US2023221A - Transmitting measurements to a remote point - Google Patents

Description

Dea 3, 1935 v F. FISCHER Al. 2,023,221

TRANSMITTING MEAsUREMENTs To A REMQTE POINT Filed July 24, 1929 5 sheets-sheet 1 Dec. s, 1935.

F. FISCHER El' AL TRANSMITTING MEASUREMENTS TO A REMOTE POINT Filed July 24, 1929 F @heats-Sheet' 2 Vfttw-p gs.

Dec. 3, 1935-. FlsCHER Er AL 2,023,221

TRANSMITTING MEASUREMENTS TO A REMOTE -POINT Filed July 24, 1929 5 vshefc-t-snee' s 10B '20"' a O 0 l 100? V3 101 ,07,

4 301 02a 5 l .-3 ,e 30

' Mb M6 k'lb V v afin/JM g gala: forzegs- F. FISCHER El' AL TRANSMITTING MEASUREMENTS TO A REMOTE POINT Filed July 24, 1929 5 sheets-sheet 5 Patented Dec. 3, 1935 TRANSMITTING MEASUREMENTS T A REMOTE POINT Fritz Fischer and Hans 'Schnchmanm Berlin- Charlottenburg, Germany, assignors to Siemens & Halske, Aktiengesellschaft, Siemensstadt, near Berlin, Germany, a corporation of Germany Application July 24, 1929, serial No. 380,532 In Germany July 25, 1928 11 Claims.

`Our invention relates to improvements in transmitting measurements to a remote point.

Briefly stated, our invention comprises transmitting measured values or magnitudes to a remote station by means of a comparatively small number of signs, and to this end the value to be transmitted is rst automatically divided into a number of terms whose sum is equal to, or very approximately equal to, such value, and these lo terms are transmitted to the ldistant station.

Each measured value is thus expressed as one or as the sumof two or more of these terms. The

terms themselves comprise a group of arbitrarily selected vnumber values. At the receiving station l5 these received terms may be indicated individually, or they may be automatically added together so that the measured value may -be read off directly. Our invention can also be employed.

yto transmit information other than measured o values provided that such information can be converted into one or a plurality of comparison values `for transmission; and accordingly we are able bymeans of our invention to transmit to a v distant station the condition of a switch, or the g5 phase relation of two alternating lines.

Stated more fully, according to our improved method, the value of the magnitude to be transmitted may be expressed in terms of a group of arbitrarily selected numbers, for instance, as a 50 sum of power'`l of the number two, and by means of signals of any suitable kind of each power of two there is reported to the receiver station l whether this power of two is contained in the thus measured value or not. In order to enable :5 those powers of two to be determined which are contained in the value to be transmitted, it may rst be determined by way of test whether thehighest power of two (or the highest number of the group of numbers employed as the comparil0 son values) is contained in .the value to be trans' mitted, then whether the next smaller power of two (i. e. the second highest number of the groups of comparison numbers) is contained in the balance, and so on. The distance to be 5 traversed is immaterial so far as our improved.

of any kind, such as impulse combinations, may be/employed for transmitting the signals.

In a method of transmission as described above, it is of course desirable that a measured value be transmitted to a remote receiving station with a 5 minimum of signals. We have found that if a value is transmitted in terms of the powers of 2, the exact values or very close approximations thereof can be transmitted with very few signals; but, of course, other combinations of comparison numbers or values may be employed.

' The transmission of measured values by combinations or" impulses to an indicating instrument comprises two fundamental problems. The rst consists in the necessity of translating the measuring value for the transmission, and the second consists in translating the signs arriving at the receiving station again into a value capable of being indicated. Both problems may be carried out by similar means. The translation go of a measured amount may according to our invention, for instance, take place in the following manner: s

The measured value to be transmitted, for instance a current, is measured by a suitable measuring instrument, such as an ammeter. The torque exerted upon the spindle of Athe ammeter is a measure of the strength of the current. l l

According to our invention the torque set up 80 by the current is compensated by a sum of individual torques stepped in powers of two in such a manner that a pointer mounted on the revolving spindle of the measuring instrument stands, after the compensation, in the zero po- 85 sition. For this purpose a device engages the spindle of the measuring instrument by means of which individual torques of dilerent magnitude may be consecutively transmitted to the revolving spindle until the torque exerted by the 0 current is counteracted. 'I'his may, for instance, be eiected by connecting the spindle of the measuring instrument rigidly with the spindle of a moving coil instrument and by increasing the current in the moving coil to such a total value that the moving coil system develops a torque which is exactly as great as the torque developed by the measuring instrument but of opposite direction. The compensation of the torque of the measuring instrument may also be eiected mechanically by rendering a series of springs of different strengths operative on the spindle of the measuring instrument. Inasmuch as the individual torques are so stepped that their values stand in -the relation of the powers of two, 64 i dierent total torques may be composed from six of such stepped individual comparison torques, in this way it is possible to transmit aj' scale of division lines with such a degree of accuracy that the adjustment oi the pointer of the indicating instrument at the receiving station deviates from the accurately measured value by not more than one division line on the scale. To each oi' the eiectlve individual comparison torques there corresponds an impulse which is transmitted to the receiving instrument. 'I'he accuracy of the transmission is extremely great.

and for the transmission of 64 measured values there are required only 6 relays if the individual torques are released in the simplest manner by a relay each. The excitation of 4the relay may,

vfor instance, be controlled by electric, pneumatic -ing the method already described for the translation of the measuring value into impulses, relays are energized at the receiver which may, for instance, be a voltmeter or ammeter of standard design, in correspondence with the arriving impulses. 'I'hese relays are capable of varying the deilection of the pointer of the indicating instrument by connecting in circuit resistances connected in series or parallel. Instead of an electric indicating instrument a measuring device may, oi' course, be used in which individual torques of different values are mechanically transmitted by the arriving impulses to the spindle of the indicating instrument which also stands under the action of a control force, such as a spring force, and which adjusts itself so that the sum of the individual torques is equal to the torque of the control force.

It will be understood that it isimmaterial for our invention in what manner the torques for the compensation of the torque oi' the measuring instrument at the transmitting station and the torques for adjusting the indicating instrument are produced. They may be produced not only electrically and mechanically, but also pneumatically. Means of diiIerent nature may be employed at the transmitting and receiving stations.

Fluther detailsof our invention will appear as Fig. 2 is a view taken along the line 2-2 of Fig. l

1 looking in the direction of the arrow:

Fig.v 3 shows the mechanism which controls the relays o! Fig. 1 for compensating the torque of the measuring instrument and illustrates the wiring diagram for such relays;

Fig. 4 is a diagrammatic .view illustrating a form f of receiving apparatus for translating the received current impulses to an 'indicating' instru- Fig. 5 shows an arrangement for repeating the impulses transmitted so as to avoid the possibility of error:

Fig. 6 shows a central station and a plurality of sub-stations connected therewith by one outgoing and one return line;

Fig. 7 shows diagrammatlcally a modiiied form of the invention; and

Fig. 8 shows an arrangement for interconnect' l ing two alternating current networks.

