EP3920202A1 - Switching arrangement and method for determining the precise switching time of an electromechanical relay - Google Patents

Abstract

The present invention relates to a switching arrangement comprising: an electromechanical relay having a relay coil and a relay switch; a switching device; a voltage source connected to the relay coil, which is set up to control the relay coil by means of the switching device and a voltage provided by the voltage source; a detection device connected to the relay coil which is configured to detect an electrical signal profile applied to the electromechanical relay; a control device connected to the detection device and the switching device, which control device is set up to send a switching signal for controlling the relay coil to the switching device at a control time and to receive and store the electrical signal profile detected by the detection device; wherein the control device is further set up to use a received and / or a stored electrical signal curve to determine a switching point in time at which the relay switch is switched.

Description

The present invention relates to a switching arrangement for determining the exact switching time of an electromechanical relay which has a relay coil and a relay switch, a socket with such a switching arrangement and a method for determining the same.

An electromechanical relay is an electromagnetically operated, remotely operated switch operated by an electric current, with two or more switching positions, which is activated via a control circuit and can switch one or more additional circuits. Electromechanical relays are known in a large number of different designs. In many of these designs, electromechanical relays have a relay coil and a relay switch. When a current is applied to the relay coil, it creates a magnetic flux. The relay switch is movably arranged in the relay and is moved by the magnetic flux in such a way that a switching process is triggered, i.e. electrical contacts are opened or closed. The activation time at which a switching signal for activating the relay coil is sent and the switching time at which the switching process of the electrical contacts is ended do not coincide. The switching duration, i.e. the time difference between the activation time and the switching time, is influenced, among other things, by the design, the relay temperature and the aging process. Furthermore, manufacturing tolerances can cause different switching times between relays of the same construction.

In a number of applications, electromechanical relays have been superseded by electronic switches that use transistors. Electronic switches are typically smaller and have shorter switching times than relays. However, some applications still require the use of electromechanical relays and do not allow the use of electronic switches for various reasons. In other applications, the use of electronic switches based on transistors is associated with disadvantages. Advantages of electromechanical relays are, for example, a high insulation resistance and a high reverse voltage due to galvanic isolation.

Electromechanical relays also have a high switch-on power and a high overload capacity. Furthermore, the switching status of electromechanical relays can be seen with the naked eye.

For some applications in which electromechanical relays can or must be used, it is again advantageous to be able to accurately predict the switching time of the relay. If the switching time of a relay can be precisely predicted and controlled, an alternating voltage switched by the relay or an alternating current switched by the relay could be switched to zero crossing, i.e. voltage-free or current-free. This allows fluctuations in the alternating voltage or alternating current to be reduced during the switching process. This in turn makes it possible, among other things, to reduce the corrosion effects of the switching contacts and thereby increase the service life of the relay.

One possibility of precisely determining the switching time of the electromechanical relay is based on determining the switching duration of the electromechanical relay and bringing the triggering time forward by the specific switching duration. Since some of the factors that have an influence on the switching duration of the relay are subject to fluctuations over time, it is not sufficient, for example, to determine the switching duration of the electromechanical relay once and to advance the activation time of each switching process by this once-determined value. Changes in the switching duration over time were not taken into account here, so that the possible uses of such a procedure remained limited.

If, on the other hand, the switching duration is known from each switching point in time of the electromechanical relay, then, in addition to increasing the service life of the electromechanical relay, malfunctioning of the electromechanical relay can be detected, for example "sticking" (not opening) or delayed opening of the relay switch. "Sticking" can be caused, for example, by a voltage flashover when the relay switch is opened, which welds the contacts to one another. But external influences such as adhesive substances can also cause the relay switch to "stick".

The present invention is therefore based on the object of precisely determining the switching time of an electromechanical relay.

The present invention is therefore also based on the object of reliably detecting a malfunction of an electromechanical relay.

