Patent GB-544644-A (GB)
Title: Improvements in or relating to electric circuit interrupters
IPC: H01H33/66
Filed: 1940-09-20
Abstract: 544,644. Converting. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Sept. 20, 1940, No. 14412. Convention date, Sept. 20, 1939. [Class 38 (ii)] [Also in Groups XXXVII and XL] Heat generation by arcing at the contacts of circuitbreaker and in commutators of current converters, is reduced by operating in a gaseous atmosphere, preferably a noble gas such as xenon, at a pressure between 0.1 to 10 cms. of mercury, I cm. being the preferred pressure, the contacts being separated to a gap of 0.1 cms. and operated by moving the wall of the enclosing container. In Fig. 2, the contacts 31, 33 are welded to opposite end plates 17, 19 of a cylindrical, vacuum tight container, contact 33 being movable by a cam 35 and cam-follower 37 which is fixed to a diaphragm 27 welded to a ring 29 of an alloy of iron, nickel and cobalt, known as " Kovar " (Registered Trade Mark), a ring 25 of similar material being welded to a steel plate 23 to which one terminal 39 is attached, whereas the other terminal 41 is connected to a block 43 making a sliding contact with follower 37. The rings 25, 29 are sealed to a glass ring 21, but the ring 21 may be replaced by a composite structure comprising alternate glass and alloy laminae. In Fig. 5 the container comprises a C-section resilient shell 59 welded to the flange 61 of a steel cylinder 55, from which a contact-carrying steel disc 71 is suspended by a structure comprising alloy rings 63, 65 welded to 55, 71 and separated by a glass ring 67. Springs (not shown) may restore the member 59 to open the contacts 73, 75. For higher voltages, a number of containers connected in series may be arranged in an oil tank and operated by compressing the oil by an electromagnetically-actuated plunger released on overload and restored by a spring Fig 6 (not shown). In Fig. 10, the container is distorted to operate the switch without work being done by changing its volume against atmospheric pressure. The contacts 151, 153 are annular and the lower plate 139 carries a peg 155 taking in a recess in the top plate, the arrangement being that when the cam 159 is rotated, the lower plate and peg tilt bodily about the recess. In a modification of this form, Fig. 8 (not shown), a sylphon is secured to the rim of a cup on one side of which is fixed the stationary contact, the movable contact being attached to a cam-catuated tiltable rod passing through the sylphon and arched underneath to receive a peg on the base. Fig. 11 shows the application of the invention to a converter connected between A.C. and D.C. lines 185, 187 respectively, and housed in a container 225. The secondaries 195, 197 of transformer 189 are connected respectively to two sets of slip-rings 205 which are connected to associated 120 degrees segments 209 of commutators 211, the slip-rings and commutator being driven at synchronous speed by a motor 213 energized from transformer 189. Brushes 215 are arranged and connected as shown, and each has an arcing tip 223 the object of which is to take the arc caused by under-commutation, when the potentials of the receding and approaching segments become equal after the brush has left the receding segment. Extinction is assisted by saturable chokes 207 which are desaturated when commutation occurs. The leads enter the container 225 by way of glass plugs 229 which are sealed to the leads and to outer alloy rings 231 welded to the housing. In a modification, Fig. 13 (not shown), the brushes and leads are replaced by a circular ring which is tangential to the segments and functions as a brush. The Specification as open to inspection under Sect. 91 described also a lightning-arrester in which a container as shown in Fig. 2 is modified by the use of the above described alternate glass and alloy laminae in place of ring 21, Fig. 3 (Cancelled) (not shown). This subject-matter does not appear in the Specification as accepted.