Vous êtes soit l'ingénieur électricien travaillant sur un projet d'extension de réseau régional, soit un responsable des achats qui s'occupe de la mise en place de l'approvisionnement pour une usine de fabrication, soit le distributeur qui gère un projet d'électrification rurale et chaque devis d'équipement que vous recevez a un élément en commun : un transformateur de distribution immergé dans l'huile de 1000 kVA 35 kV. Lorsque vous demandez un devis à vos fournisseurs, la moitié d'entre eux mentionnera “S11-1000/35-0.4”, tandis que l'autre moitié se contentera de mentionner le nom sous “transformateur à huile 1000 kVA 35 kV S11”. Si vous vous êtes demandé ce que signifie ce numéro de modèle, pourquoi exactement S11 est une amélioration par rapport au modèle S9, et quel devrait être le prix de l'appareil, continuez à lire ce guide.
S11-1000/35-0.4 est le transformateur de distribution de choix à l'international dans la catégorie 35 kV. Il s'agit d'un transformateur triphasé, immergé dans l'huile, de 50 Hz et de 1000 kVA, responsable de la conversion de la tension de 35 kV en 400/230V. Dans cet article, nous décrirons les principes de fonctionnement du modèle S11, y compris la signification de tous les composants du numéro de modèle.
Réponse courte : Le S11-1000/35-0.4 est un transformateur de distribution triphasé, immergé dans l'huile, de 50 Hz avec une capacité nominale de 1000 kVA. Il a une tension primaire de 35 kV et une tension secondaire de 400 V (0,4 kV). “S” représente la configuration triphasée ; “11” désigne le numéro de série de conception avec des pertes à vide réduites de presque 30% par rapport à un ancien type S9 ; tandis que “1000” représente la capacité nominale et “35-0.4” le rapport de tension.
Décodage du numéro de modèle : Que signifie S11-1000/35-0.4
Les numéros de modèle de transformateur semblent cryptiques, mais dans la convention de nommage chinoise/ISO, chaque partie a une signification spécifique. Pour le S11-1000/35-0.4 :
| Partie | Signification | Détail |
|---|---|---|
| S | Triphasé | “S” (san xiang, 三相) indique une unité triphasée, par opposition à “D” pour monophasé |
| 11 | Série de conception | La 11ème série de conception, caractérisée par un noyau à faible perte utilisant de l'acier au silicium orienté à grain à froid |
| 1000 | Capacité nominale | Évaluation de la puissance apparente de 1000 kVA |
| 35 | Côté haute tension | Tension primaire nominale de 35 kV |
| 0.4 | Côté basse tension | Tension secondaire nominale de 0,4 kV (400V) |
Ainsi, “S11-1000/35-0.4” peut être interprété comme un transformateur triphasé de série 11 avec une capacité de puissance de 1000 kVA fonctionnant à 35 kV du côté d'entrée et 0,4 kV du côté de sortie. Certains fabricants indiquent les transformateurs comme S11-1000/35 ou S11-M-1000/35 ; la dernière lettre signifie que l'unité de transformateur est entièrement fermée et possède une isolation électrique profonde par le biais de l'huile. Lorsque la spécification contient des informations telles que “combinaison de tension 35 ± 2×2.5% / 0,4 kV”, cela signifie que le transformateur a un changeur de prises hors circuit avec la possibilité d'effectuer des ajustements par le biais de 5% du premier côté et fonctionnant à 0,4 kV du second côté du transformateur.
Qu'est-ce qu'un transformateur immergé dans l'huile de 1000 kVA 35 kV ?
Un transformateur à huile de 1000 kVA est qualifié de transformateur de distribution à moyenne tension qui reçoit l'énergie du réseau à 35 kV (ou d'une sous-station de 35 kV) et la réduit au niveau de basse tension de 400 volts – 230 volts obtenus à l'extrémité de la charge. Le terme “ à huile ” indique que l'enroulement et le noyau sont complètement immergés dans une huile isolante à des fins d'isolation et de refroidissement.
