• Product advantages
• Product parameters
• Ordering instructions

Product advantages

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Why Choose Our 20kV Three-phase Epoxy Cast Dry Distribution Transformer？

Leading Technology

• High pressure copper tape winding – Flame retardant formula, vacuum pouring

• Low pressure copper foil winding – Thermosetting epoxy prepreg cloth insulation

• High quality iron core – 45° full oblique joint step laminated structure
 

The Iron Core

• Made of cold rolled grain oriented silicon steel sheet with mineral oxide insulation

• Precision cutting and stacking minimizes loss, no-load current, and noise

• Class F or Class H core paint prevents corrosion and rust
 

Low Voltage Winding

• High quality copper foil with thermosetting epoxy prepreg cloth insulation

• Excellent insulation resistance and radial stress resistance against short circuit

• Tinned copper bar outgoing terminal

• Oven heated to 140°C for 4 hours – excellent industrial gas corrosion resistance
 

High Voltage Winding

• Insulated copper wire with Hengfengyou Electric patented technology

• Small volume: linear voltage gradient from top to bottom

• Large capacity: tape winding technology

• Extremely low electric field between adjacent conductors

• Reliable structure during operation and transportation
 

Key Advantages

• Copper tape + copper foil winding, flame retardant vacuum casting

• 45° full oblique joint core – low loss, low noise

• Thermosetting epoxy insulation – Class F/H available

• Strong short circuit withstand and industrial gas corrosion resistance

• OEM customized solutions available

 

Company Advantages – Built for Global Buyers

• Certifications |CB, CCC, KEMA, SASO, and more |
• Quality System | SQA management – guaranteed consistency |
• Fast Response | Quick quote + electrical design support |
• Delivery | Short lead time, worldwide shipping |
• After-Sales | Complete service system |
• Customization | OEM/ODM – factory visit welcome |
 

20kV Three-phase Epoxy Cast Dry Distribution Transformer Case



20kV Three-phase Epoxy Cast Dry Distribution Transformer FAQ
1. Standard & Certification

Q1: What international standards do your 20kV dry-type transformers comply with? Can they meet industrial and grid grid-connection specifications?
A1: Our 20kV dry-type transformers are strictly designed, manufactured and tested in accordance with IEC 60076-11 (dry-type power transformer) series core standards, fully covering insulation, temperature rise, safety and performance indicators. Meanwhile, we support customized design and certification compliance with global mainstream standards including GB, EN 60076, GOST, ANSI/IEEE, AS/NZS, INMETRO, SABS and SASO. According to the end user’s project location, local grid access codes and industrial special specifications, we can complete standard matching assessment and provide full qualified certification documents to meet official grid connection and project acceptance requirements.
Q2: Can you provide official type test reports and third-party witnessed test documents? Is on-site factory witnessing acceptable?
A2: Complete CNAS-accredited full type test reports are available for all 20kV dry-type transformer models. The test items cover partial discharge detection, temperature rise test, no-load & load loss test, short-circuit impedance test, lightning impulse withstand test, switching impulse test and long-term insulation stability test, which are core unique test items for dry-type transformers. For national grid projects, large industrial EPC projects and overseas key projects, we support pre-scheduled third-party witnessed factory tests (WTT) and whole-process video monitoring to ensure test authenticity and authority.
Q3: What technical documents are included in the standard delivery package? Do you support multi-language customized manuals?
A3: The standard technical document package is fully English-version, including equipment nameplate parameter sheet, overall dimension drawing, internal wiring schematic diagram, factory acceptance test (FAT) report, professional operation and maintenance manual, installation guideline and spare parts list. To adapt to global project delivery, we support customized multi-language technical documents such as Spanish, Portuguese, Arabic, French, Russian and Vietnamese, and can match local industrial technical specification descriptions as required.

