Chapter 85 covers electrical equipment such as electric motors, generators, transformers, batteries, switches, lamps, and their parts. The core feature of this chapter is that goods must operate by electrical energy or be used for generating, converting, or storing electricity, and are usually electromechanical or electrical devices. Heading 8504 is located in the middle section of this chapter and specifically deals with static converters, inductors, and transformers, which are fundamental components for power transmission and electronic circuits. Heading 8504 includes static converters (such as rectifiers and inverters), inductors (such as reactors and chokes), and transformers. Transformers are further divided by cooling medium into liquid dielectric transformers and other transformers. Liquid dielectric transformers refer to transformers in which the windings and core are immersed in insulating oil or other liquid cooling medium. They are commonly used in power distribution, industrial power supply, and large equipment, and are characterized by good heat dissipation and large capacity. The first 2 digits 85 = Chapter 85, covering electric motors, electrical equipment, and their parts. Digits 3-4 04 = heading 8504, referring to transformers, static converters, and inductors. Digits 5-6 21 = subheading 850421, specifically referring to liquid dielectric transformers. Under heading 8504, goods are further subdivided by power and medium: 850421 is liquid dielectric transformers (power <= 650 kVA), 850422 is liquid dielectric transformers (650 kVA < power <= 10 MVA), 850423 is liquid dielectric transformers (power > 10 MVA), 850431 is other transformers (power <= 1 kVA), etc. Therefore, 850421 precisely points to small-capacity liquid transformers. This commodity is a liquid transformer, meaning the windings are immersed in insulating oil for cooling, and the rated capacity does not exceed 650 kVA. It is classified under 850421 rather than 850422 or 850423 because the capacity does not exceed 650 kVA; it is also not 850431 (other transformers) because the cooling medium is liquid rather than dry-type or gas. If the capacity exceeds 650 kVA, it is classified under 850422 or 850423; if it is a dry-type transformer, it is classified under 850431 or 850432, etc.
Chapter
Chapter 85 covers electrical equipment such as electric motors, generators, transformers, batteries, switches, lamps, and their parts. The core feature of this chapter is that goods must operate by electrical energy or be used for generating, converting, or storing electricity, and are usually electromechanical or electrical devices. Heading 8504 is located in the middle section of this chapter and specifically deals with static converters, inductors, and transformers, which are fundamental components for power transmission and electronic circuits.
Heading
Heading 8504 includes static converters (such as rectifiers and inverters), inductors (such as reactors and chokes), and transformers. Transformers are further divided by cooling medium into liquid dielectric transformers and other transformers. Liquid dielectric transformers refer to transformers in which the windings and core are immersed in insulating oil or other liquid cooling medium. They are commonly used in power distribution, industrial power supply, and large equipment, and are characterized by good heat dissipation and large capacity.
Digit Breakdown
The first 2 digits 85 = Chapter 85, covering electric motors, electrical equipment, and their parts. Digits 3-4 04 = heading 8504, referring to transformers, static converters, and inductors. Digits 5-6 21 = subheading 850421, specifically referring to liquid dielectric transformers. Under heading 8504, goods are further subdivided by power and medium: 850421 is liquid dielectric transformers (power <= 650 kVA), 850422 is liquid dielectric transformers (650 kVA < power <= 10 MVA), 850423 is liquid dielectric transformers (power > 10 MVA), 850431 is other transformers (power <= 1 kVA), etc. Therefore, 850421 precisely points to small-capacity liquid transformers.
Classification Basis
This commodity is a liquid transformer, meaning the windings are immersed in insulating oil for cooling, and the rated capacity does not exceed 650 kVA. It is classified under 850421 rather than 850422 or 850423 because the capacity does not exceed 650 kVA; it is also not 850431 (other transformers) because the cooling medium is liquid rather than dry-type or gas. If the capacity exceeds 650 kVA, it is classified under 850422 or 850423; if it is a dry-type transformer, it is classified under 850431 or 850432, etc.