Dans la gamme des transformateurs de distribution, le transformateur de 1000 kVA est suffisamment grand pour fournir de l'énergie à des usines, des bâtiments, des hôpitaux et des groupes de centaines de maisons. En même temps, il est suffisamment petit pour être transporté par le fabricant en tant qu'unité unique (sur un camion) et installé soit sur une base à l'extérieur, soit dans une petite pièce de la sous-station. C'est un transformateur standard pour les réseaux de distribution de 35 kV en Chine, en Asie du Sud-Est, en Afrique, au Moyen-Orient et en Amérique latine.
Les données les plus importantes de toute fiche technique du transformateur sont :
- Capacité nominale = 1000 kVA (peut également être noté comme 1 MVA)
- Rapport de tension = 35kV / 0.4 kV (avec des prises hors circuit à 35 ± 2×2.5% kV)
- Fréquence = 50 Hz
- Groupe vectoriel = Yyn0 (ou Dyn11 sur demande)
- Refroidissement = ONAN (Huile Naturelle, Air Naturel)
- Tension d'impédance = 6.5% (pour cette taille)
Construction & Composants Clés
Comprendre ce qu'il y a à l'intérieur du réservoir vous aide à juger de la qualité lors de la comparaison des devis. Un transformateur à huile de 1000 kVA se compose de ces principales parties :
| Composant | Fonction | Indicateur de Qualité |
|---|---|---|
| Noyau | Circuit magnétique qui transfère l'énergie entre les enroulements | Acier au silicium orienté à grain à froid (CRGO), conception de noyau en escalier, grades à faibles pertes (30Q120/30QG110 ou mieux) |
| Enroulement HT | Enroulement primaire de 35kV | Cuivre ou aluminium ; enroulement en couche ou en disque continu ; classe d'isolation appropriée (A, E, B) |
| Enroulement BT | Enroulement secondaire de 0.4kV | Enroulement en feuille ou en fil ; feuille de cuivre préférée pour le BT à fort courant |
| Huile isolante | Isolation + refroidissement | Huile minérale selon la norme IEC 60296 (par exemple, huile de transformateur 25#) ; inhibée DBPC pour une longue durée de vie |
| Réservoir & radiateur | Contient la partie active ; dissipe la chaleur | Acier soudé, testé pour les fuites, avec tubes/ailettes de refroidissement ou radiateurs ; bon traitement de surface |
| Conservateur & respirateur | Accepte l'expansion de l'huile ; élimine l'humidité | Respirateur en gel de silice avec joint d'huile ; indicateur de niveau d'huile approprié |
| Changeur de prises | Ajuste le rapport de tension | Changeur de prises hors circuit (5 prises) standard ; changeur de prises sous charge en option |
| Bagues | Amène les connexions HT/BT hors du réservoir | Bagues en porcelaine ou en résine classées pour 35kV et 1kV |
| Dispositifs de protection | Safety monitoring | Gas relay (Buchholz), oil temperature indicator, pressure relief valve, oil level gauge |
Two material choices dominate the price difference: copper vs aluminum windings. Copper offers lower losses and better long-term performance but costs significantly more. Aluminum is lighter and cheaper and is common in budget-oriented markets. Always confirm which metal is quoted — it’s one of the biggest price drivers, and the difference can be 20–40% of the transformer price.
Technical Specifications at a Glance
Here are the representative specifications for an S11-1000/35-0.4 transformer built to IEC 60076 / GB 1094 (typical values, confirm exact figures with the manufacturer’s datasheet):
| Paramètre | Valeur typique |
|---|---|
| Capacité nominale | 1000 kVA |
| Rapport de tension | 35 ± 2×2.5% / 0.4 kV |
| Fréquence | 50 Hz |
| Groupe vectoriel | Yyn0 (Dyn11 optional) |
| Méthode de refroidissement | ONAN |
| No-load loss (P0) | ~1.15 – 1.45 kW |
| Load loss (Pk at 75°C) | ~10.3 – 11.4 kW (copper) / ~11.5 – 13 kW (aluminum) |
| Impedance voltage (Uk) | 6.5% – 7.0% |
| No-load current (I0) | ~0.7 – 1.0% |
| Insulation level (HV) | LI 200 kV / AC 85 kV |
| Sound level | ~60 – 65 dB(A) |
| Normes | IEC 60076, GB 1094, GB/T 6451 |
| Oil type | Mineral oil per IEC 60296 |
| Weight (total) | ~3,200 – 4,200 kg depending on materials |
| Dimensions (approx.) | ~2.2 × 1.5 × 2.4 m (L×W×H with radiators) |
According to these numbers, the S11-1000/35-0.4 falls into the standard “T2” loss category in the Chinese system of energy efficiency classification (GB 20052), which is below high-end S13/S15 amorphous models, but still much better than outdated S7/S9 models that are still present in older networks.
