Editing Distribution transformer (section)

{{Short description|Final stage in power distribution to users}}
{{Use American English|date=January 2025}}
[[image:Polemount-singlephase-closeup.jpg|thumb|Single-phase distribution transformer in Canada]]

A '''distribution transformer''' or '''service''' [[transformer]] provides a final [[voltage]] transformation in the [[electric power distribution]] system, stepping down the voltage used in the distribution lines to the level used by the customer.{{sfn|Harlow|2012|p=3-4}}
The invention of a practical, efficient transformer made [[AC power]] distribution feasible; a system using distribution transformers was demonstrated as early as 1882.<ref>{{Cite web |title=Lightcast |url=https://lightcast.io/open-skills/skills/KS1232366XC0QSF5RGMJ/distribution-transformer |access-date=2024-09-11 |website=Lightcast |language=en}}</ref>

If mounted on a [[utility pole]], they are called '''pole-mount transformers'''. When placed either at ground level or underground, distribution transformers are mounted on concrete pads and locked in steel cases, thus known as distribution tap [[Padmount transformer|pad-mount transformers]].

Distribution transformers typically have ratings less than 200 [[Volt-ampere|kVA]],{{sfn|Bakshi|2009|p=1-24}} although some national standards allow units up to 5000 kVA to be described as distribution transformers. Since distribution transformers are energized 24 hours a day (even when they don't carry any load), reducing [[Magnetic core#Core loss|iron loss]]es is vital in their design. They usually don't operate at full load, so they are designed to have maximum efficiency at lower loads. To have better efficiency, [[voltage regulation]] in these transformers should be kept to a minimum. Hence, they are designed to have small [[leakage reactance]].{{sfn|Bakshi|2009|p=1-25}}