2. Technical Performance & Structural Advantages

Q4: What winding materials are optional for 20kV dry-type transformers? Can material quality be guaranteed in the contract?
A4: We provide two mainstream optional winding solutions: high-purity anaerobic copper winding and high-strength aluminum winding, which can be selected according to project budget and load operation requirements. All winding materials adopt high-temperature resistant insulation grade matching 20kV high-voltage level. The winding material type, insulation grade and technical parameters can be clearly specified in the technical agreement and formal contract, with official material test certificates, factory inspection reports and full production traceability records provided. The overall high-voltage insulation system is optimized for 20kV voltage level, ensuring long-term stable, low-loss and safe operation.
Q5: Can electrical parameters of 20kV dry-type transformers be customized? How to handle unqualified products during factory testing?
A5: All core electrical parameters support personalized customization, including no-load loss, load loss, short-circuit impedance, voltage tap range, temperature rise limit and partial discharge value, which can be fully matched with customer’s technical datasheet and project operation conditions. Each 20kV dry-type transformer will complete 100% full-item factory inspection before delivery. Any unqualified product found in the test will be prohibited from delivery immediately. We will conduct free rework, performance debugging or full machine replacement to ensure all delivered equipment meets standard and customer technical requirements.
Q6: Can 20kV dry-type transformers adapt to high altitude, coastal humid, dusty and seismic harsh working conditions?
A6: Targeted environmental adaptive design is available for various harsh scenarios. For high-altitude areas above 1000m, we upgrade insulation grade and optimize air heat dissipation structure to avoid altitude insulation breakdown; for coastal humid and salt-fog environments, we adopt anti-corrosion epoxy resin pouring and surface anti-aging treatment to resist salt erosion and moisture penetration; for dusty industrial workshops, we support closed protective shell design to prevent dust accumulation and partial discharge; for seismic zones, we strengthen core skeleton fixation and shockproof structural design to improve equipment seismic resistance. All designs are adjusted according to actual on-site working conditions.
Q7: Are 20kV dry-type transformers applicable for new energy power stations? What is the harmonic resistance performance?
A7: Our 20kV dry-type transformers are specially optimized for solar power plants, wind farms and energy storage power station grid-tie scenarios, and are the preferred equipment for new energy projects compared with oil-immersed transformers. The optimized silicon steel sheet core and special winding structure can effectively suppress harmonic vibration and harmonic heating, adapt to the intermittent, fluctuating and unstable characteristics of photovoltaic and wind power loads. It can resist high harmonic impact generated by new energy inverters, avoid local overheating and equipment aging, and ensure long-term safe grid-connected operation of new energy systems.
Q8: What is the standard noise level of 20kV dry-type transformers? Is low-noise customization available for urban and residential areas?
A8: Under standard IEC test conditions, the operating noise of 20kV dry-type transformers is ≤55dB, lower than traditional oil-immersed transformers. For urban commercial districts, residential communities, schools, hospitals and other noise-sensitive scenarios, we provide professional low-noise customized design (operating noise ≤48dB). By adopting core vibration damping optimization, silent winding technology and buffer shock-absorbing base structure, the equipment operating noise is further reduced. Official noise test certificates can be provided for project acceptance.
Q9: Does the 20kV dry-type transformer have lightning impulse and short-circuit fault resistance capability?
A9: The 20kV dry-type transformer adopts high-grade epoxy resin integral pouring insulation structure, with excellent lightning impulse and switching overvoltage resistance, which is far superior to ordinary oil-immersed products in insulation stability. The internal winding and skeleton adopt reinforced anti-deformation structure, which greatly improves the ability to withstand sudden short-circuit faults, effectively avoids winding displacement and insulation breakdown caused by short-circuit impact, and fully meets the strict operation requirements of urban power grids and industrial power systems. Short-circuit withstand test and lightning impulse test reports can be provided on request.
Q10: What is the design service life of 20kV dry-type transformers? Does it follow insulation aging rules?
A10: The standard design service life of our 20kV dry-type transformers is 25 years, longer than oil-immersed transformers. With standardized operation and regular maintenance, the service life can be extended to 30–35 years. The epoxy resin insulation system strictly follows the 6℃ insulation aging principle, with sufficient temperature margin and anti-aging performance. The fully sealed pouring structure isolates air and moisture, effectively slows down insulation aging and ensures long-term stable performance of the equipment.
Q11: Are you a professional manufacturer of 20kV dry-type transformers?
A11: We are a professional dry-type transformer manufacturer with decades of R&D, production and export experience, located in Qingdao, China. We focus on high, medium and low voltage dry-type transformer series products, with independent core technology and full in-house production processes including winding winding, resin pouring, high-temperature curing and finished product testing. Our products are widely used in global urban power grids, industrial manufacturing, new energy power stations, commercial buildings and other fields, serving numerous international EPC contractors and grid operators. Factory on-site audit and production inspection are warmly welcomed.

