40MVA 110kV Three Phase Oil Immersed Transformer for Substation
The 40MVA 110kV Three Phase Oil Immersed Transformer is engineered for reliable high-voltage transmission and distribution in substations and power plants. Featuring high-purity copper windings, advanced ONAN/ONAF cooling, and on-load tap changer (OLTC ±8×1.25%), it delivers superior efficiency and minimal no-load/loss performance (SZ11/SZ13 series). Fully compliant with IEC 60076, GB 6451, and IEEE standards, it withstands 200kV lightning impulse and offers partial discharge below 10pC. The corrugated tank design ensures optimal heat dissipation and mechanical strength in harsh environments. Ideal for 110/33kV, 110/11kV, or 110/6.3kV step-down applications. Vacuum oil filling and nitrogen sealing guarantee long-term insulation integrity. Trusted by utilities worldwide for stable, maintenance-free operation over 30+ years. Contact us for technical datasheet and competitive pricing.
- Primary Voltage Ratings 34.5-19.92/13.8-7.957/13.2-7.62/12.47-7.2, 33 or others
- Secondary Voltage Ratings 480/277V, 400/230V, 380/220V or customized
- H.V. Tap Range ± 2×2.5% HV taps or others
- Type Oil immersed transformer
- BIL 30/95kV
- Standards IEEE, ANSI, NEMA, IEC, CE
- Application Power Substations, Industrial Power Supply
- Power Rating 40MVA
- Certificate UL, CESI, IEEE
- Cooling Method ONAN, ONAN/ONAF, KNAN, KNAN/KNAF
- Oil Mineral Oil or FR3
- Opeartion Step Down & Step Up
Technical Specifications
Customization Optional
Packing and Shipping
Manufacturer Test
Routine Testing
Application
Technical Specifications
40MVA 110kV Three Phase Oil Immersed Transformer for Substation
Technical Specifications
Accessories
| Rated Power | 40 MVA | |
| Rating Primary Voltage | 2.4 - 110kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V 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
40MVA 110kV Three Phase Oil Immersed Transformer for Substation
The 40MVA 110kV Three Phase Oil Immersed Transformer supports extensive customization to perfectly match project requirements. Clients can select copper or aluminum windings, ONAN/ONAF or ONAF/ODAF cooling methods, ±8×1.25% or ±10×1% OLTC configurations, and YNd11, Dyn11, or custom vector groups. Voltage options cover 110±8×1.25%/33kV, 110/11kV, 110/6.3kV, or special dual-voltage designs. Impedance values from 8% to 18% are available, along with low-loss SZ13 series or ultra-low noise (<60dB) versions for urban substations.
Additional optional features include built-in CT/PT compartments, forced-air fan systems with automatic control, online oil filtration interfaces, fiber-optic temperature monitoring, sudden pressure relays, and remote terminal units (RTU) for SCADA integration. Protective enclosures (IP54/IP65), anti-seismic design up to 0.4g, high-altitude (>3000m) compensation, and special anti-corrosion C5-M painting are also offered. All customizations maintain full IEC 60076 compliance and are delivered with type test reports when required, ensuring seamless integration into any 110kV substation or power plant project worldwide.
Packing and Shipping
40MVA 110kV Three Phase Oil Immersed Transformer for Substation
To ensure the 40MVA 110kV Three Phase Oil Immersed Transformer arrives undamaged at any global substation or power plant, we strictly follow IEC 62271-207 and IMO heavy-lift standards with professional packing and logistics solutions.
After FAT approval, the transformer is vacuum-dehydrated and filled with dry nitrogen to 0.03–0.04 MPa positive pressure to prevent moisture ingress. All 110kV porcelain bushings, conservator, radiator banks, OLTC diverter, cooling fans, Buchholz relay, and instruments are dismantled and packed in separate IPPC-fumigated plywood crates with high-density foam and desiccant. The main tank is fixed on a heavy-duty steel skid with certified lifting and lashing points, then fully enclosed in a reinforced 25 mm marine plywood crate wrapped in a double-layer waterproof and aluminum-foil barrier. Clear bilingual markings (“40MVA 110kV Three Phase Oil Immersed Transformer”), weight (~70 tons), center-of-gravity, lifting points, and handling instructions are applied. Eight shock recorders and tilt indicators monitor the entire journey.
For shipping, inland transport uses police-escorted hydraulic modular trailers (height ≤5.0 m). Sea freight is break-bulk under-deck or on DNV-certified 40ft/80ft flat-racks secured with Φ32 mm wire ropes and pre-approved lashing plans. Full documentation—including packing list, origin certificate, fumigation certificate, nitrogen report, and 110% insurance—is provided. These measures guarantee every 40MVA 110kV Three Phase Oil Immersed Transformer reaches the site ready for immediate installation and commissioning.
After FAT approval, the transformer is vacuum-dehydrated and filled with dry nitrogen to 0.03–0.04 MPa positive pressure to prevent moisture ingress. All 110kV porcelain bushings, conservator, radiator banks, OLTC diverter, cooling fans, Buchholz relay, and instruments are dismantled and packed in separate IPPC-fumigated plywood crates with high-density foam and desiccant. The main tank is fixed on a heavy-duty steel skid with certified lifting and lashing points, then fully enclosed in a reinforced 25 mm marine plywood crate wrapped in a double-layer waterproof and aluminum-foil barrier. Clear bilingual markings (“40MVA 110kV Three Phase Oil Immersed Transformer”), weight (~70 tons), center-of-gravity, lifting points, and handling instructions are applied. Eight shock recorders and tilt indicators monitor the entire journey.
