Factory direct sales; made of pure copper; high efficiency with low loss; diverse specifications; wide range of applications; customization available.
Wound with 100% pure copper for performance that outclasses most comparable units — CE certified, 10-year warranty.
This oil immersed transformer series is built for buyers who need a practical balance between purchase cost, energy performance, and long service life. As a factory direct transformer range, it covers four efficiency grades—S11, S13, S20, and S22—for three-phase distribution at 10kV. When selecting an oil immersed transformer, the most important procurement question is not only the first price, but the full life cycle cost over 25 to 40 years of operation. In many projects, an oil immersed transformer chosen only for low initial cost can create higher total expense later through no-load losses, load losses, and maintenance. For this reason, the S series transformer structure here is positioned as a life-cycle decision, not a one-time purchase.
The four-grade oil immersed transformer range provides a structured decision path based on load factor, project duration, and energy tariff. Choosing an oil immersed transformer without load profile data is a common specification error. A unit optimized for continuous full-load operation may not be the best choice for a variable or lightly loaded site. That is why the S series transformer grades should be matched to the actual operating pattern. For buyers sourcing a factory direct transformer, this approach helps align technical performance with procurement budget and expected service life. The platform is also suitable as a customizable power transformer when project conditions change from standard utility practice.
This high efficiency, low loss oil immersed transformer range covers multiple specs from 30kVA through 2500kVA. Wide application coverage spans standard urban distribution to coastal, plateau, and extreme-climate sites. The series is customizable in voltage ratio, vector group, impedance, cooling configuration, and environmental protection class to meet non-standard project specifications. For utilities, EPC contractors, and industrial buyers, the S series transformer layout makes it easier to select an oil immersed transformer that fits the project instead of redesigning the project around the transformer. As a factory direct transformer source, the product also supports repeat ordering and consistent specification control. Where necessary, the same platform can be adapted into a customizable power transformer solution for special site conditions.
Every oil immersed transformer in this customizable range uses 100% pure electrolytic copper windings. Copper construction reduces DC resistance and load losses compared with aluminum alternatives, and the high efficiency winding geometry supports insulation service life by slowing thermal aging. When comparing quotations for an oil immersed transformer, buyers should ask for winding material test certificates and routine test records from each supplier. For procurement teams evaluating a factory direct transformer, this evidence helps confirm that the delivered unit matches the requested specification. The result is a more reliable S series transformer selection with better clarity on total operating value.
The corrugated fin tank on this oil immersed transformer is fully hermetically sealed, which helps eliminate air-to-oil contact and reduce moisture ingress and oil oxidation over the service life. Under normal operating conditions, no periodic oil treatment or topping is required. IP65 protection supports outdoor installation without additional enclosure. Customizable fin configurations, seal grades, and oil specifications are available for extreme-cold, coastal, and high-altitude sites above 1000m. This makes the oil immersed transformer suitable for buyers who want a robust customizable power transformer that can be matched to environmental demands without changing the base platform. It also strengthens the value of a factory direct transformer supply model because configuration can be aligned earlier in the project.
Standard off-load tap changer at ±5% or ±2×2.5% is fitted to every grade. For grid interconnection projects where voltage routinely exceeds the standard tolerance band, an off-load tap changer may not provide enough operating margin once the tap range is exhausted. The SZ11 OLTC sub-series provides continuous on-load voltage regulation without supply interruption. Circuit breaker auxiliary contact interfaces are standard, enabling connection to a numerical protection relay for trip supervision. IEC 60076 impedance records and vector group certificates support grid authority pre-energization approval. An auto sectionalizer installed upstream of this oil immersed transformer benefits from impedance documentation for correct fault isolation coordination. These features help the S series transformer range serve as a practical customizable power transformer choice for complex network conditions.
Continuous manufacturing, chemical processing, and cold storage facilities running at sustained high load factors represent the primary application for the S22 high efficiency, low loss oil immersed transformer. Grade 1 no-load loss performance reduces energy cost that accumulates 24 hours per day. Hermetically sealed construction helps limit unscheduled maintenance that could disrupt production schedules. For these facilities, transformer life cycle cost—not acquisition price—is the correct specification criterion. In these settings, a high-end S series transformer can be the best long-term choice, especially when energy savings matter more than short-term capital savings. Buyers seeking a factory direct transformer for industrial use often favor this configuration because it balances performance, durability, and controllable customization. The same oil immersed transformer platform can also be configured as a customizable power transformer for non-standard process loads.
The S20 oil immersed transformer serves standard urban and rural distribution projects with five-to-ten-year service life horizons. Utilities replacing S7 or S9 legacy equipment achieve immediate high efficiency and low loss improvement on existing feeders. For grid interconnection projects connecting new industrial or commercial loads to the distribution network, the wide primary voltage range—6kV to 11kV—and customizable secondary ratios support most standard network configurations without additional voltage matching engineering. In many procurement programs, this S series transformer is selected as the best compromise between investment and energy performance. As a factory direct transformer, it also supports direct technical communication during specification review. For special network conditions, the same platform remains a customizable power transformer that can be adapted to site-specific requirements.
| Deployment Context | Grade | Selection Basis |
|---|---|---|
| Short-term or temporary power supply | S11 | First cost priority; payback window insufficient for efficiency premium |
| Medium-term new build, 3–7 years | S13 | Grade 2 efficiency; moderate investment over S11 |
| Standard distribution, 5–10 year horizon | S20 | CRGO core; approximately 30% lower core loss versus S13 |
| High-load 24/7 continuous operation | S22 | Grade 1 efficiency; lowest lifecycle energy cost |
| Emerging market voltage instability | Any grade + SZ11 OLTC | On-load regulation required beyond off-load tap range |
| High-altitude sites above 1000m | S20 or S22 | Customizable derating for ambient air density reduction |
1. What is the cooling method of your oil immersed transformer?
ONAN natural oil circulation natural cooling and ONAF natural oil circulation forced air cooling are both available. We can select and customize the cooling system strictly according to your actual site ambient temperature, load fluctuation and ventilation condition.
2. What is the insulation level and rated voltage of your transformer?
Common rated voltage covers 10kV, 20kV, 35kV; insulation class is Class A. Special voltage grades can be customized to match your local grid standard.
3. What type of transformer oil do you use?
25# or 45# mineral transformer oil for optional selection. 45# oil is recommended for cold regions to guarantee low-temperature fluidity of the transformer.
4. Can it work in high humidity or high altitude area?
Yes, it can operate in humid environment. If the installation altitude exceeds 100om, we will upgrade the external insulation and adjust clearance in accordance with IEC requirements to avoid insulation
breakdown.
5. What rated capacity can you supply?
Standard capacity range: 30kVA ~ 2500kVA. Larger capacity above 2500kVA can be manufactured upon your project request.
Factory direct sales; made of pure copper; high efficiency with low loss; diverse specifications; wide range of applications; customization available.
Wound with 100% pure copper for performance that outclasses most comparable units — CE certified, 10-year warranty.
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