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•
•
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•
•
•
•
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Switch SF2 is used to select between variable-frequency (VF) and power-frequency (PF) switching.
When the automatic bypass cabinet is in manual operation mode, and switch SF2 is in PF position, the drive switches the system
to PF bypass status automatically.
When switch SF2 is in VF position, the drive can switch from power-frequency bypass status to variable-frequency mode auto-
matically (QS41 and QS42 must be closed). This function needs the coordination of engine racing starting-up. Therefore, engine
racing must be enabled and must comply with all the related electric motor parameters.
VF logic sequence:
KM41 is closed.
If self-detection shows normal after 10 s, bypass switch KM43 is opened.
KM42 is closed.
Automatic engine racing of the drive starts up.
PF is switched to VF.
e3
0b
i7
53
.1
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Illustration 22: Switching Mode Selection Switch SF2
3.3.7.3 Synchronous Transfer Cabinet
The synchronous transfer function can realize undisturbed transfer between the grid and the drive, and reduce the impact on the
motor and grid. The primary circuit is shown in
. The switching devices and cabinets are the same as in the automatic
bypass cabinet. QS41 and QS42 are for drive maintenance use and are closed during operation.
HV~
MCB
M
Automatic bypass/Synchronous transfer cabinet
Manual bypass cabinet
QS41
KM41
KM42
KM43
DN41
QS42
Drive
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48
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Illustration 23: Synchronous Transfer Cabinet Circuit Diagram
Process sequence of load transfer from the drive to the grid
Initial state: KM41 and KM42 are closed, and KM43 is open.
Phase lock: The drive runs to grid frequency and starts to lock phase to grid voltage.
Synchronous transfer: After phase lock, KM43 is closed and the load transfer to grid is started.
Synchronous transfer finished: After the load transfer, KM42 and KM41 are opened.
Process sequence of load transfer from the grid to the drive
Initial state: KM41 and KM42 are open, and KM43 is closed.
Phase lock: KM41 is closed. The drive runs to grid frequency and starts to lock phase to grid voltage.
Synchronous transfer: After phase lock, KM42 is closed and the load transfer to the drive is started.
Synchronous transfer finished: After the load transfer, KM43 is opened.
AQ363633621020en-000201 / 172F3117
28 | Danfoss A/S © 2021.06
Product Overview
VACON® 1000
Operating Guide
Summary of Contents for VACON 1000
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