EP1636808B1 - Method and circuit arrangement for operating a solenoid actuator - Google Patents

Description

Technical area

The invention relates to both a method and a circuit arrangement for operating a magnetic drive consisting of magnetic yoke, at least one magnetjochseitig arranged permanent magnet, a magnet armature and a retaining force performing retaining means, further the magnetic yoke surrounding electromagnetic coil means, an input side fed by a rectified control voltage and acted upon and a control circuit including a microcontroller and a capacitive charge storage. The armature is attracted from the application of the control voltage against the restraining force permanent magnetically supported, still held permanentmagnetisch with applied control voltage and drops from the elimination of the control voltage with the support of the retention force and against the permanent magnetic holding force by discharging the charge storage.

State of the art

Magnetic drives consist of a magnetic yoke, a drive coil and a magnet armature, which is attracted to the magnetic yoke with sufficient energization of the drive coil. The magnetic drives are used in electromagnetic switching devices - also called contactors - for connecting and disconnecting an electrical load with an electrical power network by closing or opening the coupled to the armature main contacts. For reasons of safety, the relevant regulations for these switchgear, disconnect the consumer from the grid with energy-free control input of the magnetic drive. Electromagnetic switching devices therefore usually have magnetic drives that hold the main contacts open by return springs in the de-energized state of the drive coil. A disadvantage of such magnetic drives is that for holding closed the main contacts a holding current through the solenoid and thus a holding power is required so that during operation heat loss occurs, for which the electrical system must be designed according to thermal.

From the document DE 101 29 153 A1 an electromagnetic valve is known with a reduction from a higher starting current to a lower holding current. Sensor means in the form of a magnetic-field-sensitive switch or a current sensor for the coil current serve for detecting the magnetic coil field or magnetic coil current which changes during switching of the valve for switching over to the holding current. According to DE 299 09 901 a microprocessor control for a magnetic drive is known in which by controlling the pulse width of the holding current is minimized. A known from DE 39 08 319 A1 electromagnetic switching device has a permanent magnet in the magnetic yoke to reduce the tightening and the holding power. A known according to DE 101 33 713 C1 magnetic drive also has a permanent magnet in the yoke, which alone provides the necessary holding power. When the control voltage is switched off, a mechanical lock, which has been held until now via an auxiliary magnetic drive, is released, which then releases a spring force counteracting the permanent magnet to drop the magnet armature. However, the aforementioned magnetic drives still require a considerable holding or auxiliary power.

EP 0 721 650 B1 shows a bistable magnetic drive with permanent magnets arranged between a magnetic yoke and a two-part magnet armature and with two magnet coils to be excited individually. At each bistable position of the armature, a low reluctance flux path and a high reluctance flux path are formed. By energizing the coupled with the flux path high reluctance magnetic coil, the movement of the armature takes place in the other stable position, the flow paths of low and high reluctance overturn each other. In an electromagnetically controlled valve drive device according to EP 0 376 715 B1, the holding state is effected solely by a permanent magnet in the magnetic yoke. The attracting and falling off of the armature, in contrast, is effected by correspondingly polarized short-time discharging of a storage capacitor which has been charged in the preceding drop-out state or holding state. From DE 199 58 888 A1 a so-called Remanzantrieb is known, whose armature between two opposite and opposite polarity arranged in the magnetic yoke permanent magnets on the one hand, the switch-off and on the other the switch-on position. The armature is moved by briefly charging or discharging a capacitor from one to the other position or vice versa. In one known from DE 201 13 647 U1 magnetic drive for an electromagnetic switching device, a permanent magnet is arranged in a two-circuit magnetic yoke, which alone applies the holding force. In order to drop the magnet armature, a storage capacitor charged during the holding operation is discharged via the secondary circuit. In the aforementioned magnetic drives no measures for safe dropping of the armature are shown in the absence of control energy.

From the document DE 101 46 110 A1 an electronic circuit arrangement with a microcontroller for reversing a magnetic drive from the electromagnetic tightening operation in the permanent magnetic holding operation is known. When the control voltage is removed, the short-term discharge current of a storage capacitor is used to demagnetize the magnetic circuit and thus to drop the magnet armature. There are no means indicated that prevent a persistence of the magnetic drive in holding operation in case of a defect of the circuit arrangement. According to DE 199 54 037 A1 a microprocessor-controlled release magnet of a circuit breaker with permanent magnetic holding force is known. To check the holding force, the trip coil is loaded at regular intervals with a short-term current pulse. If the holding force decreases, a premature release takes place for safety reasons.

Presentation of the invention

The invention is therefore based on the object to convert a magnetic drive with permanent magnetic holding operation both after switching off the control energy as well as after the occurrence of defects safely in the fall-state.

Starting from a method or a circuit arrangement of the type mentioned above, the object is achieved on the one hand by a method according to claim 1, on the other hand by a circuit arrangement according to claim 12.

The inventive method is based on the fact that the tightening and falling of the magnet armature takes place via separate coil means. The tightening operation is carried out by A Hauptabschaltspule in a conventional manner according to step C. The fall is normally carried out by the discharge of a previously charged charge storage via a Hauptabschaltspule according to process step E. In case of failure of the waste operation on the Hauptabschaltspule the fall can be done via a redundant Hilfsabschaltspule. In order to ensure a high degree of technical safety, test steps are carried out regularly in accordance with method step D by brief energization of one of the switch-off coils, without the magnet armature being moved out of its holding position. If, during testing, a failure with respect to the waste capacity of one of the shut-off coils is detected, then the magnetic armature will be forced to fall off via the other shut-off coil. Subsequently, a permanent shutdown of the control voltage is forced to prevent re-switching the faulty magnetic drive assembly. After initiation of the process by applying the control voltage with initialization of the control circuit according to step A and before the initiation of the tightening operation corresponding tests of Abschaltspulen done with subsequent shutdown of the control voltage in case of failure in accordance with step B. The method ensures on the one hand that the magnetic drive from the pemianentmagnetischen holding operation both conscious switching off as well as after faulty failure of the control voltage with certainty in the fallen state of its magnet armature passes. On the other hand, the method ensures that the magnetic drive permanently assumes or retains the fallen state in the event of detected errors, such as broken wire in or to the coil means or defects in the control circuit. The method consumes as holding energy only the energy for recharging the load memory and for supplying the electronic control circuit.

In order to make the process less sensitive to changes in the control voltage and the charging behavior of the charge storage device, the initial testing of the turn-off coils advantageously takes place only after sufficient charging of the charge storage device. The permanent shutdown of the control voltage in case of failure is expediently carried out by short-circuit release.

