| 摘要 |
1,164,782. Transformers. SIEMENS A.G. 10 Jan., 1968 [11 Jan., 1967], No. 1504/68. Heading H1T. An on-load transformer tap-changing arrangement comprises a single vacuum switch V connected between a load line L and via changeover switch U, one of two tap-selector contacts 1, 2, auxiliary switch(es) and resistor(s), such as a-d and W 1 , W 2 , being provided to enable the current flow from a first tap to be broken in the vacuum switch after current flow has already commenced from the second tap. Fig. 1 shows, for one embodiment, the switch positions when tap 11 is conducting, change-over to tap 12 being effected by changing U to U 1 and closing V to transfer the current flow to the vacuum switch, opening a and b and then closing c to commence current flow from tap 12 through resistor W 2 . The vacuum switch is then opened to break the current flow from tap 11, switch d being closed after the arc has been quenched. The switches may be sequentially operated by a cam mechanism and a relay inserted at x, y to prevent the mechanism closing d before the arc is quenched. In alternative arrangements (Figs. 2, 3, not shown), switches a and d are eliminated, the normal current path then being through the vacuum switch, which is reclosed to complete the switching operation instead of closing d or a. With this arrangement only one resistor need be used, connected between L and one or other tap by a second change-over switch (œ, Fig. 3). |