In order to simplify the illustration the system shown possesses only three relays by the aid of which three individual torques may be controlled. From three individual torques may be composed l0 eight diierent total torques.

The compensation of the measuring instrument is shown in Fig. 1 wherein the measuring instrument is shown as a moving coil instrument I with the permanent magnet 2 and the pointer lt 4 mounted on thespindle oi the revolving sys tem. On the spindle oi' the measuring instrument there is mounted a bow or loop 5 which extends underthree helical springs 6, 1, 8 (Fig. 2). the free ends of which are normally held in their 20 upper position by the three pushrods 9, yII, -II 'I'hese push rods are engaged by the springpressed armatures of relays I2, Il, and Il, and when the relays are deenergized, the rods I, Il,l II are raised by the respective armatures, so as 2.5 to prevent the springs 6, 1, l from pressing on the bow 5. When however one of the relays I2, Il,l I I is excited, its armature will allow the push rod l, I0, or II respectively to drop under the iniluence of Igravity and oi the corresponding 30 spring 6, 1, or 8 respectively, so that this spring' will press down on the bow t. The spiral springs' 8, 1, 8 are at theirpther ends secured to the outer circumference of astationary bushing Il in which is journaled the spindle 3 oi the measuring in- 35 strument. The strength of the springs i, 1, I shown in Fig. 2. is stepped in such a manner that their powers stand in the ratio of 2:4:8, as indicated by the relation of the thicknesses o! these vsprings in said gure. The value-measure`d by 40 the moving coil instrument, such as a current, develops a torque which tends to turn the pointer I and therewith the bow 5 clockwise. The springs I, 1, Il on the other hand press on bow l in such a manner that they tend to turn the spin- 45 dle of the system and therewith alsdthe pointer 4 contracloclrwise. Which of the springs C, 1 and l 8 is operative depends upon which ot the tell!! I2, I3, I4 has responded. The choice between the springs 6, 1 and l is, as described hereinbe- 50 low made so that the torque ofthe measuring in- -strument caused by the current is compensated. The .pointer l is adapted to set. itself over two contact pieces I1 and Il located below the path of the pointer'and insulated one Kfrom the other 'as 55 indicated at I6. A drop bow Il forces the pointer.v

v ,l from time to time down and on to its support,

for instance throughl the vaction of an electro'- magnet 2l energized periodically in any wellknown or approved manner. According to 0.0 whetherfthe pointer is forced downupon .the contact I1 or I8 a current oi' positive or negative direction flows across the pointer from a source auch as. i'or instance, the battery B shown in Fig. 3, the l -wires Ill, I leading from the contacts I1 and '05 Il respectively to oppodte poles'of said battery.

'Ihe compensation of the measuring instrument takesplace in such a way that by means of a contact device the relays Il., I3, I4. are energized in succession and in the sequence stated so that 70 first the greatest individual countertorque becomes operative on the bow l, then the next smaller and soton.

By means. ofa special device, one form of-which is shown m mg. 3, and the contacts n aus u 7 which are selectively closed hy the pointer 4. provision is now made that all relays are excited once but that at the end of the compensation only those relays remain switched in whose sum just suilices for the compensation of the torque of the measuring instruments. The device or exciting the relays |2, I3, I4 in Fig. 3 possesses an insulating base plate 30 upon which are located two rings 3I and 32 insulated one from the other and composed of conducting material, the rings moving together with the disc 30 in the direction indicated by the arrow. The ring 3| is connected to the positive pole of a source of current (not shown) through a sliding contact 31 and a wire 502, the ring 32 is likewise connected to such positive pole through a sliding contact 38, and wires 503, 502 if an armature 35 is brought against a contact 35,' by the proper energizing of a polarized relay 34. One' contact piece I1 or I 8. The ring 3| touches during its rotation by means of a projecting Vvane 33 in succession the stationary contacts I2I, I3I, |4I which are electrically connected with one end of the windings of the relays I2, I3, I4 and thus connects them momentarily to the positive pole ofthe source of current indicated by the -I- sign at the left-hand end of the wire 502. The other ends of all the relay windings are permanently connected to the negative pole terminal of this source of current. The relays I2, I3, I4 are momentarily excited and allow the free ends of 'the spiral springs 6, 1, 8 to drop on the bow 5 of the measuring'instrument since the push rods 3, III,v II (Fig. 1) move downwards by lway of test. If the rst countertorque exerted by the spring 8 when the latter is released by the relay I2 does not suice tocompensate `the torque of y the measuring instrument the pointer 4 is forced shortly afterwards the vane 33 leaves the con-` tact I2I a vane 36 secured to the ring 32 touches the contact |23. At this moment the relay 34 is excited because the torque of the spring 8 has v not suhiced to turn the pointer 4 back into its zero position over the contact I1; the positive pole of the exciter source of current for the relay I2.is electrically connected through the closed amature |22, the ring 32, vane 36 and contact I 23 to one end of the winding of the relay I2. Relay I2 remains excited rst through the vane 36 and armature 35 and then when the disc 30 is advanced again through the ring 3|. During the further progress the relay I3 is rendered operative exactly as described with reference to the relay I2 and in'case the power of the springs 1 and 8 together is not strong enough to compensate the torque of the measuring instrument I the relay I3 also remains in circuit and both springs 1 and 8 remain operative on the spindle,

of the measuring instrument. I f it is now assumed that bythe springs 1 and the compensation of the measuring instrument has already been attained to such an extent that by the addition of the countertorque exerted by the 5 spring 6 the sum of the individual countertorques is greater than the torque of the measuring instrument, the pointer 4 of the measuring instrument will be pressed on the contact I1 of its support after the relay I4 has been excited. The 10 relay 34 is then excited in such a manner that its larmature 35 comes against the upper stop 35" and the holding circuit for the relay I4 is broken when the vane 36 reaches the contact |43. The compensation is thus effected by the individual countertorques rendered operative by the relays I2 and I3. The relays I2 and I3 are excited. As follows from the described mode of operation, the drop bow I9 (Fig. 1) must cooperate with the contact device illustratedl in Fig. 3 in such a. manner that it depresses the pointer 4 at the moments in which the Vane or blade 36 just touches the contacts |23, |33, or |43. Every time a relay is excited by way of test to l render the countertorque exerted by the particular spring which such relay has released, operative on the spindle of the instrument, the pointer 4 is freely movable and sets itself anew over the contacts I1, I0.

