| 摘要 |
<p>1473327 Control of A.C. motors DEWHURST & PARTNER Ltd 18 Sept 1975 [23 Sept 1974] 41300/74 Heading H2J Dynamic braking apparatus for a polyphase A.C. induction motor comprises supply lines L1, L2 and L3 having terminals A, B and C for connection to the stator windings of the motor, main switching means MC1-MC3 for interrupting the supply to the motor, a braking capacitor CO having switching means MC4, for connecting the capacitor CO across the terminals B and C when the supply to the motor is interrupted, D.C. supply means DCS1, DCS2 connected to the lines L1-L3 for deriving D.C. for supply to the motor, D.C. switching means for controlling the supply of D.C. to the terminals A and B, control means for operating the main switching means MC1-MC3 and the capacitor switching means to interrupt the supply to the motor and, simultaneously therewith, connect the braking capacitor across the terminals B and C, and for substantially simultaneously operating the D.C. switching means to initiate the supply of D.C. to the terminals A and B, and means responsive to the operation of the control means for resetting the D.C. switching means after a predetermined period. As described, the D.C. switching means is operated a short time period after operation of the main switching means to ensure disconnection of the terminals A, B and C from the supply before the D.C. is initiated.</p> |
