MXPA98008731A - Static relevators with est detection - Google Patents

Abstract

The invention relates to a static relay (RS) with semiconductors (Th1, Th2), intended to be inserted into the electric circuits (CE) of alternating current and comprising means (D1, D2, T1, T2) for determining the state of the relay (RS) in the operation phase and in a supplementary state corresponding mainly to a destroyed relay, to an electrical circuit (CE) out of voltage or to the relay disconnected from the electrical circuit (CE), these means are connected to the terminals of the relay. Application: Opening and closing of electrical circuits that work in alternating current

Description

STATIC RELAYS COH STATE DETECTION FIELD OF THE INVENTION The invention relates to static relays used to effect the opening or closing of electrical circuits.

BACKGROUND OF THE INVENTION At present, there are at least two main types of relays according to their obtaining technologies, the electromechanical relays and the relays with semiconductors or static relays. Electromechanical type relays comprise one or more electrical contacts mechanically coupled to a moving element of a magnetic circuit driven by the order of feeding a coil, producing an induction flow in the magnetic circuit. The magnetic circuit opens or closes according to the position of its moving element. For example, the relay is in the rest position, the relay coil is not powered, the magnetic circuit of the relay coil opens and the electrical contacts of the relay open. The change of state of the relay is done by feeding the relay coil by a control electric current, the magnetic circuit is closed, causes the closing of electrical contacts. The relay goes from a rest position to a working position. The state of the electromagnetic relays can be quickly determined, either by visualization of the air gap between a fixed part of the moving element of the magnetic circuit, that is by the communication noise of the relay, before the change of state, assuming that the initial state is known . Static relays, contrary to electromagnetic relays, do not use mobile mechanical elements, but only semiconductors capable of making the opening or closing of an electrical circuit, where they are inserted. Generally, for safety reasons, the control circuit is galvanically isolated from the electrical circuit, where the relay is inserted, some electrical circuits put currents and high voltages into play. For example, for static relays, the isolation of the control is carried out by the photocoupler. Static relays connected to an electrical circuit operate on alternating current, using semiconductors such as triacs or thyristors, mounted in parallel head-fork, or analog components such as those marketed under the names "Snubberless" or "altermstor", which function as triads and have a greater content in untimely uncoupling. These types of semiconductors present in their normal operation two different states when they are inserted in an electrical circuit. An open state and a closed state. In the open state, all the voltage of the electrical circuit is applied to the terminals of the semiconductor. In the closed (or saturated) state, an alternating saturation voltage of approximately 1.5 Volts appears at the terminals of the semiconductor. The static relays can present another supplementary state that is not a habitual state of functioning and that is united to the destruction of the semiconductor, putting it either in short circuit, or in open circuit. When the semiconductor is destroyed and presents as a short circuit, the voltage at its terminals is practically equal to 0 Volts and when it is presented as an open circuit, all the voltage of the electrical circuit is presented at its edges. The automatisms very often use relays and in particular static relays that tend to replace electromechanical relays of old technology, and it is necessary to know the actual state of the relay depending on the state of its order. Currently, two cases can occur, either the The relay does not provide any information about your state, or whether your status is determined with the help of systems external to the relay. For example, in the hypothesis that the relay is not defective or decomposed, a measurement of the current of the electrical circuit in which the relay is inserted allows determining if the relay is open or closed, this requires a measuring device that can support the entire current of the electric circuit. This measuring device is expensive and bulky, particularly in the case of electric circuits that use high powers. In the case of static relays with semiconductors, the measurement of the voltage at the terminals of the relay can be carried out in order to determine its state. When the relay opens, all the voltage of the electrical circuit is applied to its terminals and when it closes, it should be possible to detect a voltage of the order of 1.5 Volts corresponding to the saturation voltage of the semiconductor. The device for measuring the voltage at the terminals of the relay must, on the one hand, support the voltages of the electrical circuits, often elevated in a few hundred and reach up to thousands of Volts, and on the other hand, have sufficient precision to detect the low saturation tensions of the semiconductor, approximately 1.5 Volts. This leads to a measurement device that is quite expensive and difficult to put into operation.

