Why Choose Our 33kV Three-phase Epoxy Cast Dry Distribution Transformer？
• 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
• 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
• 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
• 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
• 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 |
33kV Three-phase Epoxy Cast Dry Distribution Transformer Case
33kV Three-phase Epoxy Cast Dry Distribution Transformer FAQ
1. Standard & Certification
Q1: What international standards do your 33kV dry-type transformers comply with? Can they meet overseas grid and industrial substation grid-connection requirements?
A1: Our 33kV cast-resin dry-type transformers are fully designed and tested in accordance with core international standards IEC 60076-11 (dry-type power transformers) and IEC 60076-3 (insulation levels and dielectric tests), which are the dominant standards for global 33kV distribution and substation projects. We support multi-standard compliance with EN, GOST, ANSI/IEEE C57.12, AS/NZS, INMETRO, SABS, SASO and GB specifications. Targeted at overseas 33kV national grid codes, industrial power distribution and renewable energy substation standards, we conduct full standard matching assessment and provide complete certified documents to support official grid connection and third-party project acceptance.
Q2: Can you provide official type test reports and third-party witnessed test documents for 33kV models? Is factory witnessed test available?
A2: Complete CNAS-accredited full type test reports are available for the entire 33kV dry-type transformer series, fully compliant with IEC mandatory test items. The test scope covers 33kV exclusive dielectric tests: ultra-low partial discharge test, 150kV lightning impulse withstand test, 65kV power frequency withstand voltage test, temperature rise cycling test, short-circuit dynamic/thermal stability test and long-term insulation aging verification. For overseas EPC projects, African/Middle East 33kV grid upgrading projects and large industrial substations, we support SGS, BV, TUV third-party witnessed factory tests (WTT) and full-process video monitoring to ensure test authenticity and authority.
Q3: What technical documents are included in standard delivery? Do you support multi-language professional manuals?
A3: The standard full-English technical document package includes 33kV high-voltage grade nameplate datasheet, overall installation dimension drawing, high/low voltage wiring schematic diagram, complete FAT test report, professional high-voltage operation & maintenance manual, safety operation guideline and official spare parts list. We provide customized multi-language technical documents including Spanish, Portuguese, Arabic, French and Russian, and can revise professional clauses according to local 33kV grid operation specifications to adapt to regional project acceptance requirements.
2. Technical Performance & Structural Advantages
Q4: What winding materials are optional for 33kV dry-type transformers? Can material quality and performance be guaranteed in contract?
A4: We offer two standardized winding solutions for 33kV high-voltage scenarios: high-purity anaerobic copper winding (for grid-grade high stability requirements) and high-strength aluminum winding (for cost-effective industrial projects). All windings adoptH-class high-temperature insulation system matched with 33kV international voltage level, manufactured via full vacuum epoxy resin integral casting process. Winding material type, insulation grade and high-voltage matching parameters can be clearly defined in technical agreements and formal contracts, accompanied by official material test certificates and full production traceability records. Optimized electric field homogenization design effectively eliminates partial discharge risks, ensuring long-term stable and low-loss operation of 33kV high-voltage equipment.
Q5: Can 33kV transformer electrical parameters be fully customized? How to handle unqualified test results and defective products?
A5: All core electrical parameters of 33kV dry-type transformers support personalized customization to match client datasheets and site operating conditions, including ultra-low no-load/load loss, 6%–9% adjustable short-circuit impedance, ±2×2.5% / ±4×2.5% multi-range tap adjustment, partial discharge ≤5pC and customized temperature rise limits. Every 33kV unit undergoes 100% full-item high-voltage factory inspection before delivery. Any non-compliant product will be prohibited from shipment immediately, with free professional rework, high-voltage performance debugging or full machine replacement to ensure zero defective delivery.
Q6: Can 33kV dry-type transformers adapt to high altitude, coastal salt spray, dusty and seismic harsh working conditions?
