CA1143467A - System for recording electrical signals, displayed on a moving support - Google Patents

Abstract

ABSTRACT

A SYSTEM FOR RECORDING ELECTRICAL SIGNALS, DISPLAYED
ON A MOVING SUPPORT

Inventors : Gabriel LEJEUNE
Claude VIALATTE
Bernard GRANCOIN

Applicants : THOMSOM-CSF

A system for recording physical data in the form of electrical signals, displayed on a paper tape, in which the output paper tape recorder of the system is preceded by a magnetic recorder, with high flow rates at its input and output, of the floppy disc type, means being provided for transferring only the useful recor-dings to paper, so displayed economically and on a large scale.

Description

~1~3~7 1 This invention relates to ~ys~e~s for reicording random dis~urbances o the ~ype which ca~ occur in industrial installa~ions andjt more particularly, in elec~ricity supply net~orks .
S In this latter case in particul~r9 ~e notion of senr;ce is undamental and any incldent, such as a variatlon in the volta~e o~ the electricity9 for example an overvoltage or an u~dervoltage sufficien~ to bring about a total breakdown in supply, requires that a complete analysis of ~he phenomenon should be able to be subsequently made in order to detenmine its causes and to prevent it from recurring. Thes~ causes are various and may be related ~o accidental damage ~ the supply lines or their associated componen~s (circuit breakers, isolators); they may emanate from u~desirable ontacts or from short circuits momentarily affecting certa~n componen~s of these lines~ In the case of overhead lines nonmally s~pported by pylons, a ~requent cause of disturbances ~ay be attributed ~o atmospheric electrical discharges, such as those due to ligh t ning.
In any event, the monitoring of these unforeseeable Th-CSF 4837 .,~

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1 disturbances necessitates on the one hand continuous surve;llance and, on the other h~ndS the possibility of subsequently analysing each phenomemon which i~ tuxr~
necessitates the use of recordir~g means Recording means suGh as ~hese generally use aTI inormatiQn support in the form o~ a moving tape OII which the values ~o be monitored are recorded i~ the for~m o~ visi~le signals either directly or after a suitable treat~e~t~
In ~he majority of cases, the material used for the support is paper w~ich lends itself to convenient directvisual examination~ to subse~uent additional recording and to filing.
The recording is generally made with ink or~ less frequently, using a photographic means with, in this case, the possible need for processing.
~ wever9 the continuous recording of the ~alues to be monitored results i~ an unacceptable consumption ~f paper~ the incidents only occurring infrequen~ly and~ as already mentioned, randomly. In order to reduce the amount of recording support used, it has already been proposed to make the recording only when a disturbance occursO
This system nf operation in the tripping mode is activated by the occurrence of the distur~ance ~tself 9 the recorder remaining inactive between two disturbances.

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1 However~ the exact determination of the causes of the incidents makes it desi~able to know not only the disturbed state as a whole bu~ also the stable state prevailing immedia~ely before the incident.
According~y, when an incid~nt occurs, the re~order has to beg;n recording before the arrival of the disturbance signal, a requirement which can onl~ be satisfied by the insertion of an element which întroduces a delay between th~
mome~t when the 5ignal corresponding to the disturbance ~ctivates the recorder and the moment when the recording itself begins~
This element performs a function which will be referred to hereinafter as a pre-activation memor~.
In some known p~per tape recorders, the pre~activation me~ory is o the me~ha~ical type~ It is f~rmed by a - rotating intermediate suppor~ in the form o a cylinder on which the last few seconds of the value to be mo~itQred are graphically recorded and then per~anently erasedO
Ihe transer by contact to the paper tape, which is normally stationary9 only takes place in the event of an incident.
The pre-activation memory ls th~s represe~ted by the value of the angular displacement between the writing points and conta~t points between the rotating cylinder and the paper.
In other papex tape recorders, the pre-activation :

