US2435753A - Apparatus for recording the duration of a transient effect - Google Patents

Description

Feb. 10, 1948. w. RICHTER ETAL 2,435,753

APPARATUS FOR RECORDING THE DURATION-OF A TRANSIENT EFFECT Filed Oct. 7, 1943 Patented Feb. 10, 1948 PATENT OFF ICE APPARATUS FORRECORDING THE DURA- TION. OF A: TRANSIENT EFFECT Walther Richter, 'Wliitefish Bay, and William H.

ElliotfShorewood, Wis., assignors to Cutlerilammer; Inc., Milwaukee, Wis., a corporation ApplicationOctober 7, 1943, Serial N0. 505,274

6- Claims.

1 The invention relates to apparatus for recording the duration of a. transient. 'efiectj, and" while not limited thereto is particularly applicable" to an instrument for providinga permanent record of the duration of an arc obtaining between con'-.

tacts in an electric circuit when said contact's'are separated" and thereby-interrupt a current/which flows in the circuit.

An object of the invention is toprovid'e an instrumeni; for recording the duration ofan are" incident upon the closing or opening" of a ciT- cuit carrying a current.

Another object of the inventionis to provide an instrument of high accuracy for measuring and recording theduration ofa, transient phedisclosed .for determining the duration of as transient efiect and particularlytthe duration of arcing in a circuit, but the system -diselosed=vin said application is not capable of making; apermanent' record of the duration of.- arcing, nor is, said system capable Y of: recording separately the. duration of severalarcs which follow each. other in rapid. succession. The present system 'is-an improvement of the systemdisclosed.in-theafore mentioned.- application.

The. accompanyingdrawing is .a diagrammatic. representation ofv a. system embodying the invention. For the purpose or. illustrating-the operation ofthe system;'the drawing shows. an electromagnetic switch having an energizingwinding, I and a contact l andiit is intended to determine the arcing offlthe switch contacts; upon cidsure of the same as willhereinafter be explained; The switch'is connected tocontrol a load 2i1 "or this" purposepower is supplied' from the" direct current lines L L through amanulally operable switch 3, thecurrent' passing front line I through an adjustable resistor" 4*, through the contacts l load 2, switch 3, to line L The'en ergizingcoil l has-onetermina'r c'onnecte'd to the line L while the" otherterminal is' connected through anormally open contact 5'; through the switch-3' to line L The-measuring circuits are supplied with power from. adirect current source through the busbars 61-1, Sand 9; and'forthapurpose of illustration'it no an anode l 5 l5 are connected: to. the common points of the' 2 is assumed that the potential of the bus bar 6 is zero and that "the bus bars I, 8 and 9 are plus 90, plus 240 and plus 400 volts, respectively. The bus bar 6 is connected to line L Connected to the common point of the contact fixed contact of the switch l and'the'resistor 4, is the cathode I li of an. electron tube l0, which is also provided with an anode? l0 and a control grid 16. The controlgrid. Ifl .is connected in series with a resistor I l. and a biasingbattery I2, or other source of. direct current voltage, to the terminal of the switch II which is nearest to the line L battery !2 has its positive pole arranged nearest to the grid [0 The cathode l3 of an electron.

tube I3 is connected to the line L The electron tube l3 .is also provided with an anode l3 and acontrol grid l3; The control grid I3 is con-' nected to the common point of the resistor 4 and the. contacts l The anodes l0 and R3 are connected together and in series with a variable resistor having.anadjustable'contact I 4 connected' to the. bus ban-8. A twin electron tube l5 isprovidedwith a cathode l5 cooperating with an anode [5 and a cathode |5 cooperating with The cathode I5 and the anode anodes. Hl I31, and, resistor [4, while the oathode I5 is connected to the bus bar I. The anode [5 is connected to onev terminal of normally closed manually operated'pfush button I 6.

