125kVA Cast Resin Dry Type Transformer 3 Phase 10kV/0.4kV Copper Winding IEC Certified
The 125kVA Cast Resin Dry Type Transformer is a compact, three-phase, high-efficiency indoor power transformer engineered for safe and reliable voltage transformation in commercial, institutional, and light-to-medium industrial environments. Featuring advanced cast-resin encapsulation and full copper windings, it eliminates oil-related fire hazards, environmental risks, and routine maintenance while delivering superior performance in confined spaces, high-rise buildings, hospitals, schools, data centers, office complexes, and renewable energy tie-in applications. Fully compliant with IEC 60076-11, IEC 60076-1, IEC 60076-3, IEC 60076-5, IEC 60076-20, IEEE C57.12.01, IEEE C57.12.91, UL 1561 (optional), and DOE 2016 efficiency standards.
- Primary Voltage Ratings 10 kV (10000 V) delta or grounded wye
- Secondary Voltage Ratings 0.4 kV (400/230 V) or 0.415 kV (415/240 V) wye
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Dry Type Transformer
- BIL 30/95kV
- Standards IEEE, ANSI, NEMA,IEC,GB
- Application industrial facilities, data centers, EV charging stations
- Power Rating 125kVA
- Certificate IEC 60076-11, IEC 60076-1, IEC 60076-3, UL 1561
- Cooling Method OA/OF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
125kVA Cast Resin Dry Type Transformer 3 Phase 10kV/0.4kV Copper Winding IEC Certified
Technical Specifications
Accessories
| Rated Power | 125 kVA | |
| Rating Primary Voltage | 2.4-35kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V Customized |
|
| Frequency | 50/60Hz | |
| Vector Group | Dyn11,Yyn0,Dyn5 | |
| Winding Material | Aluminum/Copper | |
| Efficiency | As IEEE,Doe 2016,CAS Std or Customized | |
| Impedance Voltage | Nominal 2% or Customized 1.1-5.75% | |
| Altitude | ≤1,000m or Customized | |
| Enclosure material | 304 Stainless Steel | |
|
Cooling |
Natural air (AN); forced air (AF) optional for overload |
|
| HV Bushing |
| LV Bushing |
| Tap changer connector |
| Lifting hook for complete transformer |
| Name plate |
Customization Optional
125kVA Cast Resin Dry Type Transformer 3 Phase 10kV/0.4kV Copper Winding IEC Certified
The 125kVA three-phase cast resin dry type transformer supports extensive customization to meet precise project requirements, local grid codes, environmental conditions, and safety standards. Primary voltage is centered on 10 kV (10000 V) in delta or grounded wye configuration, while secondary voltage can be tailored to 400/230 V, 415/240 V, 480Y/277 V, or any custom low-voltage output. Vector groups include Dyn11 (most common), Dyn1, Yyn0, or special configurations for phase shift and harmonic mitigation. Full copper windings are standard for maximum efficiency, lower hot-spot temperatures, and superior short-circuit strength; aluminum windings are available for cost-sensitive applications.
Insulation system options are Class F (155°C) or Class H (180°C) using advanced cast-resin (epoxy) encapsulation for excellent resistance to moisture, dust, chemicals, and thermal cycling.
Enclosure choices include IP23 ventilated (indoor standard), IP54/IP55 totally enclosed (dust-tight/outdoor), or forced-air cooled (AF) for 133–150% overload capacity in high-ambient or confined spaces. Temperature rise can be specified as 100°C or 120°C. Additional features include forced-air cooling packages with fan controls, digital temperature monitoring with alarm/trip relays, surge arresters, electrostatic shielding for noise-sensitive locations, K-factor rating (K-4 to K-13) for harmonic-rich loads (data centers, EV charging, variable frequency drives), seismic bracing, low-noise fans (<48 dB), and special finishes for corrosive or cleanroom environments. All variants are fully validated to IEC 60076-11, local efficiency standards, and client specifications.
Packing and Shipping
125kVA Cast Resin Dry Type Transformer 3 Phase 10kV/0.4kV Copper Winding IEC Certified
The 125kVA three-phase cast resin dry type transformer is packaged with maximum protection to ensure safe domestic and international transport. The core-coil assembly is fully encapsulated in cast resin and rigidly secured inside the enclosure to prevent movement during transit. All terminals, taps, temperature sensors, fans (if equipped), and accessories are factory-installed and protected with caps or padding to avoid damage to bushings and connections.
