Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 263

Table 8-2
A – TRANSFER_INIT
B – WAITING_FOR_FREQUENCY_LOCK
C – WAITING_FOR_PHASE_LOCK
D – WAITING_FOR_CONTACTOR_CLOSURE
E – TRANSFER_COMPLETE
* 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.
Dow n Tr ansf er Req r em oved
Dr i ve l eaves t r ansf er st at e
line contactor open sense
Transfer Complete
Figure 8-9
NXGPro+ Control Manual
Operating Manual, A5E50491925A
Up Transfer States
STATE
E t o A
D to E
Drive enabled
Down Transfer State Diagram
Advanced Operating Functions
A t o B
( out put vol t age > 50% AND PLL i s val i d
AND VFD cont act or i s cl os ed AND
f r equency er r or < 0. 5 Hz)
Dr i ve out put di s abl ed
B to D
(frequency error < 0.5 Hz for 1
second)
Line contactor command to open
8.17 Synchronous Transfer
VALUE*
0
1
2
4
6
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