Section 1 Introduction; System Description - Liebert Series 300 Operator's Manual

SECTION 1
INTRODUCTION
1.0

SYSTEM DESCRIPTION

The Liebert Load Bus Sync™ (LBS) option keeps the output of two independent Uninterruptible
Power Systems (UPSs) in sync, even when the two UPSs are operating from two different power
sources. Any UPS will typically sync to its own bypass source. As long as both UPSs are tied to the
same input and bypass sources, they will automatically stay in sync. However, if the UPSs are
operating on batteries, or different backup generators, or asynchronous bypass sources, their outputs
will tend to drift out of sync.
Maintaining sync is critically important for installations with dual power distribution systems. These
sites typically feature Liebert Precision Power Centers (PPC) with Liebert Static Bus Transfer
Switches. Each PPC has dual inputs: it can receive power from either UPS, and switch seamlessly
between the two as long as the UPS outputs are held in close synchronization. This provides
redundancy down to the PPC level. It also permits one entire half of the distribution system (upstream
of the PPC) to be taken offline for maintenance or repairs.
The Load Bus Sync option consists of an LBS interface in each UPS module plus one LBS controller
enclosure installed between the UPSs.
Figure 1. LBS Controller Enclosure
Series 300 Load Bus Synchronization 1
DISCONTINUED
PRODUCT