic cover
Left plastic cover
Step 2 Run a ground wire from the facility ground to the DC Isolation Power Shelf using #2, #4, or #6 AWG wire.
Step 3 At the DC Isolation Power Shelf, attach a 2-hole terminal lug to the ground wire. The installation kit includes lugs for #2, #4, or #6 AWG wire. For example, #2 AWG wire uses a Panduit LCC2-14AW-Q lug or equivalent.
Step 4 On the rear panel, locate the ground terminals and remove the nuts and washers (see Figure 6)
Figure 6 DC Isolation Power Shelf Rear Panel—Ground Connection
Step 5 Slide the ground lug over the ground terminals and secure the lug using the removed nuts and washers (see Figure 6).
Step 6 Tighten the nuts to a torque of 25 inch-pounds.
Note In compliance with NEBS GR-1089, the ISLPWRSHLF uses an Isolated DC return conductor (DC-I). When correctly installed with an MGX platform that uses a Common DC return conductor (DC-C), the resulting configuration will have an Isolated DC return (DC-I) configuration, as seen from the inputs to the ISLPWRSHLF.
5 Connecting Input DC Circuits
To connect the input DC power circuits, follow these steps:
Step 1 Verify that the breakers at the distribution panel (at the facility) are off for the A and B circuits that power the DC Isolation Power Shelf.
Warning Hazardous voltages may exist on the A and B power circuits.
Step 2 Run power circuits from the distribution panel to the DC Isolation Power Shelf using #2, #4, or #6 AWG wire.
A 4-supply system requires four power circuits, two from circuit A and two from circuit B. A 2-supply system requires two power circuits, one from circuit A and one from circuit B.
Step 3 Locate the A1, A2, B1, and B2 input DC terminals on the rear panel of the DC Isolation Power Shelf (see Figure 7).
Step 4 Attach a 2-hole terminal lug to each power circuit wire. The installation kit includes lugs for #2, #4, or #6 AWG wire. For example, #2 AWG wire uses a Panduit LCC2-14AW-Q lug or equivalent.
Step 5 Connect the A1 and B1 power circuits to their corresponding input power terminals. For each circuit, remove the nuts and washers from the power terminals, slide the lug over the terminals, and then secure the lug using the nuts and washers (see Figure 7).
Position the A1 and B1 lugs and wires to the left so that the wires route out the left side of the DC Isolation Power Shelf (from the rear). The B1 terminals are offset from the A1 terminals to simplify the routing.
Note Black insulating plastic wraps over the negative power terminals, so push it aside as necessary to access the terminals.
Figure 7 Input DC Connections for the A1 Power Circuit
Step 6 In a 4-supply system, connect the A2 and B2 power circuits to the corresponding input power terminals. Route these wires out the right side of the DC Isolation Power Shelf (from the rear).
Step 7 Tighten all nuts to a torque of 25 inch-pounds.
Step 8 Visually verify the polarity of all connections. For example, make sure the A1+ terminal connects to the return and the A1- terminal connects to -54 VDC.
Step 9 Reposition the black insulating plastic over the terminals, as necessary.
Step 10 Replace the plastic covers over the input power terminals, routing the cables through the openings in the plastic. Make sure that the cables do not force the covers out of their normal position.
6 Connecting Output Circuits
Cisco provides fixed-length cable assemblies for connecting the DC Isolation Power Shelf to Cisco MGX 8800/8900 series switches. Each power supply module requires one cable assembly. For more information about cable length, see Installing the DC Isolation Power Shelf.
To connect the output DC circuits, follow these steps:
Step 1 Locate the output DC terminal blocks on the rear of the DC Isolation Power Shelf (see Figure 8).
There are four terminal blocks: A1, B1, A2, and B2. A snap-on plastic cap covers each terminal block.
Step 2 Remove the plastic cover from the top of each terminal block. These covers snap in place, and can be removed with a flat screwdriver.
Step 3 Connect the wires of the first cable assembly to the A1 terminal block. For each wire, remove the screw and washers from the terminal block, position the lug over the terminals, and then secure the lug using the screw and washers (see Figure 8). Table 1 shows the connection details.