On the one hand, the short-term current flow through the auxiliary shutoff coil can advantageously be detected as a short-term voltage drop via a resistor. On the other hand, the short-term current flow through the main shutoff coil can be detected as a short-term voltage drop across the charge storage device. After such a voltage reduction the charge storage device must still have sufficient charge to perform normal waste operation. In this case, it is advantageous to check the voltage across the supercharger memory with regard to the observance of a tolerance window during the voltage reduction in order to switch off the control voltage as a precautionary measure even with decreasing charging capacity.

An advantageous development of the method is to check whether an inductive voltage increase occurs at the switch-on coil during testing of the switch-off coils, and to initiate the permanent switch-off if such a voltage increase does not occur. The absence of such a voltage increase is generally due to a continuous energization of the Einschaltspule due to a defect.

A further advantageous development consists in the constant monitoring of a microcontroller which is decisively involved in the implementation of the method and the maintenance or acceptance of the dropped state by activation of one of the two shutdown coils in the event of failure of the microcontroller, for example in the case of a program crash.

The retaining force acting on the magnet armature to secure the fallen-down state is expediently caused by at least one restoring spring and / or by at least one further permanent magnet.

Furthermore, starting from a circuit arrangement of the type mentioned above, the object is achieved by the features of the independent arrangement claim, while the subordinate claims advantageous developments of the circuit arrangement can be seen.

The separate coil means in the form of a Einschaltspule, a Hauptabschaltspule and a Hilfsabschaltspule for redundancy to Hauptabschaltspule and associated with these coils switching elements allow in conjunction with a control circuit optimum design of the magnetic drive with regard to its switching behavior and its energy consumption. Furthermore, current and voltage monitoring means are provided as sensors for regularly and alternately expected surges, which in testing the turn-off branches by short-term, should occur without effect on the armature caused closing of the associated Abschaltglieder. Upon the disappearance of the control voltage - whether deliberately controlled or caused by a defect in the feeding supply line - the main cut-off member is closed to return the armature to the fallen position by discharging the charge accumulator via the main cut-off coil. A connected to the detection means and the switching elements microcontroller triggers after a faulty test - possibly after return of the armature in the fallen position by closing the main or Hilfsabschaltgliedes - a permanent circuit breaker for the control voltage to prevent reconnection of the faulty drive assembly.

The circuit breaker is designed in a simple manner as a short-circuit protection with a downstream short circuit contactor. As an alternative to short-circuit protection, a thermally responsive weak point of a conductor can be provided. An advantageous development results from an active low-pass filter arranged between the turn-on coil and the short-circuit switching element. When the switch-on branch is activated in a pulse-controlled manner, a charging capacitor is alternately charged and discharged without reaching a charging voltage that triggers the short-circuiting element. Should the turn-on member constantly close due to a defect, i. be permanently conductive, then reaches the charging capacitor in a short time a triggering the short-circuiting charge voltage.

Conveniently, the current monitoring means consist of a series-connected with the Hilfsabschaltspule current detection resistor and a downstream first amplifier circuit.

Advantageously, the voltage detection means consist of a high pass associated with the charge storage and a downstream second amplifier circuit. When testing the Hauptabschaltzweiges is detected whether the voltage drop caused by the surge in Hauptabschaltspule the charge storage is within a predetermined window. A further amplifier circuit, which is provided in a further development of the circuit arrangement, emits to the microcontroller the achievement of a minimum charging voltage required for testing the turn-off branches.

It is also advantageous to connect the pulse-controlled activatable switch-on coil to a freewheeling circuit which can be deactivated outside of the tightening mode and to a fourth amplifier circuit which controls the deactivation function of the freewheeling circuit. The fourth amplifier circuit detects the occurrence of momentary voltage increases induced by the surges in one of the turn-off coils during testing of the respective turn-off branch in the turn-on coil. In the case of a freewheeling circuit which can not be deactivated as a result of a defect, a short circuit is produced for the expected voltage increases, so that no voltage increases are signaled to the microcontroller by the fourth amplifier circuit, whereupon the latter triggers the permanent interrupter. This prevents that in waste operation additionally charge due to the shorted over the not-deactivated freewheeling circuit Einschaltspule drains from the charge storage, so that the remaining charge could not be sufficient for proper return of the armature.

The measures provided for securing the fallen state on the armature retaining means are expediently formed as at least one return spring and / or at least one further permanent magnet.

Brief description of the drawings

Figur 1:

die Darstellung des erfindungsgemäßen Verfahrens in einem Ablaufdiagramm;

Figur 2:

die Blockdarstellung einer erfindungsgemäßen Schaltungsanordnung;

Figur 3:

eine Detaildarstellung aus Fig. 2;

Figur 4:

eine weitere Detaildarstellung aus Fig. 2;

Figur 5:

Zeitdiagramme zur Erläuterung des Verfahrens und der Schaltungsanordnung.

Further details and advantages of the invention will become apparent from the following, explained with reference to figures embodiment. Show it

FIG. 1:

the representation of the method according to the invention in a flowchart;

FIG. 2:

the block diagram of a circuit arrangement according to the invention;

FIG. 3:

a detailed view of Fig. 2;

FIG. 4:

a further detail of Fig. 2;

FIG. 5:

Timing diagrams for explaining the method and the circuit arrangement.

Best way to carry out the invention

The method described below with reference to FIG. 1 is used to operate a magnetic drive, which in a known manner consists of a magnetic yoke, at least one permanent magnet connected thereto, a magnetic armature movable relative to the magnet yoke and electromagnetic coil means, and by means of a control circuit having a microcontroller a control voltage supplied from a control voltage source is driven. A retaining force securing the fallen state of the armature is effected by at least one return spring. By the method of permanent magnetically assisted electromagnetic tightening operation is performed against the restraining force, the only permanent magnetic holding operation and supported by the retention force, electromagnetically against the permanent magnetic holding force effected waste operation in an energy-saving and safe manner.

The flowchart shown in FIG. 1 is based on the output state OUT of the method according to the invention which corresponds to the fallen state of the magnet armature. In the first method step A, it is checked whether the control voltage Vi has risen to a value substantially different from zero. If this is the case, the control circuit Vi resets and initializes the control circuit to a defined initial state. With the application of the control voltage Vi charging of a charge storage C1 begins.

