Main Components and Structure of 750 kVA Oil Immersed Transformer

Understanding the internal architecture of your electrical equipment is the first step toward ensuring long-term grid reliability.

 

At GNEE, we are a premier global 750 kVA oil immersed transformer manufacturer and supplier, dedicated to delivering high-performance power solutions for industrial and utility sectors.

 

With over 18 years of engineering excellence, our factory produces transformers that adhere to the strictest international standards (IEC, IEEE, and ANSI).

 

This guide provides a scientific breakdown of the 750 kVA oil immersed transformer structure, helping procurement specialists and engineers make informed decisions about their power distribution needs.

 

 

The efficiency of a transformer is primarily determined by its electromagnetic heart. In a 750 kVA oil immersed transformer, the core and the windings work in tandem to facilitate voltage transformation with minimal energy loss.

 

High-Permeability Magnetic Core

GNEE utilizes high-quality, cold-rolled grain-oriented (CRGO) silicon steel for the core. The core is constructed using a multi-step "lap-joint" stacking method, which significantly reduces no-load losses and noise levels. The core is also treated with a special insulation coating to prevent eddy current circulation, ensuring the 750 kVA oil immersed transformer remains cool and efficient under continuous load.

 

Precision Copper or Aluminum Windings

The windings are the "muscles" of the transformer. For our 750 kVA oil immersed transformer models, we use high-purity electrolytic copper or high-grade aluminum. Each layer is separated by high-density insulation paper that has been vacuum-dried to ensure maximum dielectric strength. The winding structure is designed to withstand thermal expansion and the mechanical stresses of short-circuit events.

 

A detailed internal view of the 750 kVA oil immersed transformer core and winding assembly 

 

 

The structural integrity and cooling efficiency of a 750 kVA oil immersed transformer are what define its lifespan. Since these units often operate in harsh outdoor environments, the tank must be both robust and thermally conductive.

 

Corrugated Tank Walls and Radiators

Heat dissipation in an oil-filled unit is achieved through natural convection (ONAN). The tank walls of a GNEE 750 kVA oil immersed transformer are designed with corrugated fins or detachable radiators. This increases the surface area exposed to the air, allowing the transformer oil to cool rapidly as it circulates. Our tanks are made of high-strength steel plates, which are shot-blasted and powder-coated to prevent corrosion in humid or coastal areas.

 

Vacuum Oil Filling Process

To ensure the insulation oil performs at its peak, GNEE employs a strict vacuum-filling process. By removing all air and moisture from the tank before sealing, we prevent the oxidation of the transformer oil. This meticulous attention to the 750 kVA oil immersed transformer structure guarantees a service life often exceeding 25 years.

 

 

A 750 kVA oil immersed transformer is equipped with several critical external components that facilitate connection and protect the internal machinery from faults.

 

High and Low Voltage Bushings: These porcelain or resin insulators allow the electrical cables to enter the tank without grounding out. GNEE ensures that all bushings on our 750 kVA oil immersed transformer are tested for creepage distance and flashover resistance.

 

Tap Changer: To adjust for utility voltage fluctuations, a 5-position or 7-position off-circuit tap changer is standard. This allows the operator to maintain a stable secondary voltage (e.g., 400V) even if the input voltage varies.

 

Conservator Tank and Silica Gel Breather: For larger units, a conservator tank allows the oil to expand and contract with temperature changes. The silica gel breather removes moisture from the air "inhaled" by the transformer, keeping the oil dry.

 

Transformer tap changers & voltage adjustment taps

 

 

To assist your engineering team, we have compiled the standard structural parameters for our 750 kVA oil immersed transformer.

Component	Technical Specification	Material/Type
Rated Power	750 kVA	Copper / Aluminum Windings
Core Material	CRGO Silicon Steel	High-Permeability Grade
Cooling Type	ONAN (Oil Natural Air Natural)	Corrugated Tank / Radiator
Insulation Class	Class A	High-Refinement Mineral Oil
Vector Group	Dyn11 / Yyn0	Standard Distribution
Protection Degree	IP55 / IP65	Weather-Proof Sealing
Standard Accessories	Thermometer, Oil Level Gauge, Pressure Relief Valve	Stainless Steel / Brass
Tap Range	±2 x 2.5%	Off-Circuit Manually Operated

 

 

Selecting GNEE means partnering with a manufacturer that prioritizes technical precision (EEAT). Our 750 kVA oil immersed transformer structure is the result of decades of research into material science and electrical engineering.

 

Advanced Testing: Every unit undergoes a routine test (resistance, ratio, insulation, and pressure tests) and can undergo type tests like temperature rise and impulse testing upon request.

 

Custom Engineering: Need a specific bushing arrangement or a stainless steel tank for a chemical plant? Our engineers can customize the 750 kVA oil immersed transformer structure to fit your unique footprint.

 

Global Export Expertise: We ship globally with reinforced packaging that ensures the transformer arrives intact, regardless of the distance.

 

 A completed 750 kVA oil immersed transformer being crated in a heavy-duty wooden box

 

 

Safety is woven into the very structure of our products. In a GNEE 750 kVA oil immersed transformer, we include:

• Pressure Relief Valves: To instantly vent internal pressure in the event of an internal arc.
• Buchholz Relay (Optional): To detect gas accumulation or sudden oil flow, providing an early warning for internal faults.
• Oil Temperature Indicators: Featuring alarm and trip contacts to prevent thermal damage during overloads.

 

 

The structural integrity and component quality of a 750 kVA oil immersed transformer are non-negotiable for anyone seeking a stable and efficient power network. From the high-grade CRGO core to the corrosion-resistant tank and precision-wound coils, GNEE ensures that every component is built for excellence. As a leading manufacturer, we provide not just a product, but a comprehensive power solution backed by expert support and international certifications.

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