The system further" provides a pentode tube I1; having a cathode Il an anode IT, a control grid l1, a screen grid li and a' suppressorgrid H The plate current of this tube is substantiallycons'tant over a wide rangeof plate voltages for constant screen: grid voltage. The cathode I"! is connected to thebus bar 1. The control grid H is connected to the second terminal of the push button switch IS; The screen grid li isconnected to the movablecontact l8 of a resistor [8; which in turn is connected in serieswith the variable-resistor IS the resistors l3 and i9 bridging the'bus bars l'and 8. The resistor 19' is provided "with a: variable contact W The suppressor grid- N is'connectedto-the bus bar T. Resistors fll 'andfil are connected in series with each other between the" bus bars- 6' and i 1, while the common terminal of the two resistors is conne'ctedthrough'a resistor 22 to the secondthrough the resistor 21 to the bus bar 1. Thus the tube 23 and the resistor 2'! form two adjacent branches of a Wheatstone bridge. The two other branches of the Wheatstone bridge comprise the resistors 29 and 3B, which are connected in series with each other and between the bus bars I and 8. Across the common terminal of the tube 25 and resistor 2'! and the common terminal of the resistors 29 and 33, respectively, is connected a microammeter SI and a circuit par alleling the ammeter comprising the resistor 32 and the normally closed push button switch 33. The cathode 26 is further connected through a normally open contact 34 to the grid 35 of an electron tube 35 having a cathode 35 and an anode 35 The cathode 35 is connected to the bus bar 8 through a battery 48. A condenser 36 is connected between the cathode 35 and the grid 35. The anode 35 is connected through a resistor 31 to the energizing coil 38 of a recording instrument 38 having a recording needle 38 which makes a permanent record of its deflections on a ribbon or the like 38. A re- SistOr 39 is connected between the common terminal of the resistor 31 and the coil 38, and the bus bar 9, while a bias battery 4!) has its negative terminal connected to the free terminal of the coil 33 and its positive terminal to the bus bar 3. The instrument 38 may be any suitable type of recording meter, preferably of the graphic type, wherein the magnetizing coil 33 forms an armature which is rotatably supported in the air gap of a permanent magnet. A stylus or pen is fastened to the armature to rotate therewith as the armature is deflected in accordance with the current in the magnetizing coil. The pen makes contact with a chart which is moved by a clockwork and thus a diagram, showing the variation of the current for different positions of the chart and corresponding to different moments of time, is drawn on the chart in a well known manner. Thus a record of each operation of the system is obtained.

To make the operation of the system auto matic it includes an electric motor M, on the shaft of which is mounted a pinion 42 which meshes with a gear 43 having twice the diameter of the pinion 42. The gear 43 is mounted on a shaft 44, so that the motor and its shaft make two revolutions for each revolution of the shaft 44. Mounted on the shaft 44 is a cam 45 which opens and closes the switch 34 once during each revolution of the shaft 44, that is, during each second rotation of the motor 4!. A second cam 46 mounted on the motor shaft opens and closes the contacts once during every revolution of the motor, while a cam 41 opens and closes the contacts 25 upon each revolution of the motor 4I.

The system as shown is arranged to record two succeeding cycles of operation of the switch I on different recorders. To make this possible the system is further provided with the normally open contact 134 which connects the cathode 26* to the grid I35 of an electron tube I35 having a cathode I35 and an anode I35". The cathode I35 is connected to the bus bar 8 through a battery I48. A condenser I36 is connected between the cathode I35 and the grid I35. The anode I 35 is connected through a resistor I3'I to the energizing coil I38 of a recording instrument I38 having a recording needle I38 which makes a permanent record of its deflection on a ribbon or the like I3B. A resistor I39 is connected between the common terminal of the resistor I31 and the coil I38 and the ous bar 3, while a bias battery I 44 has its negative terminal connected to the free terminal of the coil I38 and its positive terminal to the bus bar 9. To operate the switch I34 the shaft 44 is provided with a cam I45 which is similar to the cam 45, but arranged to be displaced therefrom degrees so that the switches 34 and I34 are operated alternately at alternate revolutions of the motor 4 I.

It will be apparent that the second recorder and the elements connected therewith, including the switch I34 and the cam I45, may be omitted. In this case the cam 45 could be placed directly on the shaft of the motor 4|, whereupon the system would record a phenomenon for each rotation of the motor.

It will also be obvious that the motor may be geared to the shaft upon which the connections are mounted so as to record phenomena which are of longer duration than one revolution of the motor 4 I It will also be apparent that the number of recording instruments may be increased over that shown in the diagram. The necessary modification in this case is obvious.