For the transmission to the receiving instrument a contact device is then used which for each relay I2, I3, I4 connected in circuit sends a current impulse across the remote transmission line and at the receiving station accurately corresponding relays are excited by the adjustment of the indicating instrument by a synchronous contacting device. It is, of course, also possible to send a current impulse for each non-excited relay I2, I3, I4 to the receiver station, each impulse causing at the receiving-station the de- 40 excitation of a corresponding relay or the reduction of the sum of individual countertorques acting on the axle of the indicating instrument. The exciterY circuits for the Vreceiver station can be passed across contacts |24, |34, |44 (Figs. l 45 and 3) .controlled by the relays I2, I3, I4, andy the remote transmission line. Each contact |24, |34, I 44 is Vpermanently connected with one pole of a source of electricity (not shown), for instance the negative pole, as indicated in Fig. 3,v and when closed upon the energizing of one of the relays I2, I3, or I4, the corresponding contact |24, |34, or |44 respectively will, through a corresponding line wire 506, 501 or 508 respectively, cause an energizing current to now through one of the relays 6|, 62, or 63 respectively located at the receiving station. One terminal of each relay 6I, 62, 63 is connected with the other' pole of said source of electricity, the otherterminal being connected with the respective line wir'es 506, 501, 508. 'I'hose relays will then be excited at the receiving station the exciter circuit of which is closedvat the transmitter station. At the receiving station an indicating instrument may be provided, as already mentioned, on the spindle of which two opposite torquesare adapted to act. One of the torques is, for instance, produced by spring power, while the other countertorque is composed of a sum of individual torques exactly as at the transmitting station. The operation of the apparatus shown in Figs. 1-3 is as follows:

It is assumed that a current ows through the armature of the measuring instrument, the magnitude of which current is to be measured in 75 terms of the arbitrarily selected number values for transmission to the remote station. A torque acts on the armature of the instrument, which torque is proportional to the current strength. According to the invention the value of this torque is broken up into a number oi.' terms whose sum is equal to or closely approximates such value. This accomplished 'by means of the relays |2, I3 and I4 and the springs 6, 'I and 3. The strength of the springs corresponds to the magnitudes of the comparison terms or values. With the aid of the relays, the ends of the springs are shifted by a certain amount so that a. countertorque corresponding to this amount is exerted upon the armature of the measuring instrument.

The rotating rings 3| and 32 excite the relays I2, I3 and I4 in successicn. In this way there is impressed upon the armature oi.' the instrument I a series of counter-torques in the same order.

. The relay I2 is rst excited and consequently the greatest unit counter-torque exerted. If this counter-torque is greater than that exerted by the current being measured, the pointer 4 is rotated counter-clockwise against the contact I'I, the circuit of the relay 34 being thereby closed in such manner that the switch 35 opens its contact. -When the vanes 33 and 33 slide over contacts I2I and |23, the holding circuit of the relay I2 is broken and its armature falls. After the relay I2, the relay I3 is excited across the vane 33. We shall assume that the countertorque exerted by the spring released by relay I3 is smaller than that exerted by the current being measured. In such case, the circuit of relay 34. is closed across the pointer 4 in such manner that the switch 35 closes its contact. As a result, .the ring 32 is placed in circuit .with the battery, so

-that the holding circuit of the relay I3 remains closed through the vane 33 even when the vanes 33 and 36 pass the contacts |33 and I3I. The relay I3 thus remains excited. The same order of events occurs with relay I4.

^ Only three relays are shown in the drawings, but a larger number may obviously be employed. Thelarger the number of relays, the closer the approximation. After the trial tests have beenV made with all of the relays, those which are excited are a measure of the current strength.

The mode of operation of an electric receiving instrument is illustrated by way oi.' example in Fig. 4. The indicating instrument is a voltmeter V. The voltage is measured at aseries connection of resistances 54, 55, 56. There are also' provided three further resistances 5|, 52, 53 ot such value that the resistances 5| and 54, Ii2l and 33 as well as 53 and 53 are in pairs equal. The resistances of the rst pair .are so related in magnitude to those of the second and 'of the third pair that the magnitudes of the resistances of different pairs will be in the ratio of 214:8. The

resistances are controlledby relays 3|, 32 and 33 by means of the relay armatures 3| I, 3I2, 62|, 322, 33|, 332. The relays 3|, 32 and 63 are the receiver relays and the relay 3| is .excited if at the transmitting station the relay I2 is excited.' Relay 32 belongs in the same manner to relay I3 at the transmitting station and relay 33 correspondingly to relay I4. In order that the current which traverses the resistances from 5| to 33 in series connection should \not change its value when the receiver relays respond, the connection is such that the sum of the resistances 5|-53 remains unchanged. For this purpose the relays 3|, 32, 63 always short circuit by their armatures 3|I, 32|, 33| and 3|2, 322, 332 one of .the resistances 5|, 52 and 53 when they switch into c'ircuit one of the corresponding resistanc'zes 54, 55 and 53 and vice versa, the resistances 34, 33, and 53 being -equal in magnitude to the resistances 5I, 52, and 53 respectively. In order that 5 the indications of the indicating instrument V may be independent of fluctuations of the voltage f connected to the series connection of the resist--l ances, it is advisable to employ as indicating instrument a quotient instrument, for instance a cross-coil instrument. I

The reliability of the transmission may further be increased by special means. In the trans mission of the impulse combinations from the transmitting to the receiving station faults may be caused by some impulses dispatched from the transmitting station not arriving at the receiving station or by voltages impressed upon the transmission lines from any external source. As far as such faults occur accidentally and temporarily n they can not always be directly recognized. The correct transmission may in spite of this be effectively protected by repeating every impulse dispatched from the transmitting station. Each impulse may, for instance, be repeated three u times and provisions may be made at the receiving station that each of the receiving relays (3|, 62, 63) becomes excited then only ifl all three impulses or at least two impulses arrive in cof incidence. The arrangement may be such that from the transmitting station each impulse con' sists of two impulses of opposite direction, for instance of a positive and a negative current impulse or vice versa. At the receiving station each current impulse then closes one or the other u of two alternating contacts by means of a polarized relay each, the arrangement being such that only if all arriving signs consist of two opposite current impulses can the receiving instrument at the receiving station be adjusted. o A receiving connection which operates in this manner is by way of example illustrated in Fig.

5 of the drawings.

