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Capacitor Storage Technique

For these power sources, high-frequency and medium-frequency inverters with energy stores in the form of capacitor banks are connected together. In this combination, both systems demonstrate their strong points and the restrictions of separate systems are eliminated. This way, the "big" mains connection which is, otherwise, necessary for high-current inverters (up to 2400 A at the output; up to 65 kA at the welding point) can be dispensed with. With a series-connected capacitor bank, a 16 A connection is sufficient, depending on the application!

The energy of the inverter which is necessary for welding, is provided by the capacitor bank. An agreeable side effect is the quasi ideal smooth welding current, as the residual ripple which is otherwise existing in the intermediate circuit is almost completely eliminated.

Particularly the downstream high-frequency inverter (20 kHz) allows, even with short welding times, the realisation of any current profiles with ramps, plateaus, off-times, etc., which is impossible with conventional capacitor discharge systems. Adaptations to the welding task are, therefore, possible at all times at the flick of a switch.


  • low connection values, starting from 16 A
  • 3-phase balanced system load, no phase shift
  • almost none residual ripple of the welding current
  • smallest controllable unit of time period = 0,025 milliseconds with HFDC and 0,5 ms with MFDC
  • high welding currents
  • also suitable for extremely short welding times
  • uninterrupted energy input into the weld nugget

Our solutions:
Depending on the welding task, the capacitor banks of the SumoSPATZ family are used in connection with the DragSPATZ HF systems and/or the SPATZ+ MF systems.

Inverter Welding Current Inverter Welding Current
up to 45 kA DragSPATZH1600 up to 45 kA
SPATZ+Tandem1800 up to 65 kA DragSPATZH2400 up to 65 kA
SPATZ+MS2400 up to 100 kA