An inquiry came in asking why is MID FREQUENCY WELDING called MID FREQUENCY? That is a very logical question which goes back to the frequency of the power being generated in MID FREQUENCY resistance welding. In much of the world this is 1000 Hz.
In the world electricity frequency is divided into ranges of:
LINE FREQUENCY: This is the normal power grid in the world which run as 50-60 Hz
MEDIUM: 600Hz – 4000 Hz
High: 10 KHz – 50 KHz
The resistance welding inverters produce a 1000 Hz Dc output which is in the medium range which is why it is called a Mid or Medium Frequency welding.
If one looks beyond the electrical world we find that :
Speech and Sound have a similar break down and description of frequencies.
Lowest Sound Ear can detect - 20 Hz – 250 Hz
Mid Frequency (Human Voice) – 250 Hz – 4000 Hz
High Frequency (Cymbals) – 4 KHZ-20 KHz
Radio Waves have a similar but different range:
Low frequency is 30kHz to 300 kHz
Medium Frequency 300kHz to 3 MHz.
High Frequency 3 MHz to 30 MHz
VHF (Very High Frequency) 30 to 300 MHz.