According to the invention, these objects are achieved by a switching arrangement comprising: an electromechanical relay which has a relay coil and a relay switch; a switching device; a voltage source connected to the relay coil, which is set up to control the relay coil by means of the switching device and a voltage provided by the voltage source; a detection device connected to the relay coil, which detection device is configured to detect an electrical signal profile applied to the electromechanical relay; a control device connected to the detection device and the switching device, which control device is set up to send a switching signal for controlling the relay coil to the switching device at an activation time and to receive and store the electrical signal profile detected by the detection device; wherein the control device is further set up to use a received and / or a stored electrical signal curve to determine a switching point in time at which the relay switch is switched.

A relay coil is understood to be a component that is suitable for generating or detecting a magnetic field. The relay coil can have a winding of a current conductor made of wire, enamelled copper wire, silver-plated copper wire and / or high-frequency stranded wire. The winding can be wound on a bobbin, for example. The coil body can in particular comprise a soft magnetic material.

The electrical signal curve applied to the electromechanical relay can be, for example, a curve of an electrical current flowing through the electromechanical relay, the curve of an electrical voltage applied to the electromechanical relay, or the curve of another electrical variable connected to the electromechanical relay.

Furthermore, the objects are achieved by a method for determining a switching time of an electromechanical relay which is connected to a voltage source and a switching device, has a relay coil and a relay switch and is connected to a detection device, comprising the steps of: providing a voltage supply; Sending a switching signal to control the relay coil to the switching device at a control time; Detecting a signal curve applied to the electromechanical relay by means of the detection device; Receiving the electrical signal waveform at a control device; Storing the electrical waveform; Determining a switching time at which the relay switch is switched by using a received and / or a stored electrical signal curve.

In the switching arrangement, it can be provided that the electrical signal curve applied to the electromechanical relay is a current curve flowing through the electromechanical relay; the current profile flowing through the electromechanical relay is a current profile flowing through the relay coil; and the control device is further set up to determine the switching time from a local extreme of the received and / or stored current profile.

In a further special embodiment of the invention it can be provided that in the switching arrangement according to claim 1, the control device is also set up to store the control time associated with the received and / or stored electrical signal curve and a new control time from a difference between the stored control time and to determine a corresponding determined switching time.

In the switching arrangement according to claim 1, as an alternative to the two last-mentioned special embodiments of the invention, it can be provided that the relay switch comprises a changeover switch with one or more changeover contacts; the signal profile applied to the electromechanical relay is a voltage profile applied to one of the one or more changeover contacts; and the control device is set up to determine the switching point in time as a level change in the received or stored voltage profile.

The level change of the received or stored voltage curve can be, for example, a digital level change. The switching arrangement advantageously further comprises an alternating current circuit which has an alternating voltage source and a load, the relay switch being set up to switch the alternating current circuit.

The control device is also expediently set up to determine a voltage profile and / or a current profile of the AC circuit and to determine the switching time of the electromechanical relay as a function of the trigger time and the voltage profile and / or the current profile of the AC circuit.

In particular, it can be provided that the control device is set up to determine at least one zero crossing of the voltage profile and / or the current profile of the AC circuit; and to set the control time to a value by which the switching time of the electromechanical relay coincides with a zero crossing of the voltage profile and / or the current profile.

In addition, it can be provided that the control device has a microcontroller.

In a further special embodiment of the invention it can be provided that the electromechanical relay has a switching time between 1 ms and 50 ms.

The switching arrangement also advantageously comprises a temperature measuring device which is set up to measure a current temperature and to send it to the control device, the control device also being set up to use the measured temperature to determine a switching time at which the relay switch is switched .

It can advantageously be provided that the control device has a lookup table with correction values over time, and the control device is also set up to to use the lookup table to determine a switching point in time at which the relay switch is switched.

The invention further provides a socket outlet comprising a switching arrangement according to one of Claims 1 to 11.

In addition, the method can provide that the electrical signal profile applied to the electromechanical relay is a current profile flowing through the relay coil; wherein the method further comprises the step of: determining a local extreme of the received and / or the stored current profile.

