70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution
The 70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution is designed to deliver robust performance in demanding grid environments. Featuring 100% oxygen-free copper windings, the transformer ensures superior electrical conductivity, reduced losses, and enhanced overload capability. Its oil-immersed cooling system provides excellent heat dissipation, maintaining long-term stability under high-load and continuous operation conditions. The high-grade silicon steel core minimizes noise and magnetic losses, improving overall efficiency. The transformer’s reinforced tank, durable insulation system, and outdoor-ready structure enable reliable operation in harsh climates, industrial zones, and high-temperature regions. Compliant with IEC, IEEE, and GB standards, this transformer supports utility substations, industrial power networks, renewable energy integration, and high-voltage distribution systems, ensuring safe, efficient, and uninterrupted power delivery.
- Primary Voltage Ratings 69kV 66kV 70kV 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 distribution networks, industrial substations, renewable energy integration points
- Power Rating 8000kVA
- 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
70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution
Technical Specifications
Accessories
| Rated Power | 8000kVA |
| Rating Primary Voltage | 69kV 66kV 70kV 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
70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution
Customization for the 70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer is available across all electrical, mechanical, and protection parameters to meet the diverse requirements of global power systems. Electrical customization includes primary and secondary voltage configurations, vector group options such as Dyn11 or YNd1, bespoke impedance values, and tailored no-load and load-loss targets to meet efficiency standards. Customers may choose between various tap-changer configurations, including no-load tap changers or on-load tap changers, with flexible tap ranges to support fine voltage regulation. Winding materials and insulation classes can be adjusted for special applications, including high-altitude operation, high-temperature regions, or corrosive industrial environments. Enhanced insulation levels, special bushings, partial discharge-resistant materials, and eco-friendly insulating oils are also available upon request.
Mechanical and structural customization options include specialized tank materials, anti-corrosion coatings, radiator types, integrated oil conservators, explosion-proof designs, and seismic-resistant structures for earthquake-prone installations. Customers may specify advanced protection accessories such as Buchholz relays, pressure relief devices, gas relay alarms, digital temperature monitors, oil-level sensors, and SCADA-compatible smart monitoring systems. Compact footprint designs can be provided for constrained substation spaces, while noise-reduction structures are available for urban installations. Each customization ensures that the transformer aligns precisely with project requirements, environmental conditions, and long-term operational goals.
Packing and Shipping
70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution
The packing and shipping process for the 70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution is engineered to ensure maximum protection and safe handling throughout international logistics routes. Prior to packing, the transformer undergoes oil filling, sealing, drying, and surface anti-corrosion treatment. All exposed components are cleaned, coated, and secured. Accessories such as bushings, radiators, sensors, terminal boxes, and control devices are removed when necessary and individually packed in reinforced wooden crates with foam and shock-resistant padding. Each component is labeled and itemized to ensure easy identification during installation.
The main transformer body is mounted securely onto a heavy-duty steel frame or export-grade wooden pallet to prevent movement during transit. Shock-absorbing materials and structural braces are installed at critical stress points to minimize vibration and mechanical impact. The transformer is then wrapped in multiple protective layers, including moisture-proof barriers, UV-resistant tarpaulins, rust-inhibiting films, and reinforced corner guards. For transformers shipped with nitrogen-pressurized protection, all valves and ports are sealed and monitored to maintain internal insulation integrity throughout the journey.
Depending on shipment size, destination, and route, different loading methods are used, including flat rack containers, open-top containers, or break-bulk cargo handling. All materials comply with international shipping regulations, including ISPM-15 standards for wooden packaging. The logistics team coordinates directly with sea freight, land transport, and customs authorities to manage route planning, documentation, inspection protocols, and secure unloading. A full set of documents—packing list, test reports, quality certificates, user manuals, and installation guides—is provided in waterproof sealed envelopes attached to the transformer tank.
Upon arrival at the destination site, professional engineers may support unloading supervision, installation guidance, oil filling, and commissioning assistance if required. The entire packing and shipping process ensures that the transformer maintains structural integrity, insulation quality, and operational readiness from factory to field installation, minimizing risk and ensuring long-term performance reliability.
The main transformer body is mounted securely onto a heavy-duty steel frame or export-grade wooden pallet to prevent movement during transit. Shock-absorbing materials and structural braces are installed at critical stress points to minimize vibration and mechanical impact. The transformer is then wrapped in multiple protective layers, including moisture-proof barriers, UV-resistant tarpaulins, rust-inhibiting films, and reinforced corner guards. For transformers shipped with nitrogen-pressurized protection, all valves and ports are sealed and monitored to maintain internal insulation integrity throughout the journey.
