  We investigate the physical properties of large-scale wind structures around
massive hot stars with radiatively-driven winds. We observe Discrete Absorption
Components (DACs) in optical He I P Cygni lines of the LBV binary MWC 314
(Porb=60.8 d). The DACs are observed during orbital phases when the primary is
in front of the secondary star. They appear at wind velocities between -100
km/s and -600 km/s in the P Cyg profiles of He I lam5875, lam6678, and lam4471,
signaling high-temperature expanding wind regions of enhanced density and
variable outflow velocity. The DACs can result from wave propagation linked to
the orbital motion near the low-velocity wind base. The He I lines indicate DAC
formation close to the primary's surface in high-temperature wind regions in
front of its orbit, or in dynamical wind regions confined between the binary
stars. We observed the DACs with Mercator-HERMES on 5 Sep 2009, 5 May 2012, and
6 May 2014 when the primary is in front of the secondary star. XMM-Newton
observations of 6 May 2014 significantly detected MWC 314 in X-rays at an
average rate of ~0.015 cts/s.