For shipping, inland transport uses police-escorted hydraulic modular trailers (height ≤5.0 m). Sea freight is break-bulk under-deck or on DNV-certified 40ft/80ft flat-racks secured with Φ32 mm wire ropes and pre-approved lashing plans. Full documentation—including packing list, origin certificate, fumigation certificate, nitrogen report, and 110% insurance—is provided. These measures guarantee every 40MVA 110kV Three Phase Oil Immersed Transformer reaches the site ready for immediate installation and commissioning.
32
32 years of industry experience
Manufacturer Test
40MVA 110kV Three Phase Oil Immersed Transformer for Substation
Progress Test
During manufacturing, the 40MVA 110kV Three Phase Oil Immersed Transformer undergoes strict staged Progress Tests per IEC 60076:
- Core-coil assembly: winding DC resistance at all taps, insulation resistance (PI ≥ 2.5), core grounding current (<100 mA), and preliminary no-load loss check.
- Pre-tanking: voltage ratio at principal/extreme taps (deviation ≤ ±0.5%), vector group confirmation (YNd11/Dyn11), polarity, and winding power factor.
- After vapor-phase drying & vacuum oil-filling: final insulation resistance, tanδ (≤ 0.0035 at 20℃), partial discharge (<10 pC at 1.5Um/√3), and oil dielectric strength (>70 kV/2.5 mm).
- Tank sealing: 24-hour static leakage test and 0.4 bar positive/negative pressure test for 24 h.
All results are recorded and submitted for client/third-party approval before final FAT, ensuring the 40MVA 110kV Three Phase Oil Immersed Transformer fully meets design and quality requirements.
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
Conducted strictly per IEC 60076-1/3/11 with client or third-party (SGS/BV/TÜV) witness:
- Winding resistance measurement at all tap positions
- Voltage ratio & phase displacement at principal tap and ± extreme taps (deviation ≤ ±0.5%)
- Vector group and polarity verification (typically YNd11 or Dyn11)
- No-load loss and no-load current at 90%, 100%, and 110% rated voltage
- Load loss and short-circuit impedance at 75℃ and rated current
- Separate-source applied voltage withstand test
- Induced overvoltage withstand test with PD measurement (<10 pC at 1.5Um/√3, <5 pC at Um/√3)
- Full-wave lightning impulse test 350–400 kV peak (HV) & 170–200 kV (MV)
- Insulation resistance, polarization index (PI ≥ 2.5), tanδ, capacitance, and oil BDV (>70 kV)
Official FAT protocol signed upon acceptance, confirming the 40MVA 110kV Three Phase Oil Immersed Transformer is fully qualified for 110kV substation and power plant service.
Routine Test - Winding Resistance
Purpose of Testing
The purpose of winding resistance testing is to detect the continuity and connection quality of the internal conductors of the motor or transformer windings, and to promptly detect potential faults such as open circuits, poor contact or local heating.
Testing Equipment
Winding resistance tester (e.g. OMICRON, DV Power, Raytech, Megger, ISA, etc.)
Test voltage source (commonly used are 6V, 10V, 20V, 40V or 100V, depending on the equipment model or customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test)
Test voltage source (commonly used are 6V, 10V, 20V, 40V or 100V, depending on the equipment model or customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test)
Pre-Test Preparation
Check if the instrument has been calibrated to ensure the test accuracy.
Disconnect the electrical connection between the test cable and the equipment to ensure that there is no external current or voltage interference.
Select a suitable voltage range for testing and set the test voltage according to the equipment requirements.
Disconnect the electrical connection between the test cable and the equipment to ensure that there is no external current or voltage interference.
Select a suitable voltage range for testing and set the test voltage according to the equipment requirements.
Test Progress
Connect the Test Instrument:
Connect the test equipment to the winding terminals of the device under test, making sure the connections are secure and properly grounded to avoid measurement errors.
Apply Test Voltage:
Select the appropriate test current according to the equipment specifications (such as test current for low-voltage windings, single-phase or three-phase windings).
Connect the test equipment to the winding terminals of the device under test, making sure the connections are secure and properly grounded to avoid measurement errors.
Apply Test Voltage:
Select the appropriate test current according to the equipment specifications (such as test current for low-voltage windings, single-phase or three-phase windings).
Measure and Record
Start the test and record the following parameters:
Winding resistance (usually expressed in units of "Ω")
Test current (A)
Test voltage (V)
Temperature (record the winding temperature before and after the test)
Winding resistance (usually expressed in units of "Ω")
Test current (A)
Test voltage (V)
Temperature (record the winding temperature before and after the test)
Temperature Correction
The measured winding resistance values are converted to a reference temperature (usually 20°C) based on a temperature correction formula to allow accurate evaluation and comparison.
Repeat Testing (if necessary)
Test the different windings (high voltage, medium voltage, low voltage) separately and make sure to record the resistance value of each winding.
Evaluation Criteria (Reference)
Resistance deviation is less than 5% (normal)
Resistance deviation is between 5% and 10% (warning)
Resistance deviation exceeds 10% (further inspection or corrective action is required)
Resistance deviation is between 5% and 10% (warning)
Resistance deviation exceeds 10% (further inspection or corrective action is required)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
Power Substations, Industrial Power Supply, Renewable Energy Systems, Commercial Buildings, Electrical Equipment Maintenance and Upgrades
Technical Advantages
● 30+ years of manufacturing experience
● ISO and UL certified production
● Customized cable and transformer solutions
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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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