| 摘要 |
<p>375,344. Master control of D. C. motors. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.-(Assignees of Cook, W. G.; 499, Marion Avenue, Forest Hills, Wilkinsburg, Pennsylvania, U.S.A.) March 10, 1931, No. 7374. Convention date, March 17, 1930. [Class 38 (iii).] Reversing.-A motor 6, as shown, is reversed by "plugging," and during "plugging" a high resistance 56 is maintained in circuit for a period determined by a time-limit relay 8 or 9 sensitive to the back E.M.F. of the motor. In the first position of a master controller 10, one of the directional contactors 3 or 4 and line contactor 5 are closed, the coil of the latter being energized over contacts 26 on the contactor 3 and contacts 106 on the relay 8. Relay 9 opens as its magnetizing coil 23 is energized and accelerating relays 14, 15 open as their magnetizing coils are shunted across resistance sections 55, 56. In the second position of the controller 10 contactor 11 closes immediately, and contactors 12, 13 close sequentially as the relays 15, 14 close with delays after the de-energization of their magnetizing coils. If the controller 10 is thrown from "full forward" to " full reverse " position, contactors 11, 12, 13 open as the controller passes through the "off" position, but contactor 11 does not reclose immediately since its original energizing circuit is opened at contacts 26, and an alternative circuit prepared at contacts 34 on the contactor is not completed until relay 9 closes, which does not occur until the motor comes to rest. In a modified arrangement the energizing circuits of the contactors 12, 13 are taken over stepped contacts on the drum 10 as well as over contacts of the accelerating relays, in order to allow additional stages of manual and automatic acceleration and deceleration. The Specification as open to inspection under Sect. 91 (3) (a) describes other arrangements. In one of these arrangements a polarized relay in the energizing circuit of the contactor 11 is used in conjunction with timed relays having their coils connected across resistance sections. In another arrangement the polarized relay is replaced by an additional timed relay. In a third arrangement the additional timed relay is duplicated, one relay being used for each direction of running. This subject-matter does not appear in the Specification as accepted.</p> |
