Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control - Manual (Page 340)

5-32 Functional Description
7000L-UM300I-EN-P – June 2013 7000 “C” Frame
3. When the phase error between the motor voltage and bypass
voltage has remained less than the value specified by parameter
Sync Error Max (228) for the time interval specified by
parameter Sync Time (229) the drive activates its bp contactor
close output.
4. After a time delay specified by Sync Off Delay (227) the drive
shuts off. It is important that this parameter is set to the correct
value. This should be at least 1 cycle less than the contactor
closing time. If this time delay is set too short, the motor voltage
could drift out of phase with the bypass voltage. If the time delay
is set too long, a drive overcurrent fault may occur because the
drive is unable to control its output voltage and frequency once
the bypass contactor has closed.
A T T E N T I O N A T T E N T I O N If parameter Sync Off Delay is set incorrectly,
damage may occur to the drive, motor,
couplings, and driven load if a transfer to
bypass is attempted.
5. When the bp contactor status input indicates that the bypass
contactor has closed, the drive deactivates the do contactor
close output. When the output contactor opens, the drive is
disconnected from the motor, leaving the output filter capacitors
charged to bypass voltage.
6. The synchronous transfer is now complete and the motor is
running on bypass.
7. If in (3), the drive is unable to synchronize within the time
specified by parameter Sync Xfer Time (230) the synchronous
transfer is aborted. At this point the drive can either fault or issue
a warning. This is controlled by the parameter Sync Xfer Option
(419). If selected as Enable Fault the drive faults and ramps the
motor down to a stop, else if it is selected as Enable Warn, the
drive keeps running at the last commanded speed.
Synchronous Transfer
(cont.)