In addition, it can be provided that the method further comprises the steps of: storing the actuation time associated with the received and / or stored electrical signal profile; and determining a new activation time from a difference between the stored activation time and a corresponding determined switching time.

As an alternative to the two last-mentioned special embodiments of the invention, it can be provided in the method according to claim 13 that the relay switch comprises a changeover switch with one or more changeover contacts; and the electrical signal profile applied to the electromechanical relay is a voltage profile applied to one of the one or more changeover contacts; and the method further comprises the step of: determining the switching time as a level change of the received or stored voltage profile by means of the control device.

The switching device advantageously further comprises an alternating current circuit which has an alternating voltage source and a load; the method further comprising the step of: switching the AC circuit with the relay switch.

In a further particular embodiment of the invention it can be provided that the method further comprises the steps of: determining a voltage profile of the AC circuit; and determining the switching instant of the electromechanical relay as a function of the actuation instant and the voltage profile of the alternating current circuit.

The method advantageously further comprises the steps of: determining at least one zero crossing of the voltage profile and / or the current profile of the AC circuit; and setting the trigger time to a value by which the switching time of the electromechanical relay coincides with a zero crossing of the voltage profile and / or the current profile of the AC circuit.

The method advantageously provides for the electromechanical relay to have a switching time between 1 ms and 50 ms.

In addition, it can be provided that the method further comprises the steps of: measuring a current temperature by means of a temperature measuring device; Sending the measured current temperature to the control device; and determining a switching point in time by means of the measured current temperature.

Finally, the method can further include the step of using a lookup table to determine a switching point in time at which the relay switch is switched.

The invention is based on the surprising finding that a simple measurement of an electrical signal flowing through an electromechanical relay enables the exact switching time of the electromechanical relay to be determined, an alternating voltage or an alternating current to be de-energized, the service life of the electromechanical relay to be increased and to detect a malfunction of the electromechanical relay at an early stage.

Figur 1

eine Schaltskizze einer Schaltanordnung gemäß einer besonderen Ausführungsform der Erfindung;

Figur 2

eine exemplarische Darstellung des an der Erfassungsvorrichtung der Schaltanordnung gemäß Figur 1 gemessenen Stroms über den Zeitraum eines Schaltvorgangs, bei dem der Relaisschalter geschlossen wird;

Figur 3

eine exemplarische Darstellung des an der Erfassungsvorrichtung der Schaltanordnung gemäß Figur 1 gemessenen Stroms über den Zeitraum eines Schaltvorgangs, bei dem der Relaisschalter geöffnet wird;

Figur 4

eine Schaltskizze einer Schaltanordnung gemäß einer weiteren besonderen Ausführungsform der Erfindung;

Figur 5

eine exemplarische Darstellung der am Eingang der Steuereinrichtung der Schaltanordnung gemäß Figur 4 anliegenden Spannung über den Zeitraum eines Schaltvorgangs, bei dem der Wechselschalter von einer zweiten Position zu einer ersten Position geschaltet wird;

Figur 6

eine exemplarische Darstellung der am Eingang der Steuereinrichtung der Schaltanordnung gemäß Figur 4 anliegenden Spannung über den Zeitraum eines Schaltvorgangs, bei dem der Wechselschalter von der ersten Position zur zweiten Position geschaltet wird.

Further features and advantages of the invention emerge from the appended claims and the following description, in which with the aid of the schematic drawings several embodiments of the present invention will be described. It shows / show:

Figure 1

a circuit diagram of a circuit arrangement according to a particular embodiment of the invention;

Figure 2

an exemplary representation of the on the detection device of the switching arrangement according to Figure 1 measured current over the period of a switching process in which the relay switch is closed;

Figure 3

an exemplary representation of the on the detection device of the switching arrangement according to Figure 1 measured current over the period of a switching process in which the relay switch is opened;

Figure 4

a circuit diagram of a circuit arrangement according to a further particular embodiment of the invention;

Figure 5

an exemplary representation of the at the input of the control device of the switching arrangement according to Figure 4 applied voltage over the period of a switching process in which the changeover switch is switched from a second position to a first position;

Figure 6

an exemplary representation of the at the input of the control device of the switching arrangement according to Figure 4 applied voltage over the period of a switching process in which the changeover switch is switched from the first position to the second position.