A6: Targeted environmental adaptive design is available for all harsh overseas working scenarios. For high-altitude areas above 1000m, we upgrade insulation margin and optimize air cooling clearance to prevent high-altitude high-voltage breakdown; for coastal humid and salt-fog areas, we adopt anti-corrosion epoxy formula and overall anti-aging coating to resist salt erosion and moisture penetration; for heavy-dust industrial workshops and indoor closed substations, a fully sealed protective shell is equipped to avoid dust-induced partial discharge; for seismic zones, integrated reinforced framework and multi-point anti-vibration structure enhance mechanical stability against vibration and impact. All designs are customized according to actual site environmental parameters.
Q7: Are 33kV dry-type transformers suitable for renewable energy grid-tie? What is the harmonic resistance performance?
A7: 33kV cast-resin dry-type transformers are the preferred equipment for overseas solar farms, wind power stations and energy storage grid-tie substations, perfectly matching international new energy 33kV boosting and grid-connected standards. Adopting high-performance low-loss silicon steel core and optimized asymmetric winding layout, the transformer effectively suppresses harmonic heating and voltage distortion caused by inverter fluctuation and intermittent new energy load. The reinforced high-voltage insulation structure resists long-term harmonic impact and frequent load fluctuation, avoiding insulation aging and local overheating, and ensuring stable and reliable grid-tie operation of renewable energy systems.
Q8: What is the standard noise level of 33kV dry-type transformers? Is low-noise customization available for urban and residential substations?
A8: Under standard IEC test conditions, the rated operating noise of 33kV dry-type transformers is ≤53dB, significantly lower than traditional oil-immersed high-voltage transformers. For urban built-in substations, residential surrounding power distribution stations, schools and municipal commercial areas, we provide ultra-low-noise customized design (≤46dB). By adopting core magnetic flux optimization, multi-layer vibration damping structure and buffer shock-absorbing base, equipment operation resonance is fundamentally eliminated. Official noise test certificates can be provided for environmental assessment and project acceptance.
Q9: What is the lightning impulse and short-circuit fault resistance capability of 33kV dry-type transformers?
A9: Our 33kV dry-type transformers adopt international standard LI150kV/AC65kV insulation level, with excellent lightning impulse and switching overvoltage resistance, fully compliant with IEC 60076-3 dielectric test standards. The integral vacuum casting structure and reinforced winding support design greatly improve short-circuit dynamic stability, effectively resisting strong electrodynamic force impact caused by sudden short-circuit faults, preventing winding displacement and insulation breakdown. Lightning impulse and short-circuit withstand test reports can be provided upon customer request.
Q10: What is the design service life of 33kV dry-type transformers? Does it follow standard insulation aging rules?
A10: The standard design service life of 33kV high-voltage dry-type transformers is 30 years. With standardized operation and regular professional maintenance, the service life can be extended to 35–40 years. The oil-free epoxy resin insulation system strictly follows the IEC-standard 6℃ insulation aging principle, with sufficient high-temperature resistance margin and anti-aging performance. The fully sealed casting structure isolates air, moisture and dust, effectively delaying insulation degradation and maintaining stable high-voltage performance throughout the equipment lifecycle.
Q11: Are you a professional manufacturer of 33kV high-voltage dry-type transformers?
A11: We are a professional medium and high voltage dry-type transformer manufacturer based in Qingdao, China, with decades of specialized R&D and export experience in 33kV international standard models. We master core 33kV high-voltage insulation and vacuum casting technology, with all key processes including high-precision winding, integral vacuum casting, constant temperature curing and full-item high-voltage testing completed in-house. Our 33kV transformers are widely exported to Southeast Asia, Africa, Middle East, Europe and South America, serving global grid upgrading, industrial power distribution and new energy substation projects. Factory on-site audit and production process inspection are warmly welcomed.
3. Customization, Dimension & Transportation
Q12: Can you provide non-standard customized 33kV dry-type transformers for special project requirements?
