GB450060A - Improvements in or relating to electrical supply equipments - Google Patents

Abstract

450,060. Dynamos. PESTARINI, G. M., c /o Soc. San Giorgio, Genoa, Sestri, Italy. Aug. 14, 1935, No. 22919. Convention date, Aug. 15, 1934. [Class 35] In an electric supply equipment including a metadyne generator 1 supplying a variable voltage load, e.g. a traction load 2, 3, and also arranged to supply a supplementary load circuit 4, 5 with substantially constant voltage, the supplementary load circuit is connected across the primary brushes a, c in series with a primary variator winding 6 adapted to neutralize the armature flux due to the supplementary load current to a sufficient extent to render the current flowing to or from the primary constant voltage source 10, 11 substantially independent of the auxiliary load. The number of turns of the neutralizing winding placed on each pole is equal to the effective number of armature turns acting on that pole. A secondary variator winding 12 in the axis of the secondary brushes b, d may be provided for controlling the value of the secondary current, and the value of the primary magnetizing current is reduced sufficiently to cause the machine to function as a generator by the provision of a primary variator winding 7 connected as described in Specification 417,517. The primary source may comprise a small generator driven from the shaft of the metadyne or a battery. To give smoother and more stable operation, a secondary variator winding 17, Fig. 4, carrying the total primary current may be arranged to induce between the primary brushes a voltage opposing the primary current. In the form shown in this Fig., the primary source is a small shunt-excited generator 16 driven from the main machine and controlled by a vibratory regulator 25 sensitive to the primary voltage. The primary magnetizing current may be reduced further by the provision of a winding 19 inducing between the secondary brushes an electromotive force in the same direction as that induced by the rotor ampere-turns due to the primary magnetizing current and traversed only by the current from the primary source. Fig. 5 shows a modification in which the primary source is a battery 18. A stator winding 20 on the metadyne acts in the primary axis and is traversed by a current adjusted by means of a vibrating regulator 21 sensitive to the voltage at the primary brushes. If the voltage is low owing to the battery being in a discharged condition, charging current flows from the generator until the battery voltage rises to the nominal primary voltage or until the maximum excitation has been placed on the winding 20. If the battery voltage is high, the winding 20 will take the necessary current from the battery to give the nominal primary voltage. In a modification of this arrangement, an additional secondary variator winding is excited differentially from an unsaturated shunt machine and the battery 18 as described in Specification 430,009 with the object of supplying a constant secondary output. Specification 399,351 also is referred to.