Figure 1 shows a circuit diagram of a circuit arrangement 10 according to a particular embodiment of the invention. The switching arrangement has an electromechanical relay 12. The electromechanical relay 12 has a relay coil 14 and a relay switch 16. The relay coil 14 is connected to a voltage source 20 via a switching device 18 connected. The switching device 18 can be switched into an open and a closed state. When the switching device 18 is closed, the relay coil 14 is supplied with current via the voltage source 20. When the switching device 18 is open, the power supply to the relay coil 14 is interrupted. The relay coil 14 is also connected to a detection device 22 which is set up to detect an electrical signal profile flowing at the electromechanical relay. The acquisition device 22 can comprise, for example, a digital acquisition device and / or an analog acquisition device. A control device 24 is connected to the detection device 22 and the switching device 18 for signaling and / or control purposes. The detection device 22 can be designed, for example, as a current detection device or a voltage detection device which is set up to detect a current applied to the electromechanical relay or a voltage applied to the electromechanical relay 12. In the in Figure 1 The exemplary embodiment shown, the detection device 22 is designed as a current detection device which is set up to detect a coil current flowing through the relay coil 14 in order to determine the current profile.

The control device 24 can for example have a microcontroller, which can in particular have work and program memories, LCD controllers and / or interfaces, for example USB interfaces, serial or Ethernet interfaces. Furthermore, it can also be provided that the control device 24 is a microcontroller. The control device 24 is set up to send a switching signal for controlling the relay coil 14 to the switching device 18 at an activation time. The switching device 18 can be opened and / or closed by the switching signal.

In the in Figure 1 The exemplary embodiment shown, the control device 24 is set up to receive and store the current profile detected by the detection device 22. Furthermore, the control device 24 is set up to use a received and / or a stored coil current curve to determine a switching point in time at which the relay switch 16 is switched. To this end, the control device 24 can determine a local extreme of the coil current curve. Optionally, the control device 24 can be set up to approximate the received and / or stored coil current profile, for example by means of a polynomial. The time at which the Current curve reaches a local extreme, that is to say a local minimum or a local maximum, corresponds to the switching time. A switching time determined in this way, depending on the type of electromechanical relay, can be more precise by a factor of 100 to 1000 or more than if the triggering time is equated with the switching time.

The control device 24 can also be set up to determine a switching duration of the electromechanical relay 12 from the difference between the activation time and the determined switching time. A planned switching time can be precisely determined by subtracting the determined switching duration of the electromechanical relay 12 from the planned switching time. If a new activation time is set at a time determined by the difference between the planned switching time and the switching duration of the electromechanical relay 12, the switching time will also take place at the planned switching time.

The switching arrangement 10 also has an alternating current circuit 26. The AC circuit 26 has an AC voltage source 28 and a load 30. The relay switch 16 is set up to switch the alternating current circuit 26.

It can optionally be provided that the control device 24 is also set up to determine the voltage profile of the alternating current circuit 26. The voltage profile of the alternating current circuit 26 can be determined, for example, via a voltage measuring device (not shown here) connected to the alternating current circuit 26. In this case, the control device 24 can be set up to determine the switching time of the electromechanical relay 12 as a function of the activation time and the voltage profile of the alternating current circuit 26.

As an alternative or in addition, the control device 24 can be set up to determine the current profile of the alternating current circuit 26. The course of the current can be determined, for example, via a current measuring device connected to the alternating current circuit 26 (also not shown here). In this case, the control device 24 can be set up to determine the switching time of the electromechanical Relay 12 to be determined as a function of the control time and the current curve of the alternating current circuit 26.

