EP0509920B1 - Position signalling device of a movable component - Google Patents

Abstract

Device for signalling the status of an apparatus which can assume several discrete states and transmission of the corresponding information, characterised in that it comprises: - means for deriving, inside a shielded enclosure (4) a DC voltage which is free of fluctuations, the said shielded enclosure comprising within it: - a first means (5) for deriving, from the said DC voltage, electrical pulses of duration proportional to the value of an inductor (6), this inductor being capable of taking distinct values according to the various states of the apparatus, - a second means (8) for converting the said electrical pulses into optical pulses and an optical fibre (9) for transmitting these pulses out of the said enclosure to a processing unit (10). <IMAGE>

Description

The present invention as defined in the claims relates to a device to signal the position of a movable member.

The invention finds particular application in electrical engineering, and this brief will be illustrated by an example which, of course is not limiting.

The example relates to the signaling of the position of the contacts of a power cut-off device electrical, such as a circuit breaker. It is essential to the operator of a substation with devices such as circuit breakers, to know with certainty the state, open or closed, of the position of contacts of each of the circuit breakers; this information, generally available at each of the circuit breakers, is centralized in a control station and control; it is imperative that any failure of the information transmission circuit which connects each of the audit devices are immediately reported, without what the signal received at the station can make believe that a device is in a given state while it is in the reverse state; this error can cause unfortunate consequences for the network operator electric.

For the same reasons, it is essential that the device providing the signaling signals itself, to a large extent that it is down or that its power supply is failing. This self-monitoring considerably increases the availability of self-monitoring part of the device.

Of course, the problem is not limited to the detection of the position of the contacts of a circuit breaker; in electrical substations, this signaling, called also signal contact, relates to pressure switches, oil pressure of the hydraulic control circuits, oil levels, etc.

Out of 100 major failures of a station electrical, about 30 are due to poor contact signal; we therefore understand the importance of the problem.

An object of the invention is therefore to produce a device for signaling the status of a device by detecting this state and transmitting the corresponding information, which is of a functioning without possible error on the detected state, and which signals immediately his own failure as well as that of the information transmission line.

Another object of the invention is to provide a device insensitive to external influences such as electric fields or magnetic fields as well than common mode disturbances encountered when uses galvanic connections.

We know that element feeding optoelectronics, fiber optic transmission and the shielding of the device make it possible to respond to the previous requirement. We then come up against the problem of device consumption; another object of the invention is therefore to make a device that does not require operating no more energy than that available by means of a photovoltaic cell.

In U.S. Patent No. 4,626,621, it is describes a circuit for determining the position of an object, comprising two LR circuits attacked by a square signal from a pulse generator. One of the LR circuits has a fixed inductor, the other a inductor variable depending on the position of the object. The establishment of voltages in the circuits is done, from a moment t1, according to different exponential laws in two circuits, and we measure the respective times t2 and t3 corresponding to the establishment on the two circuits of a voltage of given value Vo. The report (t3 - t1) / (t2 - t1) provides a value corresponding to the position sought.

Such a circuit is complex since it includes two LR circuits, two operational amplifiers, two counters, etc., and it cannot detect its own failures.

An object of the invention is to provide a circuit with the minimum of components, and, as it already has been indicated, able to report its own failures.

Document EP-A-0 272 750 teaches means for converting electrical pulses into optical pulses and means such as an optical fiber for transmitting these pulses to a processing center.

• des moyens pour élaborer, à l'intérieur d'une enceinte blindée, une tension continue exempte de perturbations, ladite enceinte blindée comportant à son intérieur:
• un premier moyen pour élaborer, à partir de ladite tension continue, des impulsions électriques de durée proportionnelle à la valeur d'une inductance, cette inductance pouvant prendre des valeurs distinctes selon les divers états de l'appareil,
• un second moyen pour convertir lesdites impulsions électriques en impulsions optiques et une fibre optique pour transmettre ces impulsions hors de ladite enceinte vers un centre de traitement, caractérisé en ce que les moyens pour élaborer une tension continue comprennent un élément photovoltaïque placé à l'intérieur de ladite enceinte blindée et éclairé à travers une fenêtre de celle-ci par une source lumineuse. En variante, les moyens pour élaborer une tension continue comprennent une cellule photo-voltaïque intégrée placée à l'intérieur de ladite enceinte blindée et associée à une fibre optique alimentée par une diode laser placée à l'extérieur de ladite enceinte blindée.

