Dry Type Transformer

Industrial Dry Type Transformers for B2B Power Distribution & OEM Integration

Industrial distribution networks and heavy equipment skids require robust voltage transformation without fire hazards or liquid dielectrics. This dry-type transformer line utilizes air-natural (AN) or air-forced (AF) cooling, eliminating the risk of oil leakage and reducing environmental containment requirements in commercial and industrial structures.

Built for primary and secondary distribution at 10kV, 20kV, and 35kV classes, units integrate grain-oriented silicon steel cores and vacuum pressure casting (VPC) epoxy resin or NOMEX insulation systems. Engineering teams configure core geometry and winding distribution to meet strict loss evaluation formulas and low-noise footprints specified in IEC 60076-11 and IEEE C57.12.01 standards.

10kV 20kV 35kV Cast Resin Dry Type Transformer

Product Types and Configurations

Cast Resin Dry Type Transformers (SCRB Series)
Configuration: High-voltage and low-voltage windings cast under vacuum using modified epoxy resin reinforced with glass fiber.

Characteristics: Non-hygroscopic winding structure, high mechanical strength against short-circuit electrodynamic forces, and self-extinguishing fire behavior (F1, E2, and C2 certified).

Three-Dimensional Wound Core Dry Type Transformers
Configuration: Triangular symmetrical core layout constructed from continuous silicon steel strip wound on specialized CNC multi-roller machines.

Characteristics: Balanced three-phase magnetic circuit reducing no-load current by 20 percent to 30 percent, minimized acoustic noise levels, and optimized spatial footprint within compact switchgear enclosures.

Three-Phase and Single-Phase Isolation Transformers
Configuration: Class C non-encapsulated design utilizing UL-recognized NOMEX paper insulation systems (Grade 220).

Characteristics: High thermal overload margin, excellent harmonic mitigation for nonlinear loads, and complete galvanic separation between primary and secondary circuits.

Technical Specifications

Technical Parameter	Standard Specification Range
Rated Voltage (Primary)	10 kV, 20 kV, 35 kV (Custom taps available, e.g., plus-minus 2 x 2.5 percent)
Rated Voltage (Secondary)	0.4 kV, 6.9 kV, 10 kV (or custom multi-tap outputs)
Rated Capacity	30 kVA to 10,000 kVA
Frequency	50 Hz / 60 Hz
Vector Group	Dyn11, Yyn0, or custom configurations
Insulation Class	Class F (155 deg C) or Class H (180 deg C / 220 deg C)
Temperature Rise	100K (Class F) or 125K (Class H)
Cooling Method	AN (Air Natural) or AF (Air Forced via intelligent temperature controller)
Enclosure Protection	IP00 (Open type), IP20, or IP23 (with sheet steel or stainless steel housing)
Partial Discharge Level	Less than 10 pC at 1.3 Um

Design and Construction

01/

Magnetic Core Construction: Manufactured from cold-rolled grain-oriented (CRGO) silicon steel sheets (such as 0.23mm or 0.27mm thickness grades) with multi-step step-lap joint geometries. Core surfaces are coated with high-temperature inorganic insulating varnish to inhibit eddy current losses and suppress core vibration.

02/

Winding Conductor Materials: Conductors utilize 99.9 percent oxygen-free electrolytic copper (EC grade) or high-conductivity aluminum foil/strip, wound with automatic tension-controlled foil winding machines to eliminate interlayer axial stress concentrations.

03/

Resin Encapsulation Matrix: Epoxy resin mixed with active diluents and anhydride hardeners undergoes precise vacuum degassing before mold injection. This eliminates micro-voids, ensuring uniform dielectric strength and preventing thermal cracking during severe thermal cycling (-25 deg C to plus 40 deg C operating environments).

04/

Thermal Monitoring and Protection: Embedded PT100 platinum resistance sensors within the low-voltage winding phases interface with digital microprocessor-based temperature controllers to activate cooling fans or trip circuits during overload conditions.

Applications

Commercial and High-Rise Buildings: Basement and mechanical penthouse distribution substations requiring zero fire risk and minimal maintenance.

Renewable Energy Generation: Photovoltaic (PV) inverter skid stations and wind turbine nacelle/tower base step-up substations.

Data Centers: Critical power distribution units supplying redundant UPS systems where harmonic load handling and low acoustic emissions are mandatory.

Industrial Manufacturing Plants: Heavy machinery shop floors, chemical processing units, and metallurgical plants prone to ambient moisture, conductive dust, or corrosive fumes.

Railways and Mass Transit: Underground traction substations and station auxiliary power supply networks.

Manufacturing and Quality Control

CNC Core Slitting and Stacking: Automated laser-cut slitting lines process silicon steel coils with burr-free edges, followed by precision yoke stacking on pneumatic assembly jigs.