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1 memory is electrically ormed by a digital circuit of the l'shift register~' type. The analog value to be monitored is converted before~and into a digital ~alue and, after having been delayed~ is con~er~ed back into an a~atog value at ~he register output for ~he ina1 xecording on paper tape.
Given acceptance of the reduced sepa~ating power and the lack of precision inheren~ in recording in real -~ime on paper tape, it has been possible to obtain satisfac~ory results with disturbance recorders of this type at the cost o a~tentive surveillance for keep;~g the reoorder adequatel~
supplied with paper tape and the maintenance of an op~imal environment adapted to the recording process used.
However, in numerous other practical cases, these requirements cannot be sa~isfied. This is bec~use, due to their particular characteristics and to the wide band of frequencles which they contain, the electrical disturba~ce signals, whi~h often appear at extremel~ remote points of the networks to which access is dificult~ cannot be conveyed by conventional electrical lines to an operations centre where the recording apparatus can be con~eniently grouped, observed and maintained. Accordingly, one of the limita~ions of using apparatus of this type lies in the fact that they have ~o be installed on natural sites often separated by considerable distances to which only ver~

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infrequent periodic visits can be made for removing the recorded supports and, if necessary, replacing ~hem by blank supportsO
~his means that, in order ~o reduce ~he consumption o~
S papexg it is necessary to select a limited tape speed which in ~urn results in a low resolving power and ~.omplicates analysis of ~he results which have ~o be examined under a magn~ying glass7 In general, the total capacity of the system is limited by the size of the roll of paper.
In addition~ in the event of a faîlure in the operation of the paper tape recorder, no trace of the disturbance to be studied is le~t w~ich seriously andangers the reliability of surveillance at r~mote sites.
In order to improve reliabili~y, it has been proposed to replace the process of recording on paper ta~e by recording on magnetic supports, generally in the fonm of tape cassettes9 either in analog form or in digital form.
However9 in view of ~he orders of magnitude of the data to be recorded, the rlumerical input and output speed of a cassette remains low, limiting the rate of flow of information per second, particularly when several input channels have to be monitored. In addition, cassettes are fragile, difficult to change at freque~t i~tervals a-t remote si~es and leave no material graphic trace directly visible , 1 at remote sites fc\r analysis and additional annotation.
This particular disad~antage, although associated with a distinctly ~igher inpu~ rate, may be ofset in cases where the magnetic support is fonmed by a floppy disc.
The present in~en~ion rela~es to ~ recording system which is not attended by any o these clisadvantages, but instead has the combined advantages of rche two types of information supportl namely the magnetic suppor~ in the form of a floppy disc and the paper tape.
According t~ the invention, the known system ol recording on pa~er tape is co~pletely retained~ the basic feature of ~he invention consisting in the insertion between two links of ~his system of an additional recordin~ means comprising a magnetic suppor~ o the floppy disc type~
The association of a floppy disc with a paper tape thus constitutes a combination co-opera~ing to achie~e a common objective, providing on the one hand a highcapaci~y, high-resolution storage fac;lity for a large number of non~directly accessib~le data and, on the other hand, a direct visual examination means for analysis and action, the commcn obJective achie~ed being the reliability and precision in the knowledge of the disturbances in question.
In a first mode of oper~tion o the system, the paper tape recorder may remain permanently inactive, being .

