Capacitor discharge welding

In case of capacitor discharge welding (CD), the energy required for welding, from previously charged capacitors, is switched via a thyristor, to a welding transformer. Thereby, the charging times vary between 0, 5 s and 2 s, the welding times between 3 and 10 ms.

The capacitors are charged with up to 1500 V, for an optimum utilization of the capacities. These relatively high charging voltages allow thereby for great transmission ratios. In addition to a high welding current, the welding installation can be simultaneously operated with a relatively high secondary voltage.


Due to the short-circuit-like discharge of the energy stored in the capacitors, the current in the secondary circuit reaches its maximum very quickly. This rapid increase in temperature heats the welding zone, before the heat can flow off. After only a few milliseconds, the projection is welded, without the surroundings of the welding joint being fully heated.

Given this concentration of the input energy, with regard to the volume to be heated, the efficiency of capacitor discharge welding is greater than 90%. Capacitor discharge welding is a very economical process, which places low demands on the grid connection and uses the input energy without losses.

Quality assurance

In addition to the mechanical force and displacement, resistance and voltage can also be recorded, in order to monitor resistance welding. For the avoidance of gross errors, the welding current and the penetration must be checked first. PQS process monitoring represents a comprehensive and qualified system for the quality assurance of your capacitor discharge welding process.