330kV 3-Phase 2-Winding Power Transformer
NPC Electric 330kV 3-Phase 2-Winding Power Transformer is a cornerstone of Extra-High Voltage (EHV) power systems, engineered to provide seamless voltage regulation and long-term operational reliability. Designed for heavy-duty utility and industrial applications, this transformer features a high-permeability core made of premium cold-rolled grain-oriented (CRGO) silicon steel, which significantly reduces no-load losses and acoustic noise levels. The dual-winding architecture is structurally reinforced to withstand extreme electromagnetic forces and mechanical stresses during grid short-circuit events.
Safety and longevity are prioritized through an advanced insulation system, utilizing high-grade cellulose pressboard and inhibited mineral oil. This is complemented by precision-calculated electrostatic shielding to suppress partial discharge (PD) effectively. The transformer tank is a robust, fully-welded structure designed to maintain a full vacuum, ensuring hermetic sealing against environmental contaminants.
- Primary Voltage Ratings 220kV 230kV 330 kV
- Secondary Voltage Ratings 69/35/37/34.5/26.4./11/10.5/6.6/13.2 kV or others
- H.V. Tap Range ± 8×1.25% HV taps or others
- Type Oil-immersed power transformer
- BIL 900kV
- Standards IEEE, ANSI, IEC, GB
- Application regional substations, bolstering stability in wind-integrated grids
- Power Rating 500-250000kVA
- Certificate UL, ISO, CESI
- Cooling Method ONAN/ ONAF
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
330kV 3-Phase 2-Winding Power Transformer
Technical Specifications
Accessories
| Rated Power | 500-250000kVA |
| Rating Primary Voltage | 220kV 230kV 330kV |
| Secondary Voltage |
69/35/37/34.5/26.4/11/10.5/6.6/13.2 kV Customized |
| Frequency | 50/60Hz |
| Vector Group | Dyn11, YD11, YNd11 or anothers |
| 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
330kV 3-Phase 2-Winding Power Transformer
NPC Electric understands that every grid infrastructure presents unique challenges, which is why our 330kV power transformers offer extensive customization possibilities. Clients can specify the cooling method (ONAN, ONAF, or OFAF) to align with local ambient temperatures and specific load cycles. We also offer a choice of On-Load Tap Changers (OLTC) or Off-Circuit Tap Changers from globally recognized brands to ensure precise voltage control. Furthermore, bushings can be customized with various creepage distances for high-pollution zones, and specialized C5-class anti-corrosion coatings are available for coastal or aggressive industrial environments.
Beyond physical hardware, we provide sophisticated digital monitoring integration. Options include integrated fiber-optic temperature sensors for direct winding hotspot monitoring and intelligent online DGA (Dissolved Gas Analysis) systems for predictive maintenance. For substations with limited space, our engineering team can optimize the tank geometry and radiator orientation, ensuring the unit fits within existing footprints while maintaining all necessary safety clearances. This tailored approach guarantees that each transformer is perfectly synchronized with its operational environment.
Packing and Shipping
330kV 3-Phase 2-Winding Power Transformer
Shipping a 330kV transformer involves complex logistics due to its immense scale. To ensure the unit remains pristine during transit, the main transformer body is shipped dry-filled with nitrogen or dry air to maintain a constant positive internal pressure, which prevents moisture ingress. Critical external components, such as high-voltage bushings, radiators, and the conservator tank, are disassembled and secured in heavy-duty, seaworthy wooden crates. The main tank is lashed onto specialized multi-axle heavy-lift trailers or vessel decks using high-tensile steel equipment.
To maintain total transparency regarding structural integrity, we install 3D digital impact recorders on the main tank. These devices log any significant G-forces or vibrations encountered during the journey, providing a time-stamped report upon arrival. At the destination port or site, our logistics experts coordinate "roll-on/roll-off" (Ro-Ro) operations or heavy-lift crane discharges. This meticulous handling ensures that the core-and-coil assembly remains perfectly aligned and free from mechanical stress throughout the entire supply chain.
Documentation and customs compliance are handled with extreme precision. Every shipment includes a comprehensive packing list, moisture level reports, and pressure certificates. For international sea freight, we apply VCI (Volatile Corrosion Inhibitor) packaging to all control cabinets and exposed metal parts to prevent salt-air corrosion. Our shipping partners are specifically vetted for their experience in moving EHV equipment, ensuring a seamless transition from our factory to your foundation.
The final stage of the shipping process involves a joint inspection upon delivery. Before the transformer is offloaded onto its permanent pad, our technicians verify the internal nitrogen pressure and audit the impact recorder data. This proactive verification ensures that any potential transit-related issues are identified immediately, allowing for a smooth transition into the installation and commissioning phase, effectively eliminating unforeseen project delays and ensuring the highest level of client satisfaction.
