ES371468A1 - Composite selector switch and reversing switch for tap-changing regulating transformers - Google Patents

Abstract

To reduce the lateral dimensions of a tap changer having a change-over switch for reversing the polarity of the tapped regulating winding with respect to the main transformer winding (thereby doubling the regulation obtainable with a given number of taps) and wherein the fixed contacts of the tap selector are secured on vertical insulating bars in a cylindrical arrangement, the three fixed contacts of the change-over switch are also mounted on vertical insulating bars arranged in the same cylindrical path. Fixed selector contacts, such as 5, 6, of the three phases U, V, W, are arranged on vertical bars 21 to lie on circular paths with even-numbered contacts 2 to 12 co-operating with wipers 24 and odd-numbered contacts with wipers 23. A drive wheel 41 alternately steps Geneva wheels 42 and 43 coupled to wipers 23 and 24 respectively. The spacing of the end contacts (such as 2 and 12) from the mid-value contact K (which is connected to the main winding) is greater than the mutual spacing between the tap contacts to allow for the greater voltage difference, and the wheels 42 and 43 have funnel-shaped slots (44, Fig. 7, not shown) providing the smaller steps and straight slots (45) providing the two larger steps. In the larger spaces between bars 21 supporting contacts K and contacts such as 2 and 12, further bars 28 are fitted and carry outwardly-projecting change-over contacts + and - connected by leads 37 to the ends of the regulating winding. Insulating bars 32 carry arcuate bridges 30 and are pivoted concentrically with selector column 27 by means of arms 34, 35. A dog 46 on Geneva wheel 43 engages in and moves a slotted arm 49 on completion of a revolution of wheel 43, and a dog 49 on arm 34 couples this movement to the bridges 30 which are thus moved (as the wipers 24 engage the contacts K) to interconnect contacts K with the + contacts instead of the - contacts, or vice versa, whereby on completion of a tapping sequence the relative polarity of the regulating winding is reversed.