Political concerns, such as desire for self-reliance and the then-ongoing Ch'ŏllima Movement, however, led to the decision to undertake mass production domestically.

[4] This was a universal locomotive considerably larger than the Type 30E, with Co'Co' axle arrangement and distinctive body work featuring a rounded front end and trapezoidal, inset cab windows[3] The traction motors, transformers, auxiliary motors, master controller and other components used on the first prototype were imported from the USSR or China.

The first prototype rolled off the assembly line on 30 August 1961; Kim Il Sung visited the plant for the occasion and chose the locomotive's name personally.

[2] Eventually over 150 were built; in 2002 the KSR rostered 290 electric locomotives - the bulk of the motive power fleet - with the Red Flag 1 type (including variants) accounting for over half of that number.

Their distinctive features are the rounded front end with trapezoidal cab windows, and fluted skirting with smooth carbody sides.

The late-style Red Flag 1 units, numbered in the 5200 and 5300 series, were likewise all painted in the standard scheme, except for certain named vehicles.

[3] However, to add to the confusion, over the years many units were upgraded and rebuilt, and given new class names, whilst retaining their original running number.