Regarding the diameter of instrument signal cables
Thread Content
I have a question: First, what is the maximum length over which a 1.0 square millimeter gauge instrument cable can be laid? 2 Second, is the valve feedback signal a PNP switch, and is the cable insulated with polyethylene?
Instrument cables are generally YJV, with cross-linked polyethylene insulation and polyvinyl chloride sheathing.
1. The instrument cable allows switch signals to travel over long distances. Insurance coverage for 1MM2: 800-500 meters. The 4-20MA signal needs to be determined based on the minimum operating voltage of your instrument. It’s best to keep it under 100 meters. To avoid hassle, use 1.5MM2. However, most instruments nowadays support operation at low voltages. 2. Cable signals have nothing to do with your cable insulation. For instrument cables, KVVP cable is commonly used in the petroleum industry, while YJVP cable is preferred in the chemical industry. They are all used for instrument signals and control; the only difference lies in the material of the cable sheath.
I also checked websites and did some rough calculations regarding the core material; for projects with lengths of up to 100 meters, it should work fine. As for the insulating material, chemical industry standards specify certain requirements. Since our product is liquor, experts consulted said that polyethylene insulation isn’t necessary. I also looked at the design standards for electrical engineering cables – PVC isn’t suitable in situations involving high temperatures, low temperatures, or environmental concerns, and none of these apply to our project either, so it should be fine to use it
Is a PNP switch used for valve feedback considered an instrument cable?
Both the national standard KVVP and RVVP cables can be used in this area. However, depending on the cable length, both 1.0 mm2 and 1.5 mm2 cables are sufficient. At the factory, we currently use RVSP-1*2*1.5 and 1.0 mm2 cables; the shielding layer and wire diameter of these cables meet the required standards. You may consider using them as a reference. The main considerations are compliance with national standards regarding the shielding layer and wire diameter, as well as the brand and quality. Interference resistance and attenuation factors are both involved in this issue.