In a subsequent method step B is tested by the control circuit, whether a Hauptabschaltspule L3 and to this redundant Hilfsabschaltspule L4 each by themselves for transferring the armature from the holding state to the fallen state in the situation. Both shutdown coils L3, L4 are electromagnetically connected to the magnetic yoke. For this purpose, in a first test step of method step B, the auxiliary shutoff coil L4 is actuated for a time of 0.3 ms. With a positive course of this test step, a current supplied by the control voltage source_ flows through the auxiliary shutoff coil L4 for a short time. This current is detected as a voltage drop VR6 via a current detection resistor R6 connected to the auxiliary cut-off coil L4, and causes the control circuit to check whether the charge voltage VC1 across the charge storage C1 is a predetermined sufficient Height has reached. If the charging voltage VC1 is sufficiently high, the process proceeds to the second test step of method step B. Herein, the main shutoff coil L3 is driven for a time of 0.3 ms. With a positive course of this test step flows through the Hauptabschaltspule L3 for a short time a supplied from the charge storage device C1, but still leaves in the charge storage C1 sufficient charge to ensure proper waste operation. The short-term current flow through the main shutdown coil L3 causes a brief voltage drop -ΔVC1 across the charge storage C1. If the height of the voltage drop -ΔVC1 is detected within a predetermined voltage window, the process proceeds to step C. However, if in the first test step no voltage drop across the current detection resistor R6 or in the second test step no voltage drop across the charge storage device C1 within the prescribed window can be determined, the control voltage Vi is permanently switched off via a short-circuit release. With the permanent shutdown of the control voltage Vi the final state is reached STILLGELEGT. Thereafter, there is no possibility to control the magnetic drive without previous repair. The absence of the voltage drop VR6 in the first test step means that a return of the magnet armature to the fallen position by means of the redundant Hilfsabschaltspule L4 in case of need - namely, if the return of the armature over the Hauptabschaltspule fails - also would not be possible. Failure to reach the predetermined voltage window by the voltage drop -ΔVC1 across the charge storage device C1 in the second test step means that returning the attracted magnet armature to the fallen down position would fail via the main shutoff coil L3. On the other hand, exceeding the voltage window by the voltage reduction -ΔVC1 means that the capacitance of the charge accumulator C1 has dropped so far that the storable charge is no longer sufficient for returning the attracted magnet armature to the fallen position by discharging the charge accumulator C1 via the main shutoff coil L3.

After the control circuit has registered the successful execution of the test steps in method step B, the tightening operation according to the method step C for the transition of the magnetic drive is carried out in the on state. For this purpose, a Einschaltspule L1 is opened up to safely reach the tightened position of the armature and then deactivated again. The magnet armature is now held exclusively permanent magnetic. The turn-on coil L1 and the turn-off coils L3, L4 are electromagnetically connected to the magnetic yoke. The Einschaltspule L1 is controlled in a known manner (for example, according to DE 299 09 901 U1) pulse width modulated and is connected to an activatable freewheeling circuit FL. The freewheeling circuit FL is activated with the pulse-controlled control of the Einschaltspule L1 and deactivated together with this. At the end of the method step C, the switched-on state ON is assumed.

During the holding operation beginning with the ON state, the turn-off capability is tested in two subsequent steps in step D by means of the turn-off coils L3 and L4, without the magnet armature being moved out of its holding position. Analogously to method step B, in the first or second test step of method step D, the auxiliary disconnecting coil L4 or the main disconnecting coil L3 is opened for 0.3 ms and the appearance of a voltage drop VR6 at the current detection resistor R6 connected to the auxiliary disconnecting coil L4 or one in the predetermined one Voltage window falling voltage drop -ΔVC1 observed at the connected to the Hauptabschaltspule L3 charge storage C1. If the two test steps are positive, they are repeated with a certain period. However, if no voltage drop across the current sensing resistor R6 detected at any time during the first test steps, then the magnet armature is first transferred by discharging the charge storage C1 via Aufsteuerung the Hauptabschaltspule L3 in the fallen state and on the intermediate reached state OFF by shorting the control voltage Vi the final state taken STILLGELEGT. If, however, at any time during the second test steps, no voltage drop across the charge storage device C1 is detected within the prescribed window, then the magnet armature is first transferred by Aufsteuem powered by the control voltage source Hilfsabschaltspule L4 in the fallen state and on the intermediate reached state OFF by shorting the control voltage Vi the final state STILLGELEGT taken.

When the control voltage Vi is removed, be it intentionally controlled or due to a defect in the supply or the generation of the control voltage Vi, the waste operation according to method step E is carried out. This is the charge capacitor C1 discharged via the main Hauptabschaltspule L3, whereby the armature in the fallen position or the magnetic drive transitions to the off state. Now, the output state has been taken OFF again, from which by re-applying the control voltage Vi, the process, starting with the process step A, can be restarted.

During the second test step in method steps B and D, it is additionally checked whether an induced voltage increase due to the short-time current in the main shutoff coil L3 and the electromagnetic coupling between the main shutoff coil L3 and the turn on inductor L1 occurs at the turn on inductor L1. If a significant increase in voltage + .DELTA.VL1 is registered in the second test step by the control circuit, is transferred from step B to step C or the process step D is repeated periodically with the initiation of the first test step. If, however, during the second test step of method step B, no voltage increase + .DELTA.VL1 is detected, the short-circuiting of the control voltage Vi, the final state STILLGELEGT is taken. If, on the other hand, during one of the second test steps after method step D, no voltage increase + .DELTA.VL1 is detected at the Einschaltspule L1, the armature is first transferred by controlling the supplied by the control voltage source Hilfsabschaltspule L4 in the fallen state and the thus reached state OFF by shorting the control voltage Vi the final state taken STILLGELEGT. The absence of the expected voltage increase + ΔVL1 during the second test step means that the freewheeling circuit FL is not inactive due to a defect, and thus represents a short circuit for induced voltage increases. This short circuit would also occur in normal waste operation according to process step E. Because of the electromagnetic coupling between the Einschaltspule L1 and the Hauptabschaltspule L3 this short circuit would lead during the discharge of the charge storage C1 via the main waste coil L3 in step E to a significant reduction of the magnetic field strength in the magnetic yoke against the magnetic field strength occurring at inactive freewheel FL. By such a reduced magnetic field strength is no longer guaranteed the safe return of the armature in the fallen position.

With the completion of method step A, a monitoring of the microcontroller additionally takes place with the aid of watchdog signals which, when properly operated of the microcontroller are constantly output from this. Watchdog signals in connection with microcontrollers are known for example from US 5,214,560 A. In the absence of the watchdog signals, which takes place, for example, in a program crash or a program suspension, the charge storage C1 is discharged in accordance with process step E via the Hauptabschaltspule L3 and then taken back to the initial state OFF.