With knowledge of the switching duration and the voltage curve and / or the current curve, the trigger time can be set so that the electromechanical relay 12 is switched at a precise point in time, for example at the zero crossing of the AC voltage applied to the AC circuit 26 and / or at the zero crossing of the AC current applied to the AC circuit 26 will. For this purpose, the control device 24 can be set up to determine at least one zero crossing of the voltage curve and / or the current curve of the alternating current circuit 26 and to set the trigger time to a value by which the switching time of the electromechanical relay 12 with a zero crossing of the voltage curve and / or the current curve of the AC circuit 26 collapses. The voltage curve and / or the current curve can be determined by an explicit measurement of the current curve and / or the voltage curve of the AC circuit 26, or by a dedicated chip (not shown) that generates an interrupt signal at the zero crossing of the voltage curve and / or the current curve of the AC circuit 26 sends to the control device. The activation time results from the difference between the planned switching time and the switching duration. In addition, the control device 24 can also be set up to determine the frequency of the alternating voltage or alternating current of the alternating current circuit 26. As an alternative or in addition, the frequency of the alternating voltage or alternating current of the alternating current circuit 26 can also be stored separately therefrom in the control device 24.

The switching arrangement 10 can furthermore have a temperature measuring device (not shown here) which is set up to measure a current temperature of a part of the switching arrangement and / or of the electromechanical relay 12. The switching duration of the electromechanical relay 12 can be determined by means of the temperature measuring device as a function of the measured temperature. The temperature dependency of the switching duration can also be stored by the control device 24. The temperature dependency of the switching duration can be stored, for example, in the form of a lookup table. If an exact switching time is now to be determined, the control device 24 first determines the current temperature and then selects the one associated with the current temperature Switching duration from the lookup table. The exact trigger time is determined from the planned exact switching time and by means of the switching duration associated with the measured temperature. In this way, temperature-dependent fluctuations in the switching duration of the electromechanical relay 12 can be compensated for. The accuracy of the determination of the switching time is further increased relative to the temperature-independent method.

Figure 2 FIG. 13 shows an exemplary illustration of the on the detection device 22 of the switching arrangement according to FIG Figure 1 measured current over the period of a switching process in which the relay switch 16 is closed. The current curve is that of an electromechanical relay 12 in which the relay switch 16 is in a normally open state, for example a reset mechanism (not shown) opens the relay switch 16 when no external force acts on the relay switch 16. Such a return mechanism can be a spring mechanism, for example. In the in Figure 2 In the diagram shown in the diagram, the current I flowing through the relay coil is plotted against the time t, as is determined, for example, by the detection device 22 of FIG Figure 1 switching arrangement 10 shown can be detected.

At a point in time t = 0, the relay switch 16 and the switching device 18 are open and no current flows through the relay coil 14 and the detection device 22.

At a trigger time t ₁ , a switching signal is sent to the switching device 18, whereby the switching device 18 is closed and the current I flowing through the relay coil 14 increases. With the current I, the strength of the magnetic field of the relay coil 14 also increases.

At a movement onset time t ₂ , the magnetic field of the relay coil 14 has reached a field strength at which a movement of the relay switch 16 begins.

At a switching point in time t ₃ , the relay switch 16 is completely closed. The current I increases again from this point in time until a maximum current I _{max is} reached. The switching duration T _a for closing the electromechanical relay 12 can be determined via T _a = t ₃ -t ₁ .

Figure 3 FIG. 13 shows an exemplary illustration of the on the detection device 22 of the switching arrangement according to FIG Figure 1 measured current over the period of a switching process in which the relay switch 16 is opened. Here, too, the relay switch 16 of the electromechanical relay 12 is in a normally open state. The electromechanical relay 12 can therefore have a reset device which opens the relay switch 16 when no external force acts on the relay switch 16. The switching device 18 and the relay switch 16 are closed at a point in time t = 0. The current I flowing through the relay coil 14 is at a maximum at time t = 0 (I = I _max ).

