Configuration And Operation; Automatic Transfer Switch - Tripp Lite PDUMH15AT Owner's Manual

4. Configuration and Operation

4.1 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
section 4.1.2 for more information).
4.1.1 Preferred Configuration
The Automatic Transfer Switch function provides increased availability when the Primary and
Secondary inputs of the PDU are connected to separate Tripp Lite UPS Systems that are connected
to separate utility power sources. For maximum availability, Tripp Lite recommends using matching
SmartOnline UPS Systems with pure sine wave output for the Primary and Secondary input power
sources. The automatic transfer switch function will be compromised if the primary and 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.
Utility A
Utility B
Facility Circuit
Facility Circuit
Primary UPS
Secondary UPS
Secondary Input Cord Primary Input Cord
Critical Equipment PDUMH15ATNET
Loads
model shown.
Outlets may vary
by model.
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