A12: We support full-dimensional non-standard customization for 33kV international standard transformers. Customizable items include special high-voltage electrical parameters, multi-grade voltage tap adjustment, ultra-low partial discharge optimization, compact customized overall dimensions for narrow indoor substations, vertical/horizontal mounting types, flame-retardant and explosion-proof upgrades, and intelligent temperature control & monitoring system matching. Core supporting accessories can be equipped with customer-specified international brands. All customized technical requirements are sorted out in detail and signed into formal technical agreements to ensure consistent delivery quality.
Q13: Can you provide accurate weight and dimension drawings? Are 33kV transformers suitable for cross-border long-distance transportation?
A13: After confirming the technical scheme, we provide formal quotation documents attached with accurate overall dimension drawings, installation size diagrams and net/gross weight data. Adopting oil-free dry-type design, 33kV transformers have no oil leakage, pollution or safety hazards during transportation, featuring higher safety and convenience than oil-immersed products. For large-capacity oversized equipment, we pre-assess oversize and overweight risks, and provide professional hoisting, fixing and cross-border multi-modal transportation solutions to ensure intact and safe delivery.
Q14: What is the standard export packaging mode for 33kV dry-type transformers?
A14: All 33kV high-voltage dry-type transformers adopt exclusive international export standard packaging. The whole machine is fixed with high-strength steel frame and IPPC fumigated wooden box, equipped with multi-layer shockproof, anti-rust and moisture-proof protective materials. The oil-free and explosion-proof design avoids international transportation inspection risks and environmental pollution problems. For long-distance ocean transportation, we can equip impact recorders and anti-collision protective accessories to monitor transportation status in real time and protect high-precision high-voltage equipment.
4. Production & FAT Acceptance
Q15: What is the production lead time for 33kV dry-type transformers? How to guarantee on-time delivery?
A15: The standard production lead time for conventional 33kV dry-type transformers is 22–32 working days, affected by professional vacuum casting and secondary high-temperature curing processes exclusive for 33kV high voltage. For customized models, harsh environment adaptive products and ultra-low loss special transformers, the production cycle is 32–42 working days. The exact delivery schedule is clearly specified in the formal contract. We regularly update key production nodes including winding processing, vacuum casting, constant temperature curing and high-voltage testing, and adopt parallel production mechanism to avoid delivery delay, with strict contractual delivery guarantee.
Q16: Can customers or third-party institutions witness 33kV high-voltage FAT testing?
A16: We fully support customer on-site factory inspection and whole-process third-party witnessed FAT testing by authoritative institutions such as SGS, BV and TUV. Professional high-voltage test engineers cooperate with inspectors to complete all insulation resistance, partial discharge, withstand voltage and temperature rise tests, and provide complete production process records, raw material qualification certificates and full test data to realize transparent and open factory acceptance.
Q17: Are core components traceable? Are key high-voltage production processes outsourced?
A17: All core components for 33kV transformers (high-voltage special silicon steel sheet, H-class insulation materials, imported low-partial-discharge epoxy resin, high-purity winding wire) have complete batch number traceability system and official qualification certificates. Core high-voltage processes that determine equipment safety and performance, including vacuum integral casting, constant temperature curing and high-voltage pressure testing, are all independently completed in our factory without outsourcing, effectively avoiding quality instability risks and ensuring consistent product performance for each batch.
5. Quotation, Payment & Customs Clearance
Q18: How long is the quotation validity period? Will the price fluctuate with raw material costs?
A18: The standard quotation validity for 33kV dry-type transformers is 15 working days with fixed unit price, not affected by short-term raw material market fluctuations. For large-scale overseas substation and new energy EPC projects, we can extend the quotation validity up to 180 days according to customer needs. Expired quotations will be reissued free of charge with the latest official price.
Q19: What payment terms do you accept? Is L/C payment supported?