Referring to the drawing it will be observed that on account of the rectifier action of the tube !5, current can only flow in the resistor 22 in a direction to increase the negative potential of the grid I'I with respect to the cathode H. The resistors 22, 20 and 2I are so proportioned that with no current flowing in resistor 22 a current of suitable value is flowing in tube IT. The cathode I5 is connected to the resistor I4 which is the common load resistor of the tubes I0 and I3. The tube I0 is normally conducting but is rendered non-conducting when its grid I0 is made sufficiently negative with respect to its cathode III, that is, when there is a voltage drop across the contacts I exceeding the voltage of the battery I2 by the necessary amount.

The battery I2 insures a small positive potential on the grid 1 to compensate for a possible voltage drop of the switch contacts I in the closed position, which drop might render the grid l0 negative and stop current flow in the tube I8 when not desired.

The tube I3 is non-conducting if a sumcient voltage drop exists in the resistor 4. This takes place when switch I is closed and carries current or when it is open and an arc maintains current flow in the load circuit. The tube I0 responds to the voltage across the switch contacts I The time during which an arc exists between the contacts I is therefore characterized by the simultaneous stoppage of current through the tubes In and I3. When either tube I5 or I3 carries current, the current flows through the resistors I4 and 22, the normally closed contacts of push button switch I5, and anode I5 to cathode I5, through the respective tubes ID or I3 to bus bar 6. The flow of current through the resistor 22 makes the grid I'I sufficiently negative to stop the flow of charging current through the tube I'I. With the switch 25 closed the charging current can be read on the milliammeter 24.

A commercial tube which is at present available for use as tube 35 affords for the present application an optimum grid bias range of -10 to 30 volts. The lower negative potential named corresponds to the uncharged condition of the condenser 23, while the higher value corresponds to 20 volts between the terminals of the condenser 23 which voltage affords full scale of the contacts.

mamas:

gridf 35 with'respectto :the cathode 35%;

the meter registers zero deflection. Asthe current in-the tube 35 decreases due to increase of its negative grid potential, the-voltage ofthecoil fl -increases and the instrument is deflected proportional to the decrease of the tube current;

Theoperation of the instrument will now be explained in connection with the accompanying drawing. For the purpose of explanation'it is however assumed that the gears 42, 43 and the shaft are omitted and that the cam 45 is mounted directly on the motor shaft. Also omitted is the second recorder I38 with its accompanying tube and other accessory appa ratu's: The operation of the system when two or more recorders are employed will be apparent from the description given-hereinafter in connection with a single recorder.

To operate. the instrument the resistor 4 is adjusted so as to afford a voltage dropof '1 to 5 volts when theswitch l is closed. The system is adjusted with the switch I open, or closed, with out carrying load current. After the filaments of the tubes have attained their normal'temperature the push button 33 is depressed and the. current" passing through the tube 25 is adjusted by adjustment of the contact 'I9 which under these conditionsregulat'es the potential of the grid 26 The adjustment is made so that the bridge, is balanced'and the instrument 3| reads zero. In other words -the bridge is balanced .by regulating thevoltage drop across the tube to equalthe voltagedrop across the resistor 29.. Thereafter normally closed contacts of push button I6 are opened'bydepression'of thelatterand the cur-, rent of the'tube "is adjusted tothe desired value by moving the contact la so that a potential is I impressed upon the grid II which corresponds .to

the desired value of current passed by the tube. H to charge the condenser 23. Thereafter the condenser 23 is adjusted for the desired capacity. It

will be observed that the voltage rise of the condenser for a given charging period is inversely proportionalto the condensercapacity anddi-L rectly proportional to the product of charging current and charging time. The condenseris therefore adjusted to such a value that the charging current supplied by the tube I! will give the desired-potential 'on the grid 26 in a given time.

