RVVP 2×0.5 has a rated voltage of 300/300V and below and a current of 2A and below. It is used to transmit low-speed analog signals and switching signals. The transmission distance is related to the load current and the maximum allowable voltage drop of the system. Experience data :≯500 meters.
Many people use the above cable to transmit digital signals. It may be possible at low speed and short distance, but it is difficult to perform high-speed, long-term and multi-node bus communication. In this case, an impedance-matched fieldbus should be used. cable.
※ Universal fieldbus series cables
(Patent number: 2010 2 0559128.9 Beware of counterfeiting)
Twisted-pair shielded cables with a characteristic impedance of 120Ω are widely used RS485/422, CANBUS and other buses, this series of cables have many specifications. Please provide the cable laying environment, communication rate, maximum non-relay transmission distance and other parameters. We will recommend the most appropriate product according to the specific situation. The general recommendations are as follows:
Unarmored twisted pair shielded cable STP-120Ω (for RS485 & CAN) one pair 20 AWG, cable outer diameter is about 7.7mm, blue sheath. Suitable for indoor, pipeline and general industrial environments. When in use, one end of the shielding layer should be grounded!
Unarmored twisted pair shielded cable STP-120Ω (for RS485 & CAN) one pair 18 AWG, cable outer diameter is about 8.2mm, gray sheath. Suitable for indoor, pipeline and general industrial environments. When in use, one end of the shielding layer should be grounded!
Armored twisted pair shielded cable ASTP-120Ω (for RS485 & CAN) one pair 18 AWG, cable outer diameter is about 12.3mm, black sheath. 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!
Frequency converters, power cables, transformers, high-power motors, etc. are often accompanied by low-frequency interference, and this interference cannot be solved by cables shielded with high conductivity materials, including original imported cables. Only shielding layers made of high magnetic 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 - ASTP-120Ω (for RS485 & CAN) one pair 18 AWG, cable outer diameter 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. You can find it by searching "Industrial Automation Series Comprehensive Cable Solutions".