Tripp Lite PDUMH15ATNET - Manual (Page 10)

Automatic Transfer Switch Source Selection
Upon power-up, the PDU looks for a source >85V. If it is unable to find a source >85V, it remains off.
Input voltage definitions:
99V < V in < 139V Good
75V < V in < 99V Fair
V in < 75V Bad
In normal operation (after power-up), if the selected source is no longer Good, the PDU will attempt
to switch to the other source, but only if the other source is Good. If the selected source becomes Fair
and the other source is not Good, the PDU will keep the loads connected to the selected source until
the selected source becomes Bad, at which point the loads will be disconnected (note that the source
selection doesn't change). After the loads are disconnected, they remain disconnected until the
selected source becomes >85V, or until the other source becomes Good.
10
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 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.
Facility Circuit Facility Circuit
PDUMH15ATNET Critical Equipment
Loads
Secondary UPS Primary UPS
Primary Input Cord Secondary Input Cord
Utility B Utility A
200706234 93-2701 PDUMH15-20ATNET OM.qxd 7/11/2007 4:51 PM Page 10