EP1968089B1 - Actuation module for an electric protective circuit breaker, method for its operation and electric safety system - Google Patents

Abstract

Control module (20) comprises a voltage input (28) for a control voltage (U), a voltage output (32a) to which is connected a contact breaker (22) for a protective switch (10), an input (32b) for the control voltage fed from the contact beaker, a connection (36) for the protective switch connected to the input and a measuring unit (46) for measuring current and/or voltage at the input and output. Independent claims are also included for the following: (1) Electrical protective system with the above control module; and (2) Method for operating the control module. Preferred Features: An evaluation unit (42) evaluates current and/or voltage for the purpose of the functional control of the contact breaker. A control switch for the protective switch is arranged between the input and output.

Description

The invention relates to a control module with interrupt function for an electrical circuit breaker, a method for operating such a drive module and an electrical protection system.

Electric consumers of higher power classes, e.g. Electric motors in electrical drives of industrial manufacturing technology, are connected with their connections usually not directly to a voltage network, but connected via an electrical circuit breaker with this. Thus, e.g. above-mentioned Electric motors connected via so-called contactors as a circuit breaker to a 380V three-phase network. For fast and safe disconnection of the entire consumption of the voltage network then the circuit breaker is opened.

The circuit breaker is typically operated with a control voltage of 24V, i. closed by applying the control voltage of 24V to connect the electrical load to the mains. For various reasons, e.g. safety aspects, such a circuit breaker has a breaker, e.g. in the form of an emergency stop button or a limit switch. In case of emergency or fault of the consumer, the breaker is activated; interrupts the control voltage to the circuit breaker, this opens and disconnects the electrical load safely from the power supply. The circuit breaker together with the breaker forms an electrical protection system for the electrical consumer.

There are currently a variety of different solutions for protection systems. It is known, for example, to connect a circuit breaker with digital inputs to which the breaker is connected to the circuit breaker. The breaker does not actually interrupt the control voltage the circuit breaker, but merely triggers a signal for the shutdown, which will then accomplish this. Such a structure has, for example, the disadvantage that in the event of a fault in the cut-off electronics, the circuit breaker is not opened despite the breaker being triggered.

As a rule, therefore, in other variants of protection systems, the breaker is connected as the first element to the supply line of the control voltage. By triggering the breaker, the circuit breaker is safely disconnected from the control voltage and opens. However, all other components, e.g. a system control, which is also supplied by the control voltage, de-energized. After closing the breaker again, the entire system including the system control system must be restarted, which can lead to a very long recovery time of a system. The currentless system control can thus perform no other functions during the downtime of the system, but is completely switched off.

Such an arrangement leads to a high wiring complexity, as e.g. in a larger system several interrupters are distributed and the control voltage must first be routed across the system across all interrupters in series until it reaches the actual system control or the actual circuit breaker.

In addition to the need for a faultless function of the breaker with regard to its turn-off behavior, it is desirable that the breaker actually triggers the breaker only when desired. A malfunction, i. unintentional interruption of the control voltage leads to unwanted plant downtime, etc.

From the document US-A-5 585 607 a circuit board is known, which is connectable to a squib of an airbag.

The circuit board has a voltage input and output and provides an interrupt function.

From the document DE 196 22 447 A1 An electrical protection system without a measuring unit for measuring current and voltage at the input and the output is known.

From the document EP-A-1 058 283 a monitoring system with the features of the preamble of claim 1 is known.

Object of the present invention is to provide a circuit breaker for a circuit breaker and a method that provides a safe interruption of the circuit breaker and allowing fault monitoring for the breaker, with optional other system components still powered when the breaker is tripped.

With regard to the device, the object is achieved by a control module according to claim 1 for an electrical circuit breaker, a protection system according to claim 7 and a method according to claim 8. The control module has an interrupt function. The drive module includes a voltage input through which the drive module is connected to a control voltage, e.g. 24 V, can be supplied. This is thus permanently on the control module. In the control module, the control voltage is fed without interruption to an output at which, e.g. via a supply line, an interrupter can be connected. The control module has an input to which the breaker is also connected. In the case of operation, the interrupter thus returns the control voltage to the input, if the interrupter is triggered, the control voltage is no longer present at the input.

In the control module, the input and thus the depending on the switching state of the breaker existing or non-existent control voltage is passed to a terminal to which in turn the circuit breaker is connected. The circuit breaker is therefore supplied with control voltage only in the case of the untriggered breaker.

In the control module, a measuring unit is also integrated, which is used to measure current and / or voltage at the input and output. The measuring unit therefore measures an electrical quantity at the breaker and its supply line, which in the following is always meant when the breaker is addressed. The control module forwards the measured values of current and / or voltage for further processing to an evaluation unit.

The fast and safe switching off of the circuit breaker is still ensured because the breaker interrupts the control voltage to the circuit breaker or the control voltage passed over the breaker. Corresponding safety requirements (eg DIN) are therefore met. However, the control module remains connected to the control voltage even when the breaker is tripped. A system control integrated, for example, in the control module also remains in operation. The recovery time of a system is reduced as the rest of the system control is not switched off.

