Cast Resin Three-phase Dry-type Distribution Transformer up to 35kV

Structural Features

Key Advantages

High Safety & Fire Retardancy: Oil-free design. Epoxy resin is self-extinguishing (Flame Class F/F1). Even in case of failure, it will not cause oil explosions or fire spread, making it suitable for densely populated and critical facilities.

Maintenance-Free & Strong Environmental Adaptability: Encapsulated windings resist moisture, dust, and chemical corrosion. No oil changes or oil sampling are required; daily maintenance is limited to periodic dust removal.

Excellent Electrical & Mechanical Properties: Integral casting turns the winding into a rigid body, minimizing deformation under short-circuit electromagnetic forces. Low partial discharge (typically ≤5~10pC).

Low Loss & High Energy Efficiency: Models ranging from SCB10 to SCB18 offer progressively lower no-load losses compliant with higher energy efficiency standards.

Low Noise: Optimized core stacking and clamping structures result in lower operational noise compared to oil-immersed transformers of the same capacity.

Flexible Installation: Can be placed directly in floor-level substations or underground rooms without the need for oil containment pits or firewalls, saving civil construction costs.

Typical Technical Parameters

Scope of Application

High-rise residences, office buildings, star-rated hotels, shopping malls (indoor substations).

Hospitals, schools, research institutes (low noise, zero pollution).

Data centers, communication hubs, financial centers (high reliability, low PD).

Subways, airports, underground utility tunnels (underground substations, no fire hazard).

Industrial/mining enterprises, nuclear power auxiliary facilities (strict fire/environmental requirements).

Renewable energy stations, PV/Wind pad-mounted substations.

Precautions

Although moisture-resistant, it is recommended to measure insulation resistance (HV-LV & Earth) before re-energizing after long-term shutdown; perform drying if necessary.

Ensure top and side air ducts remain unobstructed when installed with an enclosure to avoid hot air recirculation.

Standard resin dry-types are not recommended for environments with strong corrosive gases or extreme humidity (heavy condensation). Special anti-corrosion customization or alternative types should be considered.

Comparison with Oil-Immersed: While the upfront cost is slightly higher, dry-type transformers feature zero oil leakage risk and simplified installation, making them the dominant choice for indoor distribution in modern cities.

Dry-Type Transformer FAQ

Q: What is the designed service life of a dry-type transformer?

A: Under standardized operation and good ventilation, high-quality dry-type transformers typically have a service life of 25 to 30 years or longer. Particularly for transformers using Vacuum Pressure Impregnation (VPI) or epoxy resin casting, the windings are tightly wrapped in a solid insulating layer, providing strong resistance to moisture, dust, and mechanical stress, effectively delaying insulation aging.

Q: What daily maintenance do dry-type transformers require?

A: Dry-type transformers are known for being "low-maintenance."

Regular Cleaning: Use dry compressed air or a vacuum cleaner to remove dust from the winding surfaces and cooling ducts to prevent overheating or tracking.

Check Fasteners: Periodically inspect and tighten coil pressure pads, core clamps, and electrical connection bolts to prevent loosening due to long-term vibration.

Inspect Cooling System: If equipped with forced air cooling (fans), check fan operation regularly and clean the inlet filters.

Q: What are the mainstream insulation processes for dry-type transformers?

A: Besides traditional varnish dipping, the mainstream eco-friendly process is Epoxy Resin Casting. Using vacuum pressure technology, the epoxy resin forms an extremely solid insulating layer around the windings. This provides excellent moisture and contamination resistance, along with UL94 V-0 level flame retardancy (self-extinguishing), making it ideal for indoor spaces with strict fire safety requirements.

Q: What are the core differences between IP00, IP20, and IP23+?

A: IP00 (Bare Unit): No enclosure. Relies on natural convection or fans. Best ventilation, no water protection. Only for dry, clean indoor rooms.

IP20 (Indoor Enclosure): Features a ventilated mesh/sheet housing preventing solid objects> 12 mm (fingers, rodents, snakes) from entering. Provides basic safety barriers. Ventilation is nearly unaffected. No water protection.

IP23+ (Weatherproof Enclosure): Equipped with a sealed alloy/stainless steel shell protecting against water splashing up to 60° and solid objects> 12 mm. Isolates the windings from the external environment.

Note: High-protection enclosures hinder airflow. When fitted with an IP23+ enclosure, the transformer typically requires derating (reduced load capacity).

Q: What are the differences between various vector groups?

