20kV Oil Immersed Transformer
The 20kV Oil Immersed Transformer is a high-capacity, three-phase power distribution transformer designed for robust step-down performance in 50/60Hz AC grids up to 20kV primary voltage. It utilizes a fully sealed corrugated tank with advanced thermal fins for oil expansion, eliminating conservators and delivering unmatched resistance to humidity, contamination, and oxidation for over 30-year service life. High-efficiency cold-rolled silicon steel cores with step-lap construction slash no-load losses by up to 40%, complemented by electrolytic copper windings (H62 conductivity).
- Primary Voltage Ratings 34.5-19.92/13.8-7.957/13.2-7.62/12.47-7.2, 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 distribution transformer
- BIL 20kV
- Standards IEEE, ANSI, NEMA, IEC, CE
- Application Temporary Power Supply Systems, Utilities
- Power Rating 30kVA - 5000kVA
- 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
20kV Oil Immersed Transformer
Technical Specifications
Accessories
| Rated Power | 30kVA - 5000kVA | |
| Rating Primary Voltage | 2.4 - 34.5kV | |
| 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 | |
| Insulating Oil Weight | 850 kg | |
| Total Weight | 5000 kg | |
| Outline Dimensions（L×W×H）in. | 2650 × 1650 × 2450（mm) | |
| 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
20kV Oil Immersed Transformer
The 20kV oil immersed transformer supports comprehensive customization for diverse grid and industrial demands, with capacities from 100kVA to 10MVA and primary voltages at 20kV (adaptable to 15/22/24kV). Secondary outputs include 0.4kV, 0.69kV, 1kV, or bespoke low-voltage setups like 0.415kV for specialized loads. Tap configurations range from off-circuit ±2×2.5%/±5% to advanced on-load (OLTC) for real-time regulation amid renewables fluctuations. Core options feature high-grade silicon steel or amorphous alloys for 60%+ no-load loss cuts, with windings in copper for peak efficiency or aluminum for budget optimization.
Enhance reliability with tailored cooling (ONAN/ONAF/KNAN for +50°C ambients), eco-oils (bio-degradable per IEC 60296), or fire-retardant variants for petrochemical sites.
Tank upgrades offer IP54+ enclosures, hot-dip galvanized frames, seismic bracing, anti-corrosion epoxy, and high-altitude adaptations (>1000m). Accessories integrate DGA online monitoring, winding hot-spot detectors, RTUs for SCADA, conservators, or gas relays. Impedance (4-6% pole-mounted to 12-14% power), vector groups (Dyn11/YNd1), BIL levels (up to 250kV), and noise packages align with IEEE/ANSI/CSA. Frequency (50/60Hz) and efficiency grades (S11/S13-NX3 Level 3) meet global regs. Engineering collaboration optimizes for ring networks, PV/wind step-up, or metro substations, slashing lifecycle costs via 99.7% efficiency and minimal maintenance.
Packing and Shipping
20kV Oil Immersed Transformer
Pre-shipment protocols for 20kV oil immersed transformers prioritize integrity with multi-stage inspections: dielectric leak tests, component torque checks, and oil quality verification (DBV >56kV). Units ship oil-filled under nitrogen blanket (0.02-0.05MPa) for <80-ton models to avert moisture; heavier ones drain oil into sealed 200L drums with vacuum degassing kits for site refill, per IEC 60076 tightness standards.
Disassembly protects detachable parts—radiators crated with foam/vibration dampers, porcelain/polymer bushings in shock-mounted boxes, OLTC/control panels shrink-wrapped with silica gel. Main tank secures on steel skids or ISPM-15 wooden cradles, braced against 5G shocks, with tilt/shock loggers, VCI inhibitors, and hygrometers. Corrugated tanks get weatherproof tarps; pole-mount variants use galvanized frames for stackability.
Sea export dominates via flat-rack/open-top containers or RoRo, lashed to IMO specs with salt-fog coatings; overland uses lowboys for weight balance at marked lugs. Full docs bundle: FAT reports, PSI certificates, BOMs, HS codes (8504.22), CoO, SDS for oils, CAD drawings, and unload manuals. Customs prep includes RoHS/REACH for EU/NL markets like Barry's Amsterdam base.
Logistics orchestration covers FOB/CIF to door, with third-party PSI/FAT witnessing options. Arrival protocols: crane unload at 4-point lifts, oil processing (<20ppm H2O), N2 purge hold, and 24-month warranty activation—zero-defect delivery assured for global utilities.
