The DeRoNi-class () was a group of four boxcab-style electric locomotives with regenerative braking and the capability for multiple-unit control manufactured by Hitachi in 1943-44, very similar to the Toshiba-built DeRoI and the Mitsubishi-built DeRoI-class locomotives.
They were built for the Chosen Government Railway (Sentetsu), who designated them DeRoNi (ãÂÂãÂÂãÂÂ) class, and after the partition of Korea were inherited by the North Korean State Railway, where they were known as the Chà Ângidu (, "Electric 2") class.
The Government-General of Korea began working on a national electric power policy in November 1926, and the resulting plan was completed in December 1931. Chapter 4, "Utilising Electricity in Transportation in Korea" dealt with the electrification of Korea's railways. In 1937, a plan to electrify the BokgyeâÂÂGosan section of the Gyeongwon Line, the JecheonâÂÂPunggi section of the Gyeonggyeong Line and the GyeongseongâÂÂIncheon Gyeongin Line was submitted to the Imperial Diet, which approved it in 1940. The Railway Bureau began implementation of the plan in 1938, and subsequently placed orders with Mitsubishi, Toshiba and Hitachi for 26 electric locomotives.
Sentetsu's order placed with Hitachi was for six electric locomotives intended for operation on the planned electrification of the Gyeongwon and Gyeonggyeong lines - four for the former and two for the latter. Of these, a total of four were delivered by war's end, 2 each in 1943 and 1944; these were designated DeRoNi class (ãÂÂãÂÂãÂÂ) by Sentetsu, and numbered ãÂÂãÂÂãÂÂ1 through ãÂÂãÂÂãÂÂ4.
This class name, ãÂÂãÂÂã (DeRoNi), comes from the Sentetsu classification system for electric locomotives: DeRoNi = De, for "electric" (from é»æ°Â, denki), Ro, to indicate six powered axles (from Japanese roku, 6), and Ni (from Japanese ni, 2), indicating the second class of electric locomotive with six powered axles.
Though generally quite similar in appearance to the DeRoI-class locomotives, there were a number of features that distinguished the DeRoNi class from those. These were: equally spaced side windows; a distinctive ventilator shape; a distinctive arrangement of the deck railings; three-point electrical connectors mounted vertically at the centre of the end decks like on Soviet VL19 class; they were slightly longer and slightly more streamlined than the DeRoI locomotives.
After the end of the Pacific War, at the time of the partition of Korea, all four of the DeRoNi locomotives remained in the North. These were operated on the Kosan-Pokkye segment of Kangwà Ân Line prior to the Korean War. As the Korean War caused the destruction of the electrification of North Korea's rail lines, they sat disused until 1956, when they were reclassified Chà Ângidu () class and numbered ì Â기ëÂÂ1 through ì Â기ëÂÂ4. They were then refurbished at the engine shops at Yangdà Âk for use on the Yangdà Âk-Ch'à Ânsà Âng section of the P'yà Ângra Line, which had been electrified in 1956 as the first stage of North Korea's electrification plans.
Originally painted brown, they were repainted in 1958âÂÂ1959 in the light blue over dark green livery to match the scheme that was made standard with the introduction of the Red Flag 1 class electric locomotives.
No information on the subsequent disposition of these locomotives is available at present.