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~7 1 activated only during periodic visits under the surveillance of the visiting official who is thus readily able immedia~ly to see a~y desired part of the recording of the floppy disc~
The choice and the surveillance of the offirial inm1y guarantees a good recording on paper with an increas~ in the tape speed to obtain better resolution~
In a second, particularly advan~ageous mode of operation of the system, the paper recorder need not be permanen~ly ins~alled at the site, but instead may be brought alon~ ~y the visiting official so that a singlP recorder may ser~e several widely scattered sites. This mode of operation is permitted by the invention9 the means required for extracting~ processin~ and recording on paper the data contained in the floppy disc already being largely present in the fixed part of the system, so that the pape~ recorder may be lighter in weigh~ and more transportable.
In a ~hird mode of operation o:E the s~s~em, ~he paper recorder is installed in a central location provided w1th technical means affording every guarantee of recording quality and the visiting official conveys the floppy disc recorded on the si~e to a rea~er for floppy discs installed in the same central location~
In this case, ~he official is no longer in possession on site of means for permanently displaying the information . ~ ;, ., 41i7 ~ 8 -1 contained in the floppy disc. However, the weight to be transported9 namel~ the floppy disc, is greatly reduced ~y comparison with the paper recorder of khe second mode of operation. I~ this case~ the invention, wh;ch ~ffords the advantage of enabling ~he secondary recording to be mad~
on paper from a primary recording on a 10ppy disc, overcomes the limitations inheren~ in conventional direct recordi~g on paper tape, namely a reduced resolu on and/or a high consumption of paper and/or poor reliability~ Thi~ is because each incident or disturbance may be readily displayed on paper on a large scale and wQth high resolution and conventional recorders, for example usîng an ink pen, may be used ~or this pu~pose~
In one preferred embodiment9 however, the in~ention may advantageously be worked ~y a particular choice o~ the paper display recorder using ultra~violet recording on a paper sensitive ~o ultra-voilet radiation crea~ed by ~he moving spot of a cathodic oscilloscope. The resultlng lightness and simplicity of the paper recorder are particularly advantageous in the case o the second mode of operation described above.
In addition to the recorded analog diagram itself, this system enables all the alpha-numeric identification data considered necessary and present on the magnetic support :

~3q~7 1 (place, date, time of recording, etc.~...) to be recorded.
It should also be poin~ed out that the insertion of a floppy disc stage, where the recording is normally made in digital fonm, ad~a~tageously lends itsal to assoc;ation with a digital pre activation memory provided either at ~he output of this stage or at its input.
In this particular case, a memory such as this enables the floppy disc to be used to particular ad~antage by also subjecting it ~o ~he tripping mode and by leaving it inactive between tw~ disturbances in the same way as the paper tape reacorder.
~ the other hand9 it is pointed out that the intermediate recording on a floppy disc provides for a signi~icant improvement in the reliability of the system, the floppy disc stage being essentially electronic in design, having a reduced power cons~mption and comprising only a small number of me~h~nical elements which, moreover, remain inactive during i~s moni~oring function between two disturbances.
Accordingly, af~er transfer to the paper tape, there are two documents which provide an additional guarantee in the event of damage or loss.
Finally, it is poin~ed QU~ that the use of a floppy disc stage as an intermediate link brings to the analysis of the random disturbances all the advantages of recording ~he data ~3~7 1 in digital ~orm, in particular the location of disturbances defined by the;r charac~eristics, ~he comparison between recordings of the same disturbance emanating from dif~erent monitoring sta~ions~ ~he possibility o using a~y law of compression for the data adapted ~o the type o disturbancas, etc.
Accordingly, the i~vention co~sists in a recordi~g syst~ ~or displaying random el~ctrical disturbances, comprising on the one hand a plurality of i~put ma~ching circults for i~troducing the sign~ls, a irst stage for multiplexing the signal, a second s~age for delaying the multiplexed signals, this second stage comprising an input analog-digi~al ; conversion circuit, and a third s~age which is activated by said introduction ~or displaying the retarded signals, characterised in that an additional stage~ comprislng a magnetic recording sys~em o~ ~he '~floppy disc~' type, is inserted between the second and third stages~
The invention will be better understood from the following description in conjunc~ion with the accompanying

2 drawings, wherein:
Figure 1 illustrates a conv~ntional paper-tape recording system.
Figure 2 shows a recording system according to the invention.

