Transfer Sequence - ABB ACS580MV Hardware Manual

20 Function and hardware description
The Motor Starting Switch (MSS) and Motor Breaker (MB) are not supplied. They must be
rated according to the specification of ABB.
Equipment requirements:The output voltage of the drive and line voltage are measured by
potential transformers (PT). The synchronizing device uses the measurements to
determine the exact transfer instant of the motor to the line.
The PTs can be supplied either by ABB or customer, in case the PTs are supplied by
customer, they must be rated according to the specification of ABB.
System overview and single line diagram of SBU with multiple motors and two grids

Transfer sequence


The transfer of the motor to the line starts with the selection of the motor to be transferred.
After the selection, bypass control checks the positions of the MSS and the MB.
When the motor start command is given, the corresponding MSS is closed, the motor is
started by the drive and operated in speed control mode.
When the drive receives the synchronizing command, the motor is accelerated to a preset
speed (frequency), and then gradually adjusted to around the detected line frequency,
when magnitude, frequency and phase angle between drive output voltage and line
voltage are within the required limit, SYNC conditions are achieved and the corresponding
motor breaker is closed, which connects the motor to the line, and after a preset waiting
time (fixed value in software, normally in the range of a few seconds) the corresponding
motor starting switch is opened.
When the synchronizing sequence has finished, another motor can be transferred to the
line supply.