Configuration And Operation; Automatic Transfer Switch - Tripp Lite PDUMH30AT Owner's Manual

Configuration and Operation

Automatic Transfer Switch

When the Primary and Secondary inputs are both connected to Tripp Lite UPS Systems,
the PDU operates as an Automatic Transfer Switch, providing redundant input power for
high-availability applications. Under normal operating conditions, the PDU will distribute
power from the Primary input source, switching to the Secondary input source under
certain conditions. The PDU will switch to the Primary source whenever it is "Good,"
according to the PDU input voltage definitions (see below).
Preferred Configuration
The Automatic Transfer Switch function
provides increased availability when the
Primary and Secondary inputs of the
Utility A
Utility B
PDU are connected to separate
Tripp Lite UPS Systems that are
Facility Circuit
Facility Circuit
connected to separate utility power
sources. For maximum availability,
Tripp Lite recommends using matching
Primary UPS
Secondary UPS
SmartOnline UPS Systems with pure sine
Primary Input Cord
Secondary Input Cord
wave output for the Primary and
Secondary input power sources. The
automatic transfer switch function will be
Critical Equipment
compromised if the primary and
PDUMH30AT
Loads
secondary inputs are connected to the
same utility power source.
Warning: DO NOT connect the primary input to a line-interactive UPS, due to
transfer-time issues, or to any source that does not supply a pure sine wave. Such
sources may be used to power the secondary input.
Automatic Transfer Switch Source Selection
The PDU will power up if one of the input sources is greater than the minimum startup
voltage. In normal operation (after power-up), if the presently selected source (primary
or secondary) degrades to a lesser condition, the unit should switch to the alternate
source, if that source is of better quality. The unit prefers the primary source, and will
always switch to it in the event both sources are of the same (fair or good) quality. If
the present source is becoming bad and the alternate source is at least fair, the unit
will switch to the alternate source.
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