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1 F;gure 1 shows a paper-tape recording system c~rresponding to the prior art.
It comprises9 on a first channel~ an ;nput matc~ing stage 11 for the valuesor electrical signals to be recorded which is formed by a plu~ality o~ celLs, such as 12, a second multiplexing stage 7 co~nected to the first stage, a third stage 21 ~or delaying the signals, a fourth mul~iplexing stage 17 synchron~sed with the multiplexing stage 7 by the co~nec~ion 20 and a fif~h and last stage, a paper-tape recorder 25 with a recording input, such as 18~ connected to the preceding stage.
The conventional recording system additionally co~prises a second channel 30 connected in parallel ~7ith the first channel after the mulitplexing stage, th;s second channel being connected to the paper-tape recorder by a recording control circuit 32. Finally, a time~and-date circuit 41 is connected ~o a recording input 70 of the recorder.
A system such as this operates as follows: The values or electrical signals corresponding to the data to be recorded are applied to the input ~erminals, such as 1,2,3~ o:E level, pass-band etc. ma~ching circuits such as 4, 5, 6...... 12.
At the output of this first stage, the signals are applied to the input ~erminals, such as 8, 9, 10, of a multiplexi~g circuit 7. The func~lon of this second stage , 1 is successively to scan all the signals by repetitive scrutinisation in order to deliver their v~lues to a single output terminal 13.
The tw~ channels 29 and 30 of the system are connected S to this terminal~ Thro~tgh the direct channel 309 the appearance of a sigDal to be recorded se~s the recording support in motion through the control circuit of the recorder 32.
Through the re~arded channel 29, the sig~al undergoes ;n the signal retarding stage 21 a delay in transmission which, af~er the demultiplexing stage 17 9 will ensure the required result of applying the signal to ~he recording input terminal 18 of the racorder only after the recording support has been set in motion.
The design o the delay stage was governed by the fact that it is easier to delay ~he propagation of an electrical signal în digîtal ~orm than ;n analog form. It is for this reason that9 according to the prior art, the retarding stage comprises an analog-digital conversion circuit 4~ a retarding circuit of the type known as a shift register 43 and a digi~al-analog converter 44.
The disadvantages of a recording system such as this havealready been mentioned and arise out of the limited resolution of the paper-tape recordings made in real time. A modification to this system, whPreby the signal is momentarily placed in :

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1 a semiconductor memory and subsequently displayed on paper with a higher resolution, would resul~ ln the need for ~ery large dimensions of this memory and/or even in a limitation o~ the duration of the recordable disturbances.
Figure 2 shows a rec~mg system accordi~g to the ;n~ention.
In a drawing where the same elemen~s as those in ~igure 1 are denoted by the same re~erence numerals5 it is c~aracterised by the insertion in the retarding stage 21 of a magnetic floppy disc recorder.
A sys~em such as this opera~es as follows3 ~le signals to be recorded~ which are applied in analog for~ to the iDpUtS, such as 19 2) 3, and multiplexed at 7, are converted into digital form in the conversion stage 42.- For the reasons explained in detail above, they are then retarded in a semiconductor memory circuit 43 and in~roduced into the floppy disc recording stage 50. This stage comprises the actual recorder 51 and the associated circuits 52 for processing the signals ~o be recorded and controlling the recording operation itself~
As in the conventional system shown in Figure 1, the signal is applied at the output of the ~loppy disc recording stage to a digital-analog conversion stage 44, a demultiple~ing stage 17 and a paper-tape recording stage 25.

1 At 53, the associated circuits 52 perform a "time and~date'~
function materialised by a real time counter controlled by synchronisation line leading to an external time-and-date clock 54. I~ addition, the real time counter supplies the S signals for activating the input scans through the line 55.
On the other hand, the associated circuits peronm at 56 a function whereby the digital signals are ~rea~ed and, a~
57, a func~ion whereby the words are shaped and the identification and date codes insertedc According ~o one advantagleous ~ aspect of the inven~ion9 this treatment co~prises a prograrnme for compressing the signals to be recorded in dependence upon their significant variations of which the objec~ is not to introduce stationary data in~o the 10ppy disc, but onl~
to memorize the necessary data in a minimal volume. Th~
15 data corrpression progra~ne according to the invention is as ollows:
On completion of each scanning cycle carried ou~ by the multiplexing stage, the treatment circuit compares the word which has just ~een memorized on each of the channels with the word memorized on the corresponding channels during a pre.ceding scanning cycle and, depending on the differences observed9 the circu;t decides whether or not to precede with the recording o~ the new scrutinisation.
- The decision is made for all the input channels in :~ .

