• Product advantages
• Product parameters
• Ordering instructions

Product advantages

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Why Choose Our 35kV 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 |

 

35kV Three-phase Epoxy Cast Dry Distribution Transformer Case



35kV Three-phase Epoxy Cast Dry Distribution Transformer FAQ
1. Standard & Certification

Q1: What international standards do your 35kV dry-type transformers comply with? Can they meet high-voltage grid access and industrial substation requirements?
A1: Our 35kV high-voltage dry-type transformers are fully designed and tested per IEC 60076-11 (dry-type transformers) and IEC 60076-3 (insulation level for power transformers), covering strict high-voltage insulation, partial discharge, lightning impulse and short-circuit withstand criteria. We support cross-standard compliance with GB/T 10228, EN 60076, GOST, ANSI/IEEE C57.12.01, AS/NZS, INMETRO, SABS and SASO. For national grid substations, industrial high-voltage power distribution and large new energy booster stations, we conduct targeted standard matching assessment and deliver complete certified documents to pass official grid connection and third-party project acceptance.
Q2: Can you provide full type test reports and third-party witnessed tests for 35kV high-voltage models? Is factory witness testing supported?
A2: Complete CNAS-accredited full type test reports are available for all 35kV dry-type transformer series. Test items cover professional high-voltage exclusive indicators: ultra-low partial discharge test, 170kV lightning impulse withstand test, 70kV power frequency withstand voltage test, temperature rise cycling test, short-circuit dynamic stability test and insulation aging test. For provincial grid projects, large industrial EPC and overseas high-voltage substation projects, we support SGS, BV, TUV third-party witnessed factory tests (WTT) and full-process video recording to ensure test authenticity and authority.
Q3: What technical documents are included in standard delivery? Do you support multi-language high-voltage professional manuals?
A3: The standard English document package includes high-voltage grade nameplate parameter sheet, overall installation dimension drawing, high-low voltage wiring schematic diagram, complete FAT test report, professional high-voltage operation & maintenance manual, safety operation specification and spare parts list. We support customized multi-language technical documents (Spanish, Portuguese, Arabic, French, Russian) and can revise professional clauses according to local high-voltage power grid operation specifications to meet regional project requirements.

