GB691168A - Improvements relating to air-blast switches - Google Patents

Abstract

691,168. Air-blast switches. CZECHOSLOVAK HEAVY ENGINEERING WORKS, NATIONAL CORPORATION, and GROSSE, V. May 14, 1948 [May 15, 1947], No. 13420/52. Class 38 (v) In an air-blast switch having main interrupting contacts 1, 2, parallel-connected auxiliary spark-gap electrodes 3, 4 with a series resistor 5, and a pneumatically-operated disconnecting switch 6, the application of compressed air to the arc chamber 8 of the electrodes 3, 4 is delayed with respect to the opening of the contacts 1, 2, and a valve 47, 48 controlled by air from the chamber 8 is used to close the outlet from the arc chamber 7 of the main contacts. The valve comprises a disc 47 mounted on sleeve 55 on a piston 46, the parts 47, 55, 46 being slidable on a fixed arc electrode 42 and the disc 47 co-operating with a valve seat 48 formed within the nozzle contact 2. The switch is opened on the application of compressed air through a hollow supporting insulator 11. The air pressure acting on a piston 56, Fig. 2, moves the piston 56 down against the bias of a spring 9 to separate the contact 1 from the nozzle contact 2. The piston 56, when the contacts 1, 2 are fully open, uncovers a port, admitting air to a pipe 58, air then passing through a spiral delay pipe 16 to the chamber 8. Air passing through an insulating nozzle 25 extinguishes the arc between the electrodes 3, 4 and air flowing through the annular space 53 around the nozzle 25 enters a pipe 21 from which air is supplied to a cylinder 44 to move the piston 46 to close the valve 47, 48 so shutting off the blast through the nozzle contact 2 and maintaining the contacts 1, 2 open under pressure. Air from the pipe 21 also enters a cylinder 22 to open the isolator, 6 the blade of the isolator moving out off engagement with a fixed contact (not shown) down into a slot formed in a gas cooler 32, as shown. Conductivity between the moving contact 1 and its holder 15 is maintained by a helical spring ring 64 disposed around an extension 61 of the contact and between conical surfaces of a disc 63 and the holder 15, the spring 9 acting on the disc 63.