How to choose between single-point and multi-point grounding for industrial servos?

The choice of grounding method for a servo system depends on the frequency, cable length, and type of interference. Audiotech's selection criteria are as follows: For low-frequency (<1MHz) analog circuits, sensitive sensors (such as encoders), and cabinet safety grounds, use **single-point grounding**, converging all ground wires to a single point on the negative terminal of the DC bus capacitor to avoid ground loops. For high-frequency (>10MHz) digital circuits, shielded cable shielding, and RF interference suppression, use **multi-point grounding**, connecting the ground wires to a low-impedance metal chassis or grounding plane via the shortest path. For example, connecting IGBT heatsinks and filter housings to the cabinet at multiple points. A hybrid grounding strategy is often used: single-point connection for signal ground, and multiple connections for chassis and shielding at both ends of the equipment, with high-frequency bonding achieved through capacitors (such as 1nF/Y1). Selection can be determined by testing the ground noise voltage: if the ground noise voltage >50mV, multi-point grounding should be considered. Correct grounding selection can reduce system common-mode noise by more than 40%.