How should an industrial servo SPD be grounded in conjunction with EMC?

If an external surge protector (SPD) is installed on a servo system, its grounding must be coordinated with the equipment's EMC grounding. The recommended coordination principle is that the SPD should be installed at the very beginning of the equipment's power supply line. The SPD's grounding wire must be short and thick (recommended cross-sectional area ≥ equipment phase wire), directly connected to the building's main grounding busbar or independent grounding stake in a low-inductance manner, with a length preferably <0.5m. The servo equipment's own protective earth (PE) should also be connected to the same point or reliably connected to the grounding busbar via an equipotential bonding strip. This ensures that lightning surge current is directly discharged to the ground through the SPD's grounding path, preventing it from flowing through the equipment's interior. Simultaneously, the equipment's internal filters (such as CMZ common-mode inductors) and shielded housing should also be connected to the equipment's PE terminal. Proper coordination ensures effective SPD operation, limits residual voltage within the equipment's tolerance range, and maintains the equipment's original EMC (filtering and shielding) performance, complying with the IEC 62305 lightning protection standard.