High-voltage transformer fire barriers
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File:Transformers at Kraftwerk Kachlet, Passau.jpg on top, separated by a fire barrier]]
High-voltage transformer fire barriers, also known as transformer firewalls, transformer ballistic firewalls, or transformer blast walls, are outdoor countermeasures against a fire or explosion involving a single transformer from damaging adjacent transformers. These barriers compartmentalize transformer fires and explosions involving combustible transformer oil.
High-voltage transformer fire barriers are typically located in electrical substations, but may also be attached to buildings, such as valve halls or manufacturing plants with large electrical distribution systems, such as pulp and paper mills. Outdoor transformer fire barriers that are attached at least on one side to a building are referred to as wing walls.
Voluntary recommendations by NFPA 850
The primary North American document that deals with outdoor high-voltage transformer fire barriers is NFPA 850.{{cite web|url=https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=850|title=NFPA 850 Recommended Practice for Fire Protection for Electric Generating Plants and High-Voltage Direct Current Converter Stations|website=NFPA.org}} NFPA 850 outlines that outdoor oil-insulated transformers should be separated from adjacent structures and from each other by firewalls, spatial separation, or other approved means for the purpose of limiting the damage and potential spread of fire from a transformer failure.
=Automatic fire suppression systems=
Instead of a passive barrier, fire protection water spray systems are sometimes used to cool a transformer to prevent damage if exposed to radiation heat transfer from a fire involving oil released from another transformer that has failed.FM Global Data Sheet 5-4 Transformers https://www.fmglobal.com/research-and-resources/fm-global-data-sheets
=Transformer Fast Depressurization Systems (FDS)=
Mechanical systems designed to quickly depressurize the transformer oil tank after the occurrence of an electrical fault [https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=850 NFPA 850] can minimize the chance that a transformer tank will rupture given a minor fault, but are not effective on major internal faults.{{cite book |title=Guide to Transformer Fire Safety Practices |date=June 2013 |publisher=cigre |page=80}}
=Alternatives to mineral-based transformer oil=
Transformer oil is available in with sufficiently low combustibility that a fire will not continue after an internal electrical fault. These fluids include those approved by FM Global.[https://www.fmapprovals.com/products-we-certify/products-we-certify/flammable-ignitable-liquids-equipment/transformer-fluids Transformers and transformer fluids] [https://www.yumpu.com/en/document/view/8419483/ds-5-4-transformers-data-sheet-fm-global FM Data Sheet 5-4] indicates different levels of protection depending on the type of fluid used. Alternatives include, but are not limited to, esters and silicone oil.{{cite web|url=https://globecore.com/8-3-comparison-of-silicone-oil-and-mineral-oil-transformers.html|website=GlobeCore.com|title=Comparison of Silicone Oil and Mineral Oil Transformers|access-date=2018-12-12|archive-date=2018-12-09|archive-url=https://web.archive.org/web/20181209123606/https://globecore.com/8-3-comparison-of-silicone-oil-and-mineral-oil-transformers.html|url-status=dead}}
See also
{{Commons category|High-voltage transformer fire barriers}}
{{Commons category|Asymmetrical fire barriers}}
{{Commons category|Time/Temperature Curves}}