ASD-B3A-0721-E-AC SERVO DRIVE .75KW 220S B3A 6.The ASD-B3A-0721-E-AC Servo Drive.The 75KW 220S B3A 6 servo drive is a high-performance, compact option for industrial automation. Its precision control and endurance make it excellent for a wide range of applications, from CNC milling to robotics.