GB159873A - - Google Patents

Abstract

159,873. Santuari, E. March 1, 1920,- [Convention date]. Regenerative systems; systems depending on the use of two or more motors.-Relates to regenerative control of direct-current traction motors. working in groups of four, six, eight or more. The general principle of the invention is, in passing from ordinary to regenerative running, to connect the motor armatures like the four arms of a. Wheatstone bridge, and the motor fields in series in the neutral wire, introducing resistances or other elements so as to disturb the balance of the bridge, and thus cause the field to be excited. In the arrangement shown in the Figure, the armatures of four similar motors 1, 2, 3, 4 constitute the four arms of the bridgo and the fields 5, 6, 7, 8 are connected in series across the neutral points, the symmetry being disturbed by placing a variable resistance 9 in shunt with the fields 6, 7. Excitation current will then traverse the fields in the manner acquired for regenerative braking. Any pairs of motors may be replaced by a single motor with double commutator. Other methods of disturbing symmetry are: (1) To put variable resistances in two arms of the bridge; (2) to use motors running at different speeds or having dissimilar saturation curves, or different numbers of turns in the windings. A resistance 12 is placed in the neutral connection to steady the exciting current. The Specification as open to inspection under Sect. 91 (3) (a) states that for some purposes the machines are preferably compounded by the provision of individual series field-windings 5<1>, 6<1>, 7<1>, 8<1>, as shown in Fig. 7 (Cancelled). When six or more motors are in use, special groupings are required, of which Fig. 9 (Cancelled) is one example, E denoting the whole excitation circuit. Load equalizing arrangements, of which the variable shunt resistance R, Fig. 17 (Cancelled), is one example, may be required. The transition from ordinary running to regenerative running takes place through an intermediate stage shown in Fig. 15 (Cancelled), in which two motors 1, 4 run idly on open circuit and the two others run in the ordinary way as series motors. Resistances or other variable elements are adjusted so that on completing the bridge connections at 10, 11 violent surg. ings of current are avoided. This subject-matter does not appear in the Specification as accepted.