Danfoss VLT AFE 302 Operating Instructions Manual page 21

Crane System Design
Auxiliary Hardware
Actions
3 3
The SC contactor
is closed.
Charge the DC bus
through the SC circuit.
The SC contactor
is open.
The AFE contactors
are closed.
DC voltage is going
up to the desired level.
Abbreviations:
AFE: ACtive Front End
CC: Control Card
PC: Power Card
PLC: Programmable Logic Controller
SC: Soft Charge
Illustration 3.14 Start-up Sequence Flow Chart
20
®
VLT Active Front End AFE 302 Operating Instructions Liebherr
AFE Drive
When the PC becomes
active, "Soft Charge Ready"
signal is ON.
The AFE drive is active.
When the DC voltage is within
the target range, "DC-link on
Ref" signal is on.
®
MG.33.X2.02 - VLT is a registered Danfoss trademark
Control PLC
: Assume that the AFE contactors
and SC contactor are open
Start-up Sequence
prior to this start-up sequence.
Crane ON
Contactor LCL cabs ON
2 sec Delay
Send close signal to
the SC contactor.
No
Protection Mode
Receive "Soft Charge
due to the Start-up
Ready" signal within
Failure
20sec?
Yes
Wait for 1 second
to have the DC capacitors
charged further.
: Assume that the SC contactor is
disengaged within 0.5sec.
Send the open signal
The DC capacitor discharge
to the SC contactor.
is negligble.
Wait for 1 second
:The waiting period can be substituted
to make sure that the
by the contactor status signal.
S/C contactor is open.
Send the close signal
: Assume that the AFE contactors
to the AFE contactors.
are fully engaged within 2seconds.
Wait for 0.5 second
:The waiting period can be substituted
to have the DC capacitors
by the contactor status signal.
charged fully.
Send the "Run"
signal to the AFE drive.
Receive "DC-Link
on Ref" signal from
No
AFE within 5 sec?
Yes
End of Start-up
Sequence
Protection Mode
due to the Start-up
Failure
No
3rd Try?
Yes