Installing Your Switch
Page 42 7210 SAS-M Installation Guide
Connecting to DC Power
The 7210 SAS-M chassis supports the -48V and +24V DC power modules. Hence, the steps below
are applicable for either the -48V or the +24V DC power modules.
To connect DC power:
Step 1 Before a VDC power supply module can be used, you must connect an external DC power
source to the DC power connection on the left side of the front panel (see Figure 1). The
external DC power supply must be between -36 to -72 VDC, and protected with a circuit
breaker.
Step 2 To provide adequate circuit protection between the DC power supply and the switch, all
intermediate wiring and circuitry should be rated to carry a load at least two times the
maximum rating for this switch (see Appendix A: Specifications on page 75).
Step 3 The wiring between the DC power supply and the switch must be stranded copper wire
within the range of 16 to 20 AWG in accordance with local electrical codes.
Step 4 Connect the VDC power feed using the VDC input and RETA/B (return) lines for power
source A and B, respectively. Insert the wires into the DC input plug (using a small flat-
tip screwdriver). Color code the wiring according to local standards to ensure that the
input power and ground lines can be easily distinguished.
Notes: Below the DC power entry block is an additional chassis ground point for attaching a
DC power chassis ground if required by local electrical codes. The ground point should be connected
with an M4 screw and a terminal lug as specified by local electrical codes.
Notes: Do NOT install BOTH the -48V and the +24V AC PEMs in the same chassis.
Notes: If a single power feed (either #A or #B) is connected to provide power to the system, it supplies power
to both the power supplies, if both of them plugged in. The DC power feeds, #A and #B, are internally bridged
using a diode.
WARNING:
Before wiring the DC plug or connecting power to the switch, ensure that power to the feed lines is
turned off at the supply circuit breaker or disconnected from the power bus.
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