Chapter 85 covers electrical machinery and equipment and parts thereof; sound recorders and reproducers, television image and sound recorders and reproducers, and parts and accessories of such articles. This chapter is one of the most technology-intensive chapters in the HS classification, involving a wide range of fields such as power generation, transformation, consumption, communications, and consumer electronics. Products within the chapter generally operate on electrical or electronic principles, but care must be taken to distinguish them from mechanical apparatus of Chapter 84: if the primary function of a good depends on electrical principles, it is classified in Chapter 85. Heading 8504 covers electrical transformers, static converters (such as rectifiers and inverters), and inductors. A transformer is a static electrical device that changes AC voltage, current, or number of phases through electromagnetic induction, and is widely used in power transmission, distribution, industrial control, and electronic equipment. This heading includes both liquid dielectric transformers and dry-type transformers, instrument transformers, ballasts, uninterruptible power supplies (UPS), and various inductors. Code 850423 is a six-digit subheading: the first two digits "85" represent Chapter 85 (electrical machinery and equipment and parts thereof; sound recorders and reproducers, television image and sound recorders and reproducers, and parts and accessories of such articles). The third and fourth digits "04" represent heading 8504 (electrical transformers, static converters, and inductors). The fifth and sixth digits "23" represent subheading 8504.23, i.e., liquid dielectric transformers having a power handling capacity exceeding 10,000 kVA. Note that 8504.23 is not further subdivided, but depending on power handling capacity, liquid transformers also fall under 8504.21 (≤650 kVA), 8504.22 (650 < capacity ≤10,000 kVA), and 8504.23 (>10,000 kVA). The good is a liquid transformer, i.e., a transformer that uses liquid such as mineral oil or synthetic oil for insulation and cooling. It is classified under 8504 rather than 8503 (electric motors and generators) or 8505 (electromagnets, etc.) because a transformer is a static electromagnetic induction device that does not produce mechanical motion. Meanwhile, 8504.23 specifically covers liquid dielectric transformers having a power handling capacity exceeding 10,000 kVA, distinguishing them from dry-type transformers (8504.31–8504.34) and liquid transformers with lower power handling capacity.

Product Name: The Chinese and English names of the declared goods, which should accurately reflect the product attributes, such as "liquid transformer" or "oil-immersed power transformer". Use: Describe the application scenario of the transformer, such as for power transmission and distribution, industrial power supply, substation, etc. Brand: Fill in the manufacturer or brand name; if there is no brand, fill in "no brand". Model: Fill in the specification and model of the product, which should be consistent with the technical documentation. Rated Capacity: Fill in the rated capacity of the transformer in kilovolt-amperes (kVA), which must be greater than 10,000 kVA. Liquid Dielectric Type: Indicate the type of insulating coolant, such as mineral oil, silicone oil, ester oil, etc. Number of Phases: Fill in the number of phases of the transformer, such as single-phase or three-phase. Brand Type: Fill in the brand type according to customs regulations, such as no brand, domestic independent brand, foreign brand, etc. Product Name: Liquid transformer (oil-immersed power transformer); Use: For voltage transformation in substations; Brand: ABB; Model: SFP-120000/220; Rated Capacity: 120,000 kVA; Liquid Dielectric Type: Mineral oil; Number of Phases: Three-phase; Brand Type: Foreign brand. The rated capacity does not exceed 10,000 kVA, mistakenly classified under 8504.23, but should actually be classified under 8504.21 or 8504.22. A dry-type transformer is mistakenly declared as a liquid transformer, resulting in incorrect classification. The liquid dielectric type is not declared, which may affect customs determination of the product attributes.

