| 摘要 |
993,315. Converters. BROWN BOVERI & CO. Ltd. Aug. 11, 1961 [Aug. 13, 1960], No. 29115/61. Heading H2F. In a converting system comprising two vessels 3, 4 for two directions of current flow in load circuit P, N, vessels 3, 4 having negative grid bias voltage sources 12, 13 and grid control devices 16, 17 which cause one vessel to conduct by grid-voltage impulses whilst the other vessel remains blocked, on changing direction of load current, after the current has been controlled to zero the firing of the incoming vessel is made dependent upon the establishment of negative grid bias voltage in the outgoing vessel by means of voltage monitors 19, 20 in conjunction with switches for devices 16, 17. When vessel 3 is conducting, the connection between device 16 and vessel 3 is established through closed contact 21a (relay 21 being energized by load current through current transformer 6), closed contact 23a (relay 23 energized by master valve 18) and closed contacts 20a (relays 20 energized by negative grid voltage in vessel 4). At the same time device 17 is cut off from vessel 4 by contacts 19a, 23b, 22a, all open. On changing over, master valve 18 reduces the current in vessel 3 to zero (opening contact 21a) and changes over relay 23, opening contact 23a and closing contact 23b. When negative grid bias voltage is established on vessel 3, relays 19 are energized closing contacts 19a and connecting device 17 to vessel 4. Load current from vessel 4 closes contact 22a. |