S11 vs S9 vs S13: How the Design Series Compare
The design ranges for Chinese distribution transformers are marked according to their generations, with each generation being more efficient than its predecessor. The following is a breakdown of the three series where efficiency at 1000 kVA at 35 kV measures.
| Série | Matériau du cœur | No-load Loss (1000kVA, approx.) | Relative Loss Level | Status |
|---|---|---|---|---|
| S7 | Hot-rolled silicon steel | ~2.0 – 2.3 kW | Baseline (highest) | Phased out (banned for new grid purchases) |
| S9 | Acier au silicium CRGO | ~1.7 – 1.8 kW | ~25% lower than S7 | Legacy, still common in service |
| S11 | High-grade CRGO silicon steel | ~1.15 – 1.45 kW | ~30% lower than S9 | Current mainstream standard |
| S13 | High-grade CRGO + improved design | ~0.9 – 1.1 kW | ~25% lower than S11 | Energy-efficiency premium option |
| S15 (amorphous) | Amorphous alloy ribbon | ~0.55 – 0.7 kW | ~50% lower than S11 | Highest efficiency, higher cost |
S11 series has grown to be the standard choice for utility and industrial distribution due to its ideal price-quality ratio. An S11’s ~30% lower no-load loss than S9 results in USD thousands in energy savings during a 20-year service life, which is why many public service companies worldwide now require S11 units from vendors, and China has stopped allowing S7 and older units to be used in the grid connections process.
If the project is located in a country with strict energy efficiency regulations like EU Eco-design or China’s GB 20052 Level 2, an S13 or amorphous S15 would be required. For the rest of the markets, the S11 would do the job.
Applications: Where This Transformer Is Used
The 1,000 kVA, 35/0.4kV S11 transformer is used in various applications, which include:
- Industrial sector: for plants involving production lines, motors, welding and HVAC.
- Commercial buildings: it provides power to office buildings, shopping malls, hospitals, hotels, and data centers as a distribution transformer for low voltage system.
- Rural electrification: for rural village and town distribution networks fed by 35 kV lines.
- Energy Sector: it reduces voltage from PV substations and powers wind and solar plants.
- Mining industry: it provides power to isolated job sites supplied by 35 kV distribution voltage.
- Infrastructure: it is used in airports, train stations, water pumping stations, etc.
- Electrical system modernization: it replaces outdated S7/S9 units with lower losses and higher reliability.
In all of these projects, transformers power low voltage switchboards, which in turn supply electricity to 400 V power systems. As a result, failure of such electrical equipment could lead to significant problems that must be avoided at all costs.
Key Advantages of the S11 Series
Why does electricity sell so well?
- Low no-load losses: about 30% lower than that of S9, meaning that there are fewer losses with stationary transformers.
- Long lifetime: It has been used around the world for many years.
- Low maintenance: The only thing that has to be done is to change oil and conduct periodic checkups.
- High overload capability: An oil tank has a large overload capability (e.g. 120% for at least 2 hours according to IEC 60076-7).
- Cost saved: Prices for oil transformers are lower than those for dry transformers in that range.
- Standardized: The devices were made according to IEC 60076 and GB 1094 standards so that the parts could be easily found all around the world.
- Simple installation: All the devices are delivered assembled and oil-mixed.
The oil transformers are less expensive than dry-type transformers as their prices vary by 30-50% depending on their ratings. Although it has to take into account that the oil unit requires the use of a concrete container as well as compliance with the fire regulations and maintenance rules.
