DIN EN And ANSI Transformer Bushing Standards Explained

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Three standards families cover most transformer bushing drawings in circulation. They are not interchangeable, and knowing which one your drawing follows decides what you can order.

Why Three Families Exist At All

A bushing does the same job everywhere, but the dimensional pattern, the test values and the part designation grew up separately in Germany, across Europe and in North America. A terminal board drilled to one pattern will not take another, which is why the standard on the drawing matters more than the electrical rating when you are ordering a replacement.

The DIN Families

DIN specifications are no longer live standards but are still utilised widely by the transformer and distribution industry. DIN 42530 covers the 1kV low voltage series, DIN 42539 the 3kV series, and DIN 42531 the high voltage NF patterns. Bushings here are also manufactured to DIN 52432, 42533, 42534 and 40680. The NF number identifies the voltage class: 10NF is 10kV, 20NF is 20kV and 30NF is 36kV.

DIN 42531 30NF250A Transformer Bushing

The EN Families

EN 50180 and EN 50386 are the current specification set. Together they cover ratings from 1kV through 52kV and up to 12500A, with a wide variety of creepage distances for different environmental conditions. EN 50386 extends the low voltage table further than DIN 42530 does, reaching 4000A at 85mm creepage. Construction type variants such as EN 50180 Type 3 are ordered by type, not just by rating.

EN 50180 24kV 250A Porcelain Transformer Bushing

The ANSI Family

ANSI transformer bushings are specified by model, with published height, arcing distance, creep distance, shed count and weight. ANSI-15/50 is 485mm tall with 310mm creep across 5 single umbrella sheds at 2.8kg, ANSI-18/50 is 541mm with 480mm creep across 8 sheds at 3.5kg, and ANSI-27/50 is 722mm with 830mm creep across 12 sheds at 5kg. The low voltage side uses imperial threaded rods with eyebolt and flat connectors rather than metric stems.

Threaded ANSI 18kV Transformer Bushing ANSI-18/50

What Testing Applies Across All Of Them

Regardless of which family the dimensional detail comes from, all outdoor bushings are manufactured and tested in accordance with IEC 60137. That is the common ground between the three, and it is the reference to quote when a specification asks for test evidence.

DIN 42531 10NF250A Transformer Bushing

How To Decide What To Order

Order against the standard printed on your drawing, not against the electrical rating alone. If the drawing is lost, send the installed bushing or a photograph with the tank hole size and stem thread and the pattern can be identified from those two figures in most cases.

Products Referenced In This Guide

High Voltage Transformer Bushings

DIN 42531 30NF250A Transformer Bushing

High Voltage Transformer Bushings

• DIN 42531 30NF Pattern 250 A

EN 50180 24kV 250A Porcelain Transformer Bushing

Screw Thread Transformer Bushings

• Standard IEC60137

Threaded ANSI 18kV Transformer Bushing ANSI-18/50

Low Voltage Transformer Bushings

• Overall Height H 541 mm
• Creep Distance 480 mm
• Weight 3.5 kg

DIN 42530 1kV 630A Ceramic Bushing DT 1/630

• Tank Hole Size 45 mm
• Creepage Distance 75 mm
• Weight 0.26 kg

Related Ranges And Applications

High Voltage Transformer Bushings

Low Voltage Transformer Bushings

Screw Thread Transformer Bushings

Distribution Transformer Manufacturers

Standards Compliance Across IEC DIN EN ANSI AS GB And GOST

Questions About This Topic

Apply This To Your Own Project

Send the drawing or describe the site and we will recommend a pattern and a creepage class.