Table 1 Terminal Block Connections
Terminal Block Label Function Wire Color
54 VDC return
Figure 8 Output DC Connections for the A1 Power Circuit
Step 4 Similarly, connect the wires of a second cable assembly to the B1 terminal block.
Step 5 In a 4-supply system, connect the third and fourth cable assemblies to the A2 and B2 terminal blocks.
Step 6 Replace the four plastic covers over the output power terminal blocks by snapping them in place.
Step 7 Route the cables to the Cisco MGX 8800/8900 series Power Entry Module (PEM) and connect them to the corresponding terminals on the PEM. Figure 9 shows the connections for an MGX 8950 switch and Figure 10 shows the connections for two MGX 8850 switches.
Figure 9 Cisco MGX 8850 Power Connections
Figure 10 Cisco MGX 8950 Power Connections
For more information about power connections for the Cisco MGX 8800/8900 series, see the Cisco MGX 8800/8900 Series Hardware Installation Guide.
7 Verifying Auxiliary Connections
The DC Isolation Power Shelf has the following DB9 connectors on the rear panel (see Figure 11):
•Programming plug—Verify that the DB9 programming plug is installed and is secure
The DC Isolation Power Shelf indicates the health of the power supply modules with a contact closure for each supply. During normal power module operation, the relay contacts are closed; the relay contacts open for a failure. Table 2 shows the alarm connector pin assignments for the relay contacts.
Table 2 Alarm Connector Pinouts
6 and 14
Health of A1 power supply module
5 and 13
Health of B1 power supply module
3 and 11
Health of A2 power supply module
4 and 12
Health of B2 power supply module
Figure 11 DC Isolation Power Shelf Connectors
8 Installing DC-DC Power Supply Modules
To install DC-DC power supply modules, follow these steps:
Step 1 From the front, insert a power supply module in the slot furthest to the right (see Figure 12 for left slot example).
Figure 12 DC-DC Power Supply Module Installation
Step 2 With the extraction lever out, firmly seat the supply with your thumbs.
Note A keying mechanism ensures that only the correct power supply module can be installed.
Step 3 Lock the supply in place by closing the extraction lever.
Step 4 Hand-tighten the thumbscrews on the insertion lever.
Step 5 Similarly, install other supplies, from right to left. You use 4 supplies for an MGX 8950 switch or 2 for each MGX 8850 switch.
Step 6 Install blank faceplates over unused slots, if any. To install the blank faceplate, position the handle on the left, slide the top flange under the opening in the shelf, slide the bottom flange in place, and then tighten the two screws at the top.
9 Applying Power
To apply power, follow these steps:
Step 1 Verify that the four breaker switches on the rear of the DC Isolation Power Shelf are in the OFF position (see Figure 13).
Step 2 Verify that the power switches on the front of each of the power supply modules is in the OFF position (see Figure 14).
Step 3 Verify that the breakers on the MGX 8800/8900 series PEMs are in the OFF position.
Step 4 Switch on the A and B circuit breakers at the distribution panel (on the facility wall). This applies power to the input cables and the DC Isolation Power Shelf.
Step 5 At the rear of the DC Isolation Power Shelf, verify that the IN OK LEDs are on (see Figure 13).
Note If any of the input LEDs are off, troubleshoot the problem before proceeding. For example, verify the input voltage and polarity.
Figure 13 Power Indicators and Breakers
Step 6 On the front panel, switch the power switches on the power supply modules to the ON position (see Figure 14). This powers the modules, but does not apply power to the output terminal blocks.
Figure 14 Power Supply Module Switches and Indicators
Step 7 On the front panel, verify that the green POWER OK LED of each power supply is on (see Figure 14).
Step 8 On the rear panel, switch the breakers to the ON position. This applies power to the output terminal blocks and the power cables to the MGX PEM (see Figure 13).
Step 9 On the rear panel, verify that the OUT OK LEDs are on (see Figure 13).
Step 10 Power on the connected MGX equipment by turning on the DC PEM circuit breaker, as appropriate.
Note The DC PEM circuit breaker must always be the first switched off and the last switched on for servicing.