115kV 35MVA Three-Phase Oil-Immersed Power Transformer
The 115kV 35MVA Three-Phase Oil-Immersed Power Transformer is designed for reliable and efficient operation in high-voltage transmission and substation applications. Built with high-permeability silicon steel cores and precision-wound copper conductors, it delivers low losses, strong short-circuit withstand capability, and excellent thermal stability. The oil-immersed cooling system ensures effective heat dissipation, enabling continuous operation under heavy-load conditions. A robust tank structure, advanced insulation system, and outdoor-rated protection make the transformer suitable for harsh environmental conditions. Manufactured in accordance with IEC, IEEE, and ANSI standards, this transformer is widely used in utility substations, industrial power systems, and regional transmission networks where long service life, stable voltage regulation, and high operational reliability are critical.
- Primary Voltage Ratings 110kV, 115kV or others
- Secondary Voltage Ratings 11/10.5/6.6/6.3kV or customized
- H.V. Tap Range ± 8×2.5% HV taps or others
- Type Oil-immersed power transformer
- BIL up to 350kV
- Standards IEEE, ANSI, IEC
- Application high-voltage substations, regional transmission networks, power systems, and infrastructure projects
- Power Rating 35MVA
- Certificate UL , CESI , CE
- Cooling Method ONAN/ ONAF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
115kV 35MVA Three-Phase Oil-Immersed Power Transformer
Technical Specifications
Accessories
| Rated Power | 35MVA |
| Rating Primary Voltage | 110kV, 115kV |
| Secondary Voltage |
6.3 kV 6.6 kV 10.5 kV 11 kV Customized |
| Frequency | 50/60Hz |
| Vector Group | Dyn11, YD11, YNd11 |
| Winding Material | Aluminum/Copper |
| Efficiency | As IEEE, CAS Std or Customized |
| Impedance Voltage | As IEC |
| Altitude | ≤1,000m or Customized |
| Enclosure material | Mid Steel |
| HV Bushing |
| LV Bushing |
| OLTC/NLTC |
| Lifting hook for complete transformer |
| Name plate |
| Oil temperature |
| Winding temperature |
| Radiators |
| Oil level |
| Pressure relief valve |
| CT |
Customization Optional
115kV 35MVA Three-Phase Oil-Immersed Power Transformer
The 115kV 35MVA Three-Phase Oil-Immersed Power Transformer can be fully customized to meet specific project, grid, and environmental requirements. Electrical customization includes tailored primary and secondary voltage levels, vector group selection (such as Dyn11, YNd1, or Yyn0), impedance adjustment, and efficiency optimization to meet local utility standards. Customers may select no-load or on-load tap changers with customized tap ranges to ensure precise voltage regulation under varying load conditions. Winding materials can be specified as high-purity copper or aluminum, while insulation systems can be enhanced for high-altitude operation, extreme temperatures, or high-humidity environments. Optional low-loss core designs and special insulating oils are also available to improve efficiency and environmental compatibility.
Mechanical and structural customization options include reinforced tank designs, corrosion-resistant coatings for coastal or industrial areas, seismic-resistant structures, and customized radiator or cooling configurations such as ONAN, ONAF, or OFAF. Advanced monitoring and protection devices—including digital temperature indicators, Buchholz relays, pressure relief valves, oil level sensors, and online condition monitoring systems—can be integrated to enhance operational safety and predictive maintenance. Noise-reduction designs, compact footprints for space-limited substations, customized bushing arrangements, and project-specific accessory configurations are also available. Each customized transformer is engineered to comply with IEC, IEEE, or customer-defined technical specifications, ensuring optimal performance and long-term reliability.
Packing and Shipping
115kV 35MVA Three-Phase Oil-Immersed Power Transformer
The packing and shipping process for the 115kV 35MVA Three-Phase Oil-Immersed Power Transformer is designed to ensure complete protection during transportation and storage. Prior to packing, the transformer undergoes final inspection, surface treatment, and oil handling according to shipping requirements. External surfaces are coated with anti-corrosion paint, and all openings are sealed to prevent moisture ingress. Sensitive components such as bushings, radiators, and monitoring devices are removed when necessary and packed separately in reinforced wooden crates with shock-absorbing materials.