In order to reduce these drawbacks, the prior art proposes a static relay (RS) intended to be inserted in an alternating current electric circuit (CE) comprising at least two connection terminals (1,2), the static relay ( RS) has at least one semiconductor component, which can take two states in phase of operation, one open and the other closed, the means for determining the state of the relay (RS) in operation phase and a supplementary state corresponding mainly to the destroyed relay, to the electrical circuit (CE) out of voltage, to the relay disconnected, these means are connected to the terminals of the relay, characterized in that the means for determining the state of the relay comprise a pair of electroluminescent diodes (DI, D2) mounted in parallel head-fork, this pair is in series with a circuit of type RC seriado (R1, C), the set of diodes (DI, D2) and the circuit RC (R 1, C) is connected in parallel on the semiconductor component (Thl, Th2) and each diode (DI, D) is optically coupled, respectively, to a transistor (TI, T) one of the diodes carries a connected current to the positive alternation of the alternative voltage of the electrical circuit and the other diode carries a current together with the negative alternation of the same electric circuit. The electroluminescent diodes are lit during almost all alternations when the component is open and is not defective. These same diodes are lit for a short moment as they pass through the zero level of the alternations, when the component closes and is not defective. The diodes remain on during the entire alternation when the component is faulty and short-circuited.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will appear from the reading of the description of the examples of the relay, according to the invention, wherein: The Figure represents the electrical diagram of the static relay according to the invention and Figure lb is a variant of the semiconductor of the relay, - Figure lc represents a variant of the means for determining the state of the relay; Figures 2a, 2b and c represent the voltage and current diagrams of the relays that are the object of Figure la, in the open state; Figures 3a, 3b, 3c represent the voltage and current diagrams of the relays which are the object of Figure la, in the closed state; Figures 4a and 4b represent the voltage and current diagrams of the relays that are the object of Figure la, in the supplementary state, when the semiconductor is a short circuit; Figures 5a, 5b and 5c represent the voltage and current diagrams of the relays that are the object of Figure la, in another supplementary state, the relay is in a closed position.

