Siemens SINAMICS PERFECT HARMONY GH180, Function Manual

Page: 263 / 538

Table 8-2 Up Transfer States
STATE VALUE*
A – TRANSFER_INIT 0
B – WAITING_FOR_FREQUENCY_LOCK 1
C – WAITING_FOR_PHASE_LOCK 2
D – WAITING_FOR_CONTACTOR_CLOSURE 4
E – TRANSFER_COMPLETE 6
* Value is the value of the state machine variable for plotting purposes.
Down Transfer with No Reactor
Two sources cannot be connected for any length of time without an interposing reactance.
Therefore, the state machine was redesigned to eliminate the wait for torque build up when
both sources are attached. This was done by aallowing the drive to remain disabled until after
the line contactor opens. The "Wait for Torque" state is skipped, and after synchronization to the
line, the line contactor is commanded open.
The loss of the line feed to the motor is detected by a drop in motor voltage signifying the line
is no longer supplying the motor. This drop is detected as the line contactor open feedback. Once
detected, the drive speed regulator and ramp is preset and then the output enabled quickly. The
drive then takes control in a manner similar to a spinning load catch.
Since the operation is so different from the normal Down Transfer sequence – which is a make-
before-break operation, a new state machine is needed. The choice of which down transfer state
machine to use is determined by the state controller with the setting of the "Sync Transfer Type"
parameter.
E to A
Dow n Transfer Req rem oved
Drive leaves transfer state
A to B
(output voltage > 50% AND PLL is valid
AND VFD contactor is closed AND
frequency error < 0.5 Hz)
Drive output disabled
B to D
(frequency error < 0.5 Hz for 1
second)
Line contactor command to open
D to E
line contactor open sense
Drive enabled
Transfer Complete
Figure 8-9 Down Transfer State Diagram
Advanced Operating Functions
8.17 Synchronous Transfer
Control Manual
Operating Manual, A5E50491925A
261