US1973286A

US1973286A - Relay

Info

Publication number: US1973286A
Application number: US506918A
Authority: US
Inventors: Dewey D Knowles
Original assignee: Westinghouse Electric Corp
Current assignee: Westinghouse Electric Corp
Priority date: 1931-01-06
Filing date: 1931-01-06
Publication date: 1934-09-11
Anticipated expiration: 1951-09-11

Description

S t 11, 1934 D. D. KNOWLES RELAY Filed Jan. 6, 1931 /1 9-? fig. 3

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W/7'A/t55f5. INVENTOR 5. WI? DeweyD. Know/e5.

Patented Sept. 11, 1934 7' UNITED STATES PATENT; OFFICE RELAY Application January 6, 1931, Serial No. 506,918 4 Claims. (01. 250-27) My invention relates to relays and has particular relation to relays of the type including electric-discharge devices.

In experimenting with relays of this type, I

5 have encounteredconsiderable trouble from the electrical properties inherent in the mechanical structure of the incorporated electric-discharge devices. These properties commonly have the same effect as resistances and capacities inherent in the geometry of the base and the connections of the device. To provide a base and connections having perfect insulating properties is, of course, out of the question. Consequently, apparatus must be provided for compensating for these properties.

A discharging device of the type, included in the relays to which reference was made hereinabove, comprises a plurality of principal electrodes and a control electrode disposed together in a partially evacuated chamber. Depending on the application of the device,-the chamber is or is not filled with an inert gas at a low pressure.

The control electrode is ordinarily located adjacent to one principal electrode, and, in general, the distance between the parts of these two electrodes that are contiguous to each other is maintained substantially less than the meanfree-path of the electrons in the gas or in the vacuum.

The control electrode thus situated has the property of preventing the flow of a substantial current between the principal electrodes until the potential, between it and its adjacent electrode is decreased to a predetermined value. The necessary variation in potential may be obtained in numerous ways. However, for the purposes of the present invention, 1 shall principally regard the variation as attained by corresponding variations in the capacity of a regulating condenser connected in an impedance network linking the control electrode and its associated electrodes.

Since the electrodes are ordinarily sealed into aglass container which is, in turn, fastened into .45 a base through which the leads pass, a certain equivalent capacity and a certain equivalent impedance may be regarded as introduced by the imperfections in the insulating properties of the base.

The presence of the resistance and the capacity has the effect of causing adjustment of the regulating condenser because the potentials between the principal electrodes and the control electrodes vary in both magnitude and phase in a very complicated way. Thus, it often happens that, as the regulating capacity is increased, the device first unexpectedly breaks down, by reason of the fact that the potential between the control electrode ,and its associated electrode has reached the necessary value. As the capacity is further increased, the discharge ceases to pass between the main electrodes by reason of the fact that the phase shift, introduced by the interaction of the regulating capacity and the inherent capacity, has caused the potentials between the electrodes 5 of the device to assume such relative values that the discharge is blocked. Further increase in the capacity may cause further shift in phase between the electrodes of the device and result in a second excitation of the device. I have, moreover, found that, in addition to the mechanical structure of the discharge devices, the nature of the impedance that is utilized in varying the condition of the relay plays an important role in producing transition points.

Thus, a photo-cell is often utilized to produce the varying impedance, and it is a well known fact that, as the illumination impinging the cathode of a photo-cell increases, the cell varies in the character of its response from a capacity to a resistance. When the transition from an apparent capacity to an apparent resistance occurs, a deleterious phase shift is introduced into the relay which causes a sudden change to occur in its electrical properties. The sudden and unexpected changes in the activity of the electricdischarge device are known as transition points .or dead spots in its characteristic.

It is, accordingly, an object of my invention to provide apparatus for compensating for the effects introduced by the inherent electrical properties of the mechanical structure of the electrical discharge devices incorporated in an electric-discharge relay.

Another object of my invention is to provide a relay of the type including an electric-discharge device wherein transition points or dead spots in the characteristics of the electric-discharge device are eliminated.

A further object of my invention is to provide, in a relay of the type including an electric-discharge device, means'for stabilizing the activity or" the discharge device. 1

An ancillary object of my invention is to provide an electric-discharge device wherein provisions are incorporated for eliminating transition points.