The present invention is not limited to the embodiment of the method described above, but also encompasses all embodiments which have the same effect in the sense of the method claims. For example, the method can be modified in such a way that in method steps B and D the first and the second test steps are interchanged with respect to their temporal succession. A further modification possibility is that the evaluation of a voltage increase + ΔVL1 to be expected in the turn-on coil L1 takes place during the first test step of method step D, ie with respect to the inductive effect of the current briefly flowing through the auxiliary cut-off coil L4, or during both test steps. A modification within the scope of the invention still consists in that the restraining force to be exerted on the magnet armature additionally or alternatively is effected by at least one further permanent magnet. Retaining springs for the retention force are listed, for example, in the already mentioned DE 101 33 713 C1. Further permanent magnets for the retention force are listed, for example, in the already mentioned EP 0 721 650 B1.

The circuit arrangement described schematically below with reference to FIG. 2 serves to operate a magnetic drive which is known to consist of a magnetic yoke, at least one permanent magnet arranged on the magnetic yoke, a magnet armature movably mounted on the magnet yoke and at least one return spring. The circuit arrangement contains electromagnetic coil means L1, L3 and L4 arranged around the magnet yoke, a control circuit supplied on the input side by a rectified control voltage Vi and acted upon by a microcontroller MC and a capacitive charge storage C1. The magnet armature is permanently magnetically supported by applying the control voltage Vi against the restraining force attracted by the magnetic yoke, is held exclusively permanent magnetic with continuing applied control voltage Vi and falls in omission of the control voltage Vi with sub support by the retention force and against the permanent magnetic holding force by discharging the charge storage device C1 from the yoke. The control voltage Vi is obtained via supply terminals S1 and S2 of an input circuit E1, which contains means for rectifying and filtering or suppressing interference, from a supply voltage Va to be applied externally to supply terminals A0 and A1. The supply voltage Va can be obtained from a DC or an AC voltage source and is switched on to initiate the tightening operation and switched off again to initiate the waste operation. The potential low-lying supply terminal S2 is connected to the ground potential of the control circuit. Connected to the high-voltage supply terminal S1 is a control voltage controller BVi, which upon reaching a sufficient level of the control voltage Vi, after the supply voltage Va has been applied, initializes the microcontroller MC.

An auxiliary cut-off branch of the series connection of an auxiliary cut-off coil L4, an auxiliary electronic cut-off member T4 and current monitoring means Bl4 is connected directly to the supply terminals S1, S2. Starting from the high-lying supply connection S1, the control voltage Vi is supplied to the remaining circuit parts via a triggerable permanent interrupter DU. A switch-on branch from the series connection of a switch-on coil L1 and an electronic switch-on element T1 is connected downstream of the permanent breaker. The series circuit breaker is further followed by a series connection of a forward-biased decoupling diode D8 and a serial Hauptabschaltzweig formed of a Hauptabschaltspule L3 and a main electronic shutdown T3. The charge storage C1 and voltage detection means BV3 are both arranged in parallel to the main shutdown branch L3-T3. The turn-on branch L1-T1 and the main shutdown branch L3-T3 and the charge storage device C1 and the voltage detection means BV3 are fed by a turn-off control voltage Vi ', which is equal to the control voltage Vi at permeable permanent breaker DU and equal to zero when the permanent breaker is triggered. Inputs of the microcontroller MC are connected to the current detection means B14 and the voltage detection means BV3. Outputs of the microcontroller MC are connected to the switching elements T1, T3 and T4 and to the permanent breaker DU. The decoupling diode D8 prevents charge from flowing away from the charge accumulator C1 via the turn-on branch L1-T1 and via the auxiliary cut-off branch L4-T4-BI4.

The microcontroller MC is programmed to be initialized with a reset signal appearing after application of the control voltage Vi at the output of the control voltage controller BVi, the auxiliary cut-off T4 and then the main cut-off T3 test-wise to close, i. for putting into the conductive state, the pulse-controlled activates the Einschaltglied T1 for transferring the armature to the tightened position and then deactivated and after elimination of the control voltage Vi the Hauptabschaltglied T4 for transferring the armature in the fallen position closes, the electromagnetic return force from the is recovered by the Hauptabschaltspule L3 effluent charge of the charge storage device C1. The test-closing of the cut-off elements T3 and T4 takes place only for a short time, for example for 0.3 ms, so that this has no effect on the magnet armature. If the microcontroller MC does not receive an output signal from the voltage detection means BV3 during the test drive of the main shut-off member T3, it closes the auxiliary shut-off member T4. The then supplied by the supply terminals S1, S2 current through the Hilfsabschaltspule L4 leads the Mag netanker from the holding position in the fallen position back - unless the armature was still in the fallen position. Subsequently, the microcontroller MC triggers the permanent breaker DU, so that the subsequent circuit parts are separated from the control voltage Vi. On the other hand, when the microcontroller MC does not receive an output from the current detection means BI4 during the test drive of the auxiliary cutoff T4, it closes the main cutoff T3. The then supplied by the charge storage C1 current through the Hauptabschaltspule L3 returns the armature from the holding position in the fallen position - unless the armature was still in the fallen position. In this case as well, the microcontroller MC triggers the permanent interrupter DU, so that the subsequent circuit parts are disconnected from the control voltage Vi.

Connected to the turn-on coil L1 and the turn-on T1 is an active low-pass AT whose output is connected to the permanent breaker DU. The active low-pass AT charges alternately up and down in the case of pulse-controlled control of the switch-on element T1, without thereby achieving a predetermined triggering voltage. If the switch-on element T1 can no longer be blocked as a result of a defect, the active low-pass filter AT reaches the triggering voltage and thus triggers the permanent breaker DU to separate the subsequent circuit parts from the control voltage Vi.

In order to protect the switch-on element T1 against overvoltages and for the rapid reduction of the magnetic energy, a freewheeling circuit FL is arranged parallel to the switch-in coil L1 in a manner known per se. The freewheeling circuit FL would mean a significant additional load for the charging capacitor C1 in the waste operation because of the electromagnetic coupling via the mutual inductance between Einschaltspule L1 and Hauptabschaltspule L3. As a result of this additional load, the charge stored on the charge storage C1 would no longer be sufficient to safely return the magnet armature to the fallen position. Therefore, the freewheeling circuit FL is designed as an activatable freewheeling circuit which is activated and deactivated by the microcontroller MC together with the switch-on element T1. That is, the deactivated outside of the tightening operation freewheeling circuit FL can not load the charging capacitor C1 in the waste mode. In the deactivated state of the freewheeling circuit FL, a voltage increase + .DELTA.VL1 is induced during testing of the main shutdown branch L3-T3 as a result of the short-term current flow through the Hauptabschaltspule L3, which is signaled via further voltage detection means BV1 the microcontroller MC. If there is no increase in voltage + .DELTA.VL1 during the test drive of Hauptabschaltgliedes T3 Hilfsabschaltglied T4 is switched on to take the fallen state by the magnetic armature and then triggered the permanent breaker DU.

