Emergency Power-Off; Parallel Operation; Decentralized Static Switch Parallel Configuration - Gamatronic POWER+ User Manual

The unit can be moved to bypass mode manually. This can be done on the unit console, or on the static
switch panel. In parallel configuration, when the POWER + units are moved to bypass mode manually (via
a console command on one of the units), to move the units back to normal (inverter) mode you must
enter the command on the same unit and on the same console that was used to move the system to
bypass mode, otherwise the command will have no effect.
2.3.1

Emergency power-off

An external EPO switch is used for system shutdown in emergency situations. This cuts the supply to the
load with immediate effect and cannot be reset. Once switched OFF by the EPO, the POWER + must be
restarted manually.
2.4

Parallel operation

When two or more POWER + units are deployed in parallel, they are connected according to the
Decentralized Static-Switch configuration (see below). Special technical solutions and control algorithms
are implemented to synchronize all units in the system to prevent circulation of energy between them and
to isolate a faulty unit from the common power bus. In addition, an active current sharing circuit regulates
the output voltage of each UPS to provide optimal load sharing between the units.
One of the system's units takes on the function of "master". This unit is synchronized to the mains power.
The other units operate as "slaves" and follow the master. The master role is not fixed to a specific unit;
any of the UPS units can operate as the master.
2.4.1

Decentralized static switch parallel configuration

Every POWER + unit is equipped with a static switch for functional override. This presents a problem in
that, were one UPS were to fail, the static switch bypass would instantly be triggered and supply the load
directly from the mains. This would connect the inverters of the other UPSs directly to the mains which
could potentially damage them.
To avoid such a hazard in decentralized mode, the Static Switches are synchronized by dedicated control
communication to ensure that all units will always transfer to static switch bypass simultaneously.
POWER +
UPS,
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