In the system illustrated in Fig. 5, an indicating instrument V is selected and adjusted by 45 means of a contact device |00 in correspondence with the impulses arriving through the entrance relay I 3|; For this purpose the contact device |00 is provided with acontact arm |32 which carries three contact pieces |03, |04 and |33 in;v 50 sulated one from the other. The contact is connected to the witive terminal of the local battery and slides during the major part o! its 203 and the contact piece |03 over contacts 33| to 333. 4With the contacts 20| to 203 are connected the relays 2|I, 22| and so on up to 23|.- The relays 2| I, 22|, 23| serve for the adjustment and the relays 24|, 25| and 23| for the selection w of the indicating instrument V. The contact. arm |02 revolves contraclockwise. II fin thev shown inoperative position of the contact am tba contact'I04 is connected by the polarized relay` `I3| to the positive pole of the local battery a gg;4 starting relay |3'I connected with the contact I 31' by a wire |01" is excited thereby which releases the contact arm |02 so that it may revolve.

the relays 2| I, 22| and 23| becomes excited when the positive pole of the local battery is connected by the contact |04 and the armature of the relay |0I to the respective contact 20|, 202 or 203. The relays 2| I, 22| and 23| each close by their armatures 2| Ia, 22Ia, 23|a a holding circuit which is closed from the minus pole oi. the local battery by the respective relay winding, the armature of each excited relay, line I|0, the contact bar |06 and the contact |05 of the contact arm |02 to positive terminal of the local 1 battery, according to which of the transmitting relays I2, I3, I4 (Fig. 1) is connected in circuit for the compensation ofthe measuring instrument I the polarized entrance relay IOI at the receiving station is excited in one or the other direction. For this purpose the relay contacts 24, |34 and |44 are, in contrast with the illustration in Fig. 1, so designed that when their relays are excited they close a connection to the positive pole of the local battery and when not excited to the negative pole. The arrangement at the transmitting station is such that for each 4relay I2, I3, I4 which remains in circuit'an impulse combination consisting of a positive .and a subsequent negative current surge is dispatched across the remote line to the relay I0 I. For each of the relays I2, I3, I4 which is not excited a negative and then a positive current surge is transmitted. At the receiving station. these arriving current surges have the eiect that the contacts 30|, 302 or 303, 304, or 305, 306 iirst receive positive and then negative potential or vice versa in pairs across the contact |03 of the contact arm |02. In this way the relays 30|a, 302a, 303e and so on up to 306a connected to these contacts are excited by a positive or a negative impulse.

If all the impulses have been properly transmitted the armatures of the relays 30Ib to 30Gb are in pairs placed against their outer or inner back contacts so that a closed circuit from the armature 30Ib to the armature 3061) is set up. If one of the impulses to be transmitted does not, arrive or if it receives a wrong direction due to external inuences in the transmission line or if a permanent current is superimposed over the impulses due to an insulation fault or the action of adjacent circuits, the circuit remains open at least at one of the said armatures 30Ib to 306b. has the effect that no indicating instrument is selected at the receiving Astation in which the impulse combination arriving could cause an indication.

The selection of the indicating instrument V is carried out by the contact arm |02 on the second half of its path. When it sweeps past the contacts 204, 205 and 206 the exciter windings of the selector relays 24|, 25| and r26| are connected to the `armature of the receiving relay IO and those of the three selector relays which through the armature of the receiver relay |0| are connected to the positive terminal of the local battery become excited. Exactly like the relays 2| I, 22| and 23|, each excited selector relay connects itself by means of its armature 24Ia, 25|a or 26|a in a holding circuit which passes over the line ||0, the contact bar |06 and the contact |05 of the contact arm |02 to the positive pole of the -local battery. To theselector relays 24|, 25| and relays and the relay 25| must remain unexcited. The relay R is then located in a closed circuit which, starting from the negative pole of the local battery, is carried back to the positive pole of the local battery across the winding of the relay R, 5 the attracted armature 26|c, the armature -25|b resting upon its lower contact, the attracted armature 24Ib `and across the series contactsI 30Gb to 30|b. The relay R cannot be excited if the series connection of the contacts 30|b to 10A 30Gb contains a gap. It is not necessary that the relays 30|a, 302a and so on should be excited in the sequence illustrated in Fig. 5 by way of example. The excitation may, for instance," start with the-relays 30Ia,'303a and` so on and then 15 the relays 302a, 3041i and so on may be excited. The arrangement shown in'Fig. 5 may also be changed in such a manner that the entrance relay I 0| does not receive impulses in both directions but in one,direction only. 'I'he combination of signs then consists of current signs and intervals. At the armature of the entrance relay |0| a spring is then provided which pulls the. armature down on one ,of its back contacts during each interval in the current.

The relay R cooperates with the relays 2| I', 22| and 23| in order to effect the adjustment of the indicating instrument V. It should be added that the relays 2| I, 22| and 23| control an armature 2| Ib, 22Ib and 23Ib, respectively. Those of the relays 2| I, 22| and 23| which have previously closed a holding circuit for themselves hold their armatures 2| Ib, 22 Ib and 23|?) attracted and thusconnected with the positive pole of the local battery. The relay R now controls double armatures 35 R11, R12, R21, R22, R31, R32. AS long as the relay R is not excited the armatures R12, R22 and R22 are connected to the positive pole of the local battery. The armatures R11, R21 and R31 are connected with the before mentioned armatures 40 2| Ib, 22 Ib and 23Ib if the relay R is excited while at the same time the relay armatures R12, R22 and R22 are released from their connection to the positive pole. With the armatures R12, R22 and R22 are connected the adjusting relays 6|, 62 and 45 63 also referred to above in connection with Fig.

4, which on excitation simultaneously attract the armatures 6II, 6|2 or 62|, 622 or 63|, 632. In addition to thesearmatures, the said adjusting relays also each possess an armature 6I0, 620 and 50 630 respectively adapted to close a holding circuit after the respective adjusting relay has been energized. The relays 6I, 62, 63 are constructed in such a manner that their armatures 6I0, 620, 630

` respectively will be delayed in their/ leaving the 55 respective contacts.

R21, or R21 and one of the armatures 2| Ib, 22Ib, 05

or 23 Ib respectively. According as the relay 2| I, 22 I, or 23| is energized,'the corresponding adjusting relay 6|, 62, or 63 will also be energized. As has been explained above. whether the relay 2| I, 22|, or 23| is energized, depends on the condition 70 of the relays I2, I3, or I4 respectively at the transmitting station. In this way the adjustment of the relays I2, I3, I4 at the transmitting station is by means of the relays 2II, 22|, 23|

transmitted to the relays 6|, 62 and 63 because 76 of these latter only such can be excited when the relay R responds and place themselves in a holding circuit which 'find a closed circuit through one of the armatures 2I|b and 22|b and 23|b as well as across the armatures Ru, Rn or Rai and one oi' the armatures 6N, 620, 83|.