The subject of the invention is a device for signaling the state of a device which can take at least two discrete states and for transmitting the corresponding information,
said device comprising:

• means for developing, inside a shielded enclosure, a DC voltage free of disturbances, said shielded enclosure comprising inside:
• a first means for developing, from said direct voltage, electrical pulses of duration proportional to the value of an inductance, this inductance being able to take on distinct values according to the various states of the apparatus,
• a second means for converting said electrical pulses into optical pulses and an optical fiber for transmitting these pulses out of said enclosure to a processing center, characterized in that the means for developing a DC voltage comprise a photovoltaic element placed inside said shielded enclosure and lit through a window thereof by a light source. As a variant, the means for developing a DC voltage comprise an integrated photovoltaic cell placed inside said shielded enclosure and associated with an optical fiber supplied by a laser diode placed outside of said shielded enclosure.

In a particular embodiment, said first means comprises a circuit for developing rectangular pulses of constant and separate duration by equal time intervals, an integrating circuit receiving said pulses, a first inverter circuit with threshold receiving the output signals from the integrator and providing as output calibrated pulses, a circuit with time constant comprising a resistance and said inductance, the output signal of said first circuit threshold inverter being sent both to the input of said time constant circuit and on a second inverter circuit, the circuit output signals to time constant and the second inverter circuit being addressed to the input of a third inverter circuit to threshold whose output is connected to an amplifier feeding said second means.

Advantageously, said second means is a photo-diode.

Said processing center includes a circuit for demodulation and a self-monitoring circuit.

In a particular embodiment, said demodulation circuit includes a converter photovoltaic receiving signal from said fiber optics, a Schmitt trigger and a type circuit MEMORY D.

Advantageously, the self-monitoring circuit includes a diode pump type circuit, supplying a output transistor.

In an alternative embodiment, the circuit self-monitoring includes an OR-type circuit exclusive inserted by a first entry upstream of said MEMORY D circuit and including a second connected input to a microcontroller that can provide on this second input a test pulse of duration dt greater than the duration of said rectangular pulses, the microcontroller being connected to the MEMORY D circuit and being scheduled to observe a change in information from position during said period when the system is at rest.

• la figure 1 est un schéma électrique par blocs du dispositif de l'invention,
• la figure 2 est un schéma d'un mode de réalisation du circuit d'élaboration des impulsions de durée proportionnelle à une la valeur d'une inductance,
• la figure 3 présentent divers diagrammes expliquant le fonctionnement du circuit de la figure 2,
• la figure 4 est un schéma du circuit de contrôle et d'auto-surveillance,
• la figure 5 présente plusieurs diagrammes expliquant le fonctionnement des circuits de la figure 4,
• la figure 6 représente une variante de réalisation du système d'auto-surveillance.

The invention will be better understood from the description given below of an exemplary embodiment given by way of illustration and in no way limiting, with reference to the appended drawing in which:

• FIG. 1 is an electrical block diagram of the device of the invention,
• FIG. 2 is a diagram of an embodiment of the circuit for producing pulses of duration proportional to the value of an inductance,
• FIG. 3 presents various diagrams explaining the operation of the circuit of FIG. 2,
• FIG. 4 is a diagram of the control and self-monitoring circuit,
• FIG. 5 presents several diagrams explaining the operation of the circuits of FIG. 4,
• FIG. 6 represents an alternative embodiment of the self-monitoring system.