3~7 dependence upon the variatîons of all the channels: the recording ;s only omitted if all the channels have r~nalned very cïose ~o the value taken as reference.
- In the interests o safety9 the treatment circuit 5 limits tlhe number of scnutinisations elirninated to a predetermined value.
~ Each scrutinisation recorded is preceded by a code ~hich indicates the number of scrutinisations which have been eliminated since the last recording.
-~ The scrutinisat;o~ taken as reference ~or the comparison a~ ~he instant t may be the scrutinisatîon made at ~e instan~ ~t-1), if the quiescent sta~e o the :Lines under surveillance is totally unknown, or the scrutinisa~ion made at ~he instan~ (t~T~ if a periodic signal of known period T
is normally present on the lines.
The tolerances o the comparison and the limi~ing value of the n~mber of scrutinisations eliminated are defi~ed in dependence upon the use of ~he recording system itsel:E.
As e~plained above, the data may readily be displayed 20 b~ using a digit:al~analog converter 44 followed hy a demultiplexer 17 synchronised with the multiplexer 42 by the lîTLe 4$ and connected to a paper-tape recorder 25o :~n addition, if the paper-tape recorder is adapted for recordi~g da~a in digital form, the insert;on according 1 to the invention of a digital floppy disc recorder af~ords the additional advantage ~hat, in addition to the analog data ~orresponding to the signals~ data charac~erising the date~ technical conditions, etc. may be dixectly adde~
S to the paper tape in alpha~numeric fonm according to any desired character code~ This possibility is permitted in particular by cathode tube recorders using paper sensitive to ultra-viole~ radiation.
For a collection of orders o magnitude given ~y way of e~ample, the following results were obtained according to whe~her the dis~urbance recording sys~em corresponds to the prior art or to the invention:
For a typical speed of the paper ~ape of 20 cm per second, a standard roll of paper ~0 metres long used in the con~entional system enables disturbances having a maxi~um total dur~tion of 150 seconds to be recorded with a given degree of resolution. ~Jith the inserti~n of a f1QPPY disc stage according to the invention, the maximum l:otal duration .i.s increased to 400 seconds without compxession o the data and to 700 seconds with compression.
Finally, by slowing down the floppy disc during the recording on paper, the expansion of the time scale on the paper enables the degree of resolution to be increased by between 5 and 6 times whilst, at the same timegkeeping the ~`

- ~7 _ consu~tion of paper at a low leveI by selecting on7y those disturbances considered to be o interest.

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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for recording electrical signals corresponding to random disturbances and displaying them on a paper-tape recorder, comprising successively: in-put matching means receiving on respective inputs said electrical signals being formed by matching circuits;
multiplexing means for cyclically sampling the matched signals; analog to digital conversion means for convert-ing the samples into digital form; a delaying device coupled to the output of said converter for delaying the multiplexed digitalized signals; a floppy disc re-cording assembly coupled to the delaying device for receiving the delayed signals, the assembly comprising a datachable floppy disc unit, the disc being normally motionless and means for actuating the disk to rotate in order to record the delayed signals upon detecting a disturbance; a demultiplexing assembly for demulti-plexing the said signals recorded on the floppy disc and delivering said signals on respective outputs; and a paper-tape recorder supplied by the said outputs of the demultiplexing means for displaying on paper floppy disc recorded information.

2. A system according to claim 1, wherein the paper-tape recorder comprises a cathode ray tube and paper sensitive to ultra-violet radiation.

3. A system according to claim 1, wherein it comprises further digital to analog conversion means connected between said floppy disc recorder assembly and said demultiplexing assembly.

4. A system according to any of claim 1, 2 or 3, wherein the floppy disc recording assembly com-prises a control unit for ensuring the synchronization and for controlling the recording, a time and date circuit, a formatter circuit and processing circuits for compressing data to be recorded onto the disc.

5. A system according to any of claim 1, 2 or 3, wherein the paper-tape recorder is a detachable and portable unit.