During the general retrofit of old Sprinter trains for regional service in 2003/04, NS plans to upgrade the power electronics by IGBT chopper devices. Choppers eliminate start-up losses and enable regenerative braking. Energy efficiency potential is therefore high on regional lines (~ 30% of traction energy). According to NS, the payback time of the measure will be 5 to 6 years.
New trains are all equipped with choppers. NS Reizigers  has a total of 800 trains, 140 of which are presently equipped with choppers. With the planned retrofit of the Sprinter trains, there will be another 60 trains with choppers.
For the Intercity it has to be decided yet, whether a retrofit is profitable.