Improvements in or relating to the Prevention of Sparking in the Control of Electric Circuits.

摘要

22,524. Price, W. A. Oct. 3. [Cognate Application, 22,542/12.] Commutator switching - arrangements. - Multiphase alternating current is produced from a continuouscurrent source by commutating the connexions between the terminals of the respective circuits, those receiving the alternating current being in series relationship with the directcurrent circuit; direct current is obtained from a multiphase alternating current by similar means, but the alternating-current circuits are placed in parallel with the direct-current circuit. Sparking is avoided by using condenser connexions of the kind described in Specification 14,380/10. A two - phase alternating current is obtained between the terminals A, B and A1, B1, Fig. 5, of two alternating-current circuits W, W1 from a direct-current potential-difference V applied to terminals C, D. The terminals mentioned are connected together and to a terminal M, as shown, by condenser connexions P, to P4 and P11 to P41 of the order referred to, and these connexions are short-circuited in the following sequence, assuming P1, P3 and P11, P21, P31, P41 short-circuited to commence with : break P21, P41 and make P2, P4 ; break P1, P3 and make P21, P41; break P11, P31 and make P1, P3; break P2, P4 and make P11, P31, and so on. Only two condenser connexions are necessary in the modified arrangement shown in Fig. 6, a similar switching cycle being employed. A commutator is described for carrying out the circuit changes according to this Figure. Twophase alternating current is changed into a practically steady continuous current by an arrangement of circuits like Fig. 10, the alternating-current circuits W, W1 being connected in parallel at C, D, C', D1 to the direct-current circuit V, instead of in series as in Fig. 5. The cycle is as follows, P21, P,' being made: make P1, P3 and break P21, P41, make P11, P31 and break P1, P3, make P2, P, and break P11, P31, make P21, P41 and break P2, P4, and so on. The condenser connexions may be reduced to four in number by the arrangement shown in Fig. 11, d, d1, e, e1, f, f1, g, g1 being simple switch connexions and the cycle being as follows, assuming e1 and g are closed: make P2, P4, d, and f1; break e1, g, P2, and P,; make P1, P3, e, and g1; break d, f1, P1, and P3; make P2, P4, d1, and f; break e, g1, P2, and P4; make P1, P3, e1, and g; break d1, f, P1, and P3, and so on. The general type of condenser connexion used is illustrated in Fig. 2. A condenser K alone is connected between the circuit terminals A, B when the circuit is open, and the circuit is closed first by the switch 1 through an inductance L and resistance It in parallel, whereby the condenser is discharged; the switch 2 is then closed to complete the discharge of the condenser; the switch 3 is finally closed so as to place a highly non-inductive circuit in shunt to the condenser. The circuit between A, B is opened sparklessly by the switches 1, 2, 3 operated in that order. The rate of discharge of the condenser K may be increased without increasing the maximum discharge current by shunting the resistance R by a lower resistance when the condenser is partly discharged.