Depending on shipment size, destination, and route, different loading methods are used, including flat rack containers, open-top containers, or break-bulk cargo handling. All materials comply with international shipping regulations, including ISPM-15 standards for wooden packaging. The logistics team coordinates directly with sea freight, land transport, and customs authorities to manage route planning, documentation, inspection protocols, and secure unloading. A full set of documents—packing list, test reports, quality certificates, user manuals, and installation guides—is provided in waterproof sealed envelopes attached to the transformer tank.
Upon arrival at the destination site, professional engineers may support unloading supervision, installation guidance, oil filling, and commissioning assistance if required. The entire packing and shipping process ensures that the transformer maintains structural integrity, insulation quality, and operational readiness from factory to field installation, minimizing risk and ensuring long-term performance reliability.
32
32 years of industry experience
Manufacturer Test
70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer for High-Voltage Distribution
Progress test
The Progress Test for the 70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer is conducted throughout the manufacturing cycle to ensure strict quality control. Initial inspections cover raw materials such as silicon steel cores, copper conductors, insulating paper, and transformer oil. During winding production, winding tightness, layer insulation, dimensional accuracy, and conductor integrity are verified. Core stacking undergoes air-gap measurement, clamping force checks, and geometric alignment testing. Subassembly tests include insulation resistance, partial discharge checks, and vacuum drying verification to eliminate moisture contamination.
Mechanical components such as tanks, radiators, and conservators are tested for welding tightness, pressure resistance, and coating quality. Before final assembly, intermediate electrical tests—ratio measurement, polarity checks, and winding resistance—ensure performance stability. These progressive inspections guarantee manufacturing precision and prevent defects before final FAT testing.
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 70kV 8000kVA Copper-Wound Oil-Immersed Power Transformer verifies full compliance with design specifications and international standards. Key electrical routine tests include winding resistance, ratio, and vector group verification, insulation resistance measurement, polarity checks, and applied and induced voltage withstand tests. Performance tests measure no-load loss, load loss, impedance, and short-circuit strength. Lightning impulse testing validates the dielectric capability of the insulation system, while partial discharge testing confirms insulation integrity.
Mechanical and functional tests include tank pressure tightness, bushing inspection, tap changer operation, cooling system performance, and transformer oil quality analysis. All protection devices—temperature controllers, Buchholz relays, and pressure relief valves—are checked for correct calibration. FAT results are reviewed with the customer before shipment to ensure the transformer meets all operational, safety, and reliability requirements.
Routine Test - On load Loss Test
Purpose of Testing
The purpose of On-load Loss Test is to measure the active power loss of the transformer under rated voltage and rated load, evaluate its energy efficiency level and design compliance, and provide a basis for energy consumption calculation and performance optimization during operation.
Testing Equipment
Power transformer test system (e.g. OMICRON, ISA, Tettex, Vanguard, etc.)
Voltage source and current source (usually rated voltage, or adjusted according to the test standard, such as 10 KV, 20 KV, 35 KV, etc.)
Temperature and humidity meter (used to record ambient temperature and humidity for correction of test data)
Voltage source and current source (usually rated voltage, or adjusted according to the test standard, such as 10 KV, 20 KV, 35 KV, etc.)
Temperature and humidity meter (used to record ambient temperature and humidity for correction of test data)
Pre-Test Preparation
Disconnect the transformer high voltage, low voltage and neutral power supply to ensure that the equipment is properly grounded and safely discharged.
The test environment should be dry and rainless, with a relative humidity of less than 75% and a recommended temperature range of 20–30°C.
The test environment should be dry and rainless, with a relative humidity of less than 75% and a recommended temperature range of 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 wiring is correct and the device is well grounded.
Apply Test Voltage:
Apply the specified test voltage at the rated frequency and adjust the low voltage side to maintain the rated current (or specified current).
Connect the test equipment to the appropriate terminals of the device under test and ensure that all wiring is correct and the device is well grounded.
Apply Test Voltage:
Apply the specified test voltage at the rated frequency and adjust the low voltage side to maintain the rated current (or specified current).
