OMD10078 rev F
14
1.4.1 Inverter
Emergency Line Transfer
The transfer is activated only if the emergency line is in tolerance (in less than 0.5
ms), for the following reasons:
CAUSES
COMMUTATION CONDITIONS
Output short-circuit
Emergency line within tolerance limits
Fault of inverter or inverter voltage out of tolerance Emergency line within tolerance limits
DC voltage out of tolerance (Inverter OFF)
Emergency line within tolerance limits
Over-temperature
Emergency line within tolerance limits
Thermal image shut down
Emergency line within tolerance limits
Forced commutation by “BYPASS SWITCH” (test or
service)
Emergency line within tolerance limits and
SYNCHRONIZED inverter
1.4.2 Emergency Line
Inverter Transfer
As soon as inverter is correctly working and synchronized, UPS automatically
switches the load to inverter in less than 1 msec. If UPS switches back and forth more
than 6 times in two minutes an alarm will be generated, to inform the user, and the load
will be locked to emergency line. A manual reset is necessary to switch the supply back
to the inverter.
1.5
MANUAL BYPASS
To safely allow maintenance and repair of the unit, UPS is provided with a manual
bypass switch.
In this mode all the testing activities to verify the efficiency of the system can be
carried out safely. Manual bypass must be inserted by following the instructions given in
the operating manual. During the transfer to manual bypass there is no interruption of
the supply to the load.