Vertiv Liebert MBSM - Both Power Bus Failure

Vertiv
™
|Liebert
®
MBSM
™
User Manual | 16
2.9.3 Both Power Bus Failure
Should both power buses be replaced by generator after a fault sequence of both the power
buses, the Liebert MBSM will do the following:
• If local priority switch is on auto, the Liebert MBSM will select one of the two generators as a source for
system synchronization.
• If local priority switch is on a preferred source, that source will be selected, unless the voltage and
frequency values are outside preset limits; under this last condition the second available source will be
selected anyway, independently from the switch position.
• If both sources are detected outside set limits, the Liebert MBSM will generate the frequency reference
by the local quartz oscillator.
• If the two power buses are supplied from a common generator and inside set limits, the Liebert MBSM will
operate as per normal conditions and checks