If it should be desired to investigate the operation of the contacts I b of switch I upon closure, forsinstance, to determine the duration of the arc resulting from the rebound "of the switch contact upon-closure, theswitch I6 is again closed and the motor M is started causing rotation of its shaftat a relatively slow speed. The camswf dfi and 4I-a-re adjustedso-that upon rotation the earn 41 opens the normally closed contacts" 25to permit a current-fiowingin the tube I! to pass into 1 the condenser- 23 and charge the-same:- Shortly thereafter the cam is'closes the contacts thereby connecting the coil I across the bus bars L and L to energize the switch I and effecting closure of the contacts I produces a potential differen'ce'at'the terminals This renders the tubes I0 and I3 non-conducting by impressing a negative po- If upon closure the contacts I rebound. an arc is created which tntialsbn thekgtidsj :.I Ba -respectively: a resuitino: currentzflowsathrough 1' the resistor 2 whichirediioes' the-negative potential of' 'bhe' gfldz-i I1:"; therebyupermitting current to' :tlow in: the;

l tube IT'Tto chargeiitheicondenser-23 and lowers thetpotentiali cf--the:grid:26 The resulting cur rentsintube ZKIimbaiancesthe bridge so thatth'e potentiaizofithe cathodelfli changes-with respect tor th'e busbar -8. Upon further rotation of thee motor- 4 I and: :afte'r thez contacts' I are at rest in 'tlie closed position following the rebound the tube" I1 becomesnon-ccnducting so that the volt age 1 'of the condehser 23ii does not increase any- 1 more and: a i steady current: proportional to the duration: or the arcin'g' of switch I flows through tne tube zsrr The'cam '45 then closes the contacts-- 34 toimpress' upon the'grid 35-'and the condenser 36' tlie =pote'ntialiof the cathode 26 This makes the tube 35 less-*condu"cting and causes a current flow through the recording instrument-38which" will be indicated thereon. The motor' M continues 'to'rota'ta-zand after the instrument 38 *ha's made a record, the contacts '34 are again lopen'edfi Thereafter the contacts 25' are closed arid-'tl'ienfi'- the contactsiare opened makingthe' instrument? availablefor another operation;

As wiil" be apparent'irom the foregoing :de scription'; the contacts 34' areclosedand a record is made by the instrument 38upon every second operation of thecontacts 5 and 25',=while,*on'the:-: other hand, the contacts" :34 and I 34 are closed" during alternateclosuresof theconta'cts S and 25* as the cam' I- IBis displaced 180 degrees from thei-icam-45." As a result; records'are made alternately on the instruments 38 and I38 upon successive closures-of the contacts 5 andZ 5'.

It willbe observed that the condenser 36* is:': charged and will maintain its charge" so as/to maintain the deflehtion of the instrumentSB 'upon cessation: of arcing.

To repeat a measurement on the switch I it is only necessaryto continue the operation of the: motor 4 I 'for another cycle.'-

Theprovision 'of the condenser '36 is of advan-c ta'ge in that-it preservesthe deflection of. the": instrument" 3& so-th'at it can'beread at leisure"? andif'the operation of the switch 'I is repeated the deflection of the instrument 38 on the'second f and subsequent'operations does: nothave to start" --from"zero; thereby eliminating the result of tha inertiaof the'movin'giparts of said instrument on itsaccuracy.

It 'should'further be pointed outithat'the cur; rent 1 which can-be handled by. the instrument 38;?

- is much higher than the current which :could: be

handled by: the-instrument 3| and inasmuch as a recording instrument requires'for the same ace. curacy a much'higher'operating' current than an indicatin :instrument; the arrangement shown afiords a graphic record of the phenomena to be investigated; Toinvestigate other phenomena: with a difie'itent sequenceit'is only necessary "to" rearrange the' sequences wof operation r of the' switches-"251 34 and'5 by changing th'e-relative shaft-of themotor'l I In some cases'it "may be I found advantageousto control the contacts 25, 34 and-I 34 by earns 41; 45--and I45 respectively}-through the medium of v .relaysr Remotecontrol er -said contacts will thereby be obtained and extension of sensitive control wires beyond the confines of "thein'stru ment will 'beunnec'essaryl We claim:

1. In apparatus for recording the period of simultaneity of two conditions of a circuit, the combination with a condenser and means responsive to each condition individually and arranged to supply a substantially constant current to said condenser while said conditions persist simultaneously, of a current responsive recording meter, an electron tube arranged to supply current to said recording meter and having a plurality of electrodes including a control electrode adapted to vary the current supplied by said tube in accordance with the voltage difference between said control electrode and another electrode of said tube, a second condenser connected to said control electrode, means for charging said second condenser to a voltage which is proportional to the ultimate voltage of said first condenser, and means for impressing between said control electrode and said other electrode of said tube 9. voltage which is a function of the voltage of said second condenser.