Furthermore, the microcontroller MC activates a watchdog monitoring circuit WC, which in the event of a malfunction of the microcontroller MC effects the transfer of the magnet armature from the tightening position into the waste position by closing the main shaft member T3.

The input circuit E1 consists on the input side of a suppression capacitor C10 and a voltage limiting resistor R35 and the output side of a full-wave rectifier with the rectifier diodes D11 to D14. The control voltage Vi present at the output of the full-wave rectifier D11-D14 or at the supply terminals S1, S2 passes as a switch-off control voltage Vi 'via the permanent interrupter DU. The circuit breaker DU consists of a short-circuit fuse F1 inserted in the control voltage line W1 and a subsequent semiconductor short-circuit switching element T6 arranged between the control voltage line W1 and the ground potential. The microcontroller MC supplies a short-circuiting signal at an output La0 CB via an integrated amplifier IV32 and a first OR diode D6 to the base electrode of the short-circuiting switching element T6.

The control voltage Vi is fed via the control voltage controller BVi a terminal A3 of the microcontroller MC and determined by conventional means and in connection with a port A2 of the microcontroller MC Einschaltbereitschaft the microcontroller MC with respect to the developing control voltage Vi and the pulse width during the pulse-width-controlled activation of the Einschaltgliedes T1.

The switch-off control voltage Vi 'feeds the capacitive charge storage C1 via a charging resistor R14 and the decoupling diode D8. The turn-off control voltage Vi 'and the charging voltage VC1 across the charge storage device C1 are separately supplied via decoupling diodes D21 and D20 a switching power supply ST. The switched-mode power supply ST supplies the DC supply voltage of +13.6 V required for the voltage supply of the control circuit and the +5 V DC supply voltage derived therefrom. In switched mode and in holding mode, the switched-mode power supply ST and thus the control circuit are fed by the switch-off control voltage Vi '. In waste operation, however, the switching power supply ST and thus the control circuit of the charging voltage VC1 are fed. The +5 V output of the switching power supply ST is also connected to a reset circuit, which consists in a conventional manner of an integrated amplifier IV7, an output-side integration capacitor C28 and a feedback resistor R65. With the structure of the disconnectable control voltage Vi 'after application of the supply voltage Va, the amplifier IV7 sends a reset signal RES to the RESET input of the microcontroller MC, whereupon the microcontroller MC is reset to a defined initial state.

The auxiliary shut-off arm consists of the auxiliary shut-off coil L4, the semiconductor auxiliary shut-off member T4 and the current monitoring resistor R6 arranged in its emitter circuit. The microcontroller MC outputs at a output La2 a test and, if necessary, a the magnet armature trailing Hilfsabschaltsignal ABr. The Hilfsabschaltsignal ABr is supplied via an integrated amplifier IV31 and a resistor R7 before the base electrode of Hilfsabschaltgliedes T4. In order to test the auxiliary cutoff branch L4-T4-R6, the auxiliary cutoff signal ABr has a duration of 0.3 ms, followed by a short-time current flow through the current detection resistor R6. The voltage drop then formed across the current detection resistor R6 VR6 is supplied via a first amplifier circuit IV21 as an auxiliary acknowledgment signal SD to an input B4 of the microcontroller MC. The current detection resistor R6 and the first amplifier circuit IV21 correspond to the current detection means BI4 of Fig. 2. From the output of the amplifier IV31 also leads via a delay element consisting of a delay resistor R9 and a delay capacitor C6, and a second OR diode D7 connects to the base electrode of the short-circuiting switching element T6. In this case, in case of failure of the main shutdown branch L3-T3, after the closing of the auxiliary shut-off member T4 which leads back the armature, the permanent breaker DU is additionally triggered via this connection.

The Hauptabschaltzweig consists of the Hauptabschaltspule L3, the semiconductor Hauptabschaltglied T3 and a first Surpressordiode D10 as a freewheeling circuit for the Hauptabschaltspule L3. The microcontroller MC outputs at a output La1 a test and, if necessary, a Hauptabschaltsignal AB leading back to the armature. The Hauptabschaltsignal AB is supplied via an integrated amplifier IV42, a fourth OR diode D44 and a series resistor R18 connected to the divider resistors R66, R67 base electrode of the Hauptabschaltgliedes T3. For testing the main shutdown branch L3-T3-D10, the main shutoff signal AB has a duration of 0.3 ms, whereupon a measurable voltage decrease -ΔVC1 should occur at the charge storage C1. The voltage drop -ΔVC1 is fed via a passive high-pass filter, consisting of a differentiating capacitor C2, a bleeder resistor R21 and a limiter diode D1, and a second amplifier circuit IV12 as the main acknowledgment signal SB to a port A4 of the microcontroller MC. The microcontroller MC monitors whether the voltage drop -ΔVC1 is within a predetermined window. Too low a voltage drop -ΔVC1 means that a missing or too low coil current IL3 in the main waste coil L3 does not lead to a return of the magnet armature during the waste operation. On the other hand, too high a voltage drop -ΔVC1 means that the capacitance of the charge storage device C1 is no longer sufficient to supply a sufficient current flow through the main waste coil L3 during the waste operation. A third amplifier circuit IV11 is additionally connected to the charge storage C1 via a voltage divider comprising the divider resistors R19, R20, which supplies at its output a voltage control signal SA proportional to the charge voltage VC1 to a terminal A5 of the microcontroller MC. Based on the voltage control signal SA, the microcontroller MC checks whether the charge storage MC has been sufficiently charged after switching on the control voltage Vi to ensure the waste operation. The high pass C2-R21, the voltage divider R19-R20 and the second and the third amplifier circuits IV12 and IV11 form the voltage detection means BV1 according to FIG. 2.

The microcontroller MC outputs at an output La3 periodically watchdog signals WDG, which are controlled by a watchdog monitoring circuit WC. The watchdog monitoring circuit WC is known per se from the document WO 03 077 396 A1 and contains a high pass, a charging capacitor which can be discharged by a semiconductor switch in the rhythm of the watchdog signals WDG and a voltage comparator. The output of the watchdog monitoring circuit WC is connected to the series resistor R18 via a fifth OR diode. In the case of a faulty microcontroller MC, the watchdog signals WDG remain off, whereupon the watchdog monitoring circuit WC initiates the waste operation by closing the main shutdown element T3.

