Portable BS-series site-power (byggstrøm) autotransformer rated 6.3 kVA, converting between 3 x 400 V and 3 x 230 V networks for tool and construction-site supply. Autotransformer topology provides high efficiency and compact size compared with an equivalent isolated transformer at the same rating. Intended for temporary distribution to power tools and small machinery where the available site supply does not match the tool voltage.