DESCRIPTION OF THE PREFERRED MODALITY In the diagrams the scales have not been fully respected in order to give clarity to the drawings. The figure shows the electrical diagram of an example embodiment of a static relay RS according to the invention, comprising a pair of thyristors Thl and Th2, connected in parallel head-fork. The thyristor cathode Th2 is connected to the thyristor anode Thl and to a terminal 1 of the RS relay, this is connected to a first side A of an electric circuit CE and the thyristor cathode Thl is connected to the thyristor anode Th2 and a terminal 2 of the relay RS, which is connected to a second side B of the electric circuit CE. The voltage appears at the terminals of the thyristors when the electric circuit CE is under voltage, it will be designated to continuation as Ucc. The RS relay is controlled by an EC control input of a CD control circuit that, according to the prior art, sends by means of its control outputs SI and S on the respective guards Gl and G2 of thyristors Thl and Th2, of the electrical signals that disconnect the closure of their thyristors. The control circuit CD integrates an optical isolation in order to isolate the EC input of the relay, from the thyristors that are at the voltage of the electric circuit CE. The means for determining the state of the relay comprises a pair of diodes DI, D2 mounted in parallel head-fork, this pair of diodes is in series with a circuit of type RC series R1, C, the set of pair of diodes DI, D and of the RC circuit - it is connected in parallel on the pair of thyristors Thl, Th and each diode DI, D2 is optically coupled, respectively, to a transistor TI, T. The RS relay comprises an input 10 connected to a power supply external to the relay, of supply voltage Vcc that allows to feed a direct current of a part of the control circuit CD of the relay and on the other hand of the means for determining the state of the relay. relay (RS). The collectors of the TI and T2 transistors are connected in an assembled manner on a terminal 6 and connected on the one hand to the supply voltage Vcc by means of a resistor R2, and on the other hand by a common ground M, by means of a capacitor C2. The emitters of the transistors TI and T2 are connected to the common ground M. The status information of the relay RS is obtained by the voltage Vs at the output of the collectors of the transistors TI and T2 (terminal 6). It is preferable to place a voltage limiter, which in this exemplary embodiment comprises two Zener diodes Zl and Z, mounted in series head-fork, to the terminals of the subassembly constituted by the pair of electroluminescent diodes DI and D2 and the resistance Rl. This limiter Zl, Z makes it possible to protect the light-emitting diodes DI and D in the event of a high amplitude front elevation of the Ucc voltage at the terminals of the thyristors, for example due to the disconnection of the thyristors when the voltage Ucc is at a high level. Next, the operation of the RS relay will be described. The RS relay is inserted in an electric circuit CE, which supposedly operates at an alternating voltage U, for example sinusoidal. It is considered the case where the relay is in an open position, that is to say where Thl and Th thyristors they are open. Reference is made for the explanation of the operation to Figures 1a, 2a, 2b and 2c, which represent the electric diagram of the relay inserted in the electric circuit CE and the voltage and current diagrams in the circuits of the RS relay. The RS relay is put in open position by order of the EC, all voltage U of the electrical circuit is applied to the terminals of the thyristors (terminals 1 and 2 of the RS relay) and in this case, Ucc is equal to the voltage U of the electric circuit CE. The diagram in Figure 2a shows the voltage Ucc as a function of time at the terminals of the thyristors. If an electric circuit operating with alternating current is considered at the frequency of 50 Hz, the period T of the voltage Ucc will be 20 ms. The diagram of Figure 2b shows the shape of current 1 in the circuit constituted by capacitor C, electroluminescent diodes DI and D2 and resistance Rl. Current 1 approximates its shape to that of a sinusoidal current. Current 1 passes through the light-emitting diode DI during a half-sleep and the electroluminescent diode D2 during the other half-sleep, alternately producing saturation of the transistor TI and after the transistor T2, and so on, except for a short period of time? t in relation to the voltage period Ucc, which corresponds to the current override 1 in the diodes DI and D2, which is due to the threshold (approximately 1.2 volts) of conduction of diodes DI and D2, at the moment of passing through 0 volts of voltage Ucc. During approximately this short time period? T, the transistors TI and T2 are blocked and the voltage Vs at the terminals of these collectors, represented in dotted lines in Figure 2c, tends to pass in a rough way, over time? T , at the level of the supply voltage Vcc. Figure 2c represents with a dotted line a voltage Vcb that appears on the collectors of the transistors TI, T2, during? T, in the case where the capacitor C2 will not connect on the collectors of the transistors. The circuit of type RC, R2, C2 is responsible for integrating the variations of the voltage Vcb during the time periods? T. The values of R2 and C2 are calculated to maintain this variation of Vcb at a low value, close to the saturation voltage of the transistors. The voltage Vs in terminal 6, connection point of the collectors of the two transistors TI and T2, is practically equal to the saturation voltage of the transistors, ie approximately 0.6 Volts. It will be said that the voltage Vs is in a low state. The RC-type circuit constituted by the components C and Rl is calculated so as to ensure a current I sufficient to saturate the transistors TI and T2. In this example of a modality, the capacitor C is approximately 10 nF and the resistance Rl of approximately 47 O. The relay is placed in the closed (or saturated) position, for the explanation of this phase of operation reference is made to Figures la, 3a, 3b and 3c. The closing of the RS relay by an order of its input EC, causes the closing of the electric circuit CE.