2. Technical Performance & High-Voltage Structural Advantages

Q4: What winding materials are optional for 35kV dry-type transformers? Can material performance be guaranteed in contract?
A4: We provide two high-grade winding solutions: high-purity anaerobic copper winding (high-end grid standard) and high-strength aluminum winding (cost-effective industrial standard). All windings adopt H-class high-temperature insulation system exclusive for 35kV high voltage, with vacuum epoxy resin integral pouring process. Winding material type, insulation grade and high-voltage matching parameters can be clearly defined in technical agreement and formal contract, accompanied by material test certificates and full production traceability records. Optimized high-voltage electric field structure eliminates partial discharge risks and ensures long-term stable operation of high-voltage equipment.
Q5: Can 35kV transformer electrical parameters be fully customized? How to handle unqualified test products?
A5: All core high-voltage parameters support personalized customization, including ultra-low no-load/load loss, 6%–8% adjustable short-circuit impedance, ±2×2.5% voltage tap range, partial discharge ≤5pC and high-temperature rise limit. All parameters can be strictly matched with customer’s high-voltage technical datasheet. Each 35kV transformer undergoes 100% full-item high-voltage factory inspection before delivery. Unqualified products will be prohibited from shipment, with free professional rework, high-voltage performance debugging or full machine replacement to guarantee zero defective delivery.
Q6: Can 35kV dry-type transformers adapt to high altitude, coastal salt spray, dusty industrial and seismic harsh environments?
A6: Exclusive high-voltage environmental adaptive design is available for harsh working conditions. For high-altitude areas above 1000m, we upgrade insulation margin and optimize air cooling structure to prevent high-altitude high-voltage breakdown; for coastal salt-fog and humid areas, we adopt anti-corrosion epoxy pouring and overall anti-aging coating to resist salt erosion; for heavy-dust industrial workshops and underground substations, fully closed protective shell is equipped to avoid dust-induced partial discharge; for seismic zones, integrated laser-cut framework and anti-vibration structure enhance mechanical stability. All designs are customized according to actual site conditions.
Q7: Are 35kV dry-type transformers suitable for new energy booster stations? What is harmonic resistance capability?
A7: 35kV high-voltage dry-type transformers are the core preferred equipment for solar/wind farm booster stations and energy storage power station grid connection. Adopting high-performance low-loss silicon steel sheet and optimized winding layout, they effectively suppress harmonic heating and voltage distortion caused by new energy inverter fluctuation. The reinforced high-voltage structure resists long-term harmonic impact and intermittent load impact, solving overheating and insulation aging problems of high-voltage equipment in new energy scenarios, ensuring stable grid-tie operation.
Q8: What is the standard noise level of 35kV dry-type transformers? Is low-noise version available for urban substations?
A8: Under IEC standard test conditions, the standard operating noise of 35kV dry-type transformers is ≤52dB, far lower than traditional high-voltage oil-immersed equipment. For urban built-in substations, residential surrounding substations and municipal power distribution projects, we provide ultra-low-noise customization (≤45dB). By adopting magnetic flux optimization, core vibration damping and buffer base shock absorption technology, operation resonance is eliminated fundamentally. Official noise test certificates can be provided for project environmental acceptance.
Q9: What is the high-voltage withstand capability of 35kV transformers for lightning impulse and short-circuit faults?
A9: Our 35kV dry-type transformers adopt standard LI170kV/AC70kV high-voltage insulation level, with excellent lightning impulse and switching overvoltage resistance. The integral vacuum pouring structure and reinforced winding support design greatly improve short-circuit dynamic stability, effectively resisting electrodynamic force impact caused by sudden short-circuit faults, avoiding winding displacement and insulation breakdown. Fully compliant with global high-voltage grid operation standards, lightning impulse and short-circuit withstand test reports are available on request.
Q10: What is the design service life of 35kV dry-type transformers? Does it follow insulation aging rules?
A10: The standard design service life of 35kV high-voltage dry-type transformers is 30 years, benefiting from H-class high-temperature resistant insulation and fully sealed epoxy structure. With standardized operation and regular professional maintenance, the service life can be extended to 35–40 years. The oil-free insulation system strictly follows the 6℃ insulation aging principle, with sufficient high-temperature margin and anti-aging performance. Isolated from air and moisture, it effectively delays insulation degradation and ensures long-term stable high-voltage performance.
Q11: Are you a professional manufacturer of 35kV high-voltage dry-type transformers?
A11: We are a professional high and medium voltage dry-type transformer manufacturer in Qingdao, China, with decades of R&D and export experience in 35kV high-voltage products. We master core high-voltage pouring and insulation technology, with all key processes including high-precision winding, vacuum integral pouring, constant temperature curing and high-voltage testing completed in-house. Our products are widely used in global high-voltage grid substations, new energy booster stations, large industrial parks and urban built-in power distribution projects. Factory audit and high-voltage process inspection are warmly welcomed.

3. Customization, Dimension & Transportation

Q12: Can you provide non-standard customized 35kV high-voltage dry-type transformers?
A12: Full non-standard customization is supported for 35kV high-voltage models. Customizable items include high-voltage special electrical parameters, multi-grade tap adjustment, ultra-low partial discharge optimization, customized overall dimensions (adaptable to indoor substation limited space), vertical/horizontal mounting, flame-retardant and explosion-proof upgrade, and intelligent monitoring system matching. Core accessories can be equipped with customer-specified international brands. All customized technical requirements are standardized in formal technical agreements to ensure consistent delivery quality.
Q13: Can you provide accurate weight and dimension drawings? Are 35kV transformers suitable for cross-border long-distance transportation?
A13: After confirming technical schemes, we provide formal quotations attached with accurate overall dimension drawings, installation drawings and net/gross weight data. 35kV dry-type transformers adopt oil-free design, with no leakage, pollution and safety hazards during transportation. For large-capacity and super-size high-voltage equipment, we pre-assess oversize and overweight risks, and provide professional hoisting, fixing and cross-border multi-modal transportation solutions to ensure intact delivery.
Q14: What is the standard export packaging mode for 35kV dry-type transformers?
A14: All 35kV high-voltage transformers adopt exclusive high-standard export 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 materials. Oil-free and explosion-proof design avoids inspection and transportation risks. For long-distance ocean transportation, we 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 35kV dry-type transformers? How to guarantee on-time delivery?
A15: Standard production lead time for conventional 35kV dry-type transformers is 25–35 working days (longer due to high-voltage vacuum pouring and secondary curing process). For customized high-voltage models, harsh environment adaptation and ultra-low loss special products, the cycle is 35–45 working days. The exact delivery schedule is specified in the contract. We regularly update key production nodes such as winding processing, vacuum pouring, high-temperature curing and high-voltage testing, and adopt parallel production mechanism to ensure on-time delivery with contractual guarantee.
Q16: Can customers or third-party institutions witness high-voltage FAT testing?
A16: We fully support customer on-site inspection and third-party (SGS, BV, TUV) whole-process witnessing of high-voltage FAT. Professional high-voltage test engineers cooperate with inspectors to complete all insulation, partial discharge and withstand voltage tests, and provide complete production records, raw material certificates and high-voltage test data to realize transparent and open acceptance.
Q17: Are core components traceable? Are key high-voltage processes outsourced?
A17: All core components (high-voltage special silicon steel sheet, H-class insulation materials, imported epoxy resin, high-voltage winding wire) have complete batch traceability and qualification certificates. Core high-voltage processes that determine equipment safety, including vacuum pouring, constant temperature curing and high-voltage pressure test, are all independently completed in our factory without outsourcing, effectively avoiding high-voltage quality risks and ensuring stable product performance.

