How to avoid loops when using dual-terminal grounding for industrial servos?

While double-end grounding of the shielding layer of servo cables (such as encoder cables and motor cables) provides good high-frequency shielding, it is prone to forming low-frequency ground loops due to potential differences between the two ends. Technical measures are needed to avoid these loops. Audiotech's solution: Ground the shielding layer directly at one end of the cable (usually the driver end), and ground the other end through a low-value resistor (e.g., 100Ω) or a Faraday cage capacitor (e.g., 10nF/Y1).

This capacitor presents low impedance to high-frequency noise, achieving high-frequency shielding; and high impedance to low-frequency potential differences, blocking loop current. Simultaneously, add a pair of independent equipotential bonding wires (cross-sectional area ≥0.75mm²) inside the cable, directly connecting them to the outer casings of the devices at both ends to balance the low-frequency potential difference. Use cables with shielding effectiveness >90% and shielding layer coverage >85%. After implementation, the loop current measured on the shielding layer should be <1mA (50Hz), and the shielding effectiveness loss in the high-frequency band (>1MHz) should be <3dB. This method complies with the IEC 60204-1 mechanical safety standard.