The alternative current that passes through the electrical circuit causes a saturation voltage of about 1.5 Volts for this type of semiconductor to appear on the terminals of the Thi and Th2 thyristors. The diagram in Figure 3a shows the form of voltage Ucc at the terminals of the thyristors. { terminals 1 and 2) . The voltage Ucc followed in a first phase, the voltage U, sinusoidal of the electric circuit, partially represented in dotted lines in Figure 3a, is stabilizes around the value of the saturation voltage of the thyristors. During the positive half-period Thl closes and the voltage Ucc between terminals 1 and 2 is of the order of 1.5 Volts, and during the other negative half-period, the other thyristor Th2 closes and the voltage Ucc is of the order of -1.5 Volts. The current I in the capacitor C is connected to the voltage variation in the terminals of the RC circuit comprising the capacitor C, the diodes DI and D and the dUcc resistance Rl, which is of. The current I appears in dt drive form during the rising or falling fronts of voltage Ucc around 0 Volts and for a time? Tl, which is short in relation to the period and depends on the value of the voltage in electric circuit ( dotted line curve in Figure 3a) in relation to the saturation voltage of the thyristors. Figure 3b shows the drive current I in the capacitor C, the current drive II occurs during the rise front Uccl of the voltage Ucc, passing through the diode DI and causing a saturation, for about? Tl, of the transistor TI optically coupled to the DI diode and an instantaneous discharge of the capacitor C2 mounted between the collector of the transistors TI and T2 and the mass M. This translates into a steep descent front Vsl (Figure 3c) of the voltage Vs of the collectors of the transistors TI and T2, after a load of the capacitor C2, towards the supply voltage Vcc applied to the resistor R2, with a time constant t2 = R2 x C2. For example in this embodiment, the resistor R2 is about 33 KO and the capacitor C2 is about 200 nF. The time constant t2 is equal to approximately 7.26 ms. In the same way, during the descent front Ucc2 (FIG. 3a) of the voltage Ucc is produced in the following half-period at a voltage Ucc of 0 Volt, the driving current 12 passing through the other electroluminescent diode D2, causing a saturation, for about a time? Tl, of the transistor T2 optically coupled to the electroluminescent diode D2, and in the same manner as for the preceding half-period, an instantaneous discharge of the capacitance C2 results in a steep descent front Vs2 of the voltage Vs of the collectors of the transistors TI and T2, after a new charge of the capacitor C2 towards the voltage Vcc applied in the resistor R2. The open state of the RS relay is determined by a succession of descending fronts. { Vsl, Vs2 ...) of the voltage Vs in all the semiperiods, either for a alternative electric circuit that operates at 50 Hz, for all 10 ms. The case where the means of state detection and is identical to the supplementary state will be explained. This occurs mainly when one or both of the thyristors are destroyed or when the circuit is out of voltage or also when the relay is disconnected. In the following case we will refer, for the explanation of this operation, to the relay of Figure la. In the case "where the two thyristors are destroyed and are in short circuit either when the electrical circuit is out of voltage or when the relay is disconnected only from the electrical circuit CE (terminals 1 and 2), the Ucc voltage at the terminals of the thyristors, represented in Figures 4a, is substantially equal to 0 Volt. The transistors TI and T2 are blocked by the absence of the current I (shown in Figure 4a) in the electroluminescent diodes DI and D2, the collectors of the transistors TI and T2 are blocked and the output voltage Vs, represented in Figure 4b , it is at the supply voltage Vcc, either in the high state. In another case, the RS relay, governed by its EC input, is in a closed state and one of the Thyristors, for example thyristor Th2, is destroyed and in open circuit. During a first alternation to that of voltage Ucc, the tipstor Thl closes and allows the passage of current from the electric circuit CE. The voltage Ucc shown in Figure 5a is of the order of 1.5 Volts, corresponding to the saturation voltage of the Thi thyristor. The current I, represented in FIG. 5b, in the circuit comprising the pair of diodes DI, D2 is zero during this first alternation al. The transistors TI and T2 are blocked and the voltage Vs, represented in Figure 5c, which is in a low state, during the preceding alternation, as will be shown below, passes with the time constant t2 (resistor R2, capacitor C2 ) from 0 Volt to the supply voltage Vcc, as in the case of Figure 3c. During the alternation following a2, the voltage Ucc changes direction and the thyristor Thl that was closed during the previous alternating to, must open in a normal operation and all the voltage of the electric circuit CE is applied in the terminals of the thyristors . A current I appears in one of the diodes of the pair of diodes D1, D2, saturating one of the thyristors T1, T2, which then carry the instantaneous discharge of the capacitor C2 and a passage with a steep front Vsx of the voltage Vs, of the Vcc level at the saturation level of the Saturated transistor, which is approximately 0.6 Volts. The voltage Vs remains at approximately 0.6 Volts during the entire alternation a2, which is in the low state. The signal Vs has a steep descending front Vsx-of all periods. For example, all 20 ms in the case of the electric circuit operate at 50 Hz.

The output voltage Vs of the means for determining the state of the relay RS will have the characteristics mentioned below.