At a trigger time t ₄ , a switching signal is sent to the switching device 18, as a result of which the switching device 18 is opened and the current I flowing through the relay coil 14 drops. With the current I, the strength of the magnetic field of the relay coil 14 also decreases.

At a point in time t ₅ , the magnetic field of the relay coil 14 has dropped to a field strength at which, for example, a reset device triggers a movement of the relay switch 16. The movement triggered, for example, by the resetting device induces a current in the relay coil 14, which can be seen as a rise in the current curve.

At a switching point in time t ₆ , the relay switch 16 is completely open. The current I decreases again from the switching time t ₆ until it has dropped to I = 0. The electrical contact of the relay switch 16 is interrupted at the beginning of the movement process, not only when the movement process is completed. The switching duration T _b for opening the electromechanical relay 12 can therefore be determined via T _b = t ₅ -t ₄ .

The switching times T _a and T _b for closing and opening the electromechanical relay 12 are fundamentally different from one another. In a particular embodiment, the switching device according to the invention can take these differences into account by storing electrical signal curves and / or switching times for opening and closing the electromechanical relay 12 separately from one another and using them separately from one another to determine a switching point in time.

Figure 4 shows a circuit diagram of a circuit arrangement 10 according to a further particular embodiment of the invention. In contrast to the in Figure 1 As shown in the embodiment of the invention, the electromechanical relay 12 has a changeover switch 32 with a first changeover contact 38, a second changeover contact 40 and a central connection 36. The changeover switch 32 connects the common center connection 36 to the first changeover contact 38 in a first position and to the second changeover contact 40 in a second position Signal resistor 44 and a diode 45 establish a contact between the center connection 36 and an input 46 of the control device 24. The input 46 is also connected to the supply voltage 50 of the control device 24 via a pull-up resistor 48. By means of this switching arrangement 10, the switching time at which the second changeover contact is switched can be detected by the control device 24 as a digital level change of the voltage present at the input 46 of the control device 24. For this purpose, the detection device 22 can be integrated in the control device 24. Alternatively, the detection device 22 can also be arranged separately from the control device 24. The detection device 22 is also designed as a voltage detection device. For the described detection of the switching time as a digital level change, however, it is also necessary that the reference potential of a second input 52 of the control device 24 is identical to the reference potential of an input 53 of a DC voltage supply 54, by means of which the control device 24 is supplied with current via the second input 52 . In the embodiment shown, this is ensured by a reference potential 56 shared by the control device 24 and the DC voltage supply 54.

The control device 24 is also connected to the DC voltage supply 54 via a supply line 58. In this exemplary embodiment of the invention, the direct voltage supply 54 converts a 230 V alternating voltage of the alternating current circuit 26 into a 3.3 V direct voltage for supplying the control device 24. Depending on the components used, however, other voltages can also be applied to the alternating current circuit 26 and / or to the control device 24. To convert the 230 V AC voltage into a DC voltage, the DC voltage supply 54 has a bridge rectifier circuit 58, two resistors 59 and connected in series a polarized capacitor 61 for smoothing the rectified voltage. In alternative embodiments, however, other rectifier circuits can also be used.

The relay coil 14 is supplied with voltage via the voltage source 20. In order to transmit a switching signal to the relay coil 14, the control device 24 is connected to the relay coil 14 via an output 60 for signaling and / or control purposes. A driver stage 62 is arranged between the control device 24 and the relay coil 14. The driver stage 62 has a switching device 18, which is designed as an NMOS transistor in the embodiment shown, a driver stage diode 64 and an internal driver stage resistor 66. As an alternative to the NMOS transistor, however, a PMOS transistor or another suitable component can also be used. The driver stage 62 amplifies the signal going out at the output 60 to such an extent that the changeover switch 32 can be switched via the relay coil 14. The switching time at which the control device 24 sends the switching signal for switching the changeover switch 32 is stored by the control device 24. The time at which a digital level change of the voltage applied to the changeover contact 40 is detected at the input 46 is also stored by the control device 24. The difference between these two times can be stored as the switching duration of the electromechanical relay 12.

