How to determine the cable tray specifications?

Is there a specification for the outer diameter of instrument cables?

HGT 20512-2014 Code for Design of Instrument Piping and Wiring: 8.4.3 The filling factor within the protective tube shall not exceed 0.4. When a single cable is passed through a protective tube, the inner diameter of the protective tube should not be less than 1.5 times the outer diameter of the cable. The width of the cable should be determined by the manufacturer, right?

Is there no unified standard for instrument cables?

7.1 Cross-sectional area of cable conductors 7.1.1 The cross-sectional area of the conductors in instrument signal cables shall meet the requirements of the measurement and control circuits regarding line impedance, as well as the requirements for the mechanical strength of the cables during installation. The minimum cross-sectional area of the conductor should not be less than 0.75 mm2. 7.1.2 In areas classified as Zone 2 in explosive hazard environments or in non-explosion-proof areas, the cross-sectional area of the conductors in two-core and three-core instrument signal cables laid in trays or protective tubes should be selected in the range of 1.0 mm2 to 1.5 mm2; for thermocouple compensation wires, the appropriate cross-sectional area is 1.0 mm2 to 2.5 mm2. For multi-core cables used as main cables, the cross-sectional area of their conductors can be reduced to the range of 0.75 mm2 to 1.5 mm2, provided that the resistance of the circuit meets the required specifications. 7.1.3 The cross-sectional area of the conductor of the grounding wire shall comply with the relevant provisions of the current industry standard \"Code for Design of Grounding in Instrumentation Systems\" HG/T 20513. 7.1.4 The cross-sectional area of the conductors in the power supply and distribution lines shall comply with the relevant provisions of the current standards **\"Code for Design of Cables in Electrical Engineering\" GB 50217** and **\"Code for Design of Electrical Installations in Explosive Atmospheres\" GB 50058**. 7.2 Types of Cables 7.2.1 For instrument signal cables, it is advisable to use flexible cables with multiple copper cores, polyethylene insulation, PVC sheathing, and shielding. 7.2.2 Selection of shielding for instrument signal cables. A combination of overall shielding and separate shielding is preferred; for cables with special requirements, the shielding type should be chosen in accordance with the manufacturer’s specific specifications. 7.2.3 When an intrinsically safe system is used, intrinsically safe cables shall be selected, and their distributed capacitance and distributed inductance parameters shall meet the requirements of the intrinsically safe circuit. The outer sheath of the intrinsically safe cable is marked in blue. 7.2.4 In high and low temperature environments, cables resistant to high and low temperatures should be selected according to the allowable temperature range of the cables. 7.2.5 For cables installed overhead in areas prone to fire, flame-retardant cables should be used. 7.2.6 The model of the thermocouple compensation cable shall match the calibration number of the thermocouple, and a compensation-type cable is preferred.

Generally, only attention is paid to the cross-sectional area of the cable core; other aspects aren’t really considered.

Selection of the trunking cross-sectional area: 1. Determine the type of cable and the cross-sectional area of each cable. 2. Create a sketch showing the arrangement of the cable cross-sections using geometric methods. 3. The trunking cross-sectional area is obtained by dividing the maximum cross-sectional area by 40%. 4. Using this value, select the appropriate trunking size from the available trunking samples