In another embodiment of the static relay with state detection, represented in Figure Ib, the semiconductor component is a Triac tr. This semiconductor comprises a single Gr trigger. The disconnection of the triac, either during the positive alternation, during the negative alternation of the alternative voltage, applied to its terminals, is carried out by this single trigger. In this case, the control circuit, according to the known technique, will be adapted to this type of semiconductor. In another embodiment shown in Figure 1c, the state determining means of the relay RS comprises two transistors TI and T2, the transistor collector TI is connected on the one hand to the supply voltage Vcc by means of a resistor R2, and another part to the common mass M, by means of a capacitor C2. The transistor collector T2 is connected on the one hand to the supply voltage Vcc, by means of a resistor R'2, and on the other hand to the common ground M by means of a capacitor C'2, the emitters of the transistors T1 , T2 are connected to the common ground M. Two information Vs and V's at the respective output of the collectors of transistors TI and T2, respectively represent the state of the relay corresponding to one or the other of the alternations of the electric circuit CE.

The order state corresponds to the voltage Ved at the output S (Figure la) of the control circuit or CD order and the different states of the output voltage Vs correspond to the open, closed or supplementary states, and are treated by a system Known electronic BS, for adaptation, for example, by tilters or monostable, generating information separated from the state of the relay. For example, you can turn on the electroluminescent diodes Ll, L2, L3 corresponding to the relay states and / or generate status information SI, S2, S3 at the output of the BS system to be treated by a computer circuit that can take into account other parameters of the relay, such as the status of its EC control input or parameters external to the relay, such as the presence or absence of voltage in the electric circuit CE. The processing possibilities of the signal Vs (and V's in Figure lc) at the output of the relay described in this document are not limiting of other treatments and combinations with the signals external to the relay, leading to a perfect determination of the relay status or of the state of a set of relays, which are part of an automatic system.

Claims (10)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. Static relay intended to be inserted into an alternating current electrical circuit comprising at least minus two connection terminals, the static relay has at least one semiconductor component that can be put into two states in the operating phase, one open and one closed, means for determining the state of the relay in the operating phase and a state supplementary corresponding mainly to the destroyed relay, to the electrical circuit out of voltage, to the relay disconnected, these means are connected to the terminals of the relay, characterized in that the means for determining the state of the relay comprise a pair of electroluminescent diodes mounted in parallel from head to fork, this pair is in series with a circuit of type R series C, the assembly of the diodes and the circuit is connected in parallel on the semiconductor component and each diode is optically coupled, respectively, to a transistor, through one of the diodes passes a current linked to the positive alternation of the alternative voltage of the electrical circuit and on the other of the diodes passes a current connected to the negative alternation of the same electric circuit, the electroluminescent diodes are lit during almost all the alternations when the component opens and is not defective, the diodes are lit for a short moment in the passage through the zero level of the alternations, when the component closes and is not defective, the diodes remain on during the entire alternation when the component is defective and is short-circuited.
2. 2. The static relay according to claim 1, characterized in that the semiconductor is a thyristor
3. 3. The static relay according to claim 1, characterized in that the semiconductor is either a triac, either an "alternistor" or "Snubberless".
4. 4. The static relay according to claim 2, characterized in that it comprises two thyristors connected in parallel head-fork to the terminals of the relay
5. 5. The static relay according to any of the preceding claims 1 to 4, characterized in that it is equipped with a control circuit of the semiconductor, in such a way that a semiconductor disconnection takes place when the voltage at the relay terminals passes sensibly to O Volt.
6. 6. The static relay according to any of the preceding claims 1 to 5, characterized in that a voltage limiter is branched in parallel with the electroluminescent diodes and the resistance of the RC-type circuit.
7. 7. The static relay according to claim 6, characterized in that the limiter comprises two Zener diodes mounted in series from head to fork.
8. The static relay according to any of the preceding claims 1 to 7, characterized in that the collectors of the transistors are connected in an assembly and connected, on the one hand, to a supply voltage by means of a resistor, and on the other hand, To a common mass by means of a capacitor, the emitters of the transistors are connected to the common ground.
9. The static relay according to any one of the preceding claims 1 to 7, characterized in that the collector of each transistor is connected, on the one hand, to the supply voltage by means of a resistance and, on the other hand, to the common ground by In the middle of a capacitor, the emitters of the transistors are connected to the common ground.
10. 10. The static relay according to any of the preceding claims 1 to 9, characterized in that the static relay is equipped by a system that performs the adaptation and / or transmission to the exterior of the relay, of the status information thereof.