This paper reports on the most comprehensive data set obtained on
differential and fully integrated cross sections for the process ep→e′pπ+π−. The data were collected with the CLAS detector at Jefferson
Laboratory. Measurements were carried out in the so-far unexplored kinematic
region of photon virtuality 0.2 <Q2< 0.6 GeV2 and invariant
mass of the final hadron system W from 1.3 to 1.57 GeV. For the first time,
nine independent 1-fold differential cross sections were determined in each bin
of W and Q2 covered by the measurements. A phenomenological analysis of
the data allowed us to establish the most significant mechanisms contributing
to the reaction. The non-resonant mechanisms account for a major part of
cross-sections. However, we find sensitivity to s-channel excitations of
low-mass nucleon resonances, especially to the N(1440)P11 and
N(1520)D13 states in kinematical dependencies of the 1-fold differential
cross-sections