31500kVA 35kV Oil-Immersed Copper Transformer For Substation
The 31500kVA 35kV Oil-Immersed Copper Transformer is engineered for high-capacity, stable, and efficient power distribution across industrial plants, substations, and utility networks. Built with a high-purity copper winding structure, the transformer ensures superior conductivity, reduced losses, and long-term reliability under continuous heavy-load operation. Its oil-immersed insulation system provides excellent thermal performance, enabling stable operation even in demanding outdoor environments. The robust 35kV design enhances voltage regulation, short-circuit resistance, and overall safety. Advanced manufacturing standards, precision coil winding, and strict quality control ensure exceptional dielectric strength and mechanical durability.
- Primary Voltage Ratings 34.5-19.92/13.8-7.957/13.2-7.62/12.47-7.2, 33 or others
- Secondary Voltage Ratings 480/277V, 400/230V, 380/220V or customized
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Oil immersed transformer
- BIL 30/95kV
- Standards IEEE, ANSI, NEMA, IEC, CE
- Application Power Substations, Industrial Power Supply
- Power Rating 31500kVA
- Certificate UL, CESI, IEEE
- Cooling Method ONAN, ONAN/ONAF, KNAN, KNAN/KNAF
- Oil Mineral Oil or FR3
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
31500kVA 35kV Oil-Immersed Copper Transformer For Substation
Technical Specifications
Accessories
| Rated Power | 31500 kVA | |
| Rating Primary Voltage | 2.4 - 34.5kV | |
| 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 | |
| Color | ANSI 70 Light gray/Munsell 7GY3.29/1.5 or customized, etc | |
| Tank material | Mild Steel, 304 Stainless Steel | |
| Insulating Oil Weight | 9500 kg | |
| Total Weight | 37600 kg | |
| Outline Dimensions（L×W×H）in. | 5200 × 3840 × 4400（mm) | |
| HV Bushing |
| LV Bushing |
| Tap changer |
| Oil level gauge |
| Oil temperature indicator |
| Pressure relief device |
| Pressure vacuum gauge |
| Lifting hook for complete transformer |
| Name plate |
| Radiators |
| Oil upper filtering valve |
| Oil drain valve with 3/8" sampler |
Customization Optional
31500kVA 35kV Oil-Immersed Copper Transformer For Substation
The 31500kVA 35kV Oil-Immersed Copper Transformer can be fully customised to meet diverse power distribution requirements across substations, industrial facilities, and utility networks. Customers may select preferred voltage ratios, impedance levels, winding configurations, and cooling systems such as ONAN, ONAF, or OFAF to match their operational demands. Core materials, insulation classes, and protection devices can also be adjusted to enhance performance in specific grid environments. Optional configurations include customised tap changers, advanced monitoring systems, and high-strength bushings suitable for harsh outdoor conditions.
In addition, the transformer offers flexible design options to support installation, maintenance, and long-term operation. Clients may request reinforced tank structures, corrosion-resistant coatings, noise-reduction designs, or enhanced thermal management systems. Smart digital features such as online oil monitoring, temperature sensors, and IoT-based diagnostic modules can be integrated for real-time performance tracking. With these customisation options, the 31500kVA 35kV oil-immersed copper transformer can be tailored to deliver optimal efficiency, reliability, and safety for any power distribution application.
Packing and Shipping
31500kVA 35kV Oil-Immersed Copper Transformer For Substation
The 31500kVA 35kV Oil-Immersed Copper Transformer is packed and shipped with the highest safety standards to ensure the unit arrives in perfect condition, ready for installation. Each transformer undergoes a thorough cleaning and drying process before packaging. The tank is sealed securely, all valves and radiators are checked for tightness, and protective caps are installed on bushings and oil ports. To prevent corrosion during transport, the exterior is coated with an anti-rust layer, while moisture-proof materials and desiccants are placed inside designated compartments. The transformer is then mounted on a reinforced steel or wooden skid designed to support its heavy weight and prevent shifting during handling.
For further protection, the 31500kVA transformer is wrapped with multi-layer protective materials, including shock-absorbing padding, waterproof covers, and high-strength binding straps. Sensitive components such as OLTCs, temperature gauges, and monitoring devices are either removed and boxed separately or reinforced with protective shields. Accessories, spare parts, and documentation—including test reports, manuals, and quality certificates—are packed in individual crates and clearly labelled for easy identification upon arrival at the site.
Shipping options are arranged according to customer requirements, destination, and project timeline. For domestic transport, the transformer is typically moved by a heavy-duty truck equipped with specialised suspension systems that minimise vibration. For international shipping, the unit is loaded onto flat racks or open-top containers using cranes with certified lifting points to avoid structural stress. All lifting, loading, and securing operations are performed by trained professionals following international standards such as IEC, ISO, and maritime regulations. During transit, GPS tracking and shock monitoring devices may be installed to observe the transformer's status in real time.
Upon reaching the destination, unloading procedures are coordinated with the site team to ensure safe handling. The packaging is removed only after a final inspection is completed, confirming the 31500kVA 35kV oil-immersed copper transformer has arrived without damage. This comprehensive packing and shipping process guarantees that every unit is delivered safely, efficiently, and in optimal condition for immediate deployment.
For further protection, the 31500kVA transformer is wrapped with multi-layer protective materials, including shock-absorbing padding, waterproof covers, and high-strength binding straps. Sensitive components such as OLTCs, temperature gauges, and monitoring devices are either removed and boxed separately or reinforced with protective shields. Accessories, spare parts, and documentation—including test reports, manuals, and quality certificates—are packed in individual crates and clearly labelled for easy identification upon arrival at the site.