The transformer's main body is securely mounted on a heavy-duty steel skid or export-grade wooden base to prevent movement during transit. Vibration dampers, structural braces, and protective padding are applied at critical points to minimize mechanical stress. The unit is then wrapped with multiple protective layers, including moisture-proof films, UV-resistant covers, and rust-inhibiting materials. For long-distance or sea transportation, nitrogen filling or vacuum sealing can be applied to maintain internal insulation integrity.
Depending on size, weight, and destination, the transformer may be shipped using flat-rack containers, open-top containers, or break-bulk cargo. All packaging materials comply with international shipping standards, including ISPM-15 requirements. Clear handling instructions, lifting marks, and center-of-gravity labels are applied to ensure safe loading and unloading. Complete shipping documentation—packing list, test reports, quality certificates, operation manuals, and drawings—is provided in waterproof packaging attached to the transformer.
Upon arrival at the destination, detailed unpacking and storage instructions are supplied. Optional on-site services include unloading supervision, reassembly of accessories, oil filling, filtration, and commissioning support. The comprehensive packing and shipping process ensures the transformer arrives in optimal condition, ready for safe installation and long-term operation.
The transformer's main body is securely mounted on a heavy-duty steel skid or export-grade wooden base to prevent movement during transit. Vibration dampers, structural braces, and protective padding are applied at critical points to minimize mechanical stress. The unit is then wrapped with multiple protective layers, including moisture-proof films, UV-resistant covers, and rust-inhibiting materials. For long-distance or sea transportation, nitrogen filling or vacuum sealing can be applied to maintain internal insulation integrity.
Depending on size, weight, and destination, the transformer may be shipped using flat-rack containers, open-top containers, or break-bulk cargo. All packaging materials comply with international shipping standards, including ISPM-15 requirements. Clear handling instructions, lifting marks, and center-of-gravity labels are applied to ensure safe loading and unloading. Complete shipping documentation—packing list, test reports, quality certificates, operation manuals, and drawings—is provided in waterproof packaging attached to the transformer.
Upon arrival at the destination, detailed unpacking and storage instructions are supplied. Optional on-site services include unloading supervision, reassembly of accessories, oil filling, filtration, and commissioning support. The comprehensive packing and shipping process ensures the transformer arrives in optimal condition, ready for safe installation and long-term operation.
32
32 years of industry experience
Manufacturer Test
115kV 35MVA Three-Phase Oil-Immersed Power Transformer
Progress test
The Progress Test for the 115kV 35MVA Three-Phase Oil-Immersed Power Transformer is conducted throughout the manufacturing process to ensure strict quality control and compliance with design specifications. Raw materials such as silicon steel laminations, copper conductors, insulation paper, and transformer oil are inspected and tested prior to production. During winding and core assembly, dimensional accuracy, insulation layering, winding tension, and clamping force are carefully verified. Intermediate electrical tests, including winding resistance, insulation resistance, and turn ratio checks, are performed at key stages to detect potential issues early. Mechanical components such as the tank, radiators, and conservator are tested for welding integrity, pressure resistance, and dimensional compliance. Vacuum drying and oil impregnation processes are closely monitored to ensure moisture-free insulation. These progressive inspections guarantee consistent manufacturing quality before final assembly and FAT.
