Connecting a Redundant Power Supply 25
Connecting a
Redundant Power
Supply
The Switch 5500 has an unearthed 48V DC Redundant Power Supply
socket.
WARNING: The installation of the Redundant Power Supply (RPS) should
only be carried out by properly trained and qualified personnel.
WARNING: These instructions must be read in conjunction with the RPS
flyer and the safety and installation instructions supplied with your RPS.
WARNING: When powering any Switch 5500 from an RPS, the unit must
be earthed (grounded). This can be achieved by either connecting the
power cord to the unit or by connecting the earth terminal on the rear of
the unit to a reliable electrical earth, or by connecting both. You must
ensure that the earth connection is made before connecting the DC
supply from the RPS.
WARNING: Any RPS must be approved as an unearthed SELV output in
accordance with IEC 60950-1/UL 60950-1/EN 60950-1.
WARNING: The characteristics of the Switch 5500 DC supply input are
given in Appendix C
on page 105.
The Switch 5500 can be powered in three different ways:
■ AC Mains only — does not offer any power redundancy. If the AC
mains supply or the AC power supply fail, the Switch will power off.
■ AC Mains and Unearthed 48V DC (primary supply) — the internal
AC supply acts as the backup in the event of a DC power failure.
■ DC only — the Switch does not need an AC supply and the resiliency
is provided by the DC supply. This is useful in an environment where
only DC power is available.
The RPS provides two main benefits to the customer:
■ Power Redundancy — if a Switch is powered from the mains supply
unit, a failure of the internal power supply will cause the Switch to fail.
This can be overcome by connecting both the AC and DC RPS supplies
to the Switch. Additional redundancy can also be added to the DC
power by using (N+1) DC power supplies to further increase the
availability of the system.
■ Uninterruptible Power — the system allows easy connection and
maintenance of batteries to the RPS shelf to further increase the
availability of the system.
DUA1715-0AAA02.book Page 25 Wednesday, March 23, 2005 11:17 AM
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