5. Quotation, Payment & Customs Clearance

Q18: How long is the quotation validity? Will prices fluctuate with raw materials?
A18: The standard quotation validity for 35kV dry-type transformers is 15 working days with fixed price, unaffected by short-term raw material fluctuations. For large-scale high-voltage substation and new energy EPC projects, we can extend the quotation validity up to 180 days. Expired quotations will be reissued free of charge with the latest price.
Q19: What payment terms are acceptable? Is L/C supported?
A19: We support flexible international payment methods, including TT telegraphic transfer and irrevocable sight L/C, which is applicable to large overseas high-voltage engineering projects. Advance payment ratio and installment terms can be negotiated according to project scale and cooperation duration, with all terms clearly stipulated in formal export contracts to protect bilateral interests.
Q20: Can you provide preferential certificates for tariff reduction and smooth customs clearance?
A20: We provide complete export customs clearance documents and preferential origin certificates including CO, FORM E and FORM A. Professional document sorting and guidance help customers complete customs clearance efficiently and apply for regional tariff reduction policies to save project procurement costs.

6. Packaging, Logistics & Insurance

Q21: What is the export packaging standard? Is it suitable for long-distance sea freight?
A21: 35kV dry-type transformer export packaging adopts international long-distance transportation super standard, integrating anti-rust, moisture-proof, shockproof and compression-resistant functions. IPPC fumigated wooden boxes meet global quarantine 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.
Q22: What logistics solutions are available for overseas delivery?
A22: We provide targeted diversified logistics solutions: sea freight for global conventional delivery; bulk carrier for super-large capacity high-voltage equipment; China-Europe railway for Eurasian inland high-voltage substation projects; road transport for neighboring cross-border projects, balancing delivery cycle and transportation cost.
Q23: What is the cargo damage insurance claim procedure?
A23: All exported 35kV transformers are fully covered by international cargo insurance. In case of cargo damage, customers only need to collect on-site photos, videos and delivery documents within 48 hours after arrival and submit a claim application. Our professional team provides full document support and one-stop claim guidance to assist efficient settlement per insurance policy and third-party assessment results.

7. SAT & On-Site Commissioning Service

Q24: Do you provide overseas on-site high-voltage installation and commissioning services?
A24: We provide global exclusive high-voltage professional technical services, including overseas on-site installation guidance, 35kV high-voltage debugging, insulation testing, SAT acceptance and on-site operator training, with independent standardized quotation. Free 24/7 remote high-voltage technical support is available for daily fault troubleshooting and technical consultation.

8. Warranty & After-sales Service

Q25: What is the warranty period and coverage for 35kV transformers?
A25: The standard warranty period for 35kV high-voltage dry-type transformers is 2 years. For grid substations and key new energy EPC projects, it can be extended to 3–5 years on demand. The warranty covers all manufacturing defects and original accessory faults, excluding damage caused by improper high-voltage operation, long-term overload, external force impact and unauthorized disassembly.
Q26: Can you supply original spare parts after warranty expiration?
A26: We provide lifelong supply of original high-voltage special spare parts and wearing components at factory price, ensuring long-term safe and stable operation of 35kV high-voltage equipment and eliminating after-sales maintenance worries.
Q27: What is the response time for high-voltage technical support and after-sales service?
A27: 24/7 all-weather online high-voltage technical support is available with immediate engineer response. Overseas on-site service can be arranged within 5–12 working days according to project location. For sudden high-voltage equipment faults affecting power supply, we activate an emergency response mechanism prioritized to minimize project losses.
Q28: What quality control system is implemented for 35kV transformer production?
A28: We implement full ISO 9001 quality control system, covering raw material high-voltage performance inspection, production process monitoring, semi-finished product testing and finished product full-item high-voltage detection. Each 35kV transformer passes exclusive strict tests including partial discharge detection, high-voltage withstand test and insulation aging test before delivery. Third-party factory audit and quality inspection by BV, SGS and other institutions are fully supported.

 

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	35	±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