JR Freight Class EF510

The Sea of Japan trunk route is electrified on three different systems: DC, 60 Hz AC and 50 Hz AC. Development of a successor for the EF81 had begun shortly after the privatisation of Japanese National Railways: an earlier prototype, the EF500, was built in 1990 for the same Sea of Japan trunk route, but with a rated output of 6,000 kW it proved excessively powerful relative to actual traffic volumes and, together with technical problems, never reached series production. The EF510 was instead developed by adapting the design of the EF210, the DC-only type built at the same period with running costs optimised, into a dual-system AC/DC machine.

The locomotive is a multi-system machine able to run under 1,500 V DC and 20 kV AC at 50/60 Hz overhead supply, collecting current by pantograph, and is built by Kawasaki Heavy Industries, with the electrical equipment supplied by Mitsubishi Electric. Its main circuit uses a Mitsubishi Electric VVVF inverter system with IGBT devices, derived from that of the Class EH500 and configured so that each of the six traction motors is controlled individually by its own inverter (a 1C1M arrangement). The six traction motors are squirrel-cage three-phase induction motors of the FMT4 type, identical to those of the EF210 and each rated at 565 kW (one-hour rating). Like the EF210, it rides on axle-beam bolsterless bogies, type FD7N at the ends and FD8A in the centre.

As a measure against the cold climate and salt damage of its operating territory, only the pantographs and the protective earthing switch are mounted on the roof, with the isolators, circuit breakers and other high-voltage apparatus that earlier locomotives carried on the roof relocated inside the body. It has a power output of 3,390 kW, a tractive effort of 199 kN and a maximum operating speed of 110 km/h.

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The first locomotive, EF510-1, was completed at Kawasaki Heavy Industries' Hyogo Works (now Kawasaki Railcar Manufacturing) on 12 December 2001, delivered in February 2002 and registered by JR Freight on 15 February 2002. It was initially based at Shin-Tsurumi Depot before being transferred to Toyama Depot in 2002. Unusually, although JR Freight normally assigns the 900 number series to its prototype locomotives, the EF510's pre-production unit was numbered EF510-1, so the class is the only one of its kind with no 900-series member. After basic performance tests and trial running with revenue trains, series production began in 2003, and the class gradually displaced the ageing EF81. The first full-production locomotive, EF510-2, was delivered in November 2003; this and subsequent locomotives carried "Red Thunder" bodyside branding. EF510-1, EF510-2 and EF510-3 entered service on the Sea of Japan trunk route on 13 March 2004. The EF510-0 subclass was given the nickname "ECO-POWER Red Thunder" through a public competition, forming a pair with the "ECO-POWER Blue Thunder" of the contemporaneous Class EH200.

The class is subdivided into the original EF510-0 subclass operated by JR Freight and fifteen EF510-500 subclass locomotives ordered by and originally operated on passenger services by JR East. The EF510-500 subclass replaced JR East's fleet of EF81 locomotives formerly used to haul the Cassiopeia and Hokutosei overnight sleeping car trains from June 2010; these were the first locomotives to be ordered by any of the JR passenger operating companies since privatisation. Each locomotive cost around 400 million yen. The first, EF510-501, was delivered from the Kawasaki Heavy Industries factory in Hyogo Prefecture on 18 December 2009, arriving at Tabata Depot in Tokyo on 19 December, and entered service on 25 June 2010, when the subclass began hauling the Cassiopeia from Ueno to Sapporo. Hokutosei duties on the same route followed from 14 July 2010, and Joban Line freight haulage from 1 December 2010. Two of the fifteen (EF510-509 and EF510-510), built in 2010, were painted in a dedicated silver scheme with five coloured stripes to match the Cassiopeia rolling stock (the E26 series); the others were finished in the Hokutosei livery of blue with gold lining and a shooting star.

From the start of the revised timetable on 16 March 2013, when JR East's Tabata Depot ceased hauling freight under contract, Joban Line freight duties operated by JR East EF510-500 locomotives were taken over by JR Freight Class EH500 locomotives, and locomotives EF510-501 to 508 and 511 became surplus and were sold to JR Freight in July 2013. JR Freight bought EF510-509, 510 and 512 to 515 in fiscal 2015 and 2016, EF510-512, 513 and 515 being transferred in December 2015, so that all fifteen JR East locomotives passed to JR Freight. The last two, EF510-509 and 510, hauled the Cassiopeia until 21 March 2016 and left Tabata Depot on 31 March, ending JR East's operation of the type.

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A further EF510-300 subclass of 17 locomotives (EF510-301 to 317), built to replace ageing locomotives in the Kyushu area, is operated there by JR Freight; the first unit, the pre-production locomotive EF510-301, was completed in 2021, and the subclass entered service on the Nippo Main Line on 25 February 2023. The EF510-300 subclass was designed with AC regenerative braking, usable only on AC-electrified sections, in addition to the dynamic (rheostatic) braking of the earlier units. Because the subclass works exclusively on AC-electrified lines in Kyushu and uses regenerative braking routinely, the production locomotives built from fiscal 2023 omit the braking resistors, and EF510-301 had its resistors removed in fiscal 2024. The subclass is also fitted with an input-current limiting function that can cap the current drawn from the overhead line to a level comparable to that of the Class EF81, in order to suit the AC feeding equipment in Kyushu.

As of 2025 JR Freight has 55 locomotives of the class (EF510-1 to 23, 501 to 515 and 301 to 317), with the EF510-0 and EF510-500 subclasses based at Toyama Depot and the EF510-300 subclass at Moji Depot. In the EF510 classification, E denotes an electric locomotive, F denotes six driving axles, and 510 denotes an AC/DC locomotive with AC motors.

• 2002The first locomotive, EF510-1 (a pre-production locomotive), is delivered in February and initially based at Shin-Tsurumi Depot before transfer to Toyama Depot the same year; JR Freight registration is 15 February 2002.
• 2004Full-scale revenue service begins: EF510-1 together with production locomotives EF510-2 and EF510-3 enter service on the Sea of Japan trunk route (Nihonkai Jukan Line) from 13 March, progressively replacing the ageing Class EF81.
• 2010The EF510-500 subclass enters JR East service: EF510-501 begins haulage on 25 June, replacing EF81 locomotives on the Cassiopeia and Hokutosei overnight sleeping-car trains; two units (EF510-509 and EF510-510) wear a dedicated Cassiopeia silver livery.
• 2013From the March timetable revision, JR East EF510-500 Joban Line freight duties pass to JR Freight Class EH500 locomotives; surplus locomotives EF510-501 to 508 and 511 are sold to JR Freight in July.
• 2016All fifteen JR East EF510-500 locomotives have been sold to JR Freight (the last, EF510-509 and 510, leave Tabata on 31 March), ending JR East operation of the type.
• 2023The Kyushu-area EF510-300 subclass (intended to total 17 locomotives) enters service on 25 February, with pre-production EF510-301 working Nippo Main Line freight, replacing ageing Class ED76 and Class EF81 locomotives.