35KV S11 Oil Immersed Transformer 50-5000KVA

1. Brief Overview

S11 series 35kV oil immersed distribution transformer is a mainstream high-efficiency power transformer ranging from 50kVA to 5000kVA, complying with IEC60076 & GB1094 standards. It features 35kV high voltage input with optional secondary voltage of 10.5kV or 0.4kV, widely used in urban & rural power grid reconstruction, industrial plants, mining, photovoltaic booster stations, infrastructure and overseas EPC power projects. Compared with old S9 type, S11 achieves lower no-load loss and higher operating efficiency with mature, stable manufacturing craft.

2. Core Structure & Features

Iron Core

Made of high-grade cold-rolled grain-oriented silicon steel sheet with full miter cut splicing technology, reducing magnetic flux leakage and no-load consumption. Non-magnetic clamping fittings avoid local overheating and effectively lower running noise.

HV & LV Windings

Winding adopts high-purity oxygen-free copper wire with tight regular winding structure. After full vacuum drying and vacuum oil filling, internal air is removed to strengthen insulation performance and short-circuit resistance. Off-circuit tap changer on HV side supports ±2×2.5% voltage adjustment to adapt fluctuating grid voltage.

Fuel Tank & Cooling System

Corrugated welded steel tank with natural oil circulation air cooling (ONAN) as standard; ONAF forced air cooling is optional for large capacity above 2500kVA to improve overload capability. Anti-corrosion paint coating suits outdoor, damp, dusty and coastal salt-spray working conditions. Transformer insulating oil acts as cooling and insulating medium simultaneously.

Standard Fittings

Standard equipped with oil level gauge, gas relay, pressure relief valve, drain valve and temperature measuring components for real-time operation monitoring. On-load tap changer and remote temperature transmission module are available as customized options.

3. Product Advantages

Economical energy consumption: Lower no-load loss and no-load current than S9, saving long-term operating electricity cost.

High reliability: Optimized mechanical structure resists sudden short-circuit impact, supports long-term continuous full-load operation.

Low running noise: Precise core assembly plus shock absorption design keeps noise within standard limits, suitable for residential area and downtown substations.

Wide capacity coverage: Complete range from 50kVA small distribution to 5000kVA heavy-duty industrial transformer; non-standard voltage ratios can be customized per client drawing.

Low maintenance cost: Standardized spare parts layout, easy for regular oil inspection and daily maintenance.

4. Application Fields

35kV urban/county substation power distribution system

Factory, mine, metallurgy and chemical enterprise power transformation

PV power station, wind farm 35kV step-down/boost system

High-speed railway, highway, commercial complex and new residential district power supply

International power grid construction & foreign bidding projects

5. Quality Certification

All units pass factory routine test, type test including temperature rise, dielectric withstand voltage, short-circuit withstand and partial discharge test, complete with formal test reports and certificates for global export clearance.