... 3) long time continue working Good performance MMA-250T DC inverter welder Use: light manufacturing, maintenance, civil steel structure ... carbon steel, carbon steel, alloy steel, etc.; Advanced inverter technology: Inverter frequency up to 100KHz, conversion rate of 85%, no ... adjustable, easy to use, easy to carry, reliable and economical and durable; Precise control system: PWM Pulse Width Modulator, ...