Siemens SINAMICS S120 Manual page 806

Service and Support Booksize
14.2 Forming the DC link capacitors
Figure 14-5
Procedure
1. Be sure to remove the DC-link bridge before forming the DC-link capacitors.
2. Make sure that the device does not receive a switch-on command (e.g. from the
keyboard, BOP20 or terminal block).
3. Connect the forming circuit.
While forming, the incandescent lamps must go dark or go out completely. If the
incandescent lamps continue to be brightly lit, a fault has occurred in the drive unit or in
the wiring.
For forming using PTC resistors, the modules must remain in the circuit for approx. 1h.
The resistors will become very hot if there is a fault in the unit (surface temperature > 80°
C).
806
Forming circuit for Motor Modules with PTC resistors
Booksize Power Units
Manual, (GH2), 07/2016, 6SL3097-4AC00-0BP8