APC SILCON 990-4053 - Manual (Page 56)

56 Installation Guide APC Silcon 480kW 400V UPS
990-4053
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6.3 Intersystem Synchronization Unit
Intersystem Synchronization Unit System (ISU System)
The ISU system consists of inter-connected ISUs. One ISU system may consist of up to 5 ISUs,
regardles of ISU configuration. The ISU system synchronizes the voltage of parallel operation
systems running in battery operation.
The ISU system may also include one or more external synchronization sources,
e.g. a gen-set or a non-APC Silcon UPS system.
Synchronization accuracy of the ISU is better than 2
o
.
Schematic overview of ISU system (example):
Intersystem Synchronization Unit (ISU)
The ISU is an active part of an ISU system, serving as the interface to the sources and the ISU
system.
The ISU can be connected to a parallel UPS configuration, using the standard parallel
communication controller in the parallel operation system.
(See Intersystem Synchronization Unit User’s Manual for further details.)
ISU System
Parallel
Operation
System 3
Parallel
Operation
System 2 Parallel
Operation
System 1
Ext.
sync
Source
UPS 2C
UPS 2B
UPS 2A
UPS 1C
UPS 1A
UPS 1B
UPS 3C
UPS 3A
UPS 3B
UPS 4
ISU
5
ISU
4
ISU
2
ISU
1
ISU
3