When the SJ was electrifying the Malmbanan between Kiruna and Riksgränsen, they also thought about a small number of passenger services on this line that was mainly used for the transport of iron ore. So they ordered two passenger locomotives from Falun which were to be equipped with electrical parts from ASEA. They were designated type P and numbered 27 and 28. 28 was actually the first one to be delivered in February 1914 and 27 followed in October. After some years the class was renamed from P to Pa to distinguish it from the Pb that was already under development.

As they did not have to reach a high tractive effort, they only had two driving axles. For best running characteristics at speed they had a driver diameter of 1,575 mm and a two-axle bogie on each end. They were powered by a single 665 kW (904 hp) motor that transmitted its power onto a crank axle and then to the two driving axles. With a top speed of 100 km/h, starting tractive effort was only 81 kN. Both were withdrawn in 1957. No. 27 was preserved, today it is on display in the museum at Gävle.