350,745. Switching systems. SIEMENS-SCHUCKERTWERKE AKT.-GES., Siemensstadt, Berlin. June 26, 1930, No. 19467. Convention date, June 29, 1929. [Class 38 (iv).] A switching arrangement comprises two twoposition relays, with auxiliary contacts, and a twoposition control switch so interconnected that on each movement of the control switch one relay changes its position, the other relay changing its position on the return movement of the control switch. In each position the energizing circuit of one relay passes through auxiliary contacts on the other. Fig. 1 shows the arrangement for relays having separate actuating and restoring coils. Fig. 2 shows an arrangement where resistances in series with the actuating coils permit a holding current to flow after energization and the relays are restored by short-circuiting their coils. The arrangement may be applied to relays having a holding winding and separate actuating and restoring windings. The control switch 170 is shown in its rest position in Figs. 1 and 2 and in the former the relays 2, 3 then take up opposite positions and in the latter similar positions. The operation of the former arrangement may be clearly seen from Fig. 1. Closure of the contacts 172 in Fig. 2 short-circuits the resistance 31 across contacts 24 and the relay 3 is lifted. Upon releasing one control switch 170 it returns to its real position and short-circuits the resistance 21 across contacts 33 and the relay 2 is lifted. The next two movements of the switch 170 similarly effect the return of the relays 3, 2 by short-circuiting their operating coils across contacts 23, 33 respectively. Several control switches may be used, the "seat " contacts being connected in series and the other contacts being connected in parallel. The invention is described as applied to the manual control of the segmental operation of electromagnetic switches each controlling one of a series of "step" switches, and Fig. 4 illustrates a similar arrangement applied to the automatic regulation of an electrical magnitude to which a two-position control relay 12 responds. The relay 3 in both arrangements operates a contact selectively energizing each of two collector leads 10, 11 to which the operating coils of the electromagnetic switches, 4, 5, 6 are alternately connected. The restoring coils are similarly connected to the same wires. Two manually operated control switches (not shown) may be used, adapted, besides controlling the relays 2, 3, to energize " in " or "out " control wires 14, 15 to which the operating or restoring windings are connected each through an interlock contact on the preceding switch in the sequence. Each depression of an " in " control switch causes operation in proper sequence of one electromagnetic switch and closure of its associated step switch 140 . . 160 and each depression of an " out " control switch the distribution in proper sequence of the said switches. A control relay 110 may be provided to operate a subsidiary relay 113 which connects together both collector leads 10, 11 and energizes the '' in " control wire to close all the electromagnetic switches 4, 5, 6 simultaneously, at the same time disconnecting the relays 2, 3. The control of the relays 2, 3 in the automatic arrangement is applied by contacts of a time delay relay 9 which, together with one or other of two relays 7, 8 controlling respectively, the " in " and " out " conductors, is set in operation by the control relay 12. Should the energization of " in " or " out " conductors be unduly prolonged a thermal switch 111 interposes an alarm device 112. The relay 9 is connected in series with a resistance 98 and choke 97, and on operation short-circuits its operating winding across the chokes so that a time delay is associated with operating and restoring movements which continue automatically. The time delay may be raised by a short-circuit winding 92 with a variable circuit resistance; the choke 97 or the relay itself may have a variable air gap, or the choke may have a secondary winding with a variable resistance. An arrangement is also described for controlling a series of electromagnetic switches, each with an operating winding in series with a "holding" resistance, and with a deenergizing winding counteracting the hold on magnetization of the operating winding. The relay 3 in this case has two additional contacts, one controlling two collector conductors for " in " switching and the other two collector conductors for " out " switching. Manually operated " in " and " out " control switches control the relays 2, 3 and, jointly with the relay 3, the respective pairs of collector conductors.