Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 284

Advanced Operating Functions
8.17 Synchronous Transfer
Note
Pre-charge benefit
The benefit of pre-charge is to limit transformer in-rush. Type 6 pre-charge is of value for this
purpose due to the make-before-break connectivity. This applies in particular for drives that
have high impedance feeds.
Type 6 Pre-charge circuit design
The pre-charge circuit consists of a collection of capacitors, resistors, and contactors mounted
in the Fuse/Pre-charge/Control (FPC) cabinet on the input section of the drive.
Figure 8-14 Type 6 Pre-charge Circuit Schematic
Located on the left side is the low voltage pre-charge source coming in through the pre-charge
circuit breaker. Located on the right side is the connection to the pre-charge secondary windings
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