US2493448A - Arrangement for counting and measuring electric current impulses of short duration - Google Patents

Description

Jan. 3, 1950 P. FEHR 2,493,448

' ARRANGEMENT R COUNTING AND MEASURING ELEcTR'Ic CURRENT IMPULSES 0F SHORT DURATION. Filed March 28, 1945 Patented Jan. 3, 1950 ARRANGEMENT FOR COUNTING AND MEAS- URING ELECTRIC CURRENT'IMPULSES'OF' SHOE-T DURATION Paul Fehr,

& Gyr, A. porate of Switzerland Zug, Switaerland, assignor to Landis G., Zug, Switzerland, a body cor-- ApplicationrMarch 28, 1945,.Serial No; 585,361, In Switzerland April 5, 19441 ZGlaims. (c1. Goa-23) Thereare well known counting devicesfor overvoltages, such as are employed for counting pressure surges arising on long overhead linesdue to atmospheric influences or switching operations. These devices serve the purpose for checking the behaviour of the discharge. arresters duringv service and to establish, for instance, how often, and in which parts of an overhead system the discharge arresters have acted during a thunderstorm and hence protected the plant from damage, and further, is possible, to ascertain the approximative strength of the suppressed currents. This may be accomplished, for instance, in that a fraction of the deflected current traversing the arrester resistance is carried through a heating filament housed within a gas-filled tank, whereby the gas expands under the influence of the warmth produced and operates a counting device through the medium of a diaphragm.

However, various objections are raised against this well known design. So, for instance, the manufacture of the corrugated metallic tube used as diaphragm is not quite easy. The filling of the tank with an inert gas of low specific heat value calls in its turn for a perfectly sealing tank to avoid any loss of gas. By this, however, the tank becomes dependent on the condition of its environment which necessitates the provision of a special compensating diaphragm, so that the arrangement will be somewhat intricate.

Fig. 1 shows a cross-section through the tank, while Figs. 2, 3 and 4 represent various embodiments of the channel with great resistance to flow.

Referring to Fig. 1, numeral 1 designates 9, cylindric wall of a tank closed at the bottom by means of an insulating disc 2 through which pass the current leads 3 and 4 over two wire holders 5 and 6 to a heating filament 1. The heating filament is tautened on two small frames 8 made of insulating material, of which only one is shown. Towards top-side the cylindrical tank is somewhat enlarged and forms a flange I0 on which rest two grip rings ll, l2 capable of being firmly pressed thereon by screws 13. Between the two rings ll, 12 there is tensioned a diaphragm M of, say, thin oil cloth. The diaphragm l4 carries a pressure transmission plate IS with upturned outer rim, being held together with the former by a press-plate l6 and two press-discs I1, 18. The press-plate 16 carries a further plate 2|] fastly connected thereon by screws 19, which latter plate is adapted to support a diaphragm piston 2| and has on its side facing the press-plate I6 a milled channel 22 being connected on the one hand through. aport? 23. with. the interior of the. tank and on the other hand through a port. 2 4'. with the atmosphere. Between plate 26 and press-plate 16' a packing layer of, say, thin oil. cloth is sandwiched in.

The diaphragm piston 2i. engagesaguide bush, 26' vertically mounted on. the protective lid 2!. furnished, with apertures 21..

Fig. 2 illustrates an example of embodiment for the channel 22 at the underside of plate 20. There, the channel is formed by concentric circles being interrupted in a sector and interconnected by radial junction channels so that a continuous channel ensues.

Figs. 3 and 4 show two further examples of embodiment of the plate 20, i. e. in Fig. 3 the channel is spirally designed thereon and in Fig. 4 helically shaped (snail-like) The action of the aforedescribed arrangement is as follows:

By the current impulse to be measured, a heating filament l in tank I is warmed more or less according to the strength and duration of the surge. This warmth transfers itself on to the air present inside the tank I so that it begins to expand. In so doing a pressure is exerted on the diaphragm 14 so that it flexes upwardly taking with it the diaphragm piston 2|. This movement of piston 2| is transmitted, as in the arrangement of my prior application Serial No. 585,131 filed March 27, 1945, to a counting mechanism.

By the channel in plate 20 it is now attained that the interactions of the environment on the diaphragm are nullified. This channel readily allows, for instance, of compensating an undesired stress on the diaphragm due to variations in temperature and atmospheric pressure, because such changes occur comparatively slowly. If, on the other hand, the air inside the tank I gets warmed through the heating filament 1 then it expands within a relatively short time and a compensation through the channel takes place only with great delay, since the resistance to flow of the long and narrow channel is appreciable. During this time the diaphragm flexes and transfers its movement on to the counting mechanism.

According to the example of embodiment, the channel 22 is arranged about the axis of the diaphragm piston 2|. Obviously, the channel may be provided just as well at another place, say in the tank wall I or on the bottom insulating disc.

What I claim is:

1. In a device for registering electric current impulses of short duration, the combination of a tank, a flexible diaphragm for defining a chamber of variable volume with the tank, a resistance heating element continuously connected to a current source and continuously responsive to current impulses of short duration mounted in said chamber to heat and thereby expand the air therein, a, channel for connecting the air in said chamber with the atmosphere mounted on said diaphragm for movement therewith, said channel being adapted to accommodate gradual pressure variations inthe chamber caused by ambient temperature changes and to resist rapid pressure variations caused by the heating of said resistance element, and a register actuating plunger actuated by movement of said diaphragm.

2. In a device for registering electric current impulses of short duration, the combination of a tank, a flexible diaphragm for defining a chamber of variable volume with the tank, a resistance heating element continuously connected to a current source and continuously responsive to current impulses of short duration mounted in said chamber to heat and thereby expand the air therein, terminals mounted on said tank for connecting said resistance element to a current source through the tank, a channel for connecting the air in said chamber with the atmosphere mounted on said diaphragm for movement therewith, said channel being adapted to accommodate gradual pressure variations in the chamber caused by ambient temperature changes and to resist rapid pressure variations caused by the heating of said resistance element, and a register actuating plunger actuated by movement of said diaphragm.

PAUL FEHR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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