Patent GB-472192-A (GB)
Title: Improvements relating to alternating current electric winder equipments
IPC: B66B1/12
Filed: 1936-06-30
Abstract: 472,192. Control of A.C. motors. WORRALL, R. W., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. June 30, 1936, No. 18183. [Class 38 (iii)] Non - regenerative braking.-Electric winding equipment includes a wound-rotor induction motor having means for effecting electric braking by supplying direct current to one of the windings and inserting resistance in the other winding, control means adapted to effect a co-ordinated control of the D.C. excitation and the resistance, and safety means for preventing application of the braking connections except when the A.C. supply is disconnected. In the arrangement shown in Fig. 1, the motor WM is fed from the main power supply MPS through forward and reverse contactors LSa and LSb and is controlled by a variable liquid resistance CN in the rotor circuit. For braking, direct current is supplied to the stator from a generator DCG driven by an auxiliary motor AM and provided with an exciter EX in series with a resistance RG, which is varied to vary the strength of the direct current applied to the stator during braking. A control lever DL effects co-ordinated control of the resistances RG and CN through linkage L, and also controls the forward running, reverse running and braking connections through a master switch MS, the arrangement being such that the braking contactor BS can only be energized when both forward and reverse contactors are de-energized. In one arrangement of the control lever, Fig. 2, the lever DL is pivoted in a stirrup 6 freely mounted on a shaft 7. Below the pivot, the lever is forked and connected by pins 8 to a block 9 which is slidably mounted on, but splined to, the shaft 7. The left end of the shaft is connected by a quadrant and pinion to an arm 10 operatively connected to the controllers RG and CN of Fig. 1, while the right end of the shaft is provided with a coupling 11 connected to the braking contacts of the master switch. The forward and reverse contacts are connected to a coupling 14 carried by a sleeve freely mounted on the shaft 7, the sleeve also carrying a block 13 which can be coupled to the block 9 when the latter is moved to the right. By moving the block 9 to the left it can be coupled with another block 12 connected by gearing 15 to the block 13 to drive the latter in the reverse direction. The lever DL passes through a slotted guide plate 18 and for forward or reverse running is moved into the slots 19 or 20, and for braking into the slot 21. In a modification, Figs. 3 and 5, the lever DL works in an H-shaped slot in a plate 18, and the master switch is arranged in two sections 22, 23 for forward and reverse running, each section containing a set of braking contacts. The forward or reverse connections are made by moving the handle into the recesses 19 or 20, and the braking connections by moving it into either of the recesses 21 or 21<1>. The lever is fixed to a block 24 pivoted at 25 to a shaft 26 carrying arms 28, 28<1> at its ends. According to the position of the lever, latches 29 or 29<1> latch the arm 28 or 28<1> to an arm 30 or 30<1> connected to one of the sections 22 or 23, and the section which is not connected is at the same time locked against movement by a rod 33 mounted in a radial slot in the end of the lever DL. In another construction, Fig. 6 (not shown), the lever moves in an h-shaped slot and is pivoted in a stirrup geared to the regulators RG, CN. By moving the lever about its pivot it can be clutched to either the braking contacts or to the forward and reverse contacts of the master switch. In another arrangement, Fig. 7 (not shown), the lever moves in a H-slot, and is pivoted in a stirrup geared to the controllers in such a manner that it can be clutch to either of two sections of the master switch, each of which carries braking contacts.