Disassembly protects detachable parts—radiators crated with foam/vibration dampers, porcelain/polymer bushings in shock-mounted boxes, OLTC/control panels shrink-wrapped with silica gel. Main tank secures on steel skids or ISPM-15 wooden cradles, braced against 5G shocks, with tilt/shock loggers, VCI inhibitors, and hygrometers. Corrugated tanks get weatherproof tarps; pole-mount variants use galvanized frames for stackability.
Sea export dominates via flat-rack/open-top containers or RoRo, lashed to IMO specs with salt-fog coatings; overland uses lowboys for weight balance at marked lugs. Full docs bundle: FAT reports, PSI certificates, BOMs, HS codes (8504.22), CoO, SDS for oils, CAD drawings, and unload manuals. Customs prep includes RoHS/REACH for EU/NL markets like Barry's Amsterdam base.
Logistics orchestration covers FOB/CIF to door, with third-party PSI/FAT witnessing options. Arrival protocols: crane unload at 4-point lifts, oil processing (<20ppm H2O), N2 purge hold, and 24-month warranty activation—zero-defect delivery assured for global utilities.
32
32 years of industry experience
Manufacturer Test
20kV Oil Immersed Transformer
Progress Test
Progress tests commence with silicon steel lamination audits for thickness uniformity magnetic permeability burr elimination via Epstein testing to optimize core flux density and cut hysteresis losses then core stacking verifies step-lap miters yoke clamping torque electromagnetic shielding against strays. Winding fabrication tracks enameled copper resistivity layer-paper insulation buildup turn-count precision via automated winders dielectric bridges for inter-layer strength post-coil drying oven logs dew points <-45°C vacuum impregnation confirms resin penetration uniformity. Core-coil assembly progress scans axial/radial clearances pressboard spacers end-rings for short-circuit force resistance tank fab checks seam X-rays hydrostatic pressure 0.5MPa holds surface blast/paint DFT>80μm corrosion spec adherence pre-oil fill mockups detect alignments.
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
Transformer Factory Acceptance Test
FAT per IEC60076-1/2 IEEE C57.12.90 opens with visual/dimensional conformity nameplate scan paint adhesion accessory fixation then insulation metrics megger PI >2000MΩ@20°C separate-source AC withstand 75kV/1min induced 2xUn/150% freq/7200s for PD<10pC BIL 250kV full wave. DC winding resistance 75°C corrected verifies joints polarity turns-ratio tester validates ±0.5% accuracy phase displacement Dyn11 across taps no-load routine rated Un loss< spec exciting I%<2% harmonics THD<5%.
Routine Test - Insulation Power Factor
Purpose of Testing
The purpose of testing the insulation power factor is to evaluate the dielectric loss of the insulation system in electrical equipment, and to determine whether issues such as moisture ingress, aging, or contamination are present. A high power factor value usually indicates insulation deterioration.
Testing Equipment
Insulation power factor tester (e.g., brands like Doble, Megger) Voltage source (typically 1 kV, 2.5 kV, or 10 kV or as the customer request standard) Temperature and humidity meter (for recording environmental conditions)
Pre-Test Preparation
De-energize tap changer the equipment and ensure it has been properly grounded and discharged. Make sure the bushings and terminal connections to prevent surface contamination from affecting test results. Perform the test under suitable environmental conditions: relative humidity below 75% and no rain (recommended temperature: 20–30°C). Calibrate and inspect the test instruments to ensure they are in good working condition.
Test Progress
Connect the Test Instrument: Connect the test equipment to the bushings or terminals of the equipment under test and ensure proper grounding. Apply Test Voltage: Select the appropriate test voltage according to the rated voltage of the equipment (e.g., 25 kV for high-voltage windings or as the request of the pad mounted transformer).
Measure and Record
Start the test and record the following parameters: Capacitive current (IC) Power current (IW) Power factor (PF) or dissipation factor (Tanδ) Capacitance Ambient temperature and humidity at the time of testing
Temperature Correction
Correct the measured power factor to the reference temperature (typically 20°C) for accurate evaluation.
Repeat Testing (if necessary)
Measure different windings (high-voltage, medium-voltage, low-voltage) and bushings separately for comparative analysis.
Evaluation Criteria (Reference)
Insulation power factor ≤ 0.5% (Excellent) 0.5% < Power factor ≤ 1% (Good) 1% (Further inspection or corrective action required) Test standard:IEEE C57.12.00 & IEEE C57.12.90 (Liquid-Immersed)
*These comprehensive tests ensure that each transformer meets performance standards and operates
reliably under various conditions.
Application
It is widely used in 20kV power distribution systems for industrial parks, agricultural irrigation areas, new energy storage access, commercial high-speed rail hubs, hospital data center backup, chemical and petroleum enterprises and other combined scenarios, ensuring efficient overload and short circuit resistance and intelligent monitoring and optimization.
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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