The turn-on branch consists of the turn-on coil L1, the semiconductor turn-on T1, the activatable freewheel FL and a Surpressordiode D9. which serves as additional overvoltage protection. The microcontroller MC outputs a pulse-width-modulated turn-on signal AN via an output La4 and a resistor circuit R45 to R48. The switch-on signal AN is supplied via an integrated amplifier IV41 and a series resistor R17 to the base electrode of the switch-on element T1. The activatable freewheeling circuit FL includes a high-pass filter connected downstream of the output of the amplifier IV41, which consists of a differentiating capacitor C4 and a leakage resistor R13, a charging circuit consisting of a series connection of a rectifier diode D4 and a charging resistor R15, starting from high-pass C4-R13, from a charging capacitor C3 , consisting of a Begrenzerdiode D3 and a discharge resistor R16, and arranged parallel to the Einschaltspule L1 series circuit of a freewheeling diode D2 and a semiconductor activation switching element T2, whose gate electrode is connected to the charging capacitor C3. With the pulse-controlled activation of the switch-on element T1, the "pumping-up" of the charging capacitor C3 begins in the rhythm of the pulses of the switch-on signal AN pending at the amplifier IV41. After a few pulses of the turn-ON signal AN, the voltage across the charging capacitor C3 has risen so far that the activation switching element T2 closes and actively connects the freewheeling diode D2 with the turn-on coil L1. The freewheeling circuit FL is now in the active state. Upon completion of the turn-ON signal, the charging capacitor C3 is again discharged via the discharge resistor R16, wherein the freewheeling diode D2 is separated from the Einschaltspule L1 by blocking the activation switching element T2. Thus, the freewheeling circuit FL is again in an inactive state.

A voltage divider R24-R25 leads from the connection point between the turn-on coil L1, the turn-on element T1 and the activatable freewheeling circuit FL to a fourth amplifier circuit IV91. The voltage reduction + ΔVL1 induced in the turn-on coil L1 when the freewheeling circuit FL is deactivated when the main turn-off branch L3-T3-D10 is tested is conducted via a fourth amplifier circuit IV91 as a blocking control signal SC to a terminal A6 of the microcontroller MC. The voltage divider R24-R25 and the fourth amplifier circuit IV91 correspond to the further voltage detection means BV1 according to FIG. 2.

From the connection point between the turn-on coil L1, turn-on T1 and freewheel FL another voltage divider R11-R12 leads to the base electrode of a switching transistor T5, whose collector electrode is connected to a charging resistor R10 and another charging capacitor C5. From the charging capacitor C5, a third OR diode D5 leads to the base electrode of the short circuit switching element T6. Outside the tightening operation, the turn-on T1 is disabled, whereby the charging capacitor C5 is discharged via the collector-emitter path of the switching transistor T5 closed by the turn-on coil L1 and the voltage divider R11-R12. In the tightening mode, the switching transistor T5 is mutually closed and blocked by the voltage pulses occurring across the switch-on element T1 in the pulse rhythm of the switch-on signal T1 so that no substantial voltage can build up across the charge capacitor C5, which is alternately charged and discharged. However, as a result of a defect permanently closed turn-on transistor T1, generally as a result of alloying, the switching transistor T5 is permanently blocked. Then, with the charging of the charging capacitor C5 progresses, the short-circuit switching element T5 is closed via the charging resistor R10, and with the subsequent triggering of the short circuit fuse F1, the disconnectable control voltage Vi 'is switched off permanently. The magnetic drive is secured against switching on. The voltage divider R11-R12, the switching transistor T5, the charging resistor R10 and the charging capacitor C5 together correspond to the active low pass AT of FIG. 2. From the node of the first to third OR diodes D5 to D7 and node resistance R8, a trigger signal SE becomes a Input B3 of the microcontroller MC out. Upon receipt of a trigger signal SE, the microcontroller is present MC as a precaution, a Hauptabschaltsignal AB off, due to the possibly already tightened armature.

In addition to the above-described functional monitoring of the switch-on element T1, the circuit arrangement also has further self-monitoring functions described below, which ensure that the circuit arrangement and the magnetic drive move into a defined safety-relevant state.

In the event of a wire break to or in the Hauptabschaltspule L3 or in the case of a permanently locked Hauptabschaltgliedes T3 after testwise output of Hauptabschaltsignals AB due to the absence of a voltage drop -ΔVC1 at the charge storage device C1 no main acknowledgment signal SB output from the second amplifier circuit IV12. The microcontroller MC then outputs first a Hilfsabschaltsignal ABr for returning the magnet armature in the fallen position and then a short-circuit signal CB for permanent shutdown of the turn-off control voltage Vi 'from. The magnetic drive can then no longer operate.

If the capacity of the charge storage device C1 has dropped to a value that can no longer be tolerated, or if the surge diode D10 connected to the main shutdown coil L3 has failed, the test signal of the main shutdown signal AB becomes a main acknowledgment signal SB exceeding the predetermined window due to an excessively large voltage drop -ΔVC1 at the charge storage C1 output from the second amplifier circuit IV12. The microcontroller MC then outputs first a Hilfsabschaltsignal ABr for returning the magnet armature in the fallen position and then a short-circuit signal CB for permanent shutdown of the turn-off control voltage Vi 'from. The magnetic drive can then no longer operate.

If the activatable freewheeling circuit is always in the active state, no inhibiting control signal SC is output from the fourth amplifier circuit IV91 after test output of the main shutdown signal AB due to a barely ascertainable voltage increase + ΔVL1 at the turn-on coil L1. The microcontroller MC then outputs first a Hilfsabschaltsignal ABr for returning the magnet armature in the fallen position and then a short-circuit signal CB for permanent shutdown of the turn-off control voltage Vi 'from. The magnetic drive can then no longer operate.

If the main cut-off member T3 breaks down, i. E. is constantly conductive, no voltage control signal SA is output from the third amplifier circuit IV11 after applying the control signal Vi due to the non-achievement of a required charging voltage VC1 across the charge storage device C1. The microcontroller MC then outputs a short-circuit signal CB for permanent disconnection of the switch-off control voltage Vi '. The magnetic drive can then no longer operate.

In the case of wire breakage to or in the auxiliary cutoff coil L4 or in the case of a permanently cut off auxiliary cutoff element T4, no auxiliary acknowledge signal SD is outputted from the first amplifier circuit IV21 after test output of the auxiliary cutoff signal ABr due to the absence of a voltage drop VR6 at the current sense resistor R6. The microcontroller MC then outputs first a Hauptabschaltsignal AB for returning the armature in the fallen position and then a short-circuit signal CB for permanent shutdown of the turn-off control voltage Vi 'from. The magnetic drive can then no longer operate.

