Shunted Field Windings

—The object of using a shunted circuit for the windings of field magnets of dynamos is that the machine may more readily excite its own fields at starting, and that the current may be produced before the rotating armature has fully taken up its speed. Some dynamos have their fields excited by a separate source of electrical energy, in which case the magnet windings are not connected to the brushes’ ends on the armature, but direct to the terminals of the outside source of electrical energy. As a usual thing, however, it is unnece ary to use a separate source of current for exciting the magnetic fields, since there is a sufficient amount of residual magnetism, acting between the poles of the magnets, to start the generation of electrical energy as soon as the armature begins to rotate.