Another ancillary object of my invention is to provide a method for determining the magnitude of the electrical device utilized in stabiliz- 110 o sistance is utilized ing a relay of the type incorporating electricdischarge devices.

Another ancillary object of my invention is to provide apparatus for reducing the phase-shift arising from the characteristics of the electrical constants incorporated in a relay including an electric-discharge device.

More specifically stated, it is an object of my invention to so regulate the impedances between the electrodes of an electric-discharge device incorporated in a relay that transition points in the activity of the relay are substantially eliminated.

According to my invention, I provide a relay including an electric-discharge device, of the type described hereinabove, wherein an impedance of predetermined character is connected between the control electrode and a principal'elem I have found that a partrode of the device. ticularly useful system is one wherein a resistance is connected-in series with the impedance (in the particular case a capacity) that is varied to regulate the activity of the device, and, consequently, of the relay. However, other types of impedance than a resistance are usable and the choice of the'impedance, which I may term a stabilization impedance, depends upon the type of impedance whereby the'activityof the relay is regulated. Thus, I have found that, if a refor regulation of the control electrode potential, a capacity may be utilized for stabilization.

As to the magnitude of the impedance that is necessary in producing stabilization, I have found that it is broadly of the order of the varying imedance. A more concise methodof determining the actual value of this impedance for any particular set up will be given in the following discussion.

The novel features that I consider'characteristic of my invention are set forth with particularity in the appended claims.- The invention itself, however, both as to its organization and its method of'operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment, when read in connection with the accompanying drawing in which:

Figure 1 is a diagram of an electric circuit in which my invention is incorporated, and,

Figs. 2 and '3 are graphs that will be utilized illustrating the method of finding the magnitude of the impedance that is necessary to produce stabilization.

The apparatus shown in the drawing comprises a power-supply source 1 connected in serice with the primary 3 of a transformer 5 through which power is transmitted to an electric-discharge device 7,-preferably of the type described hereinabove. r

The cathode 9 of the device 7 is connected directly to one terminal of the secondary 11 of the power-transmission transformer 5, while the anode 13 of the device is connected to the remaining terminal of the secondary 11 through a "current-limiting impedance 15.

The system shown in the View is applicable for many practical purposes. In particular, it may be utilized as a-general purpose-relay. In such a case, an electromagnetic relay 16 is ordinarily connected in the-p'rincipal circuit of the device '7 and its contactors cooperate to open or close a work circuit 18, depending on the condition of thedevice. For certain purposes, I have also found that theglow produced when the device 7 transmits current to be of great utility. For example, the luminous flashes which can be produced as the condition of excitation of the device 7 is varied has rather wide applicability in the signalling art.

The inherent electrical properties of the electric-discharge device are shown by broken lines and comprise a plurality pf capacitors .17 and resistors 19 connected between the control electrode 21 and the principal electrodes 9 and 13 of .the device 7.

,As is the case in the ordinary relay, an external impedance device 23 is connected between the control electrode .21 of the device 7 and the cathode 9. A variable capacitor 25 in series with 1 an impedance device 27, preferably a resistor, is

connected between the anode 13 and'the control electrode 21.

,As the capacitance of capacitor 25 is increased, the difference of potential between the anode 13 and the control electrode 21 is decreasedand, when this quantity attains a predetermined lower limit, the tube 7 breaks down, and a current flows between its principal electrodes 9 and 13., The impedance device 27 has the property 300 of stabilizing the activity of the electric-discharge device.

If the impedance device 217 is not included, the complex phase shifting and the variation in "voltage introduced by the interaction of the regulating capacitor and the inherent capacitances causes the transition points in the activity of the device to which reference was made herein.- above. I have found that, by including the impedance, these phenomena are entirely eliminated.

In Fig. 2, the characteristic curve for a par:- ticular relay is plotted. The current between the principal electrodes .of the tubes is plotted as ordinates and the impedance X,utilized in producing the breakdown of the tube, is plotted as abscissae. The graph shown is, of course, symbolical ofany type of electric-discharge relay.

