How to suppress common-mode current in frequency converters with equipotential bonding

Establishing equipotential bonding for the inverter system is one of the fundamental methods for suppressing common-mode current. Common-mode current often originates from potential differences between different parts of the system. Equipotential bonding aims to connect all metal components within the inverter cabinet (inverter body, filters, contactors, cabinet, door panels) and externally connected equipment (motors, PLC cabinets) to the same reference point via low-impedance conductors, typically the cabinet's grounding busbar. When all metal components are at the same potential, the common-mode voltage difference decreases, weakening the source voltage driving the common-mode current. Specific implementation: Use copper busbars or braided straps of sufficient cross-sectional area to connect the components.

Connections should be short and straight, with good contact at the connection points. The shielding layer of the motor cable should be connected to its respective chassis at both the inverter and motor ends, and the two chassis should be connected through an equipotential system. This allows the common-mode current to be controlled by flowing back through the shielding layer rather than to the ground. The equipotential bonding network should be mesh or star-shaped to avoid forming large loops. A good equipotential system not only suppresses common-mode current but also improves the equipment's immunity to surges, EFTs, and other interference. Yinte Electronics' grounding and equipotential bonding products form a reliable foundation for building such systems.