Dry-type transformers, as a type of transformer that does not require oil immersion treatment, have their exterior designs closely centered around(thermal dissipation efficiency, hereinafter referred to as "heat dissipation"), structural compactness, and safety protection requirements. Below is a detailed summary of their exterior features:

　　I. Overall Structural Characteristics

　　Modular and Three-Dimensional Design

　　Dry-type transformers typically consist of modules such as iron cores, windings, insulating materials, and enclosures, which are fixed together with bolts or clips to form a three-dimensional structure.

　　The high-voltage and low-voltage windings are arranged in layers, with the iron core positioned centrally, creating a "sandwich" structure to optimize magnetic field distribution and heat dissipation paths.

　　Compact Design

　　Compared to oil-immersed transformers, dry-type transformers are smaller in volume and lighter in weight, making them suitable for installation in spaces with limited room (e.g., indoor power distribution rooms, building basements).

　　Some models are available in vertical or horizontal designs, allowing flexible adjustment according to the installation environment.

　　II. Enclosure and Protection Design

　　Enclosure Material and Form

　　Metal Enclosure: Commonly made of steel plate or aluminum alloy, with a surface coated with anti-corrosion paint to provide dustproof, moisture-proof, and electric shock-proof functions.

　　Protection Level: The enclosure typically meets an IP23 rating or higher (e.g., IP23 indicates protection against solid objects ≥12.5mm in diameter and water sprays). Some models with higher protection levels can reach IP54 (dustproof and splash-proof).

　　Opening Method: Enclosures are available in top-opening and side-opening designs for easy maintenance and inspection.

　　Heat Dissipation Structure

　　Heat Sinks/Fins: Vertical or horizontal heat sinks are arranged on the enclosure surface to increase the heat dissipation area and improve natural cooling efficiency.

　　Forced Air Cooling System: Some high-capacity models are equipped with forced air cooling devices (e.g., axial fans), which create air convection through inlets and outlets on the enclosure to significantly reduce temperature rise.

　　Explosion-Proof and Safety Design

　　Pressure Relief Valve: A pressure relief valve is installed on the top or side of the enclosure to automatically open and prevent explosions when the internal pressure rises abnormally.

　　Temperature Control Device: Built-in temperature sensors and display instruments are used to monitor winding temperatures in real-time. Alarms or trip protections are triggered when temperatures exceed limits.

　　III. Appearance of Windings and Insulating Components

　　Winding Forms

　　Low-Voltage Windings: Mostly wound with copper or aluminum foil, featuring a smooth surface and cylindrical or oblate shapes.

　　High-Voltage Windings: Made of multiple layers of insulated wires, possibly employing a segmented structure to reduce interlayer voltage, with a stepped or spiral appearance.

　　Insulating Materials

　　Main Insulation: H-class insulating materials (e.g., NOMEX paper, glass fiber-reinforced resin) are used, which are resistant to high temperatures and electric arcs, with a light yellow or white appearance.

　　Auxiliary Insulation: Insulating varnish or epoxy resin is filled between windings to form a solid insulating layer with a smooth and even surface.

　　IV. Interfaces and Identification

　　Terminals

　　High-voltage and low-voltage sides are equipped with separate terminal boxes. The terminals are made of copper and are surface-plated with tin or silver to reduce contact resistance.

　　The cover plates of the terminal boxes are removable for easy wiring and maintenance.

　　Identification and Nameplate

　　A nameplate is affixed to the enclosure surface, indicating key parameters such as model, capacity, voltage ratio, impedance voltage, and manufacturing date.

　　The high-voltage and low-voltage windings are marked with phase sequences (e.g., A, B, C) and polarities to ensure correct wiring.

　　V. Typical Exterior Examples

　　Vertical Dry-Type Transformers

　　These transformers have a height greater than their width, with vertically arranged iron cores and windings, suitable for floor-mounted installation.

　　The enclosure is rectangular, and lifting rings may be provided on the top for easy handling.

　　Horizontal Dry-Type Transformers

　　These transformers have a width greater than their height, with horizontally arranged iron cores and windings, suitable for embedded installation in walls or cabinets.

　　The enclosure may be designed in a flat shape to reduce space occupation.

　　Mine Explosion-Proof Dry-Type Transformers

　　The enclosure is made of fully corrugated steel plate structure with high mechanical strength, capable of withstanding internal explosion pressures.

　　The surface is coated with an anti-corrosion layer to adapt to humid and gas-filled environments in coal mine tunnels.

　　VI. Exterior Design Trends

　　Miniaturization and Lightweighting

　　The use of new insulating materials and optimized winding structures further reduces volume and weight.

　　Intelligent Integration

　　Displays or indicator lights are integrated into the enclosure to display real-time operating status and fault information.

　　Communication interfaces (e.g., RS485, Ethernet) are reserved to support remote monitoring and data analysis.

　　Environmental Protection and Energy Efficiency

　　Enclosure materials are recyclable and comply with environmental standards such as RoHS.

　　Heat dissipation designs are optimized to reduce energy consumption and improve energy efficiency ratings.