If the Hilfsabschaltglied T4 durchlegiert, i. is constantly conductive, no voltage control signal SA is output from the third amplifier circuit IV11 after applying the control signal Vi due to the non-achievement of a required charging voltage VC1 across the charge storage device C1. The microcontroller MC then outputs a short-circuit signal CB for permanent disconnection of the switch-off control voltage Vi '. The magnetic drive can then no longer operate.

After permeation of the short-circuiting switching element T6 can occur with the collapse of the control voltage Vi two alternative cases. In the first case, by issuing the Hauptabschaltsignals AB, the armature is returned to the fallen position before the short circuit fuse F1 triggers below. In the second case, the short-circuit protection F1 triggers after the voltage dip detected via the fourth amplifier circuit IV91 has caused the microcontroller MC to output an auxiliary shutoff signal ABr for returning the magnet armature. Again, the magnetic drive can not be operated in both cases.

If the +5 V DC supply voltage fails, the return of the magnet armature to the fallen down position is initiated with the absence of watchdog signals WDG via the watchdog monitoring circuit WC. If the +13.6 V DC supply voltage fails, the watchdog monitoring circuit WC and the integrated amplifier IV42 become inactive. By closing the Hauptabschaltgliedes T3 via the connected to its base electrode voltage divider R66-R67 of the armature is returned to the fallen position. Without restoration of the DC supply voltages, the magnetic drive can no longer be operated.

The timing diagrams in FIG. 5 demonstrate both the course of the method according to the invention and the operation of the circuit arrangement according to the invention without occurrence of the above-described failure phenomena. By applying the control voltage Vi at the time tA, the charge voltage VC1 is built up by charging the charge storage C1 according to method step A, wherein the level of the charging voltage VC1 is monitored by means of the voltage control signal SA. The process step B begins at the time tB1 with the output of a Hilfsabschaltsignals ABr of 0.3 ms for testing the Hilfsabschaltkreises, whereupon an auxiliary acknowledgment signal SD is generated by the short-time current IL4 by the Hilfsabschaltspule L4. Subsequently, at a time tB2, a main shutoff signal AB is output for testing the main shutdown branch, whereupon a main acknowledge signal SB is generated by the momentary voltage decrease -ΔVC1 of the charge voltage VC1. Due to the short-term auxiliary cut-off current IL4 and the short-time main cut-off current IL3, voltages are induced in the turn-on coil L1, which voltages are output in the case of the voltage increase + ΔVL1 induced by the short-time main cut-off current IL3 with the blocking control signal SC. The method step C begins at the time tC1 and ends at the time tC2 with the pulse width-controlled switch-ON signal AN. With the delayed decay of a current IL1 considerable duration by the Einschaltspule L1 of the tightening operation ends and starts the holding operation.

In accordance with method step D, during the hold operation in periodic repetition the testing of the auxiliary shutdown branch and of the main shutdown branch with output of auxiliary shutdown signals ABr and of main shutdown signals AB of 0.3 ms duration takes place at the times tD1 and tD2, respectively. Again, the output of auxiliary acknowledgment signals SD and main acknowledgment signals SB occurs as a result of the short-term Coil currents IL4 and IL3 and the impressing of the induced voltage increases + .DELTA.VL1 on the lock control signal Sc due to the short-term coil current IL3. By switching off the control voltage Vi at the time tE1, the holding operation ends and the waste operation according to the method step E. By issuing a Hauptabschaltsignals AB of considerable duration flows supplied from the charge storage C1 current IL3 through the Hauptabschaltspule L3, whereby the armature is returned to the fallen position , The charging voltage VC1 falls almost to zero. Upon completion of the Hauptabschaltsignals AB at time tE2 of the waste operation is completed, so that the idle state of the magnetic drive is reached and this again ready to go to renewed application of the control voltage Vi in the tightening operation.

In addition, it should be pointed out that the voltage increases impressed on the blocking control signal SC are caused both by the inductive coupling between the auxiliary disconnecting coil L4 and the closing coil L1 and by the inductive coupling between the main closing coil L3 and the closing coil L1.

A modification within the scope of the invention also consists here in that the restraining force to be exerted on the magnet armature additionally or alternatively is effected by at least one further permanent magnet. Retaining springs for the retention force are listed, for example, in the already mentioned DE 101 33 713 C1. Further permanent magnets for the retention force are listed, for example, in the already mentioned EP 0 721 650 B1.

Claims (20)

1. Method for operating a solenoid actuator, consisting of a magnetic yoke, permanent magnets, an armature and electromagnetic coil means (L1, L3, L4), by means of a control voltage (Vi) to be applied to a microcontroller-implemented control circuit on the input side, including

   - permanent magnetically-assisted, electromagnetic attraction mode counter to a retaining force once the control voltage (Vi) has been applied,

   - then exclusively permanent magnetic hold mode if the control voltage (Vi) continues to be applied and

   - drop-off mode, which is assisted by the retaining force and brought about electromagnetically counter to the permanent magnetic holding force, by discharging a capacitive charge accumulator (C1), which is charged during the attraction and hold modes, once the control voltage (Vi) has been removed, characterised by the following method steps:

   A) once the control voltage (Vi) has been applied, the reset control circuit is initialised and the charging of the charge accumulator (C1) introduced,

   B) an auxiliary shut-off coil (L4) and a primary shut-off coil (L3) are then briefly activated in an arbitrarily defined order, whereupon the control voltage (Vi) is permanently deactivated if current ceases to flow through one of the two shut-off coils (L3; L4),

   C) on detection of a flow of current through both shut-off coils (L3; L4), on the other hand, a cut-in coil (L1) is activated for transferring the armature into the attracted state and is then currentlessly switched,

   D) the auxiliary shut-off coil (L4) and the primary shut-off coil (L3) are then briefly activated in an arbitrarily defined order without affecting the armature, whereupon if current ceases to flow through the auxiliary shut-off coil (L4), the charge accumulator (C1) is discharged via the primary shut-off coil (L3) for transferring the armature into the drop-off state or, if current ceases to flow through the primary shut-off coil (L3), the auxiliary shut-off coil (L4) is activated for transferring the armature into the drop-off state and, in both cases, the control voltage (Vi) is then permanently deactivated,