In Figure 1, reference 1 designates a photovoltaic element, powered by a source luminous 2, for example a lamp powered by a battery 3. The photovoltaic element is placed in a shielded enclosure 4, the light passing through a window 4A; the photovoltaic element supplied by a voltage Vcc for example 5 volts and capable of delivering 20 mA in Crete; an electronic circuit 5, placed inside the shielded enclosure and powered by element 4, develops signals representative of the state of the device; In this Indeed, the circuit includes an inductor 6 made up a winding 6A and a movable core 6B linked to the element mobile of the device which one wishes to know the position; inductance 6 takes two different values depending on whether the core 6B is inside or outside of the winding 6A, and takes values evolving in proportion to the penetration of the nucleus between the two values mentioned above. The electrical output signal from circuit 5 is converted into a light signal by a component optoelectronics 8 and routed through an optical fiber 9 up to signal processing station 10. There, a optoelectronic component 11 ensures the conversion of the light signal into electrical signal which is received by a electronic processing circuit 12 supplying by example signaling 13 and alarm 14.

Thanks to the use of shielding, power supply a photovoltaic element and transmission by fiber optics, the measurements made are protected from all possible disturbances (in particular the absence of galvanic connection makes it possible to avoid any common mode voltage on the position transducer).

Alternatively, shown in dashed lines in Figure 1, the DC voltage is developed using a 1A integrated photovoltaic cell placed at inside the shielded enclosure (this cell is by example an ASGA cell marketed by the company SPECTEC), connected by a 4B optical fiber crossing the shielded cell wall supplied by a diode laser 3A.

In Figure 2, circuit 5 includes a Schmitt trigger 20 receiving the voltage Vcc, and comprising a component 21, an adjustable resistance 22 and a capacitor 23; this trigger outputs A rectangular pulses with rising edges distant for example 100 microseconds and whose duration is for example 40 microseconds. (see figure 3 A).

At the output of the trigger is placed a circuit integrator 30 which includes a capacitor 31, a resistor 32 and a diode 33 to attenuate strongly the peaks due to the falling fronts of pulses (Figure 3B).

The integrator is followed by a reversing element 40 at threshold s1 which supplies, at output C, pulses of calibrated length, for example 10 microseconds (figure 3C).

In C, the signal is sent on a time constant circuit comprising the variable inductance 6, of value denoted L, and an adjustable resistance of value R3. The 3D curve shows, on its left side, the shape of the output signal of the LR3 circuit, at point D, when the inductance at a high value (core 6B inside the winding 6A); the 3D curve shows, on its right side, the shape of the signal in D when the inductance at a low value (core outside the winding). The difference in the shape of the curves is explained by the law for establishing the current i in a time constant circuit LR, which is: i = Imax (1-exp-t / t *)
with t * close to L / R3 and Imax close to Vcc / R3, the winding resistance being negligible.

The output signal of the reversing element is inverted by an inverter circuit 50 and the output signal in F (diagram 3F) is addressed, at the same time as the signal at D, to a threshold inverting circuit 60, the threshold s2 is shown in Figure 3D.

At the output of circuit 60, pulses are obtained of short duration (3 microseconds for example) when the inductance L is weak (nucleus released) and longer lasting (greater than 5 and less at 10 microseconds for example) when the L value is high (retracted core); these impulses are shown respectively to the left and to the right of the 3G diagram. The relation A makes it possible to show that if the trigger threshold is constant, the width of impulses is directly proportional to L / R3, therefore to L, since R3 is substantially constant.

The pulses at the output of circuit 60 are addressed to a transistor 61 supplying, through a resistor 62, a diodeemissive 63, for example type TI510 from the company Hewlett Packard, connected to a optical fiber 64 which crosses the shield 4 and routes information, in the form of light pulses, to a treatment center.

The capacitor Cc, in parallel on the resistance R3, used to compensate for the internal capacity of the winding.