As shown by way oi' example in Fig. 6 it is possible by one outgoing line and one return line to select various substations N1, Nn, Na from one central station Z by dispatching impulse combinations from the main station for the selection oi a substation or a measuring instru.- ment M1, Mz, Ma, each substation to be selected or each measuring instrument in such a station having a deilnite combination apportioned to it. At the substation the compensation of the measuring instrument provided may commence after the selection of a measuring station and after the compensation has been effected it can then in the manner described be reported to the receiving station which individual torques were needed for the compensation at the measuring station. The selection can take place in the same manner as the selection ot the measuring instrument V of the arrangement illustrated in Fig. 5. As in Fig. 5, the relays are excited only when the relays 24|, 25! and 26| are excited in a definite combination; thus there can be excited, from the receiving station Z, arelay in one of the sub-stations Ni to Na which sets into motion the compensating device illustrated in Figs. 1 to 3. At the end of a revolution of the contact elements 3|, 32 (Fig. 3), the transmission of the torques necessary to effect the compensation can be automatically released. The arrangement may, however, also be such that at each substation the compensation of the measuring instrument is repeated in' regular intervals, for instance by a clockwork. The order i'or starting the contact device at the main station and the substation is then preferably given by the substation. The individual procedures oi' the selection and the transmission of a measurement result may preferably be so interconnected, that while from the main station a substation and a measuring instrument in that station are chosen, the compensation takes place at another station which is transmitted only when the impulses sent by the main station for the selection are iinished.

In order to obtain accurate transmission. it is advantageous to control the synchronously rotating contact arms in the sending and receiving stations from that station which transmits the communication, as has already been mentioned. In the contact mechanism 10|, 102 of the main or receiving station Z illustrated in Fig. 6, there is shown a magnet 1 which is operative to attract an amature 104 and in this manner to withdraw a braking or latch member 105. By such operation, the disk '|08 is released, so that the contact device 122 is able to rotate. The impulse by which the magnet 103 is excited is the starting impulse. As all the sub-stations N1 to Na are connected by conductors in the receiving station, this starting impulse can be sent from each of these stations. In this way it is made certain that the switch mechanism in the receiving station Z runs synchronously with the contact arm in the sub-station which transmits the communication.

The process described up to now requires a vconsiderable time until the pointer of the measuriog instrument set itself anew. Although the relays controlling the compensation torques require extremely little time for their response, this remote transmission is nevertheless too slow and sluggish for many engineering purposes because after the addition of a further individual 5 torque it is necessary to wait to determine which position the pointer of the instrument takes up. The modiiication of our invention which will be described now enables a quicker transmission o! a pointer position or a measured value. This equipment is thus also suitable for protective connections such, as those i'or instance, in which the current or the output is measured at diilerent points of a plant and compared with one another. In another modication of our invention the value to be transmitted connects a transmitter resistance into a bridge connection and an automatic device sets up balance again by connecting in circuit or cutting out a number of individual resistances and in this way causes the dispatch of a denite signal or a deiinite combination 'of signals. The measuring instrument may be any suitable instrument the pointer of which controls a resistance. Preferably the pointer is periodically depressed by a drop bow and in this way connects greater or smaller resistances into a bridge connection. For setting up again the bridge balance which has been disturbed in this manner the individual resistances from the largest down to the smallest are in succession f switched into circuit or short-circuited in any suitable manner, for instance by a revolving contact device. After each addition or subtraction of an individual resistance a polarized relay in a diagonal branch of the bridge by closing one or the other of its armature contacts indicates whether the last resistance was too great or not great enough for producing the state of balance in the bridge connection. In

the iirst case the switching operation is cancelled again, while in the second case the last added or subtracted individual resistance is blocked in its connection by the armature contact of the polarized bridge relay. The same procedures are repeated at the next smaller individual resistance. The bridge relay adjusts itself much more quickly than a measuring instrument. The pointer of the transmitting instrument on the other hand is detained on the bridge re- 5o sistance by the drop bow only until the balancing of the bridge as well as the remote signalling over the individual resistances required for the balancing are iinished. 'I'he drop bow is coupled with the contact device in such a manner that both cooperate correctly as regards time.

Apart from the advantage already mentioned that the remote transmission oi' a measured value takes place more quickly, i. e. that the resetting movements oi' the indicating instrument at the receiving station can follow each other at short intervals, our invention has still other great advantages. In the rst place, any desired measuring instrument may now be used as transmitter instrument. Also, since the pointer o! the transmitter measuring instrument is able to adjust itself freely, measuring instruments with very weak directional forces may be used. The readings oi the measuring instrument may furthermore be taken at the remote measuring station as well as at the indicating instrument at the reeciving station, because the pointer of the measuring instrument is not hindered 1n taking up its indicating position u' A value is transmitted. At the measuringstation as it is not turned back into the zero position. If the transmitter measuring instrument is able to deect from the zero position towards both sides, for instance if it is a wattmeter instrument which apart from the value also indicates the direction of an energy flux the direction of the deiiection of its pointer may also be reported to the receiving station and be indicatedl there. For this purpose the transmitter instrument may influence one bridge resistance in such a manner that by its pointer standing in the zero position it connects a mean resistance value into circuit which is increased or reduced by the deil'ection of the pointer towards the right or the left. In the same way the pointer of the receiving instrument stands in the center of its scale when the transmitter instrument measures the measuring value zero and by deection towards the left or the right from the central position the direction of the deflection of the pointer of the transmitter instrument is also indicated at the receiving station.

The bridge connection also offers the possibility of combining a plurality of transmitter inuences in such a manner ythat the resistance to be connected in one branch for setting up the balance of the bridge balance is proportional to the product, the quotient or the diierence of the measuring values operative on the transmitter side. The square value or the square root value of a transmitter value or the sum of a plurality of transmitter values may also be transmitted. For the transmission of a product, for instance of a current and a voltage, no product measuring apparatus is thus necessary nor is a special instru'- ment necessary for the transmission of an effective or wattless output sum which forms the sum at the measuring station. The transmission of the ratio of two values, such as the real and the apparent output, of steam consumption and electrical output or of direct and alternating current output of a converter, which may be of imp ortance for the supervision of a remote substation of an energy supply system is according to our invention possible without the use of a quotient instrument.

If there exist a plurality of machine units for the generation of electrical energy the transmission of the total output or the total current or the like may be carried out in any other suitable manner than by letting the wattmeter of each machine act on the bridge resistance, and the indication of any preferred instrument measuring the sum of the outputs or currents may laccording to our invention be transmitted to the receiver station. The instrument which, forms.

the sum of outputs may, in known manner, be a voltmeter if by the values to be added meters areV driven in which electromotoric forces proportional to the value of the meter speed are generated the total voltage of which is measured by the voltmeter. The adding up of the individual outputs may,` however, also take place in such a way that meters are connected to the generators which during their revolution close contacts the frequency of which in time unit is proportional to the speed of the meter. various contacts cause equal current impulses the sum current may be measured by a damped measuring instrument. In this way there is obtained the total eiective or wattless output or output of current of the generators. If a 'plurality of measured values have to be transmitted an order is preferably transmitted from the receiving station which states which measuLng If the making of theA an instrument is chosen and its drop bow drops on the pointer, the indicating instrument is selected at the receiving station. The compensation of the bridge may be carried out in regular intervals by a clockwork.

