Technical information

Safety instructions
1-12
1070 080 059-101 (2001.04) GB
1.8 System perturbation
When operating a medium-frequency inverter a harmonic load must be ac-
counted for in the mains system. This load is caused by the ”B6” rectifier cir-
cuit with a smoothing capacitor.
The following figure shows the typical curve of the mains voltage (top) and
the related mains current (bottom) in one phase during the welding process:
Typical 300 Hz
The 5th, 7th, 11th, 13th, 15th, and 17th harmonic wave are the characteristic
harmonics of the mains current curve.
The harmonic component depends on the welding power.
. Note: The harmonic content may be considerably reduced, e.g., by us-
ing smoothing reactors with 4% short-circuit voltage.