What is the difference between multi-strand cables and single-strand cables in use?
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DCS control cables generally use 1.5-square copper wires; in some places multi-strand flexible wires are used, while in other places single-strand wires are used. Are there any standards in practical engineering, and what are the selection principles?
Control wires are generally multi-strand, while electrical wires are single-strand. Multi-filament wires are used because they are soft, easy to draw and route, and offer high reliability during movement. Additionally, with multiple wires, there is another advantage related to the skin effect; however, the cables used in ordinary instruments are not thick enough for this effect to be noticeable. Single-strand wires are rigid, making them easier to use for wiring inside electrical cabinets; however, instrument control cables present more challenges, as rigid wires cannot be used for such purposes. And multi-filament wires are more expensive than single-filament wires, which is important. The selection principle is quite simple: for conventional control wires in engineering projects and power supply wires with voltages below 220V, multi-strand wires are used, while single-strand wires are generally employed in electrical applications. This is because there are often high-voltage cables or other power supply wires with voltages above 220V; if multi-strand wires are used, poor connections can lead to heating and problems.
If you are in the instrumentation industry, please follow HG/T20512-2014 7.2.1: For instrument signal cables, it is advisable to use flexible cables with multiple copper cores, polyethylene insulation, PVC sheathing, and shielding.