Start-Up Sequence - Danfoss VLT Active Front End AFE 302 Operating Instructions Manual

Crane System Design

3.9 Start-up Sequence

Illustration 3.19 shows the typical AFE start-up sequence flow chart. The flow chart describes the interaction among Auxiliary
Hardware, AFE Frequency Converters, and Liebherr Control PLC. The arrowed lines indicate the flow of the actions. The
Liebherr PLC expects to receive the "Control Ready" and "Ready" signals from the AFE frequency converter and it will send
"Run" signal to AFE frequency converter. The waiting periods and the number of tries are tentative. The "Control Ready"
signal is on when the power in Control Card is on. The meaning of the "Ready" signal in the AFE frequency converter is
different from the one in the standard frequency converter. The "Ready" signal in the AFE frequency converter is on when
the DC voltage is boosted to the level where the AFE regulation is enabled.
Auxiliary Hardware
Actions
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 3.19 Start-up Sequence Flow Chart
MG33X402
Operating Instructions
AFE Drive
Contactor LCL cabs ON
2 sec Delay
When the PC becomes
active, "Soft Charge Ready"
signal is ON.
Wait for 1 second
to have the DC capacitors
charged further.
Send the open signal
to the SC contactor.
Wait for 1 second
to make sure that the
S/C contactor is open.
Send the close signal
to the AFE contactors.
Wait for 0.5 second
to have the DC capacitors
charged fully.
Send the "Run"
The AFE drive is active.
signal to the AFE drive.
When the DC voltage is within
the target range, "DC-link on
Ref" signal is on.
Danfoss A/S © Rev. 05/2014 All rights reserved.
Control PLC
: Assume that the AFE contactors
and SC contactor are open
Start-up Sequence
prior to this start-up sequence.
Crane ON
Send close signal to
the SC contactor.
No
Protection Mode
Receive "Soft Charge
due to the Start-up
Ready" signal within
Failure
20sec?
Yes
: Assume that the SC contactor is
disengaged within 0.5sec.
The DC capacitor discharge
is negligble.
:The waiting period can be substituted
by the contactor status signal.
: Assume that the AFE contactors
are fully engaged within 2seconds.
:The waiting period can be substituted
by the contactor status signal.
Receive "DC-Link
on Ref" signal from
No
AFE within 5 sec?
Yes 3rd Try?
End of Start-up
Sequence
Protection Mode
due to the Start-up
Failure
No
Yes
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