To maintain total transparency regarding structural integrity, we install 3D digital impact recorders on the main tank. These devices log any significant G-forces or vibrations encountered during the journey, providing a time-stamped report upon arrival. At the destination port or site, our logistics experts coordinate "roll-on/roll-off" (Ro-Ro) operations or heavy-lift crane discharges. This meticulous handling ensures that the core-and-coil assembly remains perfectly aligned and free from mechanical stress throughout the entire supply chain.
Documentation and customs compliance are handled with extreme precision. Every shipment includes a comprehensive packing list, moisture level reports, and pressure certificates. For international sea freight, we apply VCI (Volatile Corrosion Inhibitor) packaging to all control cabinets and exposed metal parts to prevent salt-air corrosion. Our shipping partners are specifically vetted for their experience in moving EHV equipment, ensuring a seamless transition from our factory to your foundation.
The final stage of the shipping process involves a joint inspection upon delivery. Before the transformer is offloaded onto its permanent pad, our technicians verify the internal nitrogen pressure and audit the impact recorder data. This proactive verification ensures that any potential transit-related issues are identified immediately, allowing for a smooth transition into the installation and commissioning phase, effectively eliminating unforeseen project delays and ensuring the highest level of client satisfaction.
32
32 years of industry experience
Manufacturer Test
330kV 3-Phase 2-Winding Power Transformer
Progress test
Throughout the production cycle, we perform rigorous Progress Tests to validate quality at every milestone. This starts with core loss and magnetic circuit testing once the laminations are stacked to verify the efficiency of the silicon steel. We then conduct winding resistance and turns ratio tests on individual coils prior to assembly. Once the "active part" is tanked, we perform insulation resistance checks between windings and to the ground. These intermediate steps allow for the detection of any deviations before final sealing, ensuring the transformer meets strict 330kV design tolerances.
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
In this testing sequence, we prioritize the physical and chemical stability of the unit under load. Beyond standard ratio and polarity checks, we perform Sweep Frequency Response Analysis (SFRA) to establish a mechanical "fingerprint" of the internal windings. A Vacuum Leak Test is conducted on the fully assembled tank to ensure long-term hermetic sealing. Furthermore, we perform a complete Oil Dielectric Analysis, testing for breakdown voltage, moisture content, and DGA. Finally, Zero-sequence Impedance tests are conducted to ensure predictable behavior during grid fault conditions.
Routine Test - Transformer Turns Ratio/TTR (All Tap Voltages)
Purpose of Testing
The purpose of the transformer turns ratio (TTR) test is to confirm whether the voltage ratio between each tap of the transformer meets the design requirements and ensure that the transformer winding is connected correctly. By measuring the voltage ratio of each tap, it is possible to detect whether there is a fault or deviation in the transformer winding.
Testing Equipment
TTR tester: such as Doble, Megger, Omicron and other brands of transformer winding ratio tester.
Voltage source: usually AC 10 V to 30 V , used to test different voltages for each tap.
Temperature and humidity meter: used to record environmental conditions during the test to ensure test accuracy.
Current probe: used to measure the load current of the winding and ensure the accuracy of the test results.
Voltage source: usually AC 10 V to 30 V , used to test different voltages for each tap.
Temperature and humidity meter: used to record environmental conditions during the test to ensure test accuracy.
Current probe: used to measure the load current of the winding and ensure the accuracy of the test results.
Pre-Test Preparation
Disconnect all transformer tap-changers from the power supply and ensure that all equipment is properly grounded and discharged.
Perform the test under suitable environmental conditions: relative humidity below 75% and no rain (recommended temperature: 20-30°C). Avoid high humidity or bad weather that may affect the test accuracy.
Perform the test under suitable environmental conditions: relative humidity below 75% and no rain (recommended temperature: 20-30°C). Avoid high humidity or bad weather that may affect the test accuracy.
Test Progress
Perform the test under suitable environmental conditions: relative humidity below 75% and no rain (recommended temperature: 20-30°C). Avoid high humidity or bad weather that may affect the test accuracy.
Test Standard
IEC 60076 Oil-immersed power transformers
Measure and Record
Start the test and record the following parameters:
The voltage ratio between the windings
Deviation of the measured value from the rated ratio
The voltage ratio between the windings
Deviation of the measured value from the rated ratio
Temperature Correction
If necessary, perform temperature correction on the measured turns ratio data (especially when testing at higher or lower temperatures). Generally, the standard reference temperature for temperature correction is 20°C.
Repeat Testing (if necessary)
Test the transformer's windings of different voltage levels (high voltage, medium voltage, and low voltage) separately to ensure that the turns ratios of all windings are normal.
Evaluation Criteria (Reference)
Turns ratio error ≤ 0.5% (pass)
0.5% < Turns ratio error ≤ 1% (caution)
Turns ratio error > 1% (further inspection or corrective action required)
0.5% < Turns ratio error ≤ 1% (caution)
Turns ratio error > 1% (further inspection or corrective action required)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Designed for massive energy consumers such as aluminum smelters or large-scale mining operations that require a direct 330kV grid connection to ensure voltage stability and minimize transmission losses across vast industrial sites.
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)
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Transformers Packaging (8)
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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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