📝 Declaration Elements
Product Name: The general name of the declared commodity should accurately reflect that it is a liquid dielectric transformer, such as 'oil-immersed transformer.' Use: Explain the application scenario of the transformer, such as power distribution, industrial equipment power supply, or renewable energy step-up. Brand: Fill in the manufacturer or brand name; if there is no brand, 'no brand' may be entered. Model: Fill in the product model, which should reflect key parameters such as capacity and voltage level. Rated Capacity: Fill in the rated capacity of the transformer in kVA, and the numerical value must be clear. Cooling Medium: Indicate the type of liquid medium, such as mineral oil, silicone oil, or synthetic ester. Rated Voltage: Fill in the rated voltage of the high-voltage side and low-voltage side, in kV. Frequency: Fill in the rated frequency, such as 50 Hz or 60 Hz. Product Name: Oil-immersed transformer; Use: For distribution; Brand: ABB; Model: S11-500/10; Rated Capacity: 500 kVA; Cooling Medium: Mineral oil; Rated Voltage: 10 kV/0.4 kV; Frequency: 50 Hz. Note: Liquid dielectric transformer, capacity <= 650 kVA, classified under 850421. The capacity unit is mistakenly entered as kW; kVA should be used, otherwise it may be incorrectly classified under another subheading. The cooling medium is written only as 'oil' without distinguishing liquid from dry-type, leading to classification disputes. The model does not reflect the capacity, so it cannot prove <= 650 kVA, and supplementary explanation may be required.
Product Name
The general name of the declared commodity should accurately reflect that it is a liquid dielectric transformer, such as 'oil-immersed transformer.'
⚠️ Writing only 'transformer' without indicating the liquid dielectric, leading to classification disputes.
Use
Explain the application scenario of the transformer, such as power distribution, industrial equipment power supply, or renewable energy step-up.
⚠️ Writing generally 'for power' without specifying the distribution or transformation scenario.
Brand
Fill in the manufacturer or brand name; if there is no brand, 'no brand' may be entered.
⚠️ Confusing brand with model, or omitting the brand, resulting in an incomplete customs declaration form.
Model
Fill in the product model, which should reflect key parameters such as capacity and voltage level.
⚠️ Incomplete model entry, making it impossible to determine whether the capacity is <= 650 kVA.
Rated Capacity
Fill in the rated capacity of the transformer in kVA, and the numerical value must be clear.
⚠️ Failing to fill in the capacity or using the wrong unit, such as mistakenly entering kW.
Cooling Medium
Indicate the type of liquid medium, such as mineral oil, silicone oil, or synthetic ester.
⚠️ Writing only 'oil-immersed' without specifying the exact medium, affecting classification.
Rated Voltage
Fill in the rated voltage of the high-voltage side and low-voltage side, in kV.
⚠️ Filling in only one side's voltage, or an inaccurate voltage value.
Frequency
Fill in the rated frequency, such as 50 Hz or 60 Hz.
⚠️ Omitting the frequency, resulting in unclear applicable standards.
Example： Product Name: Oil-immersed transformer; Use: For distribution; Brand: ABB; Model: S11-500/10; Rated Capacity: 500 kVA; Cooling Medium: Mineral oil; Rated Voltage: 10 kV/0.4 kV; Frequency: 50 Hz. Note: Liquid dielectric transformer, capacity <= 650 kVA, classified under 850421.
Common Mistakes：
The capacity unit is mistakenly entered as kW; kVA should be used, otherwise it may be incorrectly classified under another subheading.
The cooling medium is written only as 'oil' without distinguishing liquid from dry-type, leading to classification disputes.
The model does not reflect the capacity, so it cannot prove <= 650 kVA, and supplementary explanation may be required.