Vacuum Pressure Casting (VPC) System: Automated mixing, metering, and casting chambers maintain strict temperature and vacuum parameters during epoxy impregnation, guaranteeing bubble-free coil matrices.

Vapor Phase Drying / Heat Curing: Controlled-temperature curing ovens execute multi-stage thermal profiles to achieve complete cross-linking of the epoxy resin molecular structure.

In-Process Quality Inspection:
Winding resistance and turns ratio verification using digital bridges.
Inter-turn insulation surge testing.
Dimensional tolerance checks on coil geometry and clamping frames.

Custom Transformer Solutions

Standard frame designs do not fit every OEM or retrofit engineering constraint. Technical customization services support specific integration demands:

Enclosure Engineering

Custom IP rating enclosures (IP31/IP54) fabricated from cold-rolled steel, galvanized sheets, or marine-grade stainless steel with specialized powder coating (RAL color matching).

Electrical Topology Modifications

Special voltage ratios, electrostatic shielding (Copper foil screen between windings for high-frequency noise suppression), and phase-shifting configurations for multi-pulse rectifier drives (6-pulse, 12-pulse, 24-pulse).

Dimensional Constraints

Low-profile or narrow-width core configurations engineered to fit existing retrofit elevator shafts, older substation rooms, or restrictive skid packages.

Testing and Documentation

Every finished transformer undergoes rigorous routine testing in accordance with IEC 60076 standards prior to packaging. Factory Acceptance Testing (FAT) documentation package includes:

Measurement of Winding Resistance: Verified across all taps.
Voltage Ratio and Vector Group Verification: Phase relationship and polarity confirmation.
Measurement of Impedance Voltage and Load Loss: Conducted at rated current and reference temperature.
Measurement of No-Load Loss and Excitation Current: Evaluated at 90 percent, 100 percent, and 110 percent rated voltage.

Dielectric Routine Tests:
Applied voltage test (Power frequency withstand voltage).
Induced overvoltage withstand test (AC inter-turn insulation check).

Partial Discharge Measurement: Verified using sensitive pulse detectors to ensure discharge magnitudes remain well below specified thresholds.
Type Test Reports: Available from accredited independent laboratories covering temperature rise, short-circuit withstand capability, and lightning impulse tests upon project request.

Packaging and Delivery

Export-Grade Crating

Units are secured on heavy-duty fumigated wooden skids or enclosed in ISPM 15 compliant plywood crates with internal moisture-barrier shrink wrapping and silica gel desiccant packs.

Lifting and Handling Provisions

Integral base channels feature pulling holes and forklift pockets, with certified four-point lifting lugs rated for overhead crane hoisting.

Logistics Protection

Shock-impact recorders and tilt indicators can be attached to crates upon request for long-distance ocean freight or intermodal transit monitoring.

Report on Product Qualifications

FAQ

Q: What is the typical lead time for standard versus customized dry-type transformers?

A: Standard catalog units (10kV/20kV classes, 100kVA to 2500kVA, Dyn11) typically require 2 to 3 weeks of production time. Customized units involving non-standard voltages, special footprints, or multi-pulse configurations require 4 to 6 weeks, subject to engineering drawing sign-off and material allocation.

Q: Can these dry-type transformers be installed outdoors?

A: Standard open-core units (IP00) require indoor, weather-protected substation rooms. For outdoor installations, transformers must be housed inside an engineered weatherproof enclosure rated IP23 or higher, equipped with louvered filters or forced-air ventilation hoods to prevent direct rain ingress while maintaining required cooling airflow.

Q: How is the partial discharge (PD) controlled in cast resin transformers?

A: Partial discharge is minimized through automated vacuum mixing and high-vacuum casting processes that eliminate air pockets within the epoxy matrix. Additionally, uniform foil winding designs prevent high electrical stress concentrations at the coil edges, ensuring long-term dielectric stability.

Q: What maintenance is required for epoxy cast resin dry-type transformers?

A: Dry-type transformers require minimal maintenance compared to oil-filled alternatives. Routine maintenance is limited to periodic visual inspections of dust accumulation on winding surfaces, checking terminal bolt torque, testing temperature controller functions, and cleaning air ventilation ducts or enclosure filters annually depending on environmental particulate levels.

Q: Are your transformers compliant with international energy efficiency standards?

A: Yes. Core designs and loss values can be tailored to comply with Tier 2 efficiency requirements under EU Ecodesign regulations (EN 50588-1 / EU 2019/1783), DOE efficiency standards, or custom loss evaluations provided by project consultants.

Q: What technical documents are provided with the shipment?

A: Each transformer is shipped with a comprehensive technical dossier including the Factory Test Report (FAT), instruction and maintenance manual, wiring and schematic diagrams for temperature controllers, dimensional outline drawings, and certificate of conformity.

As one of the most experienced dry type transformer manufacturers and suppliers in China, we also support customized service. Please rest assured to wholesale bulk high quality dry type transformer in stock here from our factory. Contact us for more details.

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