"Resin-Cast vs. Oil-Immersed: What's the Difference Between the Two Major Schools of Transformers?"

In the era of electrification, electricity is the core of society's operation. Transformers, as key Electrical Equipment, bear the heavy responsibility of voltage conversion and stable power transmission, and are widely used in various scenarios such as urban landmarks, factory parks, and residential communities.

Among transformers, resin-cast dry-type transformers and Oil-immersed Transformers are the two core types, each with its own characteristics and suitable for different scenarios. The following will delve into the core differences between the two.

Structure:

In terms of appearance, oil-immersed transformers have a fully sealed metal casing with plate-type heat sinks, which can absorb the expansion of oil due to temperature changes. Resin-cast dry-type transformers do not have oil conservators or large-area heat sinks; the coils are cast with epoxy resin, and the core and windings can be directly observed, resulting in a simple design.

Internally, both types of transformers use stacked silicon steel sheets in their cores to reduce eddy current losses, but their winding insulation methods differ: oil-immersed transformers have windings submerged in insulating oil, which serves both insulation and heat dissipation functions; dry-type transformers rely on solid materials such as epoxy resin and insulating paper for insulation. The epoxy resin is vacuum-cast and cured to form a fiberglass body that tightly encapsulates the windings, resulting in high insulation reliability.

Performance differences:

 Oil-immersed transformers dissipate heat through insulating oil. The oil absorbs heat from the windings, which is then transferred to heat sinks via natural or forced convection, resulting in high heat dissipation efficiency and suitability for high-capacity, high-voltage applications. They are also affordable and maintenance-free.

Dry-type transformers rely on air convection for heat dissipation. Large-capacity models can be equipped with forced air cooling devices, but air has poor thermal conductivity, resulting in weaker heat dissipation capacity compared to oil-immersed transformers. Temperature rise needs to be carefully monitored under high loads.

In terms of fire and explosion protection, dry-type transformers do not contain insulating oil, eliminating the risk of oil leakage and fire at the source. They offer high safety and are widely used in densely populated or important locations such as hospitals, shopping malls, schools, and data centers. In terms of environmental friendliness, dry-type transformers have no insulating oil, avoiding oil leakage that pollutes soil and water sources. They are also easily recyclable after disposal, meeting environmental protection requirements and offering significant advantages.

For different application scenarios:

 The two types of transformers have clearly different applicable scenarios, each playing a core role in its respective area of expertise.

Oil-immersed transformers have good heat dissipation and large capacity, making them suitable for outdoor substations, power plants, and large industrial enterprises with high power demand and high loads, such as heavy industrial production sites like large steel mills.

Dry-type transformers are fireproof, explosion-proof, environmentally friendly, and have a small footprint, making them suitable for urban power grids, commercial centers, residential communities, hospitals, schools, and other locations with high safety and environmental requirements. They can be directly installed in building distribution rooms, saving space and reducing fire risk.

How to choose the right transformer:

Selection requires a comprehensive consideration of multiple factors, matching the application scenario requirements to choose the appropriate transformer type.

First, clarify the characteristics of the scenario:

Dry-type transformers are preferred for indoor locations with high safety and fire protection requirements (such as hospitals, shopping malls, schools, and data centers); oil-immersed transformers are suitable for outdoor locations with high power demand (such as outdoor substations, power plants, and large industrial enterprises).

Secondly, budget costs must be considered:

 resin transformers have high initial investment but low maintenance costs, making them more economical in the long run. Additionally, the transformer's capacity and voltage level must be considered. Based on actual power demand, a transformer of appropriate capacity should be selected to ensure it meets load requirements while avoiding energy waste and equipment damage caused by overcapacity or undercapacity. The voltage level also needs to match the requirements of the power grid and equipment to ensure stable power transmission and distribution.