This part of 4our invention will be better understood by reference to Fig. 1 of the drawings. In this gure 1I0 is the pointer and 1I6 the drop bow of the transmitter measuring instrument. When the drop bow 1 I6 pulls the pointer down it makes contact on a bridge resistance 1 I1. The remaining bridge resistances are 40 and 50 and 60, 10, 80, 90, 100. The bridge is fed from a battery 1I I. -In the diagonal of the bridge is connected a polarized quickly responding relay 1I2. Thev magnitude of the portion of the resistance 1 I1 connected in the bridge will of course depend upon where the pointer 1 I 0 touches the resistance. If the bridge balance is disturbed the polarized relay 1|2 responds and places its armature 1I3 against either a contact 1I4 or a stop 1I5. The disturbed bridge balance may be restored by vidual resistances 60-100 by meanseof the short circuiting contacts 16|, 11|, 18|, 19| and 10|.

The short circuiting contacts stand each by itself l under the control'of a relay 162, 112, 182, 192 or 102, respectively, which in succession are connected in circuit by a contact device 120. The contact device 120 is identical with that shown in Fig. 3. It is provided with two conducting rings 12| and 122 mounted on an insulating base plate 123. The ring 122 is equipped with a vane 124 adjacent to a gap 125. The ring 12| is entirely closed and possesses a vane 126 which projects into the gap 125 of the other ring 122. Upon the insulating disc 123 or the conducting rings 12| and 122 respectively slide contacts, the contacts 121 and 128 or 129 and 130,13I and 132, 133 and 134, 135 `and 136 belon'g to the exciter circuits of the relays 162, 112, 182, 192 or 102 respectively. On the ring 12| also slides a contact 131 and on the ring 122 a. contact 138. 'I'he contact 138 is connected to one pole of the battery 39. As soon as vane 124 reaches the contact 121 as the contact device 120 revolves, the relay 162 is iirst excited. Its exciter circuit starts from the battery 139 and passes across the winding of the. relay 162, over contact 121, the contact vane 124, the conducting ring 122, the slide contact 138 back to the battery 139. In the same manner the relays 112, 182, 192 and 102 are also connected in circuit in succession. The connection lasts until the vane 124 has again left the respective sliding contacts. On excitation the relays 162, 112, 182, 192 and 102 close holding contacts 163, 113, 183, 193 and 103. Simultaneously one of the resistances 60-100 in the bridge connection is each time short circuited by the armatures 16 I, 11 I and Vso on. In the sequence in which the relays 162-102 are excited the highest resistance 60 is rst short circuted, then the next lower one and so on down to .the lowest resistance 100. As long as' the 1I0 is not in contact with the resistance 1 the resistance in one bridge branch is nilnitely great. The balancing current conselshort circuiting suitable resistances of the indi- As already described, relay 162 is then flrst excited and short circuits the-highest of the individual resistances 66-166 by means of the armature 16|. In case the total value of the resistances 16-166 remaining in the bridge is still too great to restore the bridge balance a current of such direction iiows through the polarized relay 1|2 that the armature 1 I3 closes the contact 1|4. This has the effect that the relay 162 which has at its armature 163 prepared a holding circuit for itself remains excited even after the contact vane 124.has left the slide contact 121. The holding circuit for the relay 162 passes from battery 139 across the winding of the relay 162, over the relay contact 163, the sliding contact 128, the contact vane 126 of the conducting ring 12|, over the armature 1|3 and the closed contact 1|4 to the battery 139. During the further advance of the contact device 126 the `contact vane 126 passes beyond the sliding contact 128 and instead of it the other end of the slotted conducting ring 122 connected to the same battery pole passes under the sliding contact 128. Relay 162 thus remains connected in circuit. Immediately afterwards the same process is repeated at the relay 112 which. is again rst excited across the contact vane 124 and in case relay 'H2 keeps the contact 1|3, 1|4 still closed after the shortcircuiting of the individual resistance 16, remains excited across the contact vane 126 and its holding contact 113 until the sliding contact 136 in Y the holding circuit of this relay passes on to the contact ring 122 during the advance of the contact device 126. As was described for relays 162 and 112 or the bridge resistances 66 and 16 all the resistances 66-166 are temporarily short-circuited and according to whether the polarized relay in the diagonal branch of the bridge determines that too few or too many of the individual resistances are connected in circuit the respective relays remain excited by a holding circuit or they drop oif after the temporary excitation.

Each of the relays 162, 112, 182, 192 and 162 controls a third contact 164, 114, 184, 194 and 164 the circuit of which is shown completely only for the relay 162 and the contact 164, in order not to obscure the drawings. The disc 123 of the contact deyice 126 is mounted upon a shaft 146 upon which is also secured the contact arm of a lay 162, the relay contacts 164, 114, 184, 194 and 164 close across the contacts 152-156 and the contact arm 15| Aand the remote line F a circuit to the receiving station across which current impulses are sent from a battery 158. At the receiving station there is provided a receiving equipment operating in synchronism with the contacts 15| which, according to which of the relay contacts 154, 114, 184, 194 and 164 are closed, eil'et the excitation of corresponding reception members. The start may, particularly if there exist a plurality of measuring stations the measuring results of which. are to be reported, be preferably controlled from a point fromwhich em anates also the change over of the bridge connection to the various measuring points, for instance 'Ihe system described for the transmission of -5 measuring values by impulse combinations may with advantage also be used for the synchronizing of interconnected sources of alternating current as will be explained with reference to Fig.

