Powerware Uninterruptible Power Supply SOLA 4000 - Manual (Page 58)

SOLA 4000 - Operation
JUE 401266 58
1 OPERATING MODES
1.1 General
There are four different operating modes of the standard stand-
alone on-line UPS-system (5 for hot-standby and 6 for parallel
systems), ensuring uninterrupted power supply of the load under all
conditions. Transitions between these operating modes are per-
formed without interruption of the power supply to the load.
Security concept • In "Normal Operation" any failure, internal or external, will
transfer the UPS system either to "battery operation", to "by-
pass operation" for a stand-alone UPS or to "operation with an
inverter failure" for parallel and hot-standby systems.
• In "Battery Operation" or "Bypass Operation", with a stand-
alone UPS system, an additional failure may interrupt the
power supply to the load, depending on the kind of failure. In
both operating modes the UPS signals a failure condition
(audible and visual alarm) to indicate that any additional failure
bears the risk of interrupting the power supply to the load.
• As additional security, a second UPS unit may be added and
connected in parallel with the original unit, in a hot-standby
configuration. Therefore, in the case of a failure of one inverter,
the second inverter will take over the load. This system re-
quires the occurrence of 3 or 4 simultaneous failures (the
bypass can be also redundant) before the load is interrupted.
Any number of units can be connected together in this way, the
addition of each unit providing the addition of 1 or 2 additional
security factors. The interconnection of the SOLA 4000 in this
way requires a special cable available from your local distribu-
tor.
• Parallel Operation is used to provide redundancy in the same
way as for hot-standby units above and / or an increased
capacity to supply the load, the parallel units exactly sharing
the load requirement.
• "Maintenance Bypass Operation" is used to supply the load
directly from mains during maintenance or repair work.
Warning: Even in case of a total blackout, the UPS will continue to
supply power to the load, therefore all necessary precautions
against direct and indirect accidental contact as specified in na-
tional and local safety standards must be followed.
1 Operating Modes