🎯 Classification Logic
The core basis for classification is the provisions of the Import and Export Tariff and the HS Explanatory Notes for heading 8504. A liquid dielectric transformer must simultaneously satisfy: 1) it is a transformer; 2) the cooling medium is liquid (such as insulating oil); 3) the rated capacity is <= 650 kVA. When determining, the product technical specification sheet must be checked to confirm capacity, cooling method, and use. If the capacity exceeds 650 kVA, it is classified under 850422 or 850423; if it is a dry-type transformer, it is classified under 850431 or 850432, etc. 850422 Liquid dielectric transformers (650 kVA < capacity <= 10 MVA): The capacity range is different. 850422 applies to liquid transformers above 650 kVA up to 10 MVA, exceeding the upper capacity limit of 850421. 850423 Liquid dielectric transformers (capacity > 10 MVA): Large liquid transformers with capacity greater than 10 MVA, usually used in main power grids, distinguished from the small-capacity distribution transformers of 850421. 850431 Other transformers (capacity <= 1 kVA): 850431 covers dry-type or other non-liquid dielectric small-capacity transformers, with a different cooling method, and capacity usually <= 1 kVA. 850432 Other transformers (1 kVA < capacity <= 16 kVA): Non-liquid dielectric transformers with capacity between 1 kVA and 16 kVA, following a different classification path from liquid dielectric transformers. 850433 Other transformers (16 kVA < capacity <= 500 kVA): Non-liquid dielectric, capacity between 16 kVA and 500 kVA. Although the capacity overlaps with 850421, the cooling medium is different. Confirm whether the transformer cooling medium is liquid (such as insulating oil). Check whether the rated capacity is <= 650 kVA and whether the unit is kVA. Check whether it is used for distribution or similar scenarios, rather than large-scale power transmission. Confirm that the brand, model, and capacity parameters are consistent, with no contradictions. Exclude dry-type transformers or gas-insulated transformers to avoid misclassification.
Basis
The core basis for classification is the provisions of the Import and Export Tariff and the HS Explanatory Notes for heading 8504. A liquid dielectric transformer must simultaneously satisfy: 1) it is a transformer; 2) the cooling medium is liquid (such as insulating oil); 3) the rated capacity is <= 650 kVA. When determining, the product technical specification sheet must be checked to confirm capacity, cooling method, and use. If the capacity exceeds 650 kVA, it is classified under 850422 or 850423; if it is a dry-type transformer, it is classified under 850431 or 850432, etc.
Large liquid transformers with capacity greater than 10 MVA, usually used in main power grids, distinguished from the small-capacity distribution transformers of 850421.
850431 - Other transformers (capacity <= 1 kVA)
850431 covers dry-type or other non-liquid dielectric small-capacity transformers, with a different cooling method, and capacity usually <= 1 kVA.
850432 - Other transformers (1 kVA < capacity <= 16 kVA)
Non-liquid dielectric transformers with capacity between 1 kVA and 16 kVA, following a different classification path from liquid dielectric transformers.
850433 - Other transformers (16 kVA < capacity <= 500 kVA)
Non-liquid dielectric, capacity between 16 kVA and 500 kVA. Although the capacity overlaps with 850421, the cooling medium is different.
Self-Check：
✓ Confirm whether the transformer cooling medium is liquid (such as insulating oil).
✓ Check whether the rated capacity is <= 650 kVA and whether the unit is kVA.
✓ Check whether it is used for distribution or similar scenarios, rather than large-scale power transmission.
✓ Confirm that the brand, model, and capacity parameters are consistent, with no contradictions.
✓ Exclude dry-type transformers or gas-insulated transformers to avoid misclassification.
