Powerware 9170+ - Manual (Page 5)

1 Powerware ® 9170 User's Guide S LTM-1344 B Uncontrolled Copy
C H A P T E R 1
I
NTRODUCTION
The Powerware 9170 uninterruptible power system (UPS) is a modular
UPS that contains battery modules and power control modules (referred
to as power modules). These modules plug into a rack cabinet structure
containing additional control, communication, and display functions
that enable integrated control of all power modules. The UPS is housed
in a single cabinet, with extra battery capacity housed in auxiliary
battery cabinets.
The pluggable power modules can be removed and replaced
(hot-swapped) without powering the UPS down if the UPS has sufficient
redundant capacity. Battery modules may also be hot-swapped for
maintenance. Power control circuitry in the cabinet senses problems in
power modules, and automatically transfers control and load to the
remaining power modules.
All power modules share the load requirements equally. For example,
three power modules are capable of supplying a total of 9 kVA. If a load
requires only 4.5 kVA, each power module supplies 1.5 kVA to the
output. If one power module is removed or for some reason fails, each of
the two remaining power modules would supply half of the load, or
2.25 kVA. In other words, redundancy exists when the load can be
supplied by less than all of the installed power modules.
The UPS can be configured with up to seven power modules; its output
is limited such that an excess number of power modules allow the
failure of one or more modules without causing the UPS to lose any
functionality.
To permit UPS removal from the power path, while maintaining power
to the loads, an external bypass switch is required. This switch is
optional but recommended for system serviceability.