The in connection with the in Figure 1 The optimization and applications mentioned in the embodiment of the invention shown in FIG Figure 4 Use shown embodiment of the invention.

Figure 5 shows an exemplary representation of the at the input 46 of the control device 24 of the switching arrangement 10 according to FIG Figure 4 applied voltage over the period of a switching process in which the changeover switch 32 is moved from a second position, a contact between the center connection 36 with the second changeover contact 40, to a first position, a contact between the center connection 36 with the first changeover contact 38.

At the time t = 0, the center connection 36 is connected to the second changeover contact 40. The voltage applied to the second changeover contact 40 and to the input 46 of the control device 24 is U = 0.

At the control time t ₁ , a first switching signal is sent via the driver stage 62 and the switching device 18 located therein. In response to the first switching signal, the relay coil is activated in such a way that the toggle switch 32 is moved from the second position to the first position.

At a switching point in time t ₃ , the changeover switch 32 is released from the second position, i.e. from the contact between the center connection 36 and the second changeover contact 40. As soon as contact with the first changeover contact 38 is established, the voltage measured at the input 46 rises abruptly, until a maximum value U _{max is} reached. The switching process can thus also be recognized here as a digital level change. The switching point in time t ₃ can correspond, for example, to a point in time at which a previously established threshold value is exceeded.

The switching duration T _a for switching the changeover switch from the second position to the first position can be determined via T _a = t ₃ -t ₁ .

Figure 6 shows an exemplary representation of the at input 46 of the control device 24 of the switching arrangement according to FIG Figure 4 applied voltage over the period of a switching process in which the changeover switch 32 is switched from a first position to a second position.

At the time t = 0, the center connection 36 is connected to the first changeover contact 38. This switch position is called the first position. The voltage U present at the second changeover contact 40 and at the input 46 of the control device 24 is maximum (U = U _max )

At the trigger time t ₄ , a second switching signal is sent from the control device 24 via the driver stage 62 and the switching device 18 located therein. In response to that With the second switching signal, the relay coil 14 is controlled in such a way that the changeover switch 32 is moved from the first position, that is, in connection with the first changeover contact 38, to a second position, that is, in connection with the second changeover contact 40.

At a switching point in time t ₅ , the changeover switch 32 releases from the first position, that is to say is no longer in contact with the first changeover contact 38. As a result, the voltage U suddenly drops to U = 0. The switching process can thus be recognized as a digital level change. The switching duration T _b for switching the electromechanical relay 12 can be determined via T _b = t ₅ -t ₄ . The switching point in time t ₅ can correspond, for example, to a point in time at which a previously defined threshold value is undershot.

The features of the invention disclosed in the above description, in the drawings and in the claims can be essential both individually and in any combination for the implementation of the invention in its various embodiments.

List of reference symbols

10

Switching arrangement

12th

electromechanical relay

14th

Relay coil

16

Relay switch

18th

Switching device

20th

Voltage source

22nd

Detection device

24

Control device

26th

AC circuit

28

AC voltage source

30th

load

32

Toggle switch

36

Center connection

38

first changeover contact

40

second changeover contact

42

Signal line

44

Signal resistance

45

diode

46

input

48

Pull-up resistor

50

Supply voltage

52

second input of the control device

53

DC power supply input

54

DC power supply

56

Reference potential

58

Bridge rectifier circuit

60

exit

61

polarized capacitor

63

Driver stage

64

Driver stage diode

66

internal driver stage resistance

t1, t4

Control time

t2

Start of movement

t3, t5, t6

Switching time

Ta

Switching time for closing the electromechanical relay

Tb

Switching time for opening the electromechanical relay

Claims (15)