The core criteria for classification are: 1) whether the good is a transformer; 2) whether it uses a liquid dielectric for insulation and cooling; 3) whether the rated capacity exceeds 10,000 kVA. According to the Import and Export Tariff, liquid dielectric transformers are divided into three subheadings by rated capacity: ≤650 kVA, 650 < capacity ≤10,000 kVA, and >10,000 kVA. Only when both liquid dielectric and capacity >10,000 kVA are met is it classified under 8504.23. If it is a dry-type transformer, it is classified under 8504.31 to 8504.34. 850421 Liquid dielectric transformers (≤650 kVA): Rated capacity not exceeding 650 kVA, suitable for small distribution, whereas 850423 has a capacity exceeding 10,000 kVA. 850422 Liquid dielectric transformers (650 < capacity ≤10,000 kVA): Capacity between 650 and 10,000 kVA, commonly used in medium distribution, whereas 850423 is for large power transformers. 850431 Dry-type transformers (≤1 kVA): Uses air or solid insulation, no liquid dielectric, very small capacity, different principle and structure from liquid transformers. 850434 Dry-type transformers (>500 kVA): Dry-type transformers can have larger capacities but no liquid cooling, classified under 8504.34, whereas liquid transformers are under 8504.23. 850440 Static converters: Static converters are used to change current type or frequency (e.g., rectifiers, inverters), whereas transformers only change voltage and current, not frequency. Confirm whether the good is a transformer, not a converter or inductor. Confirm whether a liquid dielectric (e.g., mineral oil) is used for insulation and cooling. Confirm whether the rated capacity is strictly greater than 10,000 kVA. Check whether the declared elements such as brand and model are consistent with the actual product. Confirm whether it is a power transformer, not an instrument transformer or voltage regulator.

How to determine whether the rated capacity of a liquid transformer exceeds 10,000 kVA? The rated capacity is usually marked on the transformer nameplate in kilovolt-amperes (kVA). If the nameplate is marked in megavolt-amperes (MVA), conversion is required: 1 MVA = 1,000 kVA. For example, 12 MVA = 12,000 kVA, which exceeds 10,000 kVA and should be classified under 8504.23. If the nameplate is unclear, consult the product technical manual or factory test report. What is the difference in HS classification between liquid transformers and dry-type transformers? Liquid transformers use liquid such as oil for insulation and cooling and are classified under 8504.21 to 8504.23; dry-type transformers use air or solid insulation and are classified under 8504.31 to 8504.34. Both are subdivided by rated capacity, but the specific codes differ. The dielectric type must be determined first for classification. If the capacity of a liquid transformer is exactly 10,000 kVA, which code should it be classified under? According to the tariff, 8504.22 applies to liquid dielectric transformers having a power handling capacity exceeding 650 kVA but not exceeding 10,000 kVA, so a capacity equal to 10,000 kVA should be classified under 8504.22, not 8504.23. 8504.23 requires a rated capacity exceeding 10,000 kVA. What technical documents are required when declaring a liquid transformer? Typically, product nameplate photos, technical specifications, factory test reports, etc., are required to prove key parameters such as rated capacity, liquid dielectric type, and number of phases. Customs may require these documents to verify classification. It is advisable to prepare them in advance and ensure they are consistent with the declaration. After a liquid transformer is classified under 8504.23, are there other elements to declare? Yes, in addition to rated capacity and liquid dielectric type, you also need to declare product name, use, brand, model, number of phases, brand type, etc. According to customs regulations, all declaration elements must be complete and accurate; otherwise, it may affect customs clearance efficiency or lead to penalties. How to check the import tariff rate for liquid transformers? Import tariff rates are adjusted according to national policies. It is recommended to obtain the latest rates through the General Administration of Customs website, the International Trade Single Window, or professional tariff query tools by entering HS code 850423 and conditions such as country of origin and trade mode. Note that MFN rates, agreement rates, and general rates may differ. How to distinguish liquid transformers from instrument transformers in classification? Instrument transformers are transformers for measuring voltage or current, usually with very small capacity, and are classified under 8504.31 to 8504.34 (dry-type) or 8504.21 to 8504.23 (liquid). However, actual classification depends on the specific capacity and dielectric. If it is liquid dielectric and capacity exceeds 10,000 kVA, it is still classified under 8504.23; but instrument transformers generally have far smaller capacity, so they are usually classified under other subheadings. If a liquid transformer is equipped with an on-load tap changer, does it affect classification? An on-load tap changer is an accessory component of the transformer and does not change the basic character of the transformer as a liquid dielectric transformer. Therefore, as long as the rated capacity exceeds 10,000 kVA, it is still classified under 8504.23. However, this feature should be reflected in the product name or model during declaration so that customs can accurately understand the goods.