SPG series covers frequency from 10KHZ to 1100KHZ, and power ranges from 3KW to 300KW;  there are hundreds of models of SPG machines,  according to the different frequency range and technical structure, SPG machines are divided into  SPG20K series,  SPG50K series, SPG series and  SPG400K series. Due to the wide frequency range and power range, SPG machines are widely used in various metal heating applications.
1.  Working theory and structure of SPG machine 
In these machines, series oscillating circuit is applied, through high frequency transformer, low voltage and high current power is output to go through the induction coil. 
Inside SPG series machines, IGBT or MOSFET module and our third generation inverting control technology has been used, that is the soft and dual control and inverting technology. In this technology, output power and frequency can be controlled and adjusted separately, IGBT module and soft switching control technology are used in the high frequency switching circuit to control the output power.  In the inverting circuit, the IGBT and frequency tracing circuit is applied to achieve high speed and accurate soft switching control. The adoption of new technologies not only improves the quality and reliability of the machine，but also solve the technology problem on large power induction heating machine and makes it possible to work 100% duty cycle.
Compared with SP series machines,  SPG machines have much wider frequency range,  wider induction coil range and higher heating efficiency.

2.  SPG catalogue:
（1） SPG20K series : 10—40KHZ
（2） SPG50K series:  30—80KHZ
（3） SPG series:  80—200KHZ 
（4） SPG400K series:  200—500KHZ 
（5） SPG-06 and  SPG-10 series
3. SPG models meaning: