30kVA - 5000kVA 480/277V 35kv Oil Immersed Transformer
Jan 23, 2026
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35kV Oil Immersed Transformer is a premium three-phase power transformer optimized for high-voltage step-down in 50/60Hz AC systems with primary ratings of 35kV (or 33-38.5kV range).
It incorporates a robust conservator or fully sealed tank design with efficient radiator cooling (ONAN standard, ONAF optional), ensuring exceptional thermal dissipation, moisture exclusion.
Outdoor-rated with pollution-resistant bushings (BIL 170-200kV), Dyn11/Ynd1 vector groups, and low noise (<62dB), it provides stable 35kV to secondary voltages (e.g., 10kV/6.3kV/0.4kV) conversion, enhancing grid stability, minimizing transmission losses, and supporting demanding applications in harsh or high-altitude conditions.
Technical Specifications
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35kV Oil Immersed Transformer Technical Specifications
| Rated Power | 30kVA - 5000kVA | |
| Rating Primary Voltage | 2.4 - 34.5kV | |
| Secondary Voltage | 480/277V 400/230V 380/220V Customized |
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| 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) | |
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Accessories
| 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 of 35kV Oil Immersed Transformer
The 35kV oil immersed transformer offers broad customization to suit precise grid configurations, load characteristics, environmental factors, and international standards.
Rated capacities range from 630kVA to 25MVA (or beyond for special substation needs), with primary voltages at 35kV (adaptable to 33kV/34.5kV/38.5kV) and secondary voltages including 10kV, 6.3kV, 6kV, 0.4kV, or custom medium/low-voltage outputs.
Tap changers provide flexibility: off-circuit (±5% or multi-position) for fixed regulation or on-load (OLTC, 9-21 steps) for dynamic voltage control in variable renewable or industrial loads.
Core selections include conventional high-grade silicon steel for balanced performance or amorphous alloy variants to achieve up to 70% no-load loss reduction. Winding materials offer high-purity copper for superior conductivity and durability or aluminum for cost-optimized large-capacity units.
Additional tailoring includes cooling enhancements (ONAN to ONAF with forced fans/pumps for high-ambient or overload demands up to +50°C/-40°C), insulating oils (mineral, natural ester for fire-prone or eco-sensitive zones per IEC 61099), and tank constructions with conservator/breather systems, full hermetic sealing, C5 corrosion protection, seismic reinforcements, or high IP ratings for coastal/polluted environments.
Accessories encompass online dissolved gas analysis (DGA), fiber-optic hot-spot sensors, RTU/SCADA interfaces, pressure relief devices with signaling, conservators, and surge arresters. Impedance levels (8-12%), vector groups (Dyn11, YNd1, etc.), BIL insulation (170-200kV), frequency options (50/60Hz), noise suppression packages, and compliance with IEC 60076, GB1094, ANSI/IEEE, or regional efficiency classes are configurable.
Our engineering experts collaborate to deliver optimized solutions for utility primary substations, wind/solar step-up/step-down, heavy mining/industrial plants, or metro/railway applications, focusing on maximized efficiency, minimized lifecycle expenses, and reliable long-term integration.
Packing and Shipping of 35kV Oil Immersed Transformer
Shipping of 35kV Oil Immersed Transformer
Manufacturer Test of 35kV Oil Immersed Transformer
Progress Test
Progress testing of 35kV oil immersed transformer initiates with silicon steel material certification verifying lamination gauge uniformity insulation coating magnetic properties and edge quality via Epstein sampling to secure minimal hysteresis/eddy losses then core assembly checks multi-step lap joints precise clamping torque shielding effectiveness and vibration damping.
Winding production progress tracks conductor conductivity insulation wrapping density automated tension control layer accuracy and high-voltage inter-turn withstand post-winding.
Core-coil integration progress confirms critical clearances barrier materials end-turn insulation and electromagnetic force-resistant clamping structures.
Tank construction progress examines weld seam ultrasonic/NDT inspection hydrostatic overpressure holds (1.5x) surface preparation grit-blasting multi-coat epoxy/paint thickness.
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
♦ Dielectric Withstand (Hipot)
Transformer Factory Acceptance Test
Load loss impedance voltage and efficiency determination shorts secondary applies reduced primary voltage calculates copper losses percentage impedance (8-12%) and total losses at specified temperature for regulation/overload evaluation.
Oil routine tests confirm dielectric strength (>60kV/2.5mm) moisture (<20ppm) acidity and initial DGA profile with no fault gases. Thermal performance indicators verify top-oil/winding temperature rise limits (e.g. <60K/<65K) through simulated or short-duration heat run.
Functional checks include pressure relief device operation Buchholz/sudden pressure relay tripping temperature alarm settings OLTC sequencing smoothness and sound power measurement (<62dB). Mechanical validation encompasses tank overpressure endurance leak-free integrity bushing coordination and wiring continuity.
Application of 35kV transformer
It is suitable for various combined scenarios such as 35kV main substation voltage reduction, wind and solar new energy power station voltage boosting, industrial large-scale plant and mine power supply, urban high-voltage distribution network, port and mining power system, metallurgical and chemical heavy load center, railway electrification hub, etc., to achieve efficient medium and high voltage conversion and low loss stable operation.
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.
If you are planning a project requiring a 30-5000 kVA Oil Immersed Power Transformer, contact GNEE today for professional design support, technical consultation, and a fast factory-direct quotation.
📩 Send your inquiry now and work directly with a trusted transformer manufacturer.