jakelumuuntamo

jakelumuuntamo, known in English as a distribution transformer, is an electrical device in power distribution networks that steps down voltage from medium-voltage distribution lines to low-voltage levels suitable for end users. In typical European networks, the primary side operates at roughly 10–35 kilovolts and the secondary delivers 0.4 kilovolts (230/400 V) to households and businesses.

Distribution transformers are installed at substations, feeders, or in the built environment and come in oil-immersed (liquid-filled) and dry-type forms. Oil-immersed units use insulating mineral oil for insulation and cooling and require safety systems such as Buchholz relays; dry-type transformers rely on solid insulation and air cooling, and are often used indoors or in environmentally sensitive areas.

Key components include a magnetic core, windings, a metal tank, and a cooling system. Some have a load tap changer to adjust output voltage under varying load. Mounting configurations include pad-mounted, pole-mounted, and indoor rack types.

Performance-wise, distribution transformers are highly efficient, typically around 98–99% under load. They incur no-load (core) losses and load losses that depend on current and load conditions.

Maintenance and safety involve regular inspections, oil testing for oil-filled units, thermal monitoring, and protection relays. Environmental and safety considerations focus on oil leakage, fire risk, and proper ventilation for indoor installations.

Standards for design and testing follow IEC 60076 and national regulations; energy-efficiency requirements and labeling exist in many regions. The distribution transformer is a core element of electricity reliability, providing safe, scalable voltage reduction from network to consumer levels.