Not less than 30CM,
When the effective separation distance cannot be guaranteed, the communication cable can be replaced with an armored cable.
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Low-frequency interference cannot be ignored
Inverters, power cables, transformers, high-power motors, etc. are often accompanied by low-frequency interference, and this interference is caused by high conductivity materials Cables with a shielded layer cannot solve the problem, including original imported cables. Only shielding layers made of high-permeability materials (such as steel strips and steel wires) can effectively suppress low-frequency interference.
The most common method is to cover the cable with a steel pipe or directly use an armored cable made of high magnetic permeability material (Patent No.: 2010 2 0559128.9 Beware of counterfeiting) - ASTP-120Ω (for RS485 amp ; CAN) one pair 18 AWG, the outer diameter of the cable is about 12.3mm. It can be used in places with serious interference, frequent rodent infestations, and places with lightning protection and explosion-proof requirements. When in use, it is recommended that both ends of the armor layer be grounded and one end of the innermost shielding layer be grounded!
Lightning protection for outdoor laying cables is very important! The equivalent interference frequency of lightning is around 100k, which is also a low-frequency interference.
Article 6.3.1 of "GB50057-94 Design Code for Lightning Protection of Buildings": ...In the space that needs to be protected, when using shielded cables, the shielding layer should be at least at both ends. It is also advisable to make equipotential connections at the junction of lightning protection zones. When the system requires equipotential connections at only one end, two layers of shielding should be used, and the outer shielding should be processed according to the aforementioned requirements.
"GB 50217-2007 Cable Design Specification" also has similar statements. Please search for "Industrial Automation Series Comprehensive Cable Solutions" to view and communicate!