Information for ruling 600009731
This section is Advance Tariff Ruling
- Start date
- 24 Apr 2024
- Expiry date
- 23 Apr 2027
- Commodity code
- 90314990 (opens in new tab)
- Description
- Fibre optic real time thermal rating (RTTR) measurement and monitoring system for power cables. It is a system made up of several components/sub-assemblies. The inputs to the monitoring system are the construction and installation details of the power cable, distributed temperature data of the surface temperature of the power cable which is measured by a fibre-optic distributed temperature sensor (DTS) and load current data (measured by a current transducer and a data acquisition module). These inputs are fed into the Cable Safety Monitoring (CSM) software, which calculates real-time temperature of the power cable core and as well as any thermal bottlenecks. It is also used to calculate a short term permissible load and other thermal parameters of the power cable. The RTTR software takes the temperature signal from the DTS and makes a thermal calculation based on the specifics of the power cable and the environment. The user can then use this information for assessing what capacity of current the cable can safely transmit. If the heat levels go into dangerous levels where it can potentially damage the integrity of the cable then the system will alarm. Alarming is part of the functionality of this (RTTR) measurement and monitoring system. However, it is more than that as it also allows the user to proactively plan capacity so that they do not get into an alarm situation. The main sub-assemblies are: - Fibre-optic distributed temperature sensor (DTS). Distributed temperature sensing systems (DTS) are optoelectronic devices which measure temperatures by means of optical fibres functioning as linear sensors. Temperatures are recorded along the optical sensor cable, thus not at points, but as a continuous profile. A high accuracy of temperature determination is achieved over great distances. Typically the DTS systems can locate the temperature to a spatial resolution of 1 m with accuracy to within ±1 °C at a resolution of 0.01 °C. Measurement distances of greater than 30 km can be monitored and some specialised systems can provide even tighter spatial resolutions. Thermal changes along the optical fibre cause a local variation in the refractive index, which in turn leads to the inelastic scattering of the light propagating through it. Heat is held in the form of molecular or lattice vibrations in the material. The systems rely on a principle called Raman Optical Time Domain Reflectometry (OTDR). OTDR was developed more than 20 years ago and has become the industry standard for telecom loss measurements which detects the—compared to Raman signal very dominant—Rayleigh backscattering signals. The principle for OTDR is quite simple and is very similar to the time of flight measurement used for radar. Essentially a narrow laser pulse generated either by semiconductor or solid state lasers is sent into the fibre and the backscattered light is analysed. From the time it takes the backscattered light to return to the detection unit it is possible to locate the location of the temperature event. - Power distribution and host sub-assembly. This consists of power distribution, circuit protection and electrical safety components, as well as the mini computer that runs the monitoring software. - Data Acquisition and Relay sub-assembly. This consists of the data acquisition module for the load current input and the relay module for system alarm outputs. It determines the location and movement of conductor hot spots from the distributed temperature sensor (DTS) data by accurate cable modelling, taking into the account the cable’s installed environment. The product is sold and consigned to the customer as one complete RTTR system.
- Keywords
- FOR MONITORING THERMOMETERS LASERS SCIENTIFIC AND MEASURING EQUIPMENT FOR MEASURING TEMPERATURE POWER CABLES OPTICAL FIBRE CABLES THERMAL SENSORS OPTICAL TYPE MEASURING EQUIPMENT INTEGRATED OPTOELECTRONICS
- Justification
- Classification has been determined in accordance with the following: For the purposes of determining the commodity codes within which goods most appropriately fall, reg 3 (1) of The Customs Tariff (Establishment) (EU Exit) Regulations 2020 sets out that the rules of interpretation contained in the following have effect – a. Part Two (Goods Classification Table Rules of Interpretation) of the Tariff of the United Kingdom (Reg 3(1)(a)); and b. Notes to a section or chapter of the Goods Classification Table (Reg 3(1)(b)). GIR 1 has been used to classify this product by the terms of heading 9031: Measuring or checking instruments, appliances and machines, not specified or included elsewhere in this chapter; profile projectors GIR 3b has been used as the measuring/checking function is considered to be the essential character. GIR 6 has been used to classify the goods to subheading level 903149: Other optical instruments and appliances; Other than for inspecting semiconductor wafers or devices (including integrated circuits) or for inspecting photomasks or reticles used in manufacturing semiconductor devices (including integrated circuits) 8 Digit code 90314990: Other than profile projectors Also classified in accordance with: Section Notes 3 & 4 to Section XVI Chapter Note 3 to Chapter 90 Harmonized System Explanatory Note (HSEN's) to heading 90.31 (I) (B) & Subheading Explanatory Note 9031.49