A: If the transformer supplies power independently to a factory or residential area without paralleling, different vector groups (e.g., Dyn11 vs Yyn0) can be used, though performance differs. However, if expanding capacity or replacing a unit that will run in parallel with an existing one, you must strictly check the old transformer's nameplate. The new unit's vector group must match exactly—never rely solely on capacity and voltage!

Q: What should be considered in dry-type transformer selection for special environments?

A: High Pollution / Coastal Salt Mist: Standard units are unsuitable for direct salt mist exposure. Select high-protection enclosures (IP23+) and specify stainless steel hardware or heavy-duty anti-corrosion coatings for metal parts.

High-Temperature Environments: Dry-types rely entirely on air convection. In high heat, efficiency drops. Confirm winding temperature class (F/H) and recommend adding forced air cooling (fans) or derating.

Low-Temperature Environments: Dry-types start better than oil units (no viscosity issues), but extreme cold can make rubber seals/bushings brittle. Specify low-temperature resistant sealing materials and prevent condensation inside the enclosure.

High-Altitude Environments: Thin air reduces cooling efficiency (increasing temperature rise) and lowers air insulation strength (risk of flashover). Units must have increased external clearances/creepage distances and usually require larger radiators or derating.

High-Humidity Environments: High humidity causes condensation, lowering insulation. Besides high-protection enclosures, equip the room with dehumidifiers or anti-condensation heaters.

Dusty/Sandy Environments: Dust clogs cooling ducts and conductive dust causes shorts. Use high-protection enclosures with optimized dust filtration and ensure regular filter cleaning.

Q: What information is needed to get a quote for a distribution transformer?

A: To receive a quick and accurate quotation, please first provide the following core parameters:

Transformer Type: Oil-immersed / Dry-type

Rated Capacity (kVA)

Primary and Secondary Voltage Ratings (e.g., 33kV/0.4kV)

Rated Frequency (50Hz or 60Hz)

Number of Phases (Single-phase or Three-phase)

Winding Material: Supports copper or aluminum windings, each with its own cost and performance advantages.

Vector Group & impedance voltage (%): (Must be provided if parallel operation with multiple units is required)

Additionally, our transformers support customization. You can supplement the following information based on your actual needs:

Tap Changer Type (Standard off-circuit tap changer, or optional on-load tap changer)

Loss Standards: Are there specific loss standards or energy efficiency class requirements?

Installation environment (indoor/outdoor, altitude, extreme temperature, etc.)

Other Requirements (e.g., applicable standards, special protection ratings, instrument accessories, etc.)

If you are looking for reliable power support for your project, please contact the Kima Electric team.

• Direct Factory & Manufacturer: We are a professional China Cast Resin Three-phase  Dry-type Distribution Transformer manufacturer (available in 6.3kV,10kV,11kV,13.2kV,15kV,20 kV,22kV,33kV, and other voltages). Our factory is equipped with advanced production facilities and accepts OEM/ODM orders.
• Reliable Supplier: We serve as a trusted international supplier for global buyers looking to source high-efficiency and low-loss Three-phase Dry-type distribution transformers from China.
• International Standards & Global Reach: Our transformers are rigorously tested to comply with IEC 60076 and other international standards. We export to diverse markets across Southeast Asia, Africa, and the Middle East, adapting to various local grid environments.
• Competitive Quotation: Contact us today to discuss your project requirements, get a customized solution, and receive a free wholesale quote.
  
  

Convenient Inquiry Process

You can contact us via our website, email, and other channels, or download and fill out the "Inquiry Application Form" on our official website.

You can also directly provide your existing technical documents, drawings, etc., as a basis for requirement evaluation. We will provide you with a quotation as soon as possible.

Production and Quality Control

Before formal production, we will provide a detailed technical proposal, including specifications and structural drawings, for your review and confirmation.

We strictly implement the ISO quality management system, comprehensively monitoring every link including raw materials, production processes, and finished product inspection, ensuring that every customized product possesses stable and reliable quality.

Delivery and After-Sales Service

We use dedicated wooden crates that meet international standards for packaging, lined with high-performance moisture-proof materials, to ensure the equipment remains absolutely safe and dry during long-distance transportation.

Detailed user manuals, maintenance manuals, and related documents are provided with the shipment.

Remote or on-site installation guidance and commissioning services can be provided upon request.

We provide comprehensive after-sales support, including technical consultation, troubleshooting, and spare parts supply, ensuring the long-term stable operation of the product.