In most applications, the device of the invention for making contacts "signals", so that we will only need two inductance values to determine two widths impulse. We will then use for the inductance a winding with a ferromagnetic core, for example mumetal in the form of a tongue; the two values induction will be determined by the fact that the nucleus ferromagnetic will be in the winding or completely in outside the winding. It is understood that this application is not limiting and that we could consider using more than two inductance values, with intermediate positions of the core ferromagnetic and thus determine more than two durations impulse.

Figure 4 is a diagram of the control circuit the position of the signal contact and the circuit self-monitoring operation.

The optical signals emitted by the converter 63 of Figure 3 are routed through an optical fiber 64 and transformed into electrical signals using a opto-electronic converter 65, for example a circuit R2501 from the company Hewlett Packard.

The converter output signals (H point of Figure 4), are represented in the 5H diagram of the FIG. 5, in which two pulses of small width to the left of the diagram and two pulses of large width to the right of the diagram.

The pulses are reversed by a circuit inverter 66; the output signal of circuit 66 (point J in Figure 4), is shown in diagram 5J of the figure 5.

The signal at J is sent to a trigger Schmitt (for example a circuit 4093 from the company Radio Corporation of America, symbolized in Figure 5 by a resistor r and a capacitor c; the output signal of the Schmitt trigger, at point K in Figure 4, is shown in diagram 5K of figure 5.

The signal in K is sent to an inverter circuit with thresholds 67, which can take a Vcc value as output or a value 0; the signal switches from Vcc to 0 when the input signal exceeds a first threshold s3 and switches from 0 to Vcc when the signal crosses a second threshold s4 (s3> s4). The output signal (in M) of circuit 67 is shown in diagram 5M of figure 5.

The signal at M is sent to the 'DATA "input of a circuit 68 known as "MEMORY D" (for example a circuit 4013 of Control Data), whose entry "CLOCK" is connected to point M. This circuit provides on its output Q, at each 0-1 transition from signal to M, a signal corresponding to the state of the "DATA" input. The signal correspondent, in the example chosen, is represented in diagram 5Q of figure 5. We will use preferably to provide "POSITION" information from contact, the complementary signal Q *, represented in the 5Q * diagram in Figure 5.

• un transistor T à effet de champ,polarisé par une source continue Vcc à travers une résistance 70,
• une première diode 71 en série avec un condensateur entre le point J et la grille du transistor,
• un condensateur 73 et une résistance 74 en parallèle entre la base du transistor et la terre et,
• une seconde diode 75.

The demodulation circuit which has just been described is associated with a self-monitoring circuit of the signaling device of the invention. This self-monitoring circuit consists of a "diode pump" comprising, in a conventional manner:

• a field effect transistor T, polarized by a direct source Vcc through a resistor 70,
• a first diode 71 in series with a capacitor between point J and the gate of the transistor,
• a capacitor 73 and a resistor 74 in parallel between the base of the transistor and the earth and,
• a second diode 75.

The diagram in Figure 5N shows the potential on the gate of the transistor, in N, which always remains greater than or equal to Vcc as long as the chain opto-electronics works; the transistor then remains blocked.

If for any reason (disappearance of the light source, cutting of one of the optical fibers, failure of an electronic component of the chain, including diode pump circuit, etc.) the signal in J comes to disappear, the tension on the grid of transistor T disappears by discharging the capacitor 73 in resistor 74 and a signal appears in X on the drain of transistor T. It will be noted that only the memory D partially escapes this self-monitoring.

Figure 6 illustrates an alternative embodiment of the self-monitoring circuit.

Compared to the circuit of figure 4, it differs by the disappearance of the chain comprising the transistor T.

A circuit 90, of the exclusive OR type, comprising two inputs E1 and E2 and an output S, is inserted by sound input E1 between the threshold inverter circuit 67 and the MEMORY circuit D 68.

An mP microcontroller, connected to the Q * output of the circuit 68 to acquire this information, is capable send a duration pulse "1" on input E2 dt> to. This impulse corresponds to the start-up of self-monitoring and is referred to below as test pulse.