❓ FAQ
How can it be determined whether a transformer belongs to liquid dielectric transformers? Check the product technical parameters. If the windings and core are immersed in insulating oil or another liquid cooling medium, and the enclosure has features such as an oil conservator and radiator fins, it is a liquid dielectric transformer. Dry-type transformers have no oil and use air or epoxy resin cooling. What is the upper capacity limit of 850421? 850421 applies to liquid dielectric transformers with a rated capacity not exceeding 650 kVA. If the capacity exceeds 650 kVA but does not exceed 10 MVA, it is classified under 850422; if it exceeds 10 MVA, it is classified under 850423. Should the capacity unit be filled in as kVA or kW when declaring? kVA (kilovolt-ampere) must be entered, because transformer capacity is expressed as apparent power. If kW is entered, customs may question the classification as incorrect, since kW is a unit of active power. What is the difference in classification between liquid transformers and dry-type transformers? Liquid transformers are classified under 850421-850423 according to capacity, while dry-type transformers are classified under 850431-850434, etc. The core difference lies in the cooling medium, and liquid dielectric requires a separate subheading. If the transformer capacity is exactly 650 kVA, which code is it classified under? The upper capacity limit of 850421 is 'not exceeding 650 kVA,' so 650 kVA should be classified under 850421. Only capacities exceeding 650 kVA are classified under 850422. For imported used liquid transformers, is the code still 850421? The code itself remains unchanged, and it is still classified under 850421 according to capacity and medium. However, used mechanical and electrical products may involve additional regulatory conditions, and the latest customs regulations should be checked. How can the import tariff rate for 850421 be checked? Tariff rates change, so it is recommended to use the General Administration of Customs website, the Single Window, or professional tariff query tools, and enter the HS code and country of origin to obtain the MFN rate, agreement rate, etc. What declaration elements are required for exporting liquid transformers? Usually product name, use, brand, model, rated capacity, cooling medium, rated voltage, frequency, etc. are required. The specific requirements are subject to customs declaration requirements, and it is advisable to consult a customs broker.
Q: How can it be determined whether a transformer belongs to liquid dielectric transformers?
A: Check the product technical parameters. If the windings and core are immersed in insulating oil or another liquid cooling medium, and the enclosure has features such as an oil conservator and radiator fins, it is a liquid dielectric transformer. Dry-type transformers have no oil and use air or epoxy resin cooling.
Q: What is the upper capacity limit of 850421?
A: 850421 applies to liquid dielectric transformers with a rated capacity not exceeding 650 kVA. If the capacity exceeds 650 kVA but does not exceed 10 MVA, it is classified under 850422; if it exceeds 10 MVA, it is classified under 850423.
Q: Should the capacity unit be filled in as kVA or kW when declaring?
A: kVA (kilovolt-ampere) must be entered, because transformer capacity is expressed as apparent power. If kW is entered, customs may question the classification as incorrect, since kW is a unit of active power.
Q: What is the difference in classification between liquid transformers and dry-type transformers?
A: Liquid transformers are classified under 850421-850423 according to capacity, while dry-type transformers are classified under 850431-850434, etc. The core difference lies in the cooling medium, and liquid dielectric requires a separate subheading.
Q: If the transformer capacity is exactly 650 kVA, which code is it classified under?
A: The upper capacity limit of 850421 is 'not exceeding 650 kVA,' so 650 kVA should be classified under 850421. Only capacities exceeding 650 kVA are classified under 850422.
Q: For imported used liquid transformers, is the code still 850421?
A: The code itself remains unchanged, and it is still classified under 850421 according to capacity and medium. However, used mechanical and electrical products may involve additional regulatory conditions, and the latest customs regulations should be checked.
Q: How can the import tariff rate for 850421 be checked?
A: Tariff rates change, so it is recommended to use the General Administration of Customs website, the Single Window, or professional tariff query tools, and enter the HS code and country of origin to obtain the MFN rate, agreement rate, etc.
Q: What declaration elements are required for exporting liquid transformers?
A: Usually product name, use, brand, model, rated capacity, cooling medium, rated voltage, frequency, etc. are required. The specific requirements are subject to customs declaration requirements, and it is advisable to consult a customs broker.
⚠️ Disclaimer: HS code classification, declaration elements, tariff rates and regulatory conditions on this page are for reference only and do not constitute legal advice on customs classification. Tariff rates and regulations are subject to change; the latest announcements from the General Administration of Customs and on-site determinations shall prevail. Please consult professional customs brokers or customs authorities before import/export.