3. Customization, Dimension & Transportation

Q12: Can you provide non-standard customized 20kV dry-type transformers?
A12: We support full-dimensional non-standard customized services for 20kV dry-type transformers. Customizable contents include special electrical parameters, multi-range voltage tap adjustment, personalized overall dimensions (suitable for indoor narrow space installation), vertical/horizontal mounting types, special environmental protection and fire-resistant design, and customized protection shell grades. Meanwhile, core supporting accessories can be equipped with internationally renowned brands specified by customers. All customized technical requirements will be sorted out in detail and signed into formal technical agreement to ensure consistent delivery effect.
Q13: Can you provide accurate weight and dimension drawings? Is the equipment suitable for cross-border long-distance transportation?
A13: After confirming customer technical requirements, we will provide formal quotation documents attached with accurate equipment overall dimension drawings, installation size diagrams and net/gross weight data. Different from oil-immersed transformers, dry-type transformers have no oil leakage risk, with safer transportation conditions. For large-capacity 20kV dry-type equipment, we will pre-assess transportation oversize and overweight risks, and provide professional hoisting, packaging and cross-border logistics solutions to ensure safe and intact delivery.
Q14: What is the standard export packaging mode for 20kV dry-type transformers?
A14: All 20kV dry-type transformers adopt exclusive export standardized packaging. The whole machine is fixed with high-strength wooden frame and fumigated wooden box (with IPPC official mark), equipped with shockproof foam, anti-rust film and moisture-proof packaging materials. No oil filling is required for the whole process, which avoids oil leakage and pollution risks. For long-distance ocean transportation and transnational land transportation, we can equip impact recorders and fixed protective accessories to monitor transportation status in real time and protect equipment integrity.

4. Production & FAT Acceptance

Q15: What is the production lead time for 20kV dry-type transformers? How to guarantee on-time delivery?
A15: The production cycle of standard 20kV dry-type transformers is 20–30 working days (longer than oil-immersed type due to resin curing process). For customized models, special environmental adaptive equipment and large-capacity products, the production lead time is 30–45 working days. The exact delivery schedule will be clearly stipulated in the formal contract. We will regularly update production progress, including winding production, pouring curing, finished product testing and other key nodes, and adopt multi-process parallel production mode to avoid delivery delay, with contractual delivery guarantee mechanism.
Q16: Can customers or third-party institutions witness the factory acceptance test (FAT)?
A16: We fully support customer on-site factory inspection and third-party witnessed FAT. Authorized international institutions such as SGS, BV, TUV can be arranged to conduct whole-process supervision and testing. We will actively cooperate with inspectors to provide complete production process records, raw material certificates and test data, realizing transparent and open factory acceptance to ensure product quality meets customer and international standards.
Q17: Are core components traceable? Are key production processes outsourced?
A17: All core components of 20kV dry-type transformers (silicon steel sheet, winding wire, epoxy resin, insulation parts) have complete batch number traceability system and official qualification certificates. The core processes that determine product quality, such as high-precision winding, vacuum pouring, high-temperature constant curing and partial discharge testing, are all independently completed in our factory without external outsourcing, effectively avoiding quality differences caused by outsourcing links and ensuring stable and consistent product quality of each batch.

5. Quotation, Payment & Customs Clearance

Q18: How long is the validity period of the quotation? Will the price fluctuate with raw material costs?
A18: The standard quotation validity of 20kV dry-type transformers is 15 working days with fixed unit price, which is not affected by short-term raw material fluctuations. For large-scale grid and industrial EPC projects, we can extend the quotation validity up to 180 days according to customer needs. The quotation will be automatically invalid after expiration, and we will reissue the latest formal quotation free of charge.
Q19: What payment terms are supported? Is L/C payment acceptable?
A19: We support multiple flexible international payment methods, including TT telegraphic transfer and irrevocable sight L/C (letter of credit), which is the mainstream payment method for overseas engineering projects. The advance payment ratio, installment payment cycle and other commercial terms can be flexibly negotiated according to project scale, order quantity and long-term cooperation relationship, and all confirmed terms will be clearly written in the formal export contract to protect the legitimate rights and interests of both parties.
Q20: Can you provide preferential customs clearance certificates to help customers reduce tariffs?
A20: We can provide complete export customs clearance documents and preferential tariff certificates, including CO certificate of origin, FORM E, FORM A and other regional preferential origin certificates. Professional document sorting and guidance can help customers smoothly complete customs clearance procedures, apply for corresponding tariff reduction and exemption policies, and save project procurement costs.

