Power Transformers

110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC

A large three-phase oil-immersed power transformer rated 20 / 25 / 50 MVA, stepping 110–115 kV down to 11 / 23 kV, equipped with an on-load tap changer (OLTC) for automatic voltage regulation under load.

A large three-phase oil-immersed power transformer rated 20 / 25 / 50 MVA, stepping 110–115 kV down to 11 / 23 kV, equipped with an on-load tap changer (OLTC) for automatic voltage regulation under load. Built for utility substations and heavy industrial supply, it combines a sealed steel tank, radiator cooling and a conservator oil-expansion system for a 20-year design life. Copper or aluminium windings, IEC/GB compliant.

  • On-load tap changer (OLTC) — regulates output voltage without interrupting supply
  • High-capacity 20 / 25 / 50 MVA at 110–115 kV transmission class
  • Oil-immersed sealed design with radiator cooling and conservator
  • Vector group Dyn11 / Yyn0 to suit substation single-line requirements
  • 20-year service life; certified CE, UL, ISO9001, IEC/GB
Product TypeThree-Phase Oil-Immersed Power Transformer
Rated Capacity20 / 25 / 50 MVA
Input Voltage (HV)110 / 115 kV
Output Voltage (LV)11 / 23 kV
Frequency50 / 60 Hz
PhaseThree
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Lead time typically 25–45 days after drawing approval · FAT welcome · Ships worldwide (EXW / FOB / CIF / DAP)

Technical specifications

Specifications of 110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC
ParameterValue
Product TypeThree-Phase Oil-Immersed Power Transformer
Rated Capacity20 / 25 / 50 MVA
Input Voltage (HV)110 / 115 kV
Output Voltage (LV)11 / 23 kV
Frequency50 / 60 Hz
PhaseThree
Winding MaterialCopper / Aluminium
Voltage RegulationOn-Load Tap Changer (OLTC)
Vector GroupDyn11 / Yyn0
CoolingONAN / ONAF (oil-immersed, radiator)
StandardIEC / GB
CertificationCE, UL, ISO9001
Service Life20 Years
PackingWooden Case
110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — specification and nameplate detail
Specification and nameplate detail

Specifications are based on the standard configuration. Final ratings, dimensions, materials and packaging are confirmed on the approved drawing and order confirmation.

Features and construction

The sealed steel tank carries three sets of high-voltage porcelain bushings, a top-mounted conservator for oil expansion, side radiator banks for cooling and a control cabinet housing the OLTC and protection. The on-load tap changer maintains stable secondary voltage as demand varies, while the oil-immersed construction ensures efficient cooling and long, reliable substation service.

110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — construction and materials detail
Construction and materials detail
110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — internal structure
Internal structure
110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — workmanship detail
Workmanship detail
110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — safety and protection features
Safety and protection features

Typical applications

Utility and industrial substations, power transmission and distribution networks, renewable-energy step-up/step-down stations and large plants requiring regulated 110-kV-class transformation.

110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — typical application
Typical application

Customisation options

Capacity, HV/LV voltage, vector group, tap-changer type (OLTC/off-circuit), cooling class and fittings are customizable to project single-line requirements.

110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — dimensions and layout
Dimensions and layout
110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC — customisation options
Customisation options

Ordering information

  • Selling Unit: Single item
  • Packing: Wooden Case
  • Standards: IEC / GB; certified CE, UL, ISO9001

Specifications are based on the supplied product data. Final dimensions, materials, colors, and packaging are subject to the confirmed sample and order confirmation.

Standards and quality

Manufactured under an ISO 9001, ISO 14001 and ISO 45001 certified management system. Designs follow the IEC 60076 / IEC 62271 series as applicable, with ANSI/IEEE, GB and GOST variants available. Every unit passes routine testing before dispatch; type tests and customer or third-party witnessed factory acceptance tests can be arranged.

Frequently asked questions

What is the rated capacity of the 110–115 kV Three-Phase Oil-Immersed Power Transformer 20–50 MVA with OLTC?

The standard configuration is rated 20 / 25 / 50 MVA at 50 / 60 Hz. Other ratings in the same family can be built to order — tell us the load and we will confirm the nearest standard rating.

What voltage ratio is available?

The standard unit is 110 / 115 kV input to 11 / 23 kV output. Voltage ratio, tapping range and vector group can be adjusted to your network; 50 Hz and 60 Hz designs are available.

Which standards and certifications apply?

The product is designed to IEC / GB. MARS operates an ISO 9001 / 14001 / 45001 certified factory and holds CE (ECM), UDEM, EAC and CQC approvals; every unit is routine-tested before dispatch and type or witnessed tests can be arranged.

Can this product be customised?

Capacity, HV/LV voltage, vector group, tap-changer type (OLTC/off-circuit), cooling class and fittings are customizable to project single-line requirements.

What is the lead time and how is it shipped?

Packed in wooden case. Typical lead time is 25–45 days after drawing approval for distribution equipment and 60–90 days for power transformers and containerised systems. Shipment is by sea from Shanghai on EXW, FOB, CIF or DAP terms with a full document pack.

Enquire about this product

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