Price Guide: What to Expect
Transformer pricing varies widely with material, accessories, and certification. Here’s a realistic 2026 guide for an S11-1000/35-0.4 (FOB factory, excluding freight and installation):
| Configuration | Plage de prix (FOB) | Remarques |
|---|---|---|
| Aluminum windings, basic accessories | $11,000 – $15,000 | Budget option; higher losses |
| Copper windings, basic accessories | $14,000 – $18,000 | Recommended for most buyers |
| Copper windings + on-load tap changer | $18,000 – $24,000 | For voltage-regulation-sensitive loads |
| Copper windings + full protection package | $16,000 – $22,000 | Buchholz relay, oil temp gauge, pressure relief, level gauge |
| Premium brand (ABB/Siemens/Hitachi) | $25,000 – $45,000+ | Brand premium, local service network |
What’s included vs. additional things: the base price often covers the transformer itself, its oil, tank, bushing, and basic accessories (which include conservator, breather, and oil gauge). Additional costs usually apply to the cost of on-load tap changers, surge insulators, temperature control cabinets, specific type of painting, third-party inspection (SGS/BV/Intertek), and shipping/crating and documentation. Always demand a complete offer based on all these line items for comparative reasons.
For transportation: a unit with a power value of 1,000 kVA weighs around 3.5–4.5 tons while the shipping cost is about $1,500–$4,000 depending on the point of destination plus local customs and transport costs.
How to Choose & Verify a Supplier
Given the transformer’s life expectancy of 20 to 30 years, the selection of its manufacturer is equally as crucial as the specification choice. Here is a simple verification process to follow.
- Request the complete datasheet: its loss values(P0, Pk), impedance, vector group, dimensions, weight and check if the data obtained matches the standards for your rating.
- Ask the factory to provide the test report. Each unit is shipped with the details of the factory routine tests(ratio, losses, insulation voltage). Note that the report should comply with IEC 60076 rules in case of IEC/GB compliance.
- Check the certificates: check the compliance with IEC 60076, factory certificate ISO 9001 as well as the requested certificates specific for your market(having CE stamps etc.).
- Check the winding material. Confirm in writing that it is copper or aluminum. If the quotation has no information about the metal used in manufacturing, it is a bad sign.
- Check the core grade: find out the silicon steel grade(e.g. 30Q120), as well as whether it is CRGO.
- Specify third-party inspection(if applicable): in case of big orders, it is better to add SGS/BV/Intertek inspection during production and in the packing stage.
- Check total landed cost: think of FOB price + freight + insurance + customs + installation, not only about the FOB price.
- Look through warranty and after-sale conditions: the standard warranty period is 12-18 months; verify the availability of spare parts and support.
Why do buyers prefer Chinese factories? China, represented by Jiangsu Subian Electric Power and other state-owned companies, produces the majority of distribution transformers. The price of products from China is usually 30-50% lower if compared to products from Europe, so distributors and EPC contractors in 60+ countries buy their 35kV transformers from Chinese factories. However, the use of factory-direct manufacturing has efficiency only if all verification procedures are followed.
Installation & Maintenance Essentials
Installation Basics
- Install on a flat base, ensuring adequate circulation in the area surrounding the tank; adhere to the minimum requirements of the manufacturer on space between bushings and radiators.
- Check the oil conditions, while looking at the silica gel (blue = dry, pink = soaked), and gauges.
- Confirm the vector group and tapping settings are in alignment with the network at hand.
- Connect the tank to the earthing system appropriately; never switch the power on to the tank that has not been earthed.
- Undertake the essential tests: insulation resistance (IR), ratio, and oil dielectric strength if the unit has been out of operation for long.
Routine Maintenance Checklist
| Interval | Checks |
|---|---|
| Mensuel | Visual inspection; oil level and leak check; silica-gel color; unusual noise |
| Trimestriel | Check oil temperature indicator during load; confirm cooling fins are clean |
| Annually | Insulation resistance test; oil sample analysis (dielectric strength, moisture); check Buchholz relay and pressure relief device; test tap changer operation |
| Tous les 3–5 ans | Full oil test (breakdown voltage, acidity, DGA dissolved gas analysis); inspect tank coating; check gaskets and bushings |
Dissolved Gas Analysis (DGA) is considered the best analysis available as it gives alert about the fractions of impending failures (which involve overheating, partial discharge, and arcing). It is a cost-effective method for annual testing of any essential 1,000 kVA machine.
Questions Fréquemment Posées
What does S11-1000/35-0.4 mean?
