Can a motor be started by either a soft starter or a star-delta circuit alternatively?
All our softstarters can be used in parallel along with the conventional Y-D motor start method, under condition both installations are galvanicly separated. This effectively means a designer needs to assure power wiring of softstarter and Y-D need to be disconnected, assured by control logic.
The mechanical interlock system is perfectly suitable, as long as the KM4 contactor is involved as well.
Control logic needs to solve the control sequence due to its functionality, but it's not conditional if there is hardware prevention.