We immediately observe the truth table below from circuit 90. E1 E2 S 0 0 0 0 1 1 1 0 0 1 1 0

When E2 = 0, the exclusive OR copies in S the input E1, so this additional circuit does not modify the information initially delivered in Q *.

On the other hand, we notice that as soon as the impulse of test is launched, E2 = 1. The software having verified that the system is in idle state, no order has been launched, there must be a replacement for Q * by Q *, whatever the initial value of Q *, if the pulses in return from the transducer do exist. he it is sufficient for this that the test pulse has a width slightly greater than t0, period of issue of impulses

To do the self-test, the program first notes the value Q * o of Q *, then it sets E2 to "1" for dt and checks that during this window dt, Q * has become Q1 = Q *. When the pulse is cut off, the microcontroller mP opens a new time window of duration dt. In this second window, it will check that Q2 = Q1 = Qo.

By this procedure, and by a suitable choice of dt, we check the entire measurement chain, including the MEMORY circuit D 68 and gate 67 which escaped the monitoring in the circuit of figure 4.

Note that any failure of the OU exclusive 90 circuit will also be detected by self-monitoring, as it would result in the non-replacement of Q * by Q * when the test pulse is launched.

Self-monitoring can be periodic, with a own periodicity, or be part of the normal cycle of capture of information which is operated by sampling with a given frequency.

Of course, the invention is not limited to embodiments described and shown which have not been given as an example, in which we can replace the means or groups of means described by means or groups of equivalent means.

Claims (8)

1. Device for signalling remotely the state of a device able to assume a plurality of discrete states and for transmitting the corresponding information, said device comprising:

   means for producing inside a screened enclosure (4) a direct current voltage free of interference, said screened enclosure containing:

   first means (5) for producing from said direct current voltage electrical pulses whose duration is proportional to the value of an inductance (6) which can assume distinct values according to the various states of the device,

   second means (8) for converting said electrical pulses into optical pulses and an optical fibre (9) for transmitting said pulses out of said enclosure to a processor (10), characterised in that the means for producing a direct current voltage comprise a photovoltaic cell (1) inside said screened enclosure (4) and illuminated through a window in the latter by a light source (2).
2. Device according to claim 1 characterised in that the means for producing a direct current voltage comprise an integrated photovoltaic cell (1A) inside said screened enclosure (4) and associated with an optical fibre (4B) fed with light by a laser diode (3A).
3. Device according to claim 1 or claim 2 characterised in that said first means (5) comprise a circuit (20) for producing rectangular pulses of constant duration separated by equal time intervals, an integrator (30) receiving said pulses, a first inverter (40) receiving the output signals of the integrator and supplying calibrated pulses at its output, a time constant circuit comprising a resistor (R3) and said inductor (L), the output signal of said first inverter (40) being applied to the input of said time constant circuit and to a second inverter (50), the output signals of the time constant circuit and the second inverter (50) being fed to the input of a third inverter (60) whose output is connected to an amplifier (61) driving said second means (8).
4. Device according to any one of claims 1 to 3 characterised in that said second means (8) comprise a photodiode (63).
5. Device according to any one of claims 1 to 4 characterised in that said processor (10) comprises a demodulator and a self-monitor circuit.
6. Device according to claim 5 characterised in that said demodulator comprises a photovoltaic converter (65) receiving the signal from said optical fibre (64), a Schmitt trigger (r, c, 67) and a D-type flip-flop (68).
7. Device according to claim 3 characterised in that the self-monitor circuit comprises a diode pump circuit driving an output transistor (T).
8. Device according to claim 6 characterised in that the self-monitor circuit comprises an exclusive-OR gate (90) connected by a first input (E1) on the input side of said D-type flip-flop (68) and having a second input (E2) connected to a microcontroller (mP) adapted to apply to said second input a test pulse of duration dt exceeding the duration of said rectangular pulses, the microcontroller being connected to the D-type flip-flop (68) and being programmed to observe a change of the position information Q* during said period if the system is idle.

Images