GB613540A - Improvements in or relating to vibratory synchronously operating electric convertingdevices - Google Patents

Abstract

613,540. Converting. KESSELRING, F. March 20, 1946, Nos. 8649, 8650 and 8651. Convention dates, March 27, 1945, May 11, 1945, and May 18, 1945. [Class 38 (ii)] In converting apparatus for rectifying, inverting or frequency conversion, and comprising contacts operated electromagnetically in dependence on the current in a valve circuit bridging the contacts, the valve current passes through a main contact-actuating means in series with the contacts, so that. the voltage drop in the valve circuit when the contacts are opening is less than the minimum voltage required to cause arcing. In Fig. 1, the A.C. source 1 supplies rectified current through the load 7, the battery 8, and the rectifier contacts 3 synchronously operated by the series coil 5. The contacts 3 are shunted by the valve 6. When, on a half-cycle of the supply and with contacts 3 initially open, the supply voltage exceeds the voltage of battery 8 sufficiently to pass operating current through coil 5, the contacts 3 will close. When the voltage has decreased again to the value of the battery voltage, the contacts re-open. The valve 6 tends to eliminate sparking at the contacts. One coil 5 may operate three valve-shunted switches in a three-phase arrangement and there may be a choke coil in series with each switch. In a modification, the switch has two breaks in series, each break being shunted by three parallel paths made up respectively of resistance, capacity and rectifying valves in series. In Fig. 4, the contacts 3 are shunted by the valve 6 and battery 20 in series; the contacts are closed by coil 5 when the supply voltage exceeds the battery voltage and are closed by spring 19 when the supply voltage decreases again. The series choke coil 14 may be on a core pre-magnetized by coil 16 (in series with choke coil 17) and. having a secondary winding 15 supplying a coil 18 assisting the opening of the switch. The contacts may also be shunted by resistance-capacity combination 21.