Patent GB-395833-A (GB)
Title: Improvements relating to electric switches or circuit breakers
IPC: H01H33/96
Filed: 1932-04-25
Abstract: 395,833. Arc-rupturing in switches. BRITISH ELECTRICAL & ALLIED INDUSTRIES RESEARCH ASSOCIATION, WHITNEY, W. B., WEDMORE, E. B., and MASON, F. O., 36, Kingsway, London. April 25, 1932, No. 11892. [Class 38 (v).] Arc products are caused, before escaping from a switch structure, to drive continuously, for at least the duration of arcing, one or more motor elements each in driving connection with a pump element which serves to squeeze the extinguishing fluid in the arc space and force it into contact with one or more of the arcing electrodes and at the same time serves to introduce fresh fluid into that space from outside the structure. The motor and pump elements may be connected directly or through gearing or other mechanism to provide a differential action. In Fig. 1, a plate 3 carrying the fixed contact 7 has a cylindrical extension 8 in which are apertures 10 leading to a space 5 containing a series of fixed guide vanes 14 co-operating with movable vanes 13 to form a turbine. The vanes 13 forming the rotor are mounted on ball-bearings 15 for rotation about the axis of the movable contact 11 and carrv by means of a spider 16 a rotary pump with blades 17. When an arc is formed between contacts 7, 11, the arc products in escaping pass through the apertures 10 and rotate the rotor so that the blades 17 pump fluid from the main tank through the openings 18 into the space 4 so long as arcing persists. In another form, Fig. 3 (not shown), the entire structure is arranged to rotate on bearings on the lead-in conductor, special brushes being provided for conveying current therefrom to the fixed contact during the rotation of the structure. Fig. 2 shows a form in which the elements are pistons 22 connected to pumping pistons 25 of smaller surface area. The pistons 22 have ports 27 .. 30 co-operating with ports 31 .. 34 in the casing. Arc products passing through ports 31, 27 act on the upper face of the lefthand piston 22 and depress it, so closing the valve 36 and opening the valve 37 to drive fluid from the chamber 39 into the chamber 4. After a given movement, ports 28, 32 come into register to exhaust the products and ports 29, 33 also register to admit products to the lower face of piston 22 to return it, the return acting to close valve 37 and open valve 36 to refill chamber 39 with fluid. When ports 30, 34 register, the products exhaust from the lower face, and ports 31, 27 are again in register to restart the cycle of operations. A port 40 allows free return of the piston 25 to the position shown, but by providing a valve such as 36 in the port 40 and a valve such' as 37 opposite to the port, pumping will be effected on the up-stroke also. The right-hand pistons behave similarly but are arranged by their positioning- spring 42 to move upwards as the left-hand ones move downwards. A cushioned reservoir may be formed in the chamber 4 to steady the flow thereinto. In a modification of this form, Fig. 5 (not shown), the pistons are single-acting and returned, after exhaust, by means of springs, ready for a further operation if arcing persists. By providing springs of different periods it can be 'arranged that at least one piston will be pumping fluid at the zero of the cycle. Fig. 4 shows a form employing' pump rotors 51 mounted on shafts .49, which carry turbine blades 13a co-operating with fixed blades 14b and rotate on roller bearings 50. Means may be provided for imparting an nitial movement to the elements, such means being operated by the cross-bar, or an electromagnet actuated by the working-current, or a spring stressed during closing. The piston rods may be extended out of the structure for this purpose. Where a cushioned reservoir is used, initial pressure may be similarly imparted by means of a piston. The Provisional Specification states also that an additional break may open first and the arc products drive the turbine acting on the other break.