Powerware 9315 - Manual (Page 34)

28 Powerware 9315 Parallel Redundant System I & O
164202013, Rev. D 041599
Parallel Redundant System Description
The parallel redundant system consists of two identical UPS modules, a parallel
cabinet, and one or two battery racks or cabinets.
The parallel cabinet consists of two module output breakers designated MOB 1
and MOB 2. These output breakers receive power input from the AC output of the
UPS modules. If one UPS module becomes disabled, it trips off, leaving the
redundant UPS module to continue to supply power to the critical load. The
primary function of the MOBs is to allow isolation of a module for maintenance or
service. In a parallel redundant system the redundant module becomes the
system’s maintenance bypass source.
There are two lamps located on the inside of the parallel cabinet labeled
OK TO CLOSE. When one of these lamps illuminates, the corresponding MOB
can be closed. It is important to note that it is only safe to close the MOBs when
the OK TO CLOSE indicator lights are illuminated. A LAMP TEST pushbutton is
located inside the parallel cabinet for testing these indicators. The parallel cabinet
also includes associated terminal strips for making the power and control
connections to UPS modules. Figure 10 shows the controls and indicators of the
parallel cabinet.