Product Description:

The S7720A-DNF2-S3 is an AC servo drive produced by Kollmorgen within the S700 Servo Drives series. The unit converts line power into regulated output for closed-loop control of brushless servo and induction motors used in packaging, material handling, and robotics. It integrates motion control, safety, and brake energy management in one housing, acting as the intermediary between a supervisory PLC and the mechanical axis within automated production lines. This arrangement lets the drive react quickly to command changes while maintaining stable motor operation during repeated machine cycles.

The drive supplies a continuous phase current of 72 Arms, allowing sustained operation of medium-torque motors. During acceleration or rapid indexing, it can deliver up to 140 Arms, so the connected load can overcome inertia without saturation. Line loading is governed by a nominal input of 50 kVA, and internal regulation is refreshed every 62.5 µs by the current controller, helping keep torque ripple low. Two analog inputs permit velocity or torque references, while four digital inputs accept limit switches or homing commands. Two bidirectional digital I/O points can be configured for process handshaking, and a dedicated expansion slot carries a fan controller card that supervises cabinet airflow. The design uses a cold plate and coated PCBs to improve thermal transfer and resist contamination, while a residual voltage drop of 6 V across the drive keeps the control electronics active during fast transients.

Input supply ranges from 208–480 V, matching common three-phase mains. Excess regenerative energy is dissipated through the internal brake circuit, which can handle 8 kW continuously and is supplemented by an external resistor of 10 Ω for higher peaks. The mains terminals are rated for 125 A, so feeder conductors remain within standard industrial cable sizes. Functional safety is implemented with dual-channel STO, and two dedicated enable inputs with two status outputs support risk reduction without additional relays. The STO channels remove torque-producing power while allowing the control system to retain status monitoring.