Control system for electrical resistance welding machine - executes digital measurement of welding characteristics for stability of required process

The monitoring and control system uses digital measurement of the high frequency welding characteristics. The control and monitoring system has a welding characteristics counter for digital measurement of >=1 high frequency welding characteristics including the oscillating frequency and the oscillating period of the high frequency used for electrical resistance welding. It also monitors the phase difference between the high frequency voltage and the current of this high frequency. A restoring signal generator is coupled with the counter for generating the restoring signal which ensures that the welding characteristics counter will start digital measurement. Continuous quantitative values are obtd. which describe the welding phenomenon on the basis of digital measurement. The quantitative values can be held constant on a required valve according to the welding process involved.