The Siemens 3RW2920-6LD00 is a thyristor module for the SIKOSTART soft starter, rated for supply voltages from 200 to 500 V. If you're rebuilding a 3RW2245 that's lost its firing path on one or both phases, this is the OEM power assembly that bolts in.
What the voltage rating means for fit
The module covers a 200 to 500 VAC supply range, which matches the line voltage window of the 3RW2245-0DB15 SIKOSTART. The thyristors inside are sized for the soft starter's motor current rating — swapping this module into a different frame size won't work because the heat sink and gate-drive interface are specific to the 3RW2245-0DB15.