65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation
The 65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation is engineered for medium-to-high voltage distribution systems requiring stable performance and precise voltage control. Equipped with a no-load tap changer, the transformer allows flexible adjustment of voltage ratios to meet varying grid demands. Its high-grade silicon steel core and oxygen-free copper windings ensure low losses, superior thermal efficiency, and long operational life. The oil-immersed cooling system provides enhanced heat dissipation, while the durable outdoor-rated tank structure enables reliable operation in harsh climatic environments. Designed in compliance with IEC, IEEE, and GB standards, this transformer is widely used in utility substations, industrial power networks, renewable energy stations, and large commercial distribution systems. It delivers consistent voltage regulation, strong overload capability, and dependable long-term grid support.
- Primary Voltage Ratings 69kV 66kV 65kV or others
- Secondary Voltage Ratings 33/13.8/11 kV or customized
- H.V. Tap Range ±8×1.25% or others
- Type Oil-immersed power transformer
- BIL Up to 350kV
- Standards IEEE, ANSI, IEC, CSA
- Application high voltage power distribution networks, public power systems, industrial power stations
- Power Rating 100 - 1000kVA
- Certificate UL ,CESI ,ISO
- Cooling Method ONAN/ ONAF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation
Technical Specifications
Accessories
| Rated Power | 100 - 1000kVA |
| Rating Primary Voltage | 69kV 66kV 65kV or others |
| Secondary Voltage |
33kV 13.8kV 11kV Customized |
| Frequency | 50/60Hz |
| Vector Group | Dyn11, YNd1, Dyn1, YNd11 or others |
| 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
65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation
We provide extensive customization options for the 65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation to ensure compatibility with a wide range of application scenarios, grid standards, and environmental conditions. Customers may specify primary and secondary voltage ratings, impedance levels, vector group configurations (such as Dyn11 or Yyn0), and detailed load and no-load loss parameters. The tap changer can be customized as a no-load tap changer or upgraded to an on-load tap changer, depending on system control requirements, with selectable tap ranges and step quantities. Winding materials, including high-purity copper or aluminum, can be configured based on cost, performance, and installation considerations.
The external tank design is also fully customizable. Options include corrugated tanks, radiators, integrated oil conservators, explosion-proof features, and anti-corrosion coatings suitable for coastal, high-humidity, or chemically aggressive environments. For installations in cold or high-altitude regions, enhanced insulation levels, reinforced bushings, and climate-adapted cooling systems can be specified.
Customers may also choose customized protection accessories such as Buchholz relays, pressure relief valves, digital temperature controllers, intelligent monitoring sensors, oil-level gauges, and SCADA-compatible communication modules.
To meet specific industry requirements, transformers can be designed with low-noise operation, high dynamic short-circuit strength, or compact dimensions for restricted sites. Additional accessories such as cable boxes, HV/LV terminals, surge arresters, and seismic-resistant structures are also available. Every customization request is supported by our engineering team to ensure the final transformer meets technical standards, operational targets, and long-term reliability expectations.
Packing and Shipping
65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation
The packing and shipping process for the 65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation follows stringent international logistics standards to ensure safe transport and delivery. Before packing, the transformer undergoes oil filling, sealing, anti-corrosion treatment, and final quality inspection. All external surfaces are protected using rust-preventive coatings and moisture-resistant films. Accessories such as bushings, radiators, sensors, and hardware components are individually wrapped, labeled, and packed in reinforced wooden cases to prevent damage during handling.
For main-body protection, the transformer is securely anchored to a heavy-duty steel frame or export-grade wooden pallet. Shock-absorbing pads and structural braces are placed at critical points to prevent vibration, shifting, or impact damage during transit. To protect against weather exposure, the entire unit is wrapped with multi-layer waterproof coverings, UV-resistant sheets, and protective corner guards. Oil valves are sealed, and optional nitrogen-filled protection can be added for long-distance shipping or high-humidity destinations.
For international shipments, we offer containerization, flat-rack solutions, and break-bulk loading depending on transformer size and route requirements. All packaging materials meet ISPM-15 fumigation standards for global customs compliance. Detailed packing lists, quality certificates, FAT reports, manuals, and accessory inventories are included in waterproof documentation envelopes fixed to the transformer body.
The logistics team coordinates directly with professional carriers to manage loading, route planning, customs documentation, and final delivery arrangements. Upon arrival, on-site engineers can support unloading, inspection, and installation guidance if required. The entire packing and shipping workflow is designed to maintain the mechanical integrity and performance reliability of the transformer until it reaches the operational site.
For main-body protection, the transformer is securely anchored to a heavy-duty steel frame or export-grade wooden pallet. Shock-absorbing pads and structural braces are placed at critical points to prevent vibration, shifting, or impact damage during transit. To protect against weather exposure, the entire unit is wrapped with multi-layer waterproof coverings, UV-resistant sheets, and protective corner guards. Oil valves are sealed, and optional nitrogen-filled protection can be added for long-distance shipping or high-humidity destinations.
For international shipments, we offer containerization, flat-rack solutions, and break-bulk loading depending on transformer size and route requirements. All packaging materials meet ISPM-15 fumigation standards for global customs compliance. Detailed packing lists, quality certificates, FAT reports, manuals, and accessory inventories are included in waterproof documentation envelopes fixed to the transformer body.
The logistics team coordinates directly with professional carriers to manage loading, route planning, customs documentation, and final delivery arrangements. Upon arrival, on-site engineers can support unloading, inspection, and installation guidance if required. The entire packing and shipping workflow is designed to maintain the mechanical integrity and performance reliability of the transformer until it reaches the operational site.
32
32 years of industry experience
Manufacturer Test
65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation
Progress test
The Progress Test for the 65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation is performed at key manufacturing stages to ensure that every component meets design and quality requirements before moving to the next production phase. This test program includes detailed inspections of raw materials such as silicon steel laminations, copper windings, insulation paper, and transformer oil to confirm compliance with technical specifications. During coil winding and core assembly, dimensional accuracy, winding tension, insulation layering, and mechanical fastening are carefully examined. Partial discharge checks and insulation strength evaluations are conducted on subassemblies to detect early faults. As the transformer tank is manufactured, welding seams, pressure resistance, vacuum tightness, and surface treatment quality are tested. Before final assembly, the active part undergoes pre-impregnation and vacuum drying to ensure moisture-free insulation.
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 for the 65kV Three-Phase Oil-Immersed Power Transformer with No-Load Voltage Regulation is conducted after full assembly to verify compliance with design specifications and international standards. The FAT includes key electrical routine tests such as winding resistance measurement, ratio and vector group verification, insulation resistance testing, and polarity checks. Performance tests include no-load loss, load loss, impedance measurement, and applied and induced voltage withstand tests. Lightning impulse tests are performed to ensure dielectric strength, while partial discharge measurements confirm insulation quality. Mechanical inspections cover tank pressure integrity, bushing alignment, tap changer operation, oil quality analysis, and verification of all protection devices and accessories. All results are reviewed with the customer to ensure the transformer meets operational, safety, and reliability requirements before shipment.
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 suitable for medium and high voltage power distribution networks, public power systems, industrial power stations, mining areas, power plants, and large commercial facilities. It is also widely used in wind power, photovoltaic, and other new energy grid-connected projects, providing reliable voltage conversion and power quality assurance for distributed energy systems.
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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