Switching arrangement (10) comprising: an electromechanical relay (12) having a relay coil (14) and a relay switch (16); a switching device (18); a voltage source (20) connected to the relay coil (14) and set up to control the relay coil (14) by means of the switching device (18) and a voltage provided by the voltage source (20); a detection device (22) which is connected to the relay coil (14) and is set up to detect an electrical signal profile applied to the electromechanical relay (12); a control device (24) which is connected to the detection device (22) and the switching device (18) and which is set up to send a switching signal for controlling the relay coil (14) to the switching device (18) at a control time and to send the control device (18) from the detection device ( 22) receive and store captured electrical waveforms; whereby the control device (24) is also set up to use a received and / or a stored electrical signal curve to determine a switching point in time at which the relay switch (16) is switched. Switching arrangement (10) according to claim 1, wherein the electrical signal profile applied to the electromechanical relay (12) is a current profile flowing through the electromechanical relay (12); the current profile flowing through the electromechanical relay (12) is a current profile flowing through the relay coil (14); and the control device (24) is also set up to determine the switching time from a local extreme of the received and / or stored current curve. Switching arrangement (10) according to claim 1 or 2, wherein the control device (24) is further set up to store the control time associated with the received and / or stored electrical signal curve and to determine a new control time from a difference between the stored control time and an associated one To determine the switching time. Switching arrangement (10) according to claim 1, wherein the relay switch (16) comprises a changeover switch (32) with one or more changeover contacts; the signal profile applied to the electromechanical relay (12) is a voltage profile applied to one of the one or more changeover contacts; and the control device (24) is set up to determine the switching point in time as a level change in the received or stored voltage profile. Switching arrangement (10) according to one of the preceding claims, further comprising: an AC circuit (26) having an AC voltage source (28) and a load (30), wherein the relay switch (16) is set up for switching the AC circuit (26). Switching arrangement (10) according to claim 5, wherein the control device (24) is further set up to determine a voltage curve and / or a current curve of the AC circuit (26) and the switching time of the electromechanical relay (12) depending on the trigger time and the voltage curve and / or to determine the current flow of the AC circuit. Switching arrangement (10) according to claim 6, wherein the control device (24) is set up to
determine at least one zero crossing of the voltage curve and / or the current curve of the AC circuit; and to set the control time to a value by which the switching time of the electromechanical relay (12) coincides with a zero crossing of the voltage profile and / or the current profile of the alternating current circuit. Switching arrangement (10) according to one of the preceding claims, wherein the control device (24) has a microcontroller. Switching arrangement (10) according to one of the preceding claims, wherein the electromechanical relay (12) has a switching time between 1 ms and 50 ms. Switching arrangement (10) according to one of the preceding claims, further comprising a temperature measuring device which is set up to measure a current temperature and to send it to the control device (24), wherein
the control device (24) is also set up to use the measured temperature to determine a switching time at which the relay switch (16) is switched. Switching arrangement (10) according to one of the preceding claims, wherein the control device (24) has a lookup table with temporal correction values, and
the control device (24) is also set up to use the lookup table to determine a switching time at which the relay switch (16) is switched. Socket comprising a switching arrangement (10) according to one of the preceding claims. A method for determining a switching time of an electromechanical relay (12) which is connected to a voltage source (20) and a switching device (18), has a relay coil (14) and a relay switch (16) and is connected to a detection device (22), comprising the Steps: Providing a voltage supply; Sending a switching signal for controlling the relay coil (14) to the switching device (18) at a control time; Detection of an electrical signal curve applied to the electromechanical relay (12) by means of the detection device (22); Receiving the electrical signal waveform at a control device (24); Storing the electrical waveform; Determining a switching time at which the relay switch (16) is switched by using a received and / or a stored electrical signal curve. The method according to claim 13, wherein the electrical signal profile applied to the electromechanical relay (12) is a current profile flowing through the relay coil (14); and
the method further comprising the step of:
Determination of a local extreme of the received and / or stored current curve. The method of claim 13 or 14, the method further comprising the steps of: Storing the actuation time associated with the received and / or stored electrical signal profile; and Determination of a new control time from a difference between the stored control time and a corresponding determined switching time.

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