11kV Three-Phase Oil-Immersed Power Transformer
The 11kV Three-Phase Oil-Immersed Power Transformer is engineered for stable and efficient distribution across medium-voltage networks. Designed with high-grade silicon steel, advanced insulation systems, and premium mineral oil, this transformer ensures superior dielectric strength, excellent heat dissipation, and long service life. Its oil-immersed configuration delivers reliable cooling performance, enabling continuous operation under varying load conditions. The three-phase design ensures balanced power delivery, reduced energy losses, and improved grid stability. With enhanced short-circuit strength, low noise levels, and robust mechanical structure, it is suitable for industrial facilities, commercial complexes, substations, and utility distribution networks. Custom voltage ratios, tap changers, protection devices, and enclosure options are available to meet regional standards and project-specific requirements.
- Primary Voltage Ratings 35kV, 34.5kV, 33kV, 46kV or others
- Secondary Voltage Ratings 13.8kV 6kV 11kV or others
- H.V. Tap Range ±8×1.25% or others
- Type Oil-immersed power transformer
- BIL 11kV
- Standards IEEE, ANSI, NEMA, IEC, CE
- Application utility substations, industrial manufacturing plants, mining operations
- Power Rating 200kVA 250kVA 500kVA 1600kVA
- Certificate UL, CESI, IEEE
- Cooling Method ONAN/ONAF
- Oil Mineral Oil or FR3
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
11kV Three-Phase Oil-Immersed Power Transformer
Technical Specifications
Accessories
| Rated Power | 200kVA 250kVA 500kVA 1600kVA | |
| Rating Primary Voltage | 11 kV | |
| Secondary Voltage |
6.6kV 10kV 13.8kV 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 | |
| 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
11kV Three-Phase Oil-Immersed Power Transformer
The 11kV Three-Phase Oil-Immersed Power Transformer offers extensive customization options to meet different grid standards, environmental conditions, and operational demands. Customers may specify custom voltage ratios, power ratings, vector groups, tapping ranges, and insulation classes to ensure optimal compatibility with distribution systems. Both on-load and off-load tap changers can be configured to support flexible voltage regulation under varying load conditions.
Additional optional enhancements include low-loss core materials, upgraded copper windings, reinforced short-circuit resistance, smart monitoring systems, and advanced protection devices such as Buchholz relays and temperature alarms. Enclosure formats can also be customized, including hermetically sealed tanks, corrugated-wall radiators, conservator-type tanks, anti-corrosion coatings, and special paint systems for coastal or desert environments. These tailored configurations ensure the 11kV oil-immersed transformer meets the performance, safety, and operational requirements of diverse industrial, commercial, and utility applications.
Packing and Shipping
11kV Three-Phase Oil-Immersed Power Transformer
The 11kV Three-Phase Oil-Immersed Power Transformer is packed and shipped following strict international standards to ensure safety, integrity, and reliability during global transportation. Each transformer undergoes thorough external cleaning, oil treatment, and anti-moisture preparation before packing. The tank is securely sealed, nitrogen-filled if required, and equipped with protective covers for bushings, radiators, valves, and accessories. All detachable components, such as conservators, radiators, tap changers, and monitoring devices, are individually wrapped using moisture-proof and shock-resistant materials and placed in reinforced wooden crates.
The main transformer body is mounted on a heavy-duty steel or wooden pallet, secured with high-strength straps and anti-slip blocks to prevent movement during transit. Impact-resistant corner guards and vibration-damping pads are used to ensure additional protection. Detailed packing lists, wiring diagrams, and installation manuals are included within waterproof document pouches.
For shipping, logistics plans are designed according to the customer’s destination, transport mode, and handling conditions. The transformer can be shipped via sea, land, or rail, supported by lifting lugs and forklift channels to ensure safe loading and unloading. Containers, flat racks, or open-top configurations are selected based on transformer size and weight. All shipments comply with IEC, ISO, and applicable customs regulations, ensuring that the 11kV oil-immersed transformer arrives at the project site in optimal condition, ready for installation and commissioning.
The main transformer body is mounted on a heavy-duty steel or wooden pallet, secured with high-strength straps and anti-slip blocks to prevent movement during transit. Impact-resistant corner guards and vibration-damping pads are used to ensure additional protection. Detailed packing lists, wiring diagrams, and installation manuals are included within waterproof document pouches.
For shipping, logistics plans are designed according to the customer’s destination, transport mode, and handling conditions. The transformer can be shipped via sea, land, or rail, supported by lifting lugs and forklift channels to ensure safe loading and unloading. Containers, flat racks, or open-top configurations are selected based on transformer size and weight. All shipments comply with IEC, ISO, and applicable customs regulations, ensuring that the 11kV oil-immersed transformer arrives at the project site in optimal condition, ready for installation and commissioning.
