The protective earth terminal is a terminal for grounding any dangerous voltages that may occur in the motor case or driver case (due to damage, etc.) (to prevent electric shock). It also serves as a shield to ground the power line noise and protects against external radiated noise.
To prevent danger and ensure stable operation, please connect the protective earth terminal to earth. Please check the instruction manual for each product and use a protective earth wire of the appropriate diameter to be attached between the protective earth terminal and the protective conductor.