6. Packaging, Logistics & Insurance

Q21: What is the export packaging standard? Can it adapt to long-distance sea freight?
A21: The export packaging of 20kV dry-type transformers adopts international long-distance transportation standard, with integrated anti-rust, moisture-proof, shockproof and compression-resistant design. The wooden packaging box has passed IPPC fumigation certification, which meets the quarantine access standards of all countries and regions in the world. The oil-free design avoids environmental pollution and cargo inspection risks, and is more suitable for long-term sea freight and multi-modal transshipment transportation.
Q22: What logistics transportation solutions are available for overseas delivery?
A22: We provide diversified targeted logistics solutions according to customer project location and equipment parameters: sea freight for global cross-border conventional delivery; bulk cargo ship transportation for large-capacity super-size equipment; China-Europe railway transportation for Eurasian inland projects (short cycle and high efficiency); road truck transportation for neighboring countries and short-distance cross-border projects, to meet different customer’s delivery cycle and cost requirements.
Q23: What is the cargo damage insurance claim process during transportation?
A23: All exported 20kV dry-type transformers are fully insured with international cargo transportation insurance. If cargo damage occurs during transportation, customers only need to sort out on-site photos, videos, delivery bills and other valid evidence within 48 hours after cargo arrival, and submit an insurance claim application. Our professional international trade team will provide full set of document support and claim guidance, and assist customers to complete claim settlement efficiently according to insurance policy terms and third-party assessment results.

7. SAT & On-Site Commissioning Service

Q24: Do you provide overseas on-site installation guidance and commissioning services?
A24: We provide global one-stop after-sales technical services, including overseas on-site installation guidance, equipment debugging, parameter testing, SAT on-site acceptance and personnel training services, with independent standardized quotation. Meanwhile, we provide free 24/7 online remote technical support, solving daily operation faults and technical consultation problems for customers at any time.

8. Warranty & After-sales Service

Q25: What is the equipment warranty period and coverage scope?
A25: The standard warranty period of 20kV dry-type transformers is 2 years, which is longer than oil-immersed products. For national grid, new energy and large EPC key projects, the warranty period can be extended to 3–5 years on demand. The warranty covers all manufacturing defects and original accessory quality faults, excluding equipment damage caused by improper on-site operation, long-term overload operation, external force impact and unauthorized disassembly and modification.
Q26: Can you supply original spare parts after the warranty period expires?
A26: We provide lifelong original spare parts supply service for all 20kV dry-type transformer products. Core wearing parts and matching accessories can be supplied at factory price for a long time, ensuring the long-term stable and safe operation of customer equipment and solving after-sales maintenance worries.
Q27: What is the response speed of technical support and after-sales service?
A27: We implement 24/7 all-weather online technical support mechanism, with professional engineers responding to customer fault feedback and technical consultation immediately. For on-site service demands, we can arrange professional overseas engineers to arrive at the site within 5–12 working days according to project location. For sudden equipment major faults affecting power supply, we will start emergency response mechanism priority to solve problems and reduce customer project losses.
Q28: What quality control system is adopted in factory production?
A28: Our factory fully implements ISO 9001 full-process quality management and control system, covering raw material incoming inspection, production process monitoring, semi-finished product detection and finished product full-item test. Each 20kV dry-type transformer must pass partial discharge test, insulation resistance test, temperature rise test and other exclusive core tests before delivery. We support factory audit and quality inspection by international third-party authoritative institutions such as BV and SGS at any time.

Product parameters

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额定容量Capacity	额定电压及分接范围Rated voltage&Off-load tapping				联结组标号 Vector  GroupSymbol		空载损耗 NO-load loss（W）	负载损耗 Load loss（W） F级绝缘	空载电流 NO-load current（%）	短路阻抗Short circuit impedance(%)
	高压 H.V(kv)	高压分接范围  High pressure   Tap range（%）		低压 L.V(kv)
30	20	±5% ±2.5%		0.4 0.69	Dyn11 Yyn0		150	710	2	4
50							215	1000	2	4
80							295	1380	1.5	4
100							320	1570	1.5	4
125							375	1850	1.3	4
160							430	2130	1.3	4
200		±5% ±2x2.5%					495	2530	1.1	4
250							575	2760	1.1	4
315							705	3470	1	4
400							785	3990	1	4
500							930	4880	1	4
630							1070	5880	0.85	4
630							1040	5960	0.85	6
800							1215	6960	0.85	6
1000							1415	8130	0.85	6
1250							1670	9100	0.85	6
1600							1960	11700	0.85	6
2000							2440	14400	0.7	6
2500							2880	17100	0.7	6

 

Ordering instructions

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- Main parameters of transformer (voltage, capacity, loss and other main parameters)
- Transformer operating environment (altitude, temperature, humidity, location, etc.)
- Other customization requirements (coupling groups, colors, oil pillows, etc.)
- The minimum order quantity is 1 sets, worldwide delivery within 7 days
- Normal delivery period of 30 days, worldwide fast delivery