   E) on detection of current flowing through the shut-off coils (L3; L4), on the other hand, method step D is initiated, although once the control voltage (Vi) has been removed, the charge accumulator (C1) is discharged via the primary shut-off coil (L3) for transferring the armature into the drop-off state.
2. Method according to the preceding claim, characterised in that the brief activation of the primary shut-off coil (L1) according to method step B takes place only once the charge accumulator (C1) has been sufficiently charged.
3. Method according to either of the preceding claims, characterised in that the permanent deactivation of the control voltage (Vi) according to method steps B and D takes place by the triggering of a short circuit.
4. Method according to any one of the preceding claims, characterised in that the brief flow of current through the auxiliary shut-off coils (L4) according to method steps B and D is detected as a drop in voltage (VR6) affected by resistance.
5. Method according to any one of the preceding claims, characterised in that the brief flow of current through the primary shut-off coil (L3) according to method steps B and D is detected as a reduction in voltage (-ΔVC1) via the charge accumulator (C1).
6. Method according to the preceding claim, characterised in that the auxiliary shut-off coil (L4) is activated both in the event of an excessively low and in the event of an excessively high reduction in voltage (-ΔVC1), the control voltage (Vi) then being permanently deactivated.
7. Method according to any one of the preceding claims, characterised in that in the absence of an increase in voltage (+ΔVL1) induced at the cut-in coil (L1) as a result of the brief flow of current through one of the two shut-off coils (L3; L4), the respective other shut-off coil (L4; L3) is, if necessary, activated for transferring the armature into the drop-off state, the control voltage (Vi) necessarily being permanently deactivated.
8. Method according to any one of the preceding claims, characterised in that in the event of the microcontroller failing, the charge accumulator (C1) is discharged via the primary shut-off coil (L3) for transferring the armature into the drop-off state.
9. Method according to any one of claims 1 to 7, characterised in that in the event of the microcontroller failing, the auxiliary shut-off coil (L4) is activated for transferring the armature into the drop-off state.
10. Method according to any one of the preceding claims, characterised in that the retaining force is applied by at least one restoring spring actively connected to the armature.
11. Method according to any one of the preceding claims, characterised in that the retaining force is applied by at least one further permanent magnet actively connected to the armature.
12. Circuit arrangement for operating a solenoid actuator consisting of a magnetic yoke, at least one permanent magnet arranged on the side of the magnetic yoke, an armature and retaining means exerting a retaining force, containing electromagnetic coil means (L1; L3; L4) surrounding the magnetic yoke, a control circuit, which on the input side is supplied with and acted on by a rectified control voltage (Vi) and contains a microcontroller (MC), and a capacitive charge accumulator (C1), the armature being attracted in a permanent magnetically-assisted manner counter to the retaining force once the control voltage (Vi) has been applied, being exclusively permanent magnetically held if the control voltage (Vi) continues to be applied, and dropping off once the control voltage (Vi) has been removed, assisted by the retaining force and counter to the permanent magnetic holding force, by discharging of the load accumulator (C1), characterised by

    - a triggerable permanent circuit breaker (DU) for permanently deactivating the control voltage (Vi) which may be supplied via feed terminals (S1; S2),

    - an auxiliary shut-off branch, connected to the feed terminals (S1; S2), from the connection in series of an auxiliary shut-off coil (L4), an auxiliary shut-off member (T4) and current-monitoring means (BI4),

    - a cut-in branch, connected downstream of the permanent circuit breaker (DU), from the connection in series of a cut-in coil (L1) and a cut-in member (T1),

    - a primary shut-off branch, connected downstream of the permanent circuit breaker (DU), from the connection in series of a decoupling diode (D8) polarised in the conducting direction, a primary shut-off coil (L3) and a primary shut-off member (T3), the charge accumulator (C1) being arranged parallel to the primary shut-off coil (L3) and to the primary shut-off member (T3),

    - voltage detection means (BV3) arranged parallel to the charge accumulator (C1),

    - input-side connections of the microcontroller (MC) to the current detection means (BI4), the voltage detection means (BV3) and a control voltage controller (BVi), connected on the input side to the feed terminals (S1; S2), and output-side connections of the microcontroller (MC) to the switching members (T1; T3; T4) and the permanent circuit breaker (DU), the microcontroller (MU) being programmed in such a way that it is initialised following application of a control voltage (Vi), briefly closes in a definable order the auxiliary and primary shut-off members (T4; T3) without possibly affecting the armature, activates in a pulse-controlled manner and then deactivates the cut-in member (T1) for transferring the armature into the attracted state and, once the control voltage (Vi) has been removed, closes the primary shut-off member (T3) for transferring the armature into the drop-off state, but if the output signal from the current detection means (BI4) or the voltage detection means (BV3) is not issued, closes the primary or auxiliary shut-off member (T3; T4) for transferring the armature into the drop-off state and then triggers the permanent circuit breaker (DU).
13. Circuit arrangement according to the preceding claim, characterised in that the permanent circuit breaker (DU) consists of a short-circuit protection means (F1) leading to one of the feed terminals (S1) and having a downstream short-circuit switching member (T6).
14. Circuit arrangement according to the preceding claim, characterised in that an active high-pass filter (AT) is connected on the input side to the cut-in coil (L1) and on the output side to the short-circuit switching member (T6) in such a way that a charging capacitor (C5), which discharges or charges when the cut-in member (T1) is closed or opened, closes the short-circuit switching member (T6) when a defined charging voltage is reached.
15. Circuit arrangement according to any one of claims 12 to 14, characterised in that the current-monitoring means (BI4) consist of a current detection resistor (R6) and a first amplifying circuit (IV21) issuing therefrom.
16. Circuit arrangement according to any one of claims 12 to 15, characterised in that the voltage detection means (BV3) have a high-pass filter (C2-R21), connected to the charge accumulator (C1), and a second amplifying circuit (IV12) issuing therefrom and leading to the microcontroller (MC).
17. Circuit arrangement according to the preceding claim, characterised in that the voltage detection means (BV3) comprise a third amplifying circuit (IV11) issuing from the load accumulator (C1) and leading to the microcontroller (MC).
18. Circuit arrangement according to any one of claims 12 to 17, characterised in that an activatable free-running circuit (FL) and further voltage detection means (BV1), which detect an increase in voltage (+ΔVL1) induced during the brief closure of the primary shut-off coil (L3) and/or the auxiliary shut-off coil (L4) and lead to the microcontroller (MC), are connected to the cut-in coil (L1) and, in the absence of an increase in voltage (+ΔVL1), the microcontroller (MC) closes the auxiliary shut-off member (T4) or the primary shut-off member (T3) for transferring the armature into the drop-off state and then triggers the permanent circuit breaker (DU).
19. Circuit arrangement according to any one of claims 12 to 18, characterised in that at least one restoring spring, which is actively connected to the armature, is provided as the retaining means.
20. Circuit arrangement according to any one of claims 12 to 18, characterised in that at least one further permanent magnet, which is actively connected to the armature, is provided as the retaining means.

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