Quick Answer

A 500 kVA 10 kV three-phase oil-immersed transformer for a data center is a hermetically sealed, copper-wound distribution transformer that steps 10 kV medium voltage down to 400/415/480 V to feed the UPS input switchgear, mechanical cooling and site services of a data hall. Data center sites choose sealed oil-immersed units for outdoor campus substations and main distribution feeds because the corrugated sealed tank removes the conservator and every periodic oil maintenance task, absorbs the sustained high base load of IT racks running 24/7, and costs roughly 10–15% less per kVA than cast resin. For UPS and rectifier loads, specify a K-13 rated design and Dyn11 vector group.

Product Overview

This is a three-phase, 50/60 Hz oil-immersed distribution transformer rated 500 kVA with a primary voltage of 10 kV and a secondary voltage of 0.4 kV (415 V, 480 V or 690 V on request). Both HV and LV windings are copper. The active part is sealed inside a corrugated-fin steel tank with no conservator, so the insulating oil never contacts air, never needs sampling, filtration or topping-up, and the unit is genuinely maintenance-free for its design life of 25 years.

It is built for data center campuses: outdoor site substations, utility-entry transformers, main distribution feeders and PV-plus-storage or emergency-supply transformers. The standard supply includes oil-temperature monitoring and an RS485/Modbus RTU interface, with an optional 4G or LoRa DTU so winding and oil temperature, load current and voltage can be read directly by the building management system (BMS), the DCIM platform or the site SCADA. Manufactured under ISO 9001 and designed and tested to IEC 60076-1/-2/-3/-5/-10, GB 1094 and GB 20052-2024.

Why Data Centers Choose Sealed Oil-Immersed Over Dry Type

Our recommendation: for an outdoor data center campus substation, utility-entry transformer or any main distribution feed outside the server hall, specify a hermetically sealed oil-immersed transformer. Reserve cast resin dry type for indoor electrical rooms, the server hall itself and any location where the local fire code rules out combustible oil.

The reason is sustained duty and cost. A data center transformer runs energised 24/7 and, unlike a utility distribution transformer, carries a high and relatively steady base load near its design point. Oil has far greater thermal mass than air, so the tank absorbs the thermal cycling of IT, cooling and UPS loads without driving the winding hot spot up. A sealed tank also removes the OPEX item most operators forget to budget: no annual oil sampling, no filtration, no conservator breathers to replace.

Key Features

• Hermetically sealed corrugated tank — no conservator, the oil never contacts air. No oil sampling, filtration or topping-up for the whole 25-year design life; this removes the OPEX item most operators forget to budget.
• Built for sustained 24/7 data center duty — ONAN cooling with high oil thermal mass absorbs the high base load and thermal cycling of IT, cooling and UPS loads without winding hot-spot excursions.
• Harmonic-capable K-13 winding design — modern double-conversion UPS systems and server PSUs inject total harmonic current distortion (THDi) commonly 15–30%; a K-13 rated design prevents overheating where a standard transformer would derate or fail early.
• Dyn11 vector group as standard — traps zero-sequence and 3rd-order harmonics inside the delta winding so they do not travel upstream into the utility feeder or other site loads.
• Copper windings on both HV and LV — lower load loss, lower temperature rise and better short-circuit withstand than aluminium, verified by type test to IEC 60076-5.
• Class 1 or Class 2 efficiency available — S22 (lowest loss) or S20 per GB 20052-2024; on a 24/7 data center the efficiency grade directly lowers both the electrical bill and the cooling load, improving PUE.
• Outdoor-ready construction — fluororubber gasket sealing from -25 °C to +55 °C, optional C4 / C5-M coating for coastal and industrial sites, IP54 cable boxes, anti-theft locks and vandal-resistant hardware.
• Smart-ready for the data center — oil and winding temperature, load current and voltage via RS485/Modbus RTU, with optional 4G or LoRa DTU feeding the BMS, DCIM platform or site SCADA.
• Higher overload capacity — oil thermal mass handles cooling-plant and UPS-transient peaks that would drive a dry-type winding hot spot too high.
• Low noise — ≤ 55 dB(A) at 1 m as standard, with a low-noise core and clamping design available at ≤ 50 dB(A) for sites adjacent to offices or retail.

Typical Applications

• Outdoor campus substations and utility-entry transformers
• Main distribution feeds to UPS input switchgear
• Mechanical cooling and chilled-water plant feeders
• Co-location, cloud and edge data centers (campus or single-building)
• PV + battery + grid integrated power plants feeding data halls
• Emergency and standby distribution tied to generator sets
• Compact substation (YBW-12) for turnkey data center power delivery

Standards and Certifications

Designed and tested in accordance with IEC 60076-1 (general), IEC 60076-2 (temperature rise), IEC 60076-3 (insulation levels and dielectric tests), IEC 60076-5 (short-circuit withstand) and IEC 60076-10 (sound level), plus GB 1094 series and GB/T 6451. Energy performance meets GB 20052-2024 Class 2 as standard and Class 1 with the S22 design. Manufactured under ISO 9001, ISO 14001 and ISO 45001. CE conformity available; third-party type test reports (CNAS-accredited laboratory, KEMA or equivalent) available on request. Harmonic duty designed with reference to IEEE C57.110 and IEEE 519.