The transformer is mounted on a reinforced wooden pallet or steel skid designed for forklift and crane handling, wrapped in multi-layer stretch film and moisture-barrier material. Desiccant packs are included to control humidity, critical for cast-resin units that must remain dry before energization. The entire unit is then placed in a sturdy export-grade wooden crate (ISPM-15 heat-treated) with foam corner protectors, wooden bracing, and steel strapping for stability. Clear markings include gross/net weight, center of gravity, lift points, dimensions (approx. 1.8–2.4 m L × 1.2–1.6 m W × 1.8–2.2 m H), and handling instructions (“Fragile – Electrical Equipment – No Tipping”).
Domestic shipping uses enclosed trailers or flatbeds with secure blocking and tie-downs to minimize vibration. International shipments typically utilize 20ft/40ft containers (palletized and shrink-wrapped) or flat-rack loading, with professional lashing using chains and timber dunnage for sea and road stability. Real-time GPS tracking and full-value cargo insurance are standard for high-value units. Upon arrival, detailed handling and installation manuals are provided, covering lifting procedures (via integrated lifting eyes), foundation placement with ventilation clearances, electrical connections, grounding, and pre-energization checks (insulation resistance, turns ratio, temperature sensor calibration).
The transformer is mounted on a reinforced wooden pallet or steel skid designed for forklift and crane handling, wrapped in multi-layer stretch film and moisture-barrier material. Desiccant packs are included to control humidity, critical for cast-resin units that must remain dry before energization. The entire unit is then placed in a sturdy export-grade wooden crate (ISPM-15 heat-treated) with foam corner protectors, wooden bracing, and steel strapping for stability. Clear markings include gross/net weight, center of gravity, lift points, dimensions (approx. 1.8–2.4 m L × 1.2–1.6 m W × 1.8–2.2 m H), and handling instructions (“Fragile – Electrical Equipment – No Tipping”).
Domestic shipping uses enclosed trailers or flatbeds with secure blocking and tie-downs to minimize vibration. International shipments typically utilize 20ft/40ft containers (palletized and shrink-wrapped) or flat-rack loading, with professional lashing using chains and timber dunnage for sea and road stability. Real-time GPS tracking and full-value cargo insurance are standard for high-value units. Upon arrival, detailed handling and installation manuals are provided, covering lifting procedures (via integrated lifting eyes), foundation placement with ventilation clearances, electrical connections, grounding, and pre-energization checks (insulation resistance, turns ratio, temperature sensor calibration).
32
32 years of industry experience
Manufacturer Test
125kVA Cast Resin Dry Type Transformer 3 Phase 10kV/0.4kV Copper Winding IEC Certified
Progress Test
During core-coil encapsulation progress of the 125kVA dry type transformer, resin penetration and void detection are validated through multiple vacuum cycles and partial discharge measurements to guarantee superior dielectric strength. Post-encapsulation high-voltage leads routing, bracing, and clearance distances are verified to withstand impulse and power-frequency withstand requirements. After enclosure assembly, preliminary insulation resistance and dielectric withstand tests prove overall system robustness. Temperature sensor, fan (if AF), and alarm circuit progress includes repeated functional cycling for operational reliability. Paint dry film thickness and adhesion are measured for long-term environmental protection. Final pre-acceptance inspections cover nameplate engraving accuracy, labeling compliance, enclosure grounding, and overall cosmetic/structural quality. Cumulative progress testing facilitates real-time corrective actions, building confidence for smooth factory acceptance and dependable long-term indoor operation.
