| 摘要 |
<p>330,528. Langley, E. H. M., and Associated Electrical Industries, Ltd. March 7, 1929. Reversing arrangements.-A continuous current motor for a planning-machine &c., when reversed has the series resistance controlled by an accelerating relay having two coils, one connected across the armature and the reversing contactors, and the other across the supply. The resistance may be cut in or out in stages if desired by using several relays. The procedure for starting a planing machine motor is as follows :-closure of the line switch LS and " start " push button causes energization of the no-volt coil OCNV and closure of contacts NV4, NV1- Contacts NV3 when closed effect the release of the brake (not shown) and NV2 when closed permits the energization of coils OCC and OCC1, the controller being in the "cut" position as shown, and the contacts C and C1 are thereby closed. The closing of contact C closes the switch AXC, whereupon coils OCAC1<1> and OCAC1 of the accelerating relay are energized, by the armature and supply voltages respectively. When the armature E.M.F. reaches a predetermined value, this relay closes contacts AC1 and AXAC1 and opens contacts BXAC1. The closing of AC1 short-circuits the accelerating resistance SR and the series field SF, whilst the closing of AXAC1 results in the closing of contacts AC2 and the opening of contacts AXAC2 and BXAC2. Contacts BXAC1 and AXAC2 now being opened, coils OCC and OCC1 are energized with reduced current through the resistance E. The motor is reversed by the controller being thrown to the " return" position. The contacts C and C1 open and thereby AXC is opened, causing coils OCAC1 and OCAC1<1> to be de-energized. The contact AC1 then opens and causes contacts AXAC1 to open and BXAC1 to close. The opening of contacts AXAC1 de-energizes coil OCAC2, thus opening contacts AC2 and closing AXAC2. As BXC and BXC1 closed when contacts C and C1 opened, and as the resistance E is now shortcircuited, contacts Rand R1 will close, coils OCR and OCR1 now being energized and will close AXR. At this stage the armature E.M.F. is still in the original direction, though the connections have been reversed, consequetly the current in coils OCAC1 and OCAC1<1> are in opposition, and contacts AC1 cannot therefore close until the direction of the armature E.M.F. has reversed and then reached a predetermined value. Alternatively these coils may be arranged so that contacts AC1 cannot close until the armature voltage, is lower than a predetermined value but is not opposed to the supply voltage. The procedure will then be similar to that in the " cut " direction except that in this case the opening of contacts BXAC2 will be effective to de-energize the coil OCFR and hence introduce resistance into the shunt field. The push buttons IPB and IPB1 are for inching, contacts NV5 being closed when the no volt coil OCNV is de-energized.</p> |
