Transformers for capacitor discharge welding

EXPERT has been building and developing pulse transformers for capacitor discharge welding applications for many years.

This process is characterised by the very high application of energy into the workpiece in a short period of time (typically 10-60 ms).

The energy for the welding process is stored in capacitor banks.

Through targeted discharging via a matching transformer, a current pulse is generated which welds the components together. The welding process itself involves projection welding in most applications.

In order to save large amounts of energy in the capacitors, relatively high charging voltages are required. Typical charging voltages are 2000 to 3000 V.

Thanks to the application of high levels of energy, this process enables large-sized components and critical material combinations to be welded. For example, it is used to weld gear wheels in the automotive industry.

Optimal energy efficiency is a key characteristic. Only very small heat affected zones are created in the material with welding processes. The energy is used almost exclusively to melt the materials together at the point of connection.

Welding currents of up to 1,000,000 A have been achieved in systems with EXPERT transformers.

Another advantage of capacitor discharge welding is the relatively low loading of the power supply since the capacitors, as energy buffers, are able to be recharged evenly during the breaks between welding.

These systems are used predominately for large-scale production at automated joining stations.

The matching transformer (pulse transformer) not only serves to ensure an optimal energy supply for the joining process but also, with its design and configuration, plays a key role in determining the timing of the welding current (pulse form) and thus also the welding process.

EXPERT boasts many years of experience in the dimensioning of pulse transformers in the high-current sector.
In-house calculation and simulation tools enable transformers to be ideally designed and adapted to meet customers’ requirements.

We would be delighted to use our experience to optimise your welding processes.


Output range

  • Pulse power: 5 to 200 kJ
  • Transformer ratio: Fixed or adjustable
  • Max. charging voltage up to 4000 V
  • Water cooling with higher pulse rates
  • Standard temperature monitoring
  • Fully potted design
  • High dynamic strength

Following a small choice of transformers is being described. Please contact us for your requirements.

100 5 200 59 approx. 120 x 235 x 600
150 10 160 112 approx. 184 x 235 x 612
250 20 300 200 approx. 312 x 337 x 470
250 20 150 / 200 / 250 / 300 275 approx. 312 x 337 x 670
400 40 150 / 200 / 250 / 300 380ca. approx. 400 x 620 x 477
1900 120 108 / 90 / 72 / 54 900 approx. 500 x 600 x 800