A19: We support flexible and universal international payment methods, including TT telegraphic transfer and irrevocable sight L/C, which is widely applicable to overseas 33kV engineering projects. The advance payment ratio and installment cycle can be flexibly negotiated according to project scale and long-term cooperation relationship, and all commercial terms are clearly stipulated in formal export contracts to protect bilateral legitimate rights and interests.
Q20: Can you provide preferential customs clearance certificates to help customers reduce tariffs?
A20: We provide complete export customs clearance documents and preferential tariff certificates including CO certificate of origin, FORM E, FORM A and other regional preferential certificates. Professional document sorting and guidance help customers smoothly complete customs clearance procedures and apply for corresponding tariff reduction and exemption policies, effectively saving project procurement costs.
6. Packaging, Logistics & Insurance
Q21: What is the export packaging standard? Is it suitable for long-distance sea freight?
A21: The export packaging of 33kV dry-type transformers adopts international long-distance transportation super standard, integrating anti-rust, moisture-proof, shockproof and compression-resistant functions. IPPC fumigated wooden boxes fully meet global quarantine access standards. The oil-free, explosion-proof and pollution-free design adapts to long-term sea freight and multi-modal transshipment, with zero environmental and inspection risks, which is more suitable for overseas project delivery than oil-immersed transformers.
Q22: What logistics solutions are available for overseas delivery of 33kV transformers?
A22: We provide diversified targeted logistics solutions according to project location and equipment parameters: sea freight for global conventional cross-border delivery; bulk carrier transportation for super-large capacity high-voltage equipment; China-Europe railway for Eurasian inland substation projects with short cycle requirements; road truck transportation for neighboring cross-border projects, balancing delivery efficiency and transportation cost.
Q23: What is the cargo damage insurance claim procedure during transportation?
A23: All exported 33kV transformers are fully covered by international cargo transportation insurance. In case of cargo damage during transportation, customers only need to collect 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 provides full set of document support and one-stop claim guidance to assist efficient settlement 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 high-voltage commissioning services?
A24: We provide global one-stop professional high-voltage technical services, including overseas on-site installation guidance, 33kV high-voltage debugging, insulation performance testing, SAT on-site acceptance and on-site operator training services, with independent standardized quotation. Free 24/7 online remote technical support is permanently available to solve daily equipment faults and technical consultation problems for customers.
8. Warranty & After-sales Service
Q25: What is the warranty period and coverage scope for 33kV transformers?
A25: The standard warranty period for 33kV high-voltage dry-type transformers is 2 years. For overseas key grid substations and large new energy EPC 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 high-voltage 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 supply of original special spare parts and core wearing components for all 33kV transformer products at factory price, ensuring long-term safe and stable operation of customer equipment and eliminating 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 high-voltage technical support mechanism with professional engineers responding to customer fault feedback and technical consultation immediately. Overseas on-site service can be arranged within 5–12 working days according to project location. For sudden major equipment faults affecting power supply, we will activate an emergency response mechanism prioritized to solve problems and minimize project economic losses.
Q28: What quality control system is adopted for 33kV transformer production?
A28: Our factory fully implements ISO 9001 full-process quality management and control system, covering raw material incoming high-voltage performance inspection, production process real-time monitoring, semi-finished product sampling test and finished product full-item high-voltage detection. Each 33kV transformer passes exclusive strict tests including partial discharge detection, 150kV lightning impulse test and 65kV power frequency withstand test before delivery. We fully support factory audit and quality inspection by international third-party authoritative institutions such as BV and SGS.
| 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 | 33 | ±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 | ||||||
Qingdao Hengfengshuai Electric Co., Ltd
WhatsApp： +86 152 6625 8801
Address: No. 251, Xingyang Road, Chengyang District, Qingdao, Shandong
Email: hfs@hengfengshuai.com
Customer service email: service@hengfengshuai.com
website:https://www.hengfengshuai.com