Design Tests
All transformers will be tested after finishing the production test items as below:
♦ Leak testing with pressure for liquid-immersed transformers
♦ Test of transformer oil
♦ Measurement of voltage ratio and check of phase displacement
♦ Measurement of winding DC resistance
♦ Measurement of d. c. Insulation resistance between each winding to earth, and check of the core and frame insulation
♦ Capacitive bushing test
♦ Measurement of dissipation factor (tan δ) of the insulation system capacitances, and determination of capacitances windings-to-earth
♦ Measurement of no-load loss and current at 90%,100%,110% of rated voltage
♦ Operation test on on-load tap-changer
♦ Measurement of short-circuit impedance and load loss
♦ Lightning impulse test
♦ Induced-voltage test with partial discharge measurement
♦ Auxiliary wiring check
♦ Current transformer test
♦ Frequency response analysis test
Transformer Factory Acceptance Test
The Factory Acceptance Test (FAT) for the 115kV 35MVA Three-Phase Oil-Immersed Power Transformer is performed after final assembly in accordance with IEC and IEEE standards. Routine tests include winding resistance measurement, ratio and vector group verification, insulation resistance testing, and polarity checks. Dielectric tests, such as applied voltage and induced voltage withstand tests, confirm insulation strength. Performance tests measure no-load loss, load loss, impedance voltage, and temperature rise. Partial discharge and lightning impulse tests are conducted to verify dielectric reliability under overvoltage conditions. Mechanical inspections cover tank pressure tightness, oil leakage checks, bushing installation, cooling system operation, and tap changer functionality. All protection and monitoring devices are calibrated and verified. FAT results are documented and reviewed with the customer prior to shipment.
Routine Test - Excitation & No-Load Loss (Rated Voltage)
Purpose of Testing
The purpose of testing Excitation & No-Load Loss at rated voltage is to assess the transformer's core loss and magnetizing current under normal operating conditions, ensuring efficient performance and identifying any potential issues in the core or windings. This test helps verify that the transformer operates within specified parameters and meets its design requirements.
Testing Equipment
Test equipment: Excitation Test instrument (such as OMICRON, Megger, etc.)
Voltage source: usually rated voltage (such as 230V, 400V, 660V, customized according to equipment requirements)
Temperature and humidity meter: used to record ambient temperature and humidity conditions
Voltage source: usually rated voltage (such as 230V, 400V, 660V, customized according to equipment requirements)
Temperature and humidity meter: used to record ambient temperature and humidity conditions
Pre-Test Preparation
Disconnect and make sure the device is powered off and properly grounded and discharged.
Check the device terminals and wiring to ensure that the connection is secure and not loose or contaminated.
Ensure the test environment is suitable: relative humidity below 75%, no rain, and recommended temperature is 20-30°C.
Check the device terminals and wiring to ensure that the connection is secure and not loose or contaminated.
Ensure the test environment is suitable: relative humidity below 75%, no rain, and recommended temperature is 20-30°C.
Test Progress
Connect the Test Instrument:
Connect the test equipment to the appropriate terminals of the device under test and ensure that all connection points are properly grounded to avoid current leakage during the test.
Apply Test Voltage:
Select a suitable test voltage according to the rated voltage of the equipment (for example, the rated voltage is 11kV, 33kV or others), and ensure that the applied voltage is stable.
Connect the test equipment to the appropriate terminals of the device under test and ensure that all connection points are properly grounded to avoid current leakage during the test.
Apply Test Voltage:
Select a suitable test voltage according to the rated voltage of the equipment (for example, the rated voltage is 11kV, 33kV or others), and ensure that the applied voltage is stable.
Measure and Record
No-load current
No-load loss
Excitation loss
Power factor
Voltage
Current
Ambient temperature and humidity during testing
No-load loss
Excitation loss
Power factor
Voltage
Current
Ambient temperature and humidity during testing
Temperature Correction
The measured loss values and currents are corrected to a reference temperature (typically 20°C) for an accurate evaluation.
Repeat Testing (if necessary)
If necessary, measure the no-load loss and excitation loss of different windings (high voltage, medium voltage, low voltage) and at different voltage levels for comparative analysis.
Evaluation Criteria (Reference)
No-load loss ≤ rated loss (meets specifications)
No-load loss > rated loss (further inspection or corrective action required)
No-load loss > rated loss (further inspection or corrective action required)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
It supports stable voltage transformation, heavy-load operation, and long-distance power transmission in environments requiring high reliability, efficiency, and continuous service performance.
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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