| 摘要 |
1,196,848. Control of D.C. motors. SPERRY RAND CORP. 16 Dec., 1968 [17 Jan., 1968], No. 59733/68. Heading H2J. [Also in Division H1] An electric motor 24 is prepared for operation in a downward direction when a relay is energized to close contacts D2 in series with a rectifier SCR. The latter is not rendered conductive, however, until contacts D-3 of the relay are closed with some delay whereby the armature current does not pass through the contact D2 until they are firmly engaged. The contacts D2, D3, are opened in reverse order when the relay is de-energized. A capacitor C1X is charged initially through contacts D2, diode D2X, and resistors B5X-R2X, until contacts D3 close to complete a direct charging circuit. A diac DC1X then breaks down to trigger the rectifier SCR for the remainder of the half-cycle involved, after which the capacitor is discharged through diode D1X, resistor R1X, and field winding 42. A network comprising resistor R6X and capcitor C2X serves to bias the breakdown voltage of diac DC1X, this network being subjected to the line voltage through a varistor V1X. If the line voltage increases, capacitor C1X is charged at a greater rate but will be required to reach a higher voltage before triggering occurs. Slow operation is provided by shunting the armature by a swamping resistor R6 and connecting resistors R4X, R5X, into the timing circuit. A slow starting relay has a coil across the armature and delayed contacts which close to short-circuit the resistor R2X, Figs. 4, 5 (not shown). |