Shipping options are arranged according to customer requirements, destination, and project timeline. For domestic transport, the transformer is typically moved by a heavy-duty truck equipped with specialised suspension systems that minimise vibration. For international shipping, the unit is loaded onto flat racks or open-top containers using cranes with certified lifting points to avoid structural stress. All lifting, loading, and securing operations are performed by trained professionals following international standards such as IEC, ISO, and maritime regulations. During transit, GPS tracking and shock monitoring devices may be installed to observe the transformer's status in real time.
Upon reaching the destination, unloading procedures are coordinated with the site team to ensure safe handling. The packaging is removed only after a final inspection is completed, confirming the 31500kVA 35kV oil-immersed copper transformer has arrived without damage. This comprehensive packing and shipping process guarantees that every unit is delivered safely, efficiently, and in optimal condition for immediate deployment.
32
32 years of industry experience
Manufacturer Test
31500kVA 35kV Oil-Immersed Copper Transformer For Substation
Progress Test
During the manufacturing of the 31500kVA 35kV Oil-Immersed Copper Transformer, rigorous Progress Tests are conducted at key stages to ensure premium quality and compliance with IEC 60076 standards.
After core-coil assembly, tests include winding DC resistance at all taps, insulation resistance between copper windings and core (PI ≥ 2.5), core grounding current (<100 mA), and preliminary no-load loss measurement. Before tanking, the voltage ratio at principal and extreme taps (deviation ≤ ±0.5%) and vector group (typically Yd11 or Dyn11) are verified.
Design Tests
All transformer will be test after finished the production, test items as below:
♦ Insulation Power Factor
♦ Ratio, Polarity, and Phase Relation
♦ 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)
♦ Polarity, 1-Ph / Phase Relation, 3-Ph (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Induced Voltage
♦ Lightning Impulse
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise
♦ Dielectric Withstand (Hipot)
Transformer Factory Acceptance Test
Conducted per IEC 60076 with client/third-party witness:
- Winding resistance at all taps
- Ratio & vector group verification (deviation ≤±0.5%)
- No-load loss & current at 90%-110% voltage
- Load loss & impedance at rated current
- Separate-source & induced withstand voltage with PD (<10 pC at 1.5Um/√3)
- Full-wave lightning impulse 170 kV peak (HV)
- Insulation resistance, PI (≥2.5), tanδ, oil BDV
- Temperature rise test (when specified)
- OLTC 10-cycle operation at max current
- Final accessory & painting inspection
Official protocol signed upon acceptance, ensuring the 31500kVA 35kV Oil-Immersed Copper Transformer is fully qualified for reliable high-voltage service.
Routine Test - Lightning Impulse
Purpose of Testing
The purpose of the lightning impulse test is to simulate the performance of the equipment when it is subjected to lightning or high voltage transient pulses, so as to evaluate its lightning resistance and insulation performance.
Testing Equipment
Lightning Impulse Tester. Usually a high voltage DC power supply, used to simulate lightning impulse waves. The voltage range can be adjusted according to the test standards and equipment requirements. Common voltages are 200 kV, 500 kV or higher. The specific voltage is customized according to customer requirements.
Pre-Test Preparation
Disconnect the device from the power supply and ensure that the device is properly grounded and discharged.
Check all terminals and connections to ensure they are secure and free of contamination.
Perform the test under suitable environmental conditions: relative humidity less than 75%, temperature between 20-30°C, no rain.
Check all terminals and connections to ensure they are secure and free of contamination.
Perform the test under suitable environmental conditions: relative humidity less than 75%, temperature between 20-30°C, no rain.
Test Progress
Connect the Test Instrument: Connect the lightning impulse test equipment to the high-voltage terminal or bushing of the device under test. Apply Test Voltage: According to the rated voltage of the equipment and the test standard, select the appropriate test voltage.
Measure and Record
Start the test and record the following parameters: Applied impulse voltage (kV)
Current waveform Impedance
Reaction voltage waveform
Ambient temperature and humidity during testing
Current waveform Impedance
Reaction voltage waveform
Ambient temperature and humidity during testing
Temperature Correction
The measured test data is temperature corrected according to the ambient temperature during the test, usually with a reference temperature of 20°C, to ensure the accuracy of the test results.
Repeat Testing (if necessary)
Repeated testing of different windings (high voltage, medium voltage, low voltage) or bushings under different test conditions ensures that the insulation performance of each part meets the standards.
Evaluation Criteria (Reference)
The lightning impulse test did not produce breakdown or irreversible damage: qualified
The voltage waveform meets the standard requirements, and the equipment does not have abnormal discharge or local breakdown: good
Obvious damage or non-standard waveform during the test: Further inspection or corrective measures are required
The voltage waveform meets the standard requirements, and the equipment does not have abnormal discharge or local breakdown: good
Obvious damage or non-standard waveform during the test: Further inspection or corrective measures are required
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Power Substations, Industrial Power Supply, Renewable Energy Systems, Commercial Buildings, Electrical Equipment Maintenance and Upgrades
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
Product Packaging
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What is a Transformer?A transformer is an electrical device used to change the voltage of alternating current (AC). It works on the principle of electromagnetic induction, converting high-voltage current into low-voltage current or low-voltage current into high-voltage current. Transformers are widely used in power transmission, distribution systems, and various electronic devices.
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What are the main uses of a transformer?The main use of a transformer is voltage conversion. Transformers are used in power transmission systems to help transfer electricity from power plants to consumers. In addition, transformers are also used in electronic devices such as chargers, televisions, power adapters, etc., to adjust the voltage to meet the requirements of different devices.
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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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