DIN 30NF250 Transformer Bushing Insulators

Specifies adherence to German industrial standards, ensuring specific dimensional, material, and performance characteristics. Standards like DIN 42531 or DIN 42532 typically cover these types of bushings. 

Represents the nominal voltage (Un​) rating in kilovolts (kV). This bushing is designed for electrical systems operating at 30 kV. The maximum system voltage (Um​) it's rated for is usually 36 kV. 

“NF” Indicates that the specific type or series according to the DIN standard. This generally designates a standard outdoor bushing suitable for use with oil-filled transformers.

Function 

Provides electrical insulation between the live conductor and the transformer tank, provides a passage for the conductor, acts as an external connection point, and seals the transformer tank opening. 

Application 

They are primarily used on the high-voltage side of medium-voltage, oil-filled distribution transformers or smaller power transformers operating in the 30 kV voltage class. They are typically installed outdoors. 

Material 

Most commonly made from high-quality electrical porcelain (usually brown or grey glazed), known for its insulating properties and durability. Composite materials (like silicone rubber over a fiberglass core) are also used. 

Construction 

Consists of a central conductor rod, an insulating body (porcelain or composite) with external sheds (skirts) to increase creepage distance and prevent flashover in polluted or wet conditions, mounting hardware (like a flange) to attach to the transformer, and terminals at both ends for electrical connections (internal to the winding lead, external to the power line/cable).