3
One-Line Diagram
True Front-Access Design
All mechanical and electronic components of the Liebert
STS2 are accessible from the front of the unit for
installation and service—no side or rear access required.
This gives you several immediate benefits:
Greater freedom in system design. The Liebert STS2
can be placed adjacent to or in back of other
equipment. It can also be placed against a wall or
partition.
Simplified installation, with ample space for cable
connections through top and bottom access plates.
Less floor space required for maintenance access.
Designed for maintainability, with all key components
visible and accessible from the front of the unit,
without shutting down the connected load.
For units up to 600 amps,
the entire power and
control module can be
removed as an assembly.
A separate compartment
for option modules
provides safe and
convenient field access.
Source 1
Source 2
System Output
CB1
CB3
CB4
CB2
CB5
K1
K2
K2
K3
K1
K3
True Internal Redundancy
The Liebert STS2 has triple-
redundant logic. Each DSP
controller is capable of working
independently, and each helps
monitor the other two. If one
malfunctions, the other two lock it
out. Each controller has power
feeds from both power supplies.
The two power supplies feature true
dual-bus power distribution. Both
have dual inputs, one from each AC
input source. All power connections
have diode protection, so that internal
or external faults cannot propagate.
The result is a rugged, fault-resilient
package that is optimized for real-
world applications.
