Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 293

Figure 8-16
Sequence of Operation
1. To start pre-charge, DriveReadyToPrecharge_I must be
true. PrechargeStartEnable_O is set true to start the sequence.
2. M2 is closed to begin resonance by connecting a capacitor in series with the
secondary, PrechargeM2Close_I is set equal to true.
3. When the input primary voltage reaches the max phase voltage set by the parameter
"Precharge voltage level" (2634), a damping resistor is connected through
M3. PrechargeM3Close_I is set equal to true.
4. The M3 acknowledge comes back, PrechargeM3CloseAck_O is set equal to true. M2
contactor is commanded to open, PrechargeM2Close_I is set equal to false.
5. The M2 acknowledge comes back, PrechargeM2CloseAck_O is set equal to true. M1
contactor is commanded to close, PrechargeM1Close_I is set equal to true.
NXGPro+ Control Manual
Operating Manual, A5E50491925A
Type 1 Pre-charge Component Connections
Advanced Operating Functions
8.18 Pre-charge using SOP
291