2. In apparatus for recording individually the duration of each of a plurality of successive transient effects, the combination with means for charging a condenser to a voltage which is proportional to the duration of said effects, of a plurality of current responsive recording meters, one for each effect to be recorded individually, an electron tube for each meter arranged to supply current to the respective meter and each having a plurality of electrodes including a control electrode adapted to vary the current supplied by said tube in accordance with the voltage difi'erence between said control electrode and another electrode of said tube, and selective means for selec tively impressing between said control electrode and said other electrode of any one of said tubes a voltage which 'is a function of the voltage of said condenser.

3. In apparatus for recording individually the duration of each of a plurality of successive transient efiects, the combination with means arranged to supply a charge to a condenser which modifies its voltage in proportion to the duration of said eiTects, of a plurality of current responsive recording meters, one for each efi'ect to be recorded individually, an electron tube for each meter arranged to supply current to the respective meter and having a plurality of electrodes including a control electrode adapted to vary the current supplied by said tube in accordance with the voltage difference between said control electrode and another electrode of said tube, an individual condenser connected to said control electrode, and selective means for selectively impressing upon any one of said last named condensers a voltage which is a function of the voltage of said first named condenser.

4. In apparatus for recording the duration of a transient effect, by providing a voltage which is proportional to the duration of said effect, the combination of a first condenser, a current responsive recording meter, an electron tube arranged to supply current to said recording meter and having a plurality of electrodes including a control electrode adapted to vary the current supplied by said tube in accordance with the voltage difierence between said control electrode and another electrode of said tube, a second condenser connected to said control electrode, means for charging said first condenser during the existence of said transient effect, means for charging said second condenser to a voltage which is proportional to the ultimate voltage of said first condenser, means for impressing between said control electrode and said other electrode of said tube a voltage which is a function of the voltage of said second condenser, and means for thereafter discharging said first condenser, while maintaining the charge of said second condenser.

5. In apparatus for recording a characteristic of a transient effect, the combination with a condenser and means responsive to a characteristic of a transient and adapted to supply a substantially constant charging current to said condenser while said transient persists, of a current responsive recording meter, an electron tube arranged to supply current to said recording meter and having a plurality of electrodes including a control electrode adapted to vary the current supplied by said tube in accordance with the voltage diilerence between said control electrode and another electrode of said tube, a second condenser connected to said control electrode, means for charging said second condenser to a voltage which is proportional to the ultimate voltage of said first condenser, means for impressing between said control electrode and said other electrode of said tube a voltage which is a function of the voltage of said second condenser, and means for thereafter discharging said first condenser, while maintaining the charge of said second condenser.

6. In apparatus for measuring the period of simultaneity of two conditions of a circuit, the combination with a condenser, and means responsive to each condition individually and adapted to supply a substantially constant current to said condenser while said conditions persist simultaneously, of a current responsive recording meter, an electron tube arranged to supply current to said recording meter and having a plurality of electrodes including a control electrode adapted to vary the current supplied by said tube in accordance with the voltage difference between said control electrode and another electrode of said tube, a second condenser connected to said control electrode, means for charging said second condenser to a voltage which is proportional to the ultimate voltage of said first condenser, means for impressing between said control electrode and said other electrode of said tube a voltage which is a function of the voltage'of said second condenser, and means for thereafter discharging said first condenser, while maintaining the charge of said second condenser.

WALTHER RICHTER. WILLIAM H. ELLIOT.

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

UNITED STATES PATENTS Number Name Date 2,021,766 Bivens Nov. 19, 1935 2,329,504 Young Sept. 14, 194d! 2,332,300 Cook Oct. 19, 1943 2,245,168 Suits June 10, 1941 2,009,459 Turner July 30, 1935 2,377,969 Richter June 12, 1945 FOREIGN PATENTS Number Country Date 227,887 Great Britain Jan. 19, 1925

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