Measure and Record
Start the test and record the following parameters:
On-Load Loss Power
Input Power and Output Power
Current
Voltage
Temperature (temperature rise or winding temperature)
Ambient temperature and humidity during the test
On-Load Loss Power
Input Power and Output Power
Current
Voltage
Temperature (temperature rise or winding temperature)
Ambient temperature and humidity during the test
Temperature Correction
The measured loss data is corrected based on a reference temperature (usually 20°C) to ensure the accuracy of the results.
Repeat Testing (if necessary)
Test different tap positions (Tap Changer) and record and compare the load loss data of each tap point.
Evaluation Criteria (Reference)
Evaluate the test results based on the equipment type and manufacturer requirements. If the load losses are low and the efficiency is high, it is considered "normal". If the load losses are too high or the efficiency is low, further inspection or corrective action is required.
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
It is ideal for high-voltage distribution networks, industrial substations, renewable energy integration points, mining operations, and large commercial facilities. It ensures stable voltage regulation, efficient long-distance power transmission, and reliable performance under continuous or heavy-load operating environments.
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
Product Packaging
Transformers Packaging (1)
Transformers Packaging (2)
Transformers Packaging (3)
Transformers Packaging (4)
Transformers Packaging (5)
Transformers Packaging (6)
Transformers Packaging (7)
Transformers Packaging (8)
Related Products
42MVA 220kV Three Phase Oil Filled Transformer for Substation
The 42MVA 220kV Three Phase Oil Filled Transformer is specifically engineered for high-voltage transmission substations and utility grid applications. Featuring 99.9% electrolytic copper windings, advanced ONAN/ONAF cooling, and ±8×1.25% on-load tap changer, it ensures ultra-low no-load and load losses (SZ13 series available). Fully compliant with IEC 60076, GB/T 6451, and ANSI/IEEE standards, it successfully passes 460 kV lightning impulse, PD level below 10 pC, and induced test at 1.5Um/√3. Robust corrugated tank and conservator design provide excellent thermal and mechanical performance in extreme climates. Ideal for 220/33kV, 220/11kV, or 220/6.6kV step-down configurations. Vacuum oil processing and nitrogen blanketing guarantee long-term reliability and 35+ year service life. Trusted by national grids worldwide. Contact us for datasheet, pricing, and customization options.
10kVA Conventional Type Single Phase Pole Mounted Transformer
NPC ELECTRIC specializes in designing and manufacturing 10 kVA single-phase pole-mounted transformers that comply with international standards, including IEEE C57.12.00, IEEE C57.12.20, DOE-2016 Efficiency, CSA C2.1 & C2.2, and CSA C802.1. Our unwavering commitment to excellence drives us to provide tailored solutions, ensuring that each transformer aligns precisely with your unique technical requirements. Regardless of the voltage level or operating environment, you can trust NPC ELECTRIC to deliver the ideal solution to meet your specific needs. Your satisfaction and the reliability of our transformers remain central to our dedication to quality.
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.
225kVA Three Phase Pad Mounted Transformer
The 225kVA three-phase pad transformer is an efficient and reliable power conversion device designed for commercial, industrial and distribution systems. With a high power capacity of 225kVA, the transformer is able to provide a stable three-phase power supply for large-scale equipment to meet high load requirements. Its rugged housing is made of weather-resistant materials and meets NEMA 3R standards, ensuring long-term stable operation in outdoor environments and preventing the influence of external factors such as water, dust and corrosion.
100kVA Dry Type Transformer
The 100kVA dry-type transformer adopts efficient dry-type insulation technology and is designed for industrial, commercial and residential power systems. With its excellent performance and compact structure, the transformer provides stable and reliable power support and is suitable for small and medium-sized power distribution needs. Through strict quality control, NPC ELECTRIC's 100kVA dry-type transformer provides users with high-quality, low-maintenance power solutions.
100kVA Conventional Type Single Phase Pole Mounted Transformer
NPC ELECTRIC has been specialized in manufacturing 100kVA Conventional Type Single Phase pole Mounted transformer for more than 20 years, which complies with international standards such as ANSI/IEEE C57, IEC60076 and other standards. Its main function is to convert high voltage electricity (such as 11kV, 13.8kV, etc.) into low voltage electricity (such as 120V/240V), providing stable and reliable power supply to end users. It is suitable for residential, commercial, agricultural and small industrial loads.FAQ From Customers
-
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.
-
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.
-
Do you have UL listed?Yes, our transformer has UL listed. We have exported to America many pad mounted transformer,substation transformer and HV.
Welcome your inquiry
Honesty, Integrity, Frugality, Activeness and Passion