APC SU042-1 3000 VA User Manual download pdf (Page 9)

Redundant Switch - Applications Guide March 22, 1999

power, battery back up, and safe server shutdown functionality through the other Smart-UPS unit. Visit the

installation to further diagnose the situation / restore the System,

SWITCHING FROM PREFERRED SOURCE TO REDUNDANT SOURCE

Redundant Switch switches load delivery and communications to the redundant Smart-UPS when it detects

that the power feed from Source A is unable to deliver power to the load. In this case, the availability of the

system drops from very high (with both Smart-UPS available to provide AC power, battery back up, and

safe server shutdown) to the standard availability power protection afforded by a single Smart-UPS.

PowerChute plus records the event of switching to Source B as Self Test Failed: Invalid Test. Examine the

Redundant Switch front panel or the front panels of the Smart-UPS units for details.

MONITORING THE AVAILABILITY OF THE REDUNDANT SMART-UPS

Redundant Switch continuously monitors the power delivery capability of the redundant Smart-UPS. When

Redundant Switch senses that its power feed from Source B is unable to deliver power to the load (if it were

to be engaged) PowerChute plus records the event as Self Test Failed: Invalid Test. Examine the Redundant

Switch front panel or the front panels of the Smart-UPS units for details. In this case, the availability of the

system drops from very high (with both Smart-UPS available to provide AC power, battery back up, and

safe server shutdown) to the standard availability power protection afforded by a single Smart-UPS.

EXTENDED BLACKOUT

During an extended blackout to the preferred (engaged) Smart - UPS, Redundant Switch remains engaged

to the preferred Smart - UPS (UPS-A). Redundant Switch does not engage the alternate Smart - UPS (UPS-

B) automatically since it does not sense an AC power fault from the preferred Smart - UPS. When the

preferred Smart - UPS battery runs low, the preferred Smart - UPS and the server work together to

gracefully shut down the server.

When UPS-A shuts down (after safe server shutdown), Redundant Switch shuts down the alternate Smart -

UPS, UPS-B. After power is restored to the UPS-A, Redundant Switch resets the alternate UPS-B to

operate.

UPS-B is not tapped to deliver AC power in this case. The purpose of the alternate Smart - UPS is to

provide clean AC power, battery back-up, and safe server shutdown in case of failure. The user should not

expect the alternate Smart - UPS to provide extended run time. If a single AC circuit that was supplying

power to both Smart - UPS units were to go down, PowerChute plus and Redundant Switch can not extend

run time by toggling between the preferred and the alternate Smart - UPS. If PowerChute plus and

Redundant Switch were to try to manage this, an unsafe server shutdown could result - the functionality of

the Redundant UPS System, continuous availability of safe server shutdown, would be compromised.

Operation without PowerChute plus:

The Redundant Smart-UPS System running without PowerChute plus provides very high AC power

availability. This is the condition in which both Smart-UPS units are available to provide AC power and

battery back up. The Redundant Smart-UPS System running without PowerChute plus does not provide

safe server shutdown functionality.

Note the following change to the setup procedure: When configuring the number of battery packs with

the Battpack utility set the value to be programed into each Smart-UPS XL to the actual number of battery

packs connected to the rear of each Smart-UPS XL.

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APC SU042-1 3000 VA User Manual Page 9