OEM Oil-immersed Transformer Supplier

As a manufacturer and supplier of various types of transformers, Yibaling’s product range includes oil-immersed transformers. With our extensive experience and advanced, comprehensive technical capabilities, we are able to accommodate custom requirements and provide one-stop OEM services.

What is an Oil-immersed Transformer?

An oil-immersed transformer is a classic power transformer in which the core and windings are completely submerged in special insulating oil. The insulating oil is the core component, playing multiple critical roles:
Firstly, it serves as an efficient insulating medium to prevent internal high-voltage breakdowns;
Secondly, it acts as a coolant, effectively dissipating the heat generated during operation through convection and external cooling devices (such as radiators and fans), enabling the transformer to handle large capacities and high voltages;
Simultaneously, it suppresses electrical arcs and protects metal components from oxidation.

Product Structure

The main structure of the transformer is a "core-winding assembly" sealed within an oil tank, which is filled with insulating oil. Above the tank is an oil reservoir for regulating the expansion and contraction of the oil volume caused by temperature changes.
For safety, a gas relay and a pressure relief valve are also installed - the former can detect the gas generated by internal faults, and the latter automatically releases pressure when the pressure is too high.

Product Application Scope

This type of oil-immersed transformer is widely used. It has a large capacity, high voltage, can withstand overload, mature technology and a long lifespan. It has always been the "main force" in substations and power plants.
Therefore, it is generally used in outdoor areas or in power distribution facilities with fire prevention measures.
While in indoor areas or places with high fire requirements, dry-type transformers are more commonly used - although they have a slightly smaller capacity, they do not require oil, are maintenance-free, and are more fire-resistant.
Both have their own features, and they work together to ensure the stable operation of the power grid.

How Oil-immersed Transformer Works？

The working principle of an oil-immersed transformer is the collaboration of electromagnetic induction and the oil-cooled insulation system. Its core functions involve two aspects:

1. Electromagnetic conversion

AC current is input into the primary winding, generating a magnetic field in the iron core. This magnetic field induces voltage in the secondary winding and outputs it, while achieving voltage regulation through the ratio of winding turns.

2. Key guarantee of the oil system

This is the most different from dry-type transformers:
● Insulation: The insulating capacity of oil is much stronger than that of air, effectively isolating high-voltage components and preventing internal arcing.
● Heat dissipation: The generated heat during operation is first transferred to the oil, which heats up and rises, colliding with the oil tank wall or heat dissipation pipes and cooling down and sinking, forming natural convection and continuously removing heat. Large transformers also use oil pumps to enhance circulation, resulting in better heat dissipation.
● Protection and monitoring: Oil not only delays material aging and inhibits arc spread, but also acts as a "diagnostic medium". If there is abnormal heating or discharge inside, specific gases (such as hydrogen and acetylene) will dissolve in the oil.
By regularly testing oil samples, potential hazards can be detected in advance.
Therefore, the oil-immersed transformer actually has an "insulation - heat dissipation - monitoring" integrated system based on oil, in addition to the core of electromagnetic conversion. This is why it can become a key equipment in the power grid that undertakes high-voltage and large-capacity power transmission tasks.

Compare with dry transformer

How to carry out OEM customization？

Define Customer Requirements

Determine the core guaranteed parameters of the transformer, including capacity, voltage, short-circuit impedance (UK%), no-load loss (PO), and load loss (PK).

Select Raw Materials and Process Requirements

Core: Use specified grade silicon steel sheets, such as Nippon Steel 27ZH100, or equivalent domestic 30QG120 high permeability, low loss grain-oriented silicon steel sheets.
Windings: Conductors use T2 oxygen-free copper, with flat copper wire wrapped in insulating paper; inter-turn insulation uses 0.08mm thick cable paper.
Insulating Oil: Use No. 25 naphthenic mineral insulating oil. Must undergo degassing and dehydration treatment before shipment, with a breakdown voltage ≥50kV.

Define Outdoor Waterproofing Standards

Apply an epoxy zinc-rich primer + acrylic polyurethane topcoat coating process to the tank's outer surface to enhance the outdoor waterproofing performance of oil-immersed transformers.

Shipping Transportation Service

As a factory with extensive export experience, Zhejiang Yibaling Power Equipment Co., Ltd. employs unique transportation and packaging methods for product shipping.
The packaging and transport of oil-immersed transformers follow strict standardized procedures, with the core focus on protecting the main body, insulating oil, and auxiliary components from damage while adapting to various transportation scenarios.
Packaging is divided into main body and accessory components. For inland short-distance transport, the main body is first wrapped in plastic moisture-proof film over the oil tank, then secured with thickened woven fabric or waterproof canvas. All critical areas—flange interfaces, bushing terminals, etc.—are individually fitted with plastic protective caps and rubber seals.
Loading/unloading operations during transportation must use cranes or forklifts, strictly adhering to marked lifting points and fork slots. Maintain the transformer horizontally with a tilt angle not exceeding 15°. Hooking vulnerable parts is strictly prohibited.

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