The inside-delta connection (640 A) applies when the softstarter is wired in the delta legs of a six-lead motor, which reduces the current through each phase device; the 355 kW figure at 400 V tells you the motor power it can start in that configuration. The ramp time from 0 to 120 seconds gives you a wide window to tune acceleration for soft-start applications like conveyors or pumps, avoiding mechanical shock.
Deployment context
This is a panel-mount softstarter — main circuit terminals are bars (hole diameter 10.5 mm), control circuit terminals accept 1 x 2.5 mm² rigid, tightened to 0.5 N·m. The IP00 main terminals mean it lives inside an enclosure; plan for adequate clearance and cooling, especially at the 640 A delta rating where heat dissipation matters.