Precharging And Bypass Contactor Chassis - Siemens SINAMICS S120 Function Manual

2.5

Precharging and bypass contactor chassis

Precharging is the procedure for charging the DC link capacitors via resistors. Precharging is
carried out from the feeding supply network. The precharging input circuit limits the charging
current of the DC link capacitors.
The precharging input circuit for Active and Smart Infeed in the chassis design comprises a
precharging contactor with precharging resistors and a bypass contactor. The Active Line
Module controls the precharging input circuit in the Active Interface Module via terminals.
The precharging input circuit in the Active Interface Module of module types FI and GI
contains the bypass contactor. The bypass contactor must be provided separately for frame
sizes HI and JI.
With the Smart Line Module, precharging is integrated in the Smart Line Module itself,
although the bypass contactor must be provided externally.
Unlike Basic Line Modules in frame sizes FB and GB, a Basic Line Module in frame size GD
requires a separate precharging circuit. The bypass contactor must be designed as circuit
breaker.
The precharging circuit comprises a precharging contactor and precharging resistors; the
circuit must be protected against overcurrent using suitable protection measures. To
increase the permissible DC-link capacitance, the precharging resistors can also be
connected in parallel in each phase.
Further information:
● SINAMICS S120 Manual for Chassis Power Units, Air-cooled
Procedure during power ON/OFF
Power ON:
● The precharging contactor is closed and the DC link is charged via the precharging
resistors.
● Once precharging is complete, the bypass contactor is closed and the precharging
contactor opened. The DC link is precharged and ready for operation. If precharging
could not be completed, fault F06000 is output.
Power OFF:
● The pulses are inhibited and the bypass contactor is then opened.
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
2.5 Precharging and bypass contactor chassis
Infeed
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