8 of the drawings. In this gure the phases of 10 the alternating current sources to be interconnected are marked by the reference letters U, V, W and u, v, w. Between the line ends U and u, V and v, W and w there must exist no difference ofpotential in the movement of joining the networks.- One or a plurality of voltmeters may thus be built into the described device for remote measuring as transmitter measuring instruments. The indication of these measuring instruments is then reported to the main station and indicated by a receiving instrument. Since, however, the voltages between -the line ends to be connected are constantly changing an extraordinarily high transmitting speed is necessary. For this reason it is preferable to indicate at the receiving station only when the frequencies of the networks to be connected have come close together. For this purpose zero voltage relays 8|6, 826, 836 are used which by their dropping armatures 8| 82|, 83 connect definite but dif- 30 fering resistances 8|2, 822, 832 in the bridge connection. The bridge connection in the illustration also contains the resistances 85| and 852 and the individual resistances 866, 816, 886, 89|), 666. In one bridge diagonal is located one source ofcurrent 846, in the other again a polarized relay 84|- the armature of which places itself in one position against the stop 842 and in the other position against a contactl 843. The circuits starting from the contact 843 correspond with Fig. 1. When the frequencies of the alternating current differ only slightly from one another the potentials between the corresponding line ends U and u, V and v, W and w disappear in succession. In consequence thereof the relays 8|6, 826, 45 836 drop in slow succession their armatures 8| I, 82|, 83|. In this way the fourth bridge branch receives oncel the resistance value of the resistance 8|2, another time that of the resistance 822 and again that of the resistance 832. In correspondence therewith the bridge balance must be restored again in each case by a different combination of the individual resistances 656. 816, 886, 896 and 866. Across the contact device 856 there is at the receiving station reported again which of the individual resistances 666, 816, 886, 890 and 866 are connected in circuit. Before the interconnection ofthe two alternating current sources can take place all the zero voltage relays 8|6, 826 and 836 must have 00 dropped their armatures. The resistance of the one bridge branch is then equal to the value of the parallel connection of the resistances 8|2, 822 and 832 which are so stepped that there are no two combinations of these resistances which, Awhen connected in parallel, give the same total resistance. The receiving equipment may control a rotary ileld indicator which indicates whether .the alternating current machine runs too quickly or too slowly but a usual three-lamp 70 connection may' be controlled in which the lamps light up in a certain cycle. Instead of the individualv resistances 866, 816, 886, '896 and 866 there may, if theproblem is to connect by remote indication the correct moment for connecting two alternating current sources, be used three equal resistancesequal to the resistances BID, 820 and 830. 'The bridge connection may then be abandoned altogether. 'I'he relays 8| 0, 820, 830Vv then directly control the impulse combination. By means of any desired change-over device the same bridge connection may be selectively used for the synchronization of a plurality of generators to be synchronized. After the synchronization the bridge connection may be changed over to a measuring instrument which measures the output of the substation, for instance. The changing over may, as indicated 4be eiected by a change over switch 841 which is operated by a relay 846 likewise remotely controlled by a combination of impulses.

The arrangement may be such that at each substation the compensation of the bridge con- Y nection is effected anew at regular intervals by a clockwork, for instance. The order for starting the contact devices at the main station and substation is preferably given from the substation. The same bridge connection may there in succession cooperate with a plurality of measuring instruments. The changing over may, for instance, be carried out by a distributor coupled with the contact equipment. 'I'he various procedures of the selection of a measuring instrument and the transmission of a measured result may preferably be so connected that while from the main station a substation and a measuring instrument at this station are selected, the compensation takes place 'at another station which is then transmitted when the impulses for the selection dispatched from the main station are finished. It is an advantage o f the mode of transmission described that the transmission is independent of the resistance of the transmission line as long as the arriving impulses suice at all for the excitation of the relays.

By the same instruments by which an indicating instrument for measured values is adjusted it is also possible to adjust from a transmitting station any other adjustable member at the receiving station. In a control station position indicators may thus be arranged which indicate the positions of switches located at the transmitting station. Conversely the'control station may be- I come the transmitting station by, for instance, reversing a switch a corresponding adjustment of a line switch being eiected at the remote receiving station. The apparatus illustrated in Fig. 5 may be used for operating the position indicator as well as for the remote control of switches. The selection of a switch or a position indicator maybe effected in the same manner as the selection of the measuring instrument V (Fig. 5). The relay R will then control the position indicator or the operating coil of a line switch. The number of the orders possible or of the position indicators becomes still greater if the control relays or the relays of the position indicators are so combined in groups that they take the place of the relays 6l, 62, 63 which serve for the adjustment of a measuring instrument. The relays 6I, 62, 63 in Fig. 5 may, for instance, control certain movable members which belong vto a group to be selected by the 'relay R. Re-

ports of switch positions and remote control of switches and the like are in this mode of transmission independent of the resistance of the transmission line as long as the arriving impulses suice at all for the excitation of the relays.

It is also an important advantage of our invention that all the transmitting means known in the art of telegraphy may be used. The im'- pulses may also be transmitted without wires, either by space waves or line-directed waves, for instance across telephone lines, particularly telephone lines in high-tension networks. The 5 impulses may also be transmitted across telephone lines and telegraph lines as well known in the underposed orgsound frequency telegraphy.

In some cases it is of value of add a number of measured values for instance, if it is desired 10 to control at a central control station the entire output of a`plurality of cooperating electricity stations. TheA added value may then be easily indicated by providing an indicating instrument which is voperated by the action of the impulses sent out from the various power stations or measuring stations. lf for the indication of the service values measured at the individual measuring stations electrical measuring instruments are used which set themselves according to the resistances or conducting values of the arriving values, the device indicating the value of the sum may be a similar instrument which responds to the sum of these resistances or conducting values,

i. e. a voltmeter or an ammeter of considerable measuring range.

If only twomeasuring values are to be transmitted their sum or diiference may at the starting station be formed, for instance, so that one measured value adjusts the pointer and the other a movable scale of the same indicating instrument inY the same or opposite direction of motion. When using product meters or quotient meters of known construction it is also possible to form at the lreceiving station the product or the quotient of two measured values. Ii the two transmitted service values correspond with the voltage and the current of an alternating current circuit the product indicated is equal to the apparent output of the respective alternating current circuit in volt-amperes and the quotient equal to the impedance of this circuit.

Various modiiications and changes `may be made without departing from the spirit and the s cope of the invention, and we desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art.

We claim as our invention: O

1. In an apparatus for transmitting the condition of a measuring instrument which is operated by a measuring torque on a pivoted part thereof, in combination, a plurality of comparison elements for exerting a plurality of countertorques on saidpivoted part, said elements being graduated in power so that each of the countertorques produced by them will be of a magnitude differing from the magnitudes of the other counter-torques, means for'comparing first the element exerting the greatest counter-torque and then successively the others, in the order of the magnitude of their counter-torques, withA the measuring torque acting on said pivoted part, means for eliminating successively that countertorque or those counter-torques, from the largest down, which either alone or by addition to some larger retained counter-torque exceed said measuring torque, a remote receiving apparatus including a plurality of elements bearing the same magnitude-relationl to each other as the counter-torques exerted by said comparison elements, and means for transmitting to said remote receiving apparatus, by impulse combinations acting on said elements` of the receiving apparatus, the value of that counter-torque,4 or the sum of the values of those successively commation thereto.

2. In an apparatus for transmitting the indications of a measuring instrument, in combination, a variable resistance, mechanism operative to vary the magnitude of said resistance in dependence upon the indication of the measuring instrument, a second resistance comprising a plurality of comparison resistance units each of a magnitude differing from the magnitudes of the other comparison resistance units, means for comparing rst the largest of said resistance units and then successively the others, in the order of their magnitudes, with the iirst-mentioned variable resistance, means for eliminating successively that comparison resistance unit or those comparison resistance units, from the largest down, which either alone or by addition to some larger retained unit exceed said first-mentioned variable resistance, a remote receiving apparatus including a plurality of elements bearing the same magnitude relation to each other as said comparison resistance units, means for transmitting the magnitudes of the other comparison resistance units to' said receiving apparatus by impulse combinations acting on said elements, and an indicating device adjustable by said receiving apparatus in accordance with the message received.