The designation S11-1000/35-0.4 stands for a three-phase low-loss distribution transformer of series-11(S11) which is oil-immersed and has a capacity of 1000 kVA with the primary voltage of 35 kV and the secondary voltage of 0.4 kV. In series number 11, the transformers are made of cold-rolled grain-oriented silicon steel which makes them achieve a reduction in the no-load losses by about 30% compared to those of the S9 series transformers.
How much does a 1000 kVA 35kV transformer cost?
A comprehensive S11-1000/35-0.4 oil-immersed transformer usually goes for $11,000–$22,000 FOB from a Chinese production facility, according to whether the windings are made of copper or aluminum and based on the type of tap changer being used along with other accessories. Copper-wound units with normal accessories cost $14,000–$18,000; leading European brands prices are $25,000–$45,000+. Finally, add $1,500–$4,000 for maritime freight charges to most destinations.
What is the difference between S9, S11, and S13 transformers?
They refer to the recent design generations where each has less no-load loss than its predecessor. For 1000 kVA, the no-load losses are (approx): S9: 1.7- 1.8 kW, S11: 1.15-1.45 kW (30 percent less than the previous S9); S13: 0.9-1.1 kW (25 percent less than S11). New amorphous core S15 units have around 50 percent less losses, although their cost is higher than S11. In the meantime, S11 is the currently leading technology, whereas S7 and older types are gradually being discontinued on a global scale.
Can a 1000 kVA 35kV transformer be used for a factory?
Yes, it is one of the most used capacities among medium manufacturing plants. A 1000 kVA transformer at 400V has a current capacity of about 1400A per phase (roughly 800-900 kW of continuous load depending on the operating power factor). In a factory with multiple manufacturing lines, engines, and HVAC systems, this is an ideal first size; larger factories may have multiple transformers or a bigger one.
How long does an oil-immersed transformer last?
Provided that the transformer is properly maintained, S11 oil-filled transformers have a normal working life of 25 to 30 years. To this end, some of the most important factors affecting the lifetime of oil transformers are: oil quality (annual tests for oil quality), DGA, load profile (i.e. in order to prevent continuous overloads), operating temperature, and conditions of the environment. Well-installed and well-maintained transformers may serve for more than 40 years.
Références
- IEC 60076-1: Power Transformers — General — The core international standard governing ratings, losses, impedance, and testing of power transformers, including the 35kV class.
- IEC 60076-7: Power Transformer Loading Guide — The loading guide defining overload capability and thermal limits for oil-immersed transformers.
- GB 1094 Series (Chinese Power Transformer Standard) — The Chinese national standard for power transformers, functionally equivalent to IEC 60076 and required for grid-connected units in China.
- IEC 60296: Fluids for Electrotechnical Applications — Unused Mineral Insulating Oils — The standard specifying quality requirements for transformer mineral oil.
- U.S. DOE — Distribution Transformer Efficiency — Background on why transformer efficiency matters for energy consumption and loss cost economics.
- Jiangsu Subian Electric Power Co., Ltd. — Chinese manufacturer of oil-immersed and dry-type transformers (S11/S13/S15 series, 10–110kV), IEC 60076 certified and exporting worldwide; a factory-direct reference for pricing and supply.
Conclusion
The S11-1000/35-0.4 is an extremely reliable transformer used in the 35 kV distribution systems. The three-phase transformer is oil-impregnated and has 1 000 kVA of power. The device’s model name serves as a description. It is characterized by a three-phase low-loss design of the S11-type, being a three-phase transformer with 1 000 kVA of power.Here is a list of what the customers should follow:
- Be as specific as you can regarding the specifications. It is essential to indicate whether the windings of the transformer have been made of copper or aluminum, the type of tap changer, accessories, and certifications (IEC 60076 / GB 1094).
- Double-check everything before you make a purchase. Ask your supplier for the detailed specifications, the factory test report, and offer with a detailed list of extras.
- Estimate the money you plan to spend realistically. The price of the transformer will fluctuate from $11,000 to $22,000 with delivery from China.
- Buy what is properly maintained. Annual testing of the oil and diagnostic tests will help you to protect an asset for nearly 30 years.
- Make smart shopping as for the suppliers of the unit in China. The right suppliers will help you to save your money significantly.
The S11-1000/35-0.4 is definitely your best choice if you are replacing your old S7/S9 unit or putting S11 for a new place.