32
32 years of industry experience
Manufacturer Test
11kV Three-Phase Oil-Immersed Power Transformer
Progress Test
During the production of the 11kV Three-Phase Oil-Immersed Power Transformer, a comprehensive Progress Test is conducted at each manufacturing stage to ensure product integrity and compliance with technical standards. The test process includes raw material inspection, coil winding accuracy verification, core assembly alignment, insulation quality assessment, and vacuum oil filling checks. Intermediate electrical tests such as DC resistance measurement, turns ratio verification, insulation resistance testing, and partial discharge screening are executed to detect early anomalies. Dimensional checks, mechanical strength evaluations, and workmanship inspections are performed before final assembly. This staged testing framework ensures that every component of the 11kV oil-immersed transformer meets design requirements, providing high reliability and stable electrical performance before entering final testing.
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
Before shipment, the 11kV Three-Phase Oil-Immersed Power Transformer undergoes a rigorous Factory Acceptance Test (FAT) in accordance with IEC 60076 and customer specifications. The FAT includes measurement of winding resistance, verification of voltage ratio and vector group, insulation resistance testing, induced overvoltage tests, and applied high-voltage withstand tests to confirm dielectric strength. Load loss and no-load loss measurements are performed to validate efficiency levels, while temperature rise simulation and partial discharge tests ensure operational safety. Additional mechanical inspections, protection device checks, and oil quality analyses confirm overall equipment readiness. The FAT guarantees that the 11kV oil-immersed transformer meets performance, reliability, and safety requirements prior to delivery.
Routine Test - Impulse Tests
Purpose of Testing
The purpose of Impulse Tests is to verify the insulation strength of electrical equipment when it is subjected to lightning strikes or switching overvoltages. By applying high-energy impulse voltages, it is possible to detect potential defects in the insulation system.
Testing Equipment
Impulse voltage generator (e.g. Haefely, Hipotronics, Tettex, etc.)
Voltage divider (used to measure impulse voltage waveform, resistor divider or capacitor divider)
Oscilloscope (used to record impulse waveform, common brands such as Tektronix, Keysight)
Voltage divider (used to measure impulse voltage waveform, resistor divider or capacitor divider)
Oscilloscope (used to record impulse waveform, common brands such as Tektronix, Keysight)
Pre-Test Preparation
Please test under suitable environmental conditions: relative humidity less than 65%, no rain or condensation (recommended temperature: 15-30°C).
Calibrate and check the impulse voltage generator, measurement system, and control system to ensure that the instruments and equipment are in good condition and meet the test standards.
Calibrate and check the impulse voltage generator, measurement system, and control system to ensure that the instruments and equipment are in good condition and meet the test standards.
Test Progress
Connect the Test Instrument:
Connect the impulse voltage generator correctly to each winding terminal (high voltage terminal, ground terminal) of the device under test, and ensure that all test instruments are well grounded.
Apply Test Voltage:
Select the appropriate impulse voltage waveform and amplitude according to the rated voltage of the equipment
Connect the impulse voltage generator correctly to each winding terminal (high voltage terminal, ground terminal) of the device under test, and ensure that all test instruments are well grounded.
Apply Test Voltage:
Select the appropriate impulse voltage waveform and amplitude according to the rated voltage of the equipment
Measure and Record
Collect and record the impact waveform, including:
Front Time
Time to Half-Value
Peak Voltage
Distortion
Ambient temperature and humidity (especially when the test environment needs to be corrected)
Front Time
Time to Half-Value
Peak Voltage
Distortion
Ambient temperature and humidity (especially when the test environment needs to be corrected)
Waveform Correction
Check whether the impulse voltage waveform meets the specification requirements (wave head time 1.2μs ±30%, half-peak time 50μs ±20%).
If the waveform deviation is too large, adjust the impulse generator parameters and reapply the test.
If the waveform deviation is too large, adjust the impulse generator parameters and reapply the test.
Repeat Testing (if necessary)
Impact tests are performed for different phases and windings (HV/MV/LV).
In special cases, inter-winding impact, voltage-to-ground impact or coil corner impact are performed (according to the test plan).
In special cases, inter-winding impact, voltage-to-ground impact or coil corner impact are performed (according to the test plan).
Evaluation Criteria (Reference)
No internal insulation breakdown or flashover (detected by observing waveform continuity and audibly).
Waveforms are stable and meet standard specifications.
Waveform variations between repeated tests are minimal (usually good waveform overlap with no noticeable abnormal excursions).
Waveforms are stable and meet standard specifications.
Waveform variations between repeated tests are minimal (usually good waveform overlap with no noticeable abnormal excursions).
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
It is commonly deployed in utility substations, industrial manufacturing plants, mining operations, commercial complexes, agricultural power systems, and renewable energy projects such as solar and wind farms.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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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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