3. In an apparatus for transmitting the indications of a measuring instrument, in combination, a variable resistance, mechanism operative to vary the magnitude of said resistance in dependence upon the indication of the measuring instrument, a second resistance comprising a plurality of comparison resistance units each of a magnitude diiering from the magnitudes of the other comparison resistance units, means for comparing rst the largest of said resistance units and then successively the others, in the order of their magnitudes, with the first-mentioned variable resistance, said means comprising a contact device, relays controlled by said device, holding circuits for said relays, said relays arranged to select successively the comparison resistance units corresponding to said first-mentioned variable resistance, said rst and second resistances being each arranged in a branch of a bridge connection, a bridge relay in a diagonal .of the bridge operable upon excitation in one direction to close a holding circuit, and, upon excitation in the opposite direction, to cause such holding circuit to be opened to eliminate the particular comparison resistance unit associated with such holding circuit, a remote receiving apparatus including a plurality of elements bearing the same magnitude relation to each other as said comparison resistance units, mechanism for transmitting to said remote receiving apparatus impulse combinations acting on said elements in correspondence with the comparison resistance units required to match accurately or approximately the first-mentioned variable resistance, and an indicator actuated in accordance with the action of said impulse combinations on said elements.

4. In an apparatus for transmitting the condition of a movable member whose condition can be expressed as a measurable value, in combination, a plurality of comparison elements all of the same character but each of a magnitude dilering from the magnitudes of the other comparison elements, means for comparing rst the largest of said elements and then successively the others, in

the order of their magnitude, with the condition of said movable member, moans for producing impulse combinations in dependence upon the result of such comparison, means for sending an auxiliary impulse of a different kind for every impulse of the impulse combination, a receiving apparatus including a plurality of elements bearing the same magnitude relation to each other as said comparison elements, means for taking up the impulse combinations and the auxiliary impulses, and a stop device for arresting the operation of the 'receiving apparatus when the reception of the impulse combinations or of the auxiliary impulses is disturbed.

5. In an apparatus for transmitting the condition of a movable member Whose condition can be expressed as a measurable value, in combination, a plurality of comparison elements all of the same character and each of a magnitude different irom the magnitudes of the other elements, means for comparing rst the largest of said elements and then successively the others, in the order of their magnitude, with the condition of the movable member, means for producing electric impulse combinations in dependence upon the result of said comparison, means for sending an auxiliary impulse of opposite direction for each impulse of an impulse combination, a receiving apparatus including a plurality of elements bearing the same magnitude relation to each other as said comparison elements, means for taking up the impulse combinations and the auxiliary impulses, and a stop device for arresting the operation of the receiving apparatus when the reception of the impulse combinations or of the auxiliary impulses is disturbed.

6. In an apparatus for transmitting the indications of a measuring instrument, in combination, a plurality of comparison elements all of the same character and each of a magnitude dif- .ferent from the magnitudes of the other elements, means operative periodically for comparing iirst the largest of said elements and then successively the others, in the order of their magnitude, with the indication to be. transmitted, a remote receiving apparatus including a plurality of elements bearing the same magnitude relation to each other as said comparison elements, means for establishing a transmitting relation between the comparison element or elements which or the sum of which corresponds exactly or approximately to the indication to be transmitted, and the receiving apparatus element or elements corresponding in magnitude to such comparison element or elements, and means for transmitting an indication of the magnitude of such'comparison element or elements to the corresponding receiving apparatus element or elements by means of impulse combinations.

'1. In an apparatus for transmitting values, in 60 combination, transmission apparatus including a plurality of comparison elements and means for comparing the value to be transmitted succes- .sively with the values of a pluralityof said comparison elements until a value or group of values is found which equals or closely approximates the value to be transmitted, a remote receiving apparatus including a plurality of elements bearing the same relation to each other as the values of said comparison elements, and means for communicating to said remote receiving apparatus, by impulse combinations acting on its elements, that value or group of values determined at the transmission apparatus as equaling or closely approximating the value to be transmitted.

8. In an apparatus for transmitting values, in combination, transmission apparatus including a plurality of comparison elements each of a value differing from those of the other elements and means for comparing the value to be transmitted, successively with the element having the largest .value and then in sequence with the others, until of values determined at the transmission apparatus as 'equaling or closely approximating the value to be transmitted.

9. In an apparatus for transmitting values, in'

combination, transmission apparatus including a plurality of comparison elements each of a value diiering from those of the other elements, means for comparing the value to be transmitted, successively with the element having the largest value and then in sequence with the others, means for eliminating successively that comparison element or those comparison elements, vfrom the largest down, which eitner alone or by addition to some previously compared element, exceeds or`exceed the value to be transmitted, until a'value or group of values is found which equals or closely approximates the value to be transmitted, a remote receiving apparatus including a plurality of elements bearing the same relation to each other as the values of the said comparison elements, and means for communieating to said remote receiving apparatus, by impulse combinations acting on its elements, that value or group of values determined( at the transmission apparatus as equaling or closely approximating the value to be transmitted.

10. In an apparatus for transmitting the condition of a measuring instrument which is operated by a measuring torque on a pivoted part thereof', in combination, a plura1ity-of comparison elementsfor exerting a plurality oi countertorques on said pivoted part. means i" comparing rst the counter-torque exerted by one of said elements and then successively those exerted by the other comparison elements, with the measuring torque acting on said pivoted part, means for eliminating successively that counter-torque or those counter-turques which either alone or added to the counter-torque of some previously compared element exceed said measuring torque, until la value or group of values represented by such counter-turques isfound which equals or closely approximates said measuring torque, a remote receiving apparatus including a plurality of elements bearing the same relation to each other as the values of the counter-torques exerted by said comparison elements, and means for communicating to said remote receiving apparatus, by impulse combinations acting on its elements, that value or group of values determined at the transmission apparatus as equaling or closely approximating the said measuring torque.

11. In an'apparatus for transmitting the indications of a measuring instrument, in combination, a variable resistance, mechanism operative to vary the magnitude oi said resistance in dependence upon the indication of the measuring instrument, a second resistance comprising a plurality of comparison resistance units, means for comparing iirst one of said resistance units and then the others with the rst-mentioned variable resistance, means for eliminating successively that comparison resistance unit or those units which either alone or added to some previously compared unit exceed the value of said variable resistance corresponding to the indication of the measuring instrument, until a value or group of values represented by said units is found which equals or closely approximates that value of said variable resi. tance which corresponds to the indication of e measuring instrument, a remote receiving apparatus including a plurality of elements bearingithe same relation to each other as the values of'said comparison resistance units, and means for communicating to said remote reo ceiving apparatus, by, impulse combinations acting on its elements, that value or group of values determined at the transmission apparatus 'as equaling or closely approximating that value of said mst-mentioned variable resistance /which corresponds to thev indication of the measuring instrument. y

FRITZ FISCHER. HANS SCHUCHMANN.

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