The curve has two branches 29 and 31 between which is a region 33 of length G. 3 I

When the tube is broken down, as is indicated by the branch 29, an increase in the impedance X causes a decrease in thecurre-nt This con-- dition persists until the relative phase of gridanode and cathode-anode voltages assumes such a value that the tube becomes deenergiz-ed. The current in-the tube is then substantially zero over a region G'of values of X, and begins to increase when the relative phases of the voltages on the electrodes of the tube attain the requisite values, L as is illustrated in the branchBl.

I have found that, if an impedance Z is added in series with the impedance X which regulates the activity of the tube, the magnitudeof the gap 33 decreases, as is illustrated by the curve 335 35, in Fig. 3. The tubeioperates without transition points when the value of the added impedance is greater than the value at the. point. 37 where the curve 35 and the axis of Z meet, As has been intimated above, this value pf .Z is of the order of the impedance X and varies from a fraction of a .megohm to a value of theorder of 100 megohms depending on the character of the impedance X. I have found, however, that as a ,general rule an impedance of the .crder of 3145 10 megohms will yield satisfactory results.

It is to -be noted that my invention has, in the above description, been applied to a specific system. Itis not my purpose to restrict theinvention to this specific system as it is apparent that 1150 it may be applied to any relay of the type including an electric-discharge device. It may, in fact, be regarded as applying to the device itself rather than to the relay, and the necessary impedance means may be affixed to the device during its manufacture and may thus be included as a permanent element of the device. It is apparent that the impedance may be located within the container of the electric-discharge device utilized in a particular relay.

Again, I have found that my invention may be applied to a relay of the type wherein the current is interrupted by the variation of an impedance in the cathode and grid circuit of an electricdischarge device.

In a light control relay, I have recently found that, whereas a predetermined increase in the illumination reduces the relay to an unexcited state, a further increase in the illumination causes the relay to become energized. By adding a resistance in series with the varying impedance, which was, in the case question, a photo-cell, this effect was entirely eliminated. It is to be noted that, in the above discussed light-control relay, the transition point was probably caused by the change in the nature of the response of the cell as the illumination on its cathode increased.

A further matter of some importance is the restriction of the device per so. My invention is apparently applicable to any device wherein an electric discharge takes place between a plurality of electrodes. Thus, it has application to thermionic tubes, mercury discharge tubes and other vacuum and gaseous discharge tubes well known in the art.

However, it is well to point out that I have found that my invention has specific application to discharge devices of the type commonly known as grid-glow tubes and specifically described above. In devices of this type, it has accomplished a very useful purpose and has considerably increased the utility cf the tubes. My invention is, therefore, to be regarded as specifically applicable to tubes of any type.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In a relay of the type including an electricdischarge device of the type having a control electrode and a plurality of principal electrodes, said device exhibiting transition phenomena evidenced by transition gaps in its characteristic, and an impedance coupled between said control electrode and one of said principal electrodes for regulating the activity of said device, a second impedance connected in a series with said network first impedance and with said control electrode and said last-named principal electrode and having a magnitude greater than the magnitude at which the transition gaps of said device substantially vanish.

2. In a relay of the type including an electricdischarge device of the type having a control electrode and a plurality of principal electrodes, said device exhibiting transition phenomena evidenced by transition gaps in its characteristic and an impedance coupled between said control electrode and one of said principal electrodes for re 'ulating the activity of said device, a resistance connected in a series network with said impedance and with said control electrode and said last-named principal electrode and having a magnitude greater than the magnitude at which the transition gaps of said device substantially vanish.

3. In a relay of the type including an electricdischarge device of the type having a control electrode and a plurality of principal electrodes, said device exhibiting transition phenomena evidenced by transition gaps in its characteristic and an impedance coupled between said control electrode and one of said principal electrodes for regulating the activity of said device, a second impedance connected in a series network with said first impedance and with said control electrode and said last-named principal electrode and having a magnitude of the order of said activity-regulating means.

4. In a relay of the type including an electricdischarge device of the type having a control electrode and a plurality of principal electrodes, said device exhibiting transition phenomena evidenced by transition gaps in its characteristic, and an impedance coupled between said control electrode and one of said principal electrodes for regulating the activity of said device, means in a series network with said impedance and with said control electrode and said last named principal electrode for maintaining the total impedance in said network at a magnitude greater than the magnitude at which the transition gaps of said device substantially vanish.

DEWEY D. KNOWLES.