Design Tests
All transformer will be test after finished the production, test items as below:
♦ Insulation Power Factor
♦ Winding Resistance
♦ Impulse Tests
♦ On load Loss Test
♦ No Load Loss Test
♦ Leak Test
♦ DC Insulation Resistance Test
♦ Transformer Turns Ratio/TTR (All Tap Voltages)
♦ Impedance Voltage & Load Loss (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
Transformer Factory Acceptance Test
Factory acceptance testing (FAT) for the 125kVA three-phase cast resin dry type transformer strictly follows IEC 60076-11, IEEE C57.12.91, and UL 1561 protocols to confirm full compliance before shipment. Routine visual and mechanical inspections verify enclosure finish, weld quality (if applicable), nameplate data accuracy, accessory mounting, and terminal tightness. Winding resistance is measured across all tap positions at reference temperature to confirm conductor uniformity and match calculated loss values. Turns ratio (TTR) testing is performed on every tap to ensure ratio accuracy within 0.5% and correct vector group alignment. Polarity and phase relation checks confirm proper connection. Insulation resistance (megger at 2500–5000 V) evaluates winding-to-winding and winding-to-ground paths for multi-gigohm readings. Applied potential withstand test applies one-minute power-frequency voltage to HV and LV separately per insulation class without breakdown or excessive corona. Functional verification operates tap changer through all positions, checks temperature sensors, fan controls (if AF), and alarms. Certified test reports with traceable calibration data and customer witness provisions (if requested) document all results, confirming the transformer exceeds efficiency, dielectric strength, safety, and performance requirements for reliable dry-type service.
Routine Test - Winding Resistance
Purpose of Testing
The purpose of winding resistance testing is to detect the continuity and connection quality of the internal conductors of the motor or transformer windings, and to promptly detect potential faults such as open circuits, poor contact or local heating.
Testing Equipment
Winding resistance tester (e.g. OMICRON, DV Power, Raytech, Megger, ISA, etc.)
Test voltage source (commonly used are 6V, 10V, 20V, 40V or 100V, depending on the equipment model or customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test)
Test voltage source (commonly used are 6V, 10V, 20V, 40V or 100V, depending on the equipment model or customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test)
Pre-Test Preparation
Check if the instrument has been calibrated to ensure the test accuracy.
Disconnect the electrical connection between the test cable and the equipment to ensure that there is no external current or voltage interference.
Select a suitable voltage range for testing and set the test voltage according to the equipment requirements.
Disconnect the electrical connection between the test cable and the equipment to ensure that there is no external current or voltage interference.
Select a suitable voltage range for testing and set the test voltage according to the equipment requirements.
Test Progress
Connect the Test Instrument:
Connect the test equipment to the winding terminals of the device under test, making sure the connections are secure and properly grounded to avoid measurement errors.
Apply Test Voltage:
Select the appropriate test current according to the equipment specifications (such as test current for low-voltage windings, single-phase or three-phase windings).
Connect the test equipment to the winding terminals of the device under test, making sure the connections are secure and properly grounded to avoid measurement errors.
Apply Test Voltage:
Select the appropriate test current according to the equipment specifications (such as test current for low-voltage windings, single-phase or three-phase windings).
Measure and Record
Start the test and record the following parameters:
Winding resistance (usually expressed in units of "Ω")
Test current (A)
Test voltage (V)
Temperature (record the winding temperature before and after the test)
Winding resistance (usually expressed in units of "Ω")
Test current (A)
Test voltage (V)
Temperature (record the winding temperature before and after the test)
Temperature Correction
The measured winding resistance values are converted to a reference temperature (usually 20°C) based on a temperature correction formula to allow accurate evaluation and comparison.
Repeat Testing (if necessary)
Test the different windings (high voltage, medium voltage, low voltage) separately and make sure to record the resistance value of each winding.
Evaluation Criteria (Reference)
Resistance deviation is less than 5% (normal)
Resistance deviation is between 5% and 10% (warning)
Resistance deviation exceeds 10% (further inspection or corrective action is required)
Resistance deviation is between 5% and 10% (warning)
Resistance deviation exceeds 10% (further inspection or corrective action is required)
Test standard
IEEE C57.12.01 & IEEE C57.12.91 (Dry-Type)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Frequently used in light-to-medium industrial facilities, data centers, EV charging stations, renewable energy inverter connections, telecommunication sites, and cleanroom environments requiring high reliability, harmonic tolerance, and zero oil-spill risk. Also supports pharmaceutical plants, food & beverage processing facilities, underground substations, and indoor power rooms demanding low noise, minimal maintenance, and long-term operation in controlled or harsh indoor conditions.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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Do you have UL listed?Yes, our transformer has UL listed. We have exported to America many pad mounted transformer,substation transformer and HV.
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