35kV Oil-Immersed Transformer for Utility and Industrial Power Systems

A 35kV Oil-Immersed Transformer provides the voltage interface between a high-voltage network and a downstream distribution system. This S11/SZ11 series is offered for projects that need a 35kV primary connection, with stated capacity coverage from 800kVA to 31,500kVA. The selection should start with the site voltage, load profile, required secondary voltage, and the way the local grid behaves in operation. A 35kV Oil-Immersed Transformer is not simply chosen by its highest kVA value; the tap range, cooling arrangement, impedance, and protection scope should be aligned with the actual installation conditions.

The series uses copper windings and CRGO silicon-steel cores. The supplied material identifies S11 units with off-circuit tap changing and SZ11 units with on-load tap changing. That distinction matters where voltage varies during normal service. For stable networks where a planned interruption is acceptable for adjustment, an S11 configuration can be considered. Where voltage regulation must continue under load, an SZ11 configuration with OLTC may be the more suitable technical route. Final selection should be reviewed against the project specification and the applicable grid requirements.

Available Technical Configuration

A 35kV Oil-Immersed Transformer can be configured around the listed voltage and capacity ranges, but the final datasheet should confirm vector group, impedance, loss values, insulation coordination, and accessory scope. The original product material lists 6.5%–8.0% short-circuit impedance, a stated noise level of no more than 65dB(A), and copper winding material. These values should be treated as configuration references, not a substitute for the approved technical schedule. IEC 60076, GB 1094, and GB/T 6451 are identified in the supplied product information; applicable editions and market-specific clauses should be confirmed during specification.

Key Design Considerations

Copper Windings and Core Materials

The specified 35kV Oil-Immersed Transformer uses 100% pure copper windings and high-grade CRGO silicon steel. Buyers comparing offers can request routine-test records and manufacturing documentation to verify the proposed winding material and rated-loss values. Low-loss language is useful only when the load profile is also understood: no-load and load losses affect operating cost differently. A 35kV Oil-Immersed Transformer should therefore be evaluated using the project duty cycle, expected loading, and operating hours rather than a single headline claim.

Tap Changer Selection

Voltage variation is often underweighted in early procurement. A 35kV Oil-Immersed Transformer with an off-circuit tap changer is intended for adjustment when de-energized; it is not a replacement for on-load regulation where the network varies through the day. The supplied SZ11 option uses an OLTC with ±8×1.25% adjustment. If the site has stable voltage and planned outages are workable, the simpler arrangement may fit. If the project requires continuous ratio adjustment, specify the operating duty and tap control expectations clearly in the RFQ.

Tank, Cooling, and Protection Scope

For units up to 6,300kVA, the supplied description identifies a hermetically sealed corrugated tank intended to limit contact between mineral oil and ambient air. Larger capacities of 8,000kVA and above may use a conservator tank with a dehydrating breather. The stated protection-device scope includes a Buchholz relay, pressure-relief device, magnetic oil-level indicator, and dial thermometer; winding-temperature indication and remote RTD monitoring are described as optional. Confirm all accessories, alarm contacts, and communication requirements in the final order documentation.

Application Fit

A 35kV Oil-Immersed Transformer may be specified for collector substations serving wind or solar projects, where voltage behavior and protection coordination need careful review. It can also be considered for utility substations, large industrial facilities, steel, cement, chemical, or mining applications when the project voltage class and site conditions match the offered design. For high-altitude, cold-climate, or corrosive locations, the supplied material indicates that project-specific arrangements may be available. Those conditions should be stated at inquiry stage, along with ambient temperature, altitude, installation type, and local standards.

For grid-scale battery storage, the transformer interface must be coordinated with the full substation design, including voltage ratio, protection philosophy, and commissioning documentation. This product page does not replace a transformer dc resistance test procedure or the project protection study. Likewise, first pole to clear factor is a system-protection topic that should be verified by qualified engineers rather than inferred from a transformer catalog. These terms are included to help procurement teams identify related technical discussions, not to claim product-specific compliance.

Procurement and Verification Checklist

• Confirm primary and secondary voltages, capacity, vector group, and impedance.
• Match S11 or SZ11 tap control to measured grid-voltage variation.
• Review cooling method, tank type, protection devices, and monitoring accessories.
• Confirm the applicable IEC, GB, local-grid, and tender test requirements.
• Request factory acceptance testing scope, including winding resistance, ratio, insulation, no-load, load-loss, and oil-dielectric checks where applicable.
• Define installation environment, corrosion category, altitude, transport, and delivery constraints before design lock.

The supplied commercial information states a minimum order quantity of one set, T/T payment, and an indicated 25–45 working-day delivery range after deposit confirmation, depending on capacity. It also describes export packaging and available ports. Timing, tests, certifications, warranty, and logistics should be reconfirmed in the quotation because these items depend on the selected 35kV Oil-Immersed Transformer configuration. Contact the supplier with a single-line diagram and technical specification to obtain a project-specific proposal.

Before purchase, confirm the approved drawings, terminal arrangement, losses, test schedule, shipment method, commissioning responsibilities, and all local acceptance requirements with the project team.

FAQ

1. What is the core design feature of your 35kV oil immersed power transformer?

Our 35kV oil immersed power transformer adopts robust tank structure, with ONAN or ONAF coolingoptions. The product is designed for 35kV high voltage distribution grid, featuring low noise, low loss andstable running performance. It is suitable for power station, mining, industrial park and large substation projects.

2. What capacity and voltage combinations can you supply for the 35kV oil immersed transformer?

Main voltage combination is 35kV/0.4kV or 35kV/10kV. The capacity range covers 500kVA to 31500kVA.We can adjust tapping range, insulation clearance and other technical parameters according to your localgrid requirements.

3. Can this 35kV oil immersed transformer be used in high altitude, coastal salt spray or low-temperature areas?

Yes. When installation altitude exceeds 1000m, we will strengthen external insulation. For coastal salt spray environment, anti-corrosion coating for tank is available. For cold regions, 45# transformer oil can be selected to guarantee good fluidity under low temperature.

4. What certifications do you have for the 35kV oil immersed power transformer?

All our 35kV oil immersed power transformers are equipped with CE certification. Relevant CE documentsand complete technical datasheets can be provided for tender submission and customs clearance.

5. What is the warranty period for your 35kV oil immersed transformer?

We provide 10 years warranty for all 35kV oil immersed power transformers. Professional remote technicalsupport will be available throughout the whole warranty period to solve equipment operation problems.