Tripp Lite PDUMH20ATNET - Manual (Page 10)

10
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.
Facility Circuit Facility Circuit
PDUMH15ATNET Critical Equipment
Loads
Secondary UPS Primary UPS
Primary Input Cord Secondary Input Cord
Utility B Utility A
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.
4. Configuration and Operation
4.1 Automatic Transfer Switch
4.1.1 Preferred Configuration
4.1.2 Automatic Transfer Switch Source Selection
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).
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.
English.indd 10 1/16/2009 4:37:26 PM