How can poor grounding cause EMC problems in industrial servos?

Poor grounding is a common root cause of EMC problems in servo systems, leading to various issues:

1) Excessively long or thin grounding wires result in high high-frequency impedance, preventing effective common-mode noise discharge and causing excessive conducted interference, especially above 10MHz.

2) Loose or oxidized grounding connections increase contact resistance, creating a potential difference that drives shielding current, turning the cable into a radiating antenna and causing excessive radiated interference.

3) Grounding loops form, inducing current at power frequency or switching frequency, interfering with analog sampling (such as current and position), causing control oscillations or alarms.

4) Chaotic multi-point grounding leads to crosstalk between different grounds. A case study from Yinte Electronics shows that repairing a loose grounding bolt (reducing it from 100mΩ to 1mΩ) can reduce the radiated peak at 30MHz of a certain servo system by 8dB.

Therefore, systematic, low-impedance grounding is the first step in solving servo EMC problems.