By measuring the current and / or voltage flowing through the interrupter, a characteristic correlated with the quality of the interrupter, e.g. whose volume resistance, be determined. Newer circuit breakers are e.g. operated with pulsed control voltage. Here then also e.g. Rising times, edge steepness and the like at the input and output can be determined as a current voltage characteristic for the breaker as a parameter. Here it is e.g. also possible to refer to a measured voltage with a known characteristic of the circuit breaker the associated stream of a look-up table.

For example, the known when Gutzustand (novelty) of the breaker characteristic, eg current characteristic can be monitored over the life of it. If the corresponding current characteristic and thus the determined characteristic variable changes, eg if its ohmic resistance suddenly increases, this indicates an approaching failure of the breaker. However, by the control module according to the invention this is detected early, ie before the actual failure of the breaker and thus the unintentional interruption of the control voltage and thus the standstill of the system. A corresponding breaker susceptible to breakdown can thus be replaced without any other disadvantages before its actual failure, eg during regular maintenance or downtime of the system. The control module also knows the status of the circuit breaker (on or off) due to the control switch and can thus calculate, for example by means of the above-mentioned current characteristic, ie the characteristic value, the resistance of the breaker.

Changes in measured current and voltage or a correspondingly determined characteristic value can be used, for example. also close early on line heating or contact wear. Even too long or incorrectly dimensioned connecting cables for the breaker can be detected. For example, Conductor heating as a result of miswiring or improper sizing can be detected early and result in a shutdown of the load by the drive module prior to a final fault. Due to the control of the control voltage in the control module, the corresponding measurement of current and / or voltage can be monitored even in the tripped state of the breaker and thus the operational readiness of the protection system can be ensured.

In addition, an evaluation unit can be provided in the control module, which evaluates the current determined by the measuring unit or the voltage or at least forwards it for further processing.

In addition, a control switch for the circuit breaker in the control module can be integrated between input and connection. Even if the breaker is not triggered, the control switch can interrupt the forwarding of the control voltage from the input to the connection and thus to the circuit breaker and thus open the circuit breaker. The control switch thus serves the - in contrast to the breaker - regular switching of the circuit breaker.

The breaker can, as mentioned above, in particular be an emergency stop switch or a limit switch. For such breakers, a corresponding function monitoring is particularly important.

The control module may additionally have a bus interface to a system controller. In general, the plant control the control of the control switch, but also, for example the evaluation of the currents and / or voltages measured by the measuring unit and the corresponding functional check of the breaker. The evaluation unit can then be integrated in other words in the plant control. Because of the permanent connection of the control module with the control voltage, the communication with the system control via the bus interface is ensured even when tripped breaker.

The circuit breaker may be the circuit breaker of an engine start system. A so-called motor starter fulfills, e.g. in addition to a soft start or stop of the engine, an interruption function or emergency stop function. Especially with motors on the one hand, the safe standstill when triggering the breaker is particularly important as well as the possibility according to the invention to minimize its Wiederbereitschaftszeit or to avoid its faulty shutdown due to a malfunctioning breaker.

The control module can be part of a complete electrical protection system, in which then connected to the control module, the electrical circuit breaker and a breaker.

With regard to the method, the object of the invention is achieved by a method for operating a control module, as described above, in which the circuit breaker is supplied during its operation via the terminal with voltage and current, the measuring unit thereby currents and / or voltages at input and / or output determined, and an evaluation unit of currents and / or voltages determined a correlated with the quality of the breaker characteristic value.

In its basic version, therefore, the method is based on determining the current flowing back to the breaker or from this to the control module and / or the voltage across the breaker, and from this a characteristic value for the quality to determine the breaker. This can then be compared, for example, with a reference value or a characteristic value determined when new. The latter leads to a check of the breaker for aging, wear or the like. The first, for example, to check the correct dimensioning of breakers and connecting cables and their correct wiring.

Further aspects of the method according to the invention and advantageous embodiments have already been explained in detail in conjunction with the control module according to the invention and the electrical protection system together with corresponding advantages.

• Fig. 1 ein elektrisches Antriebssystem mit erfindungsgemäßem Schutzsystem in einem Blockdiagramm.

For a further description of the invention reference is made to the embodiments of the drawing. It shows in a schematic outline sketch:

• Fig. 1 shows an electric drive system with inventive protection system in a block diagram.

Fig. 1 shows an electric drive system 2, consisting of an electric motor 4 and a controlling this control 6. The motor 4 is connected via a connecting line 8, in which a motor starter 10 is connected to a three-phase system 12. The motor starter 10 as a circuit breaker in this case includes unspecified contactors, which can disconnect or connect the connecting line 8.

The control 6 includes a control module, an interface module 20, an emergency stop button 22 as a breaker, a system controller 24 and a power supply 26th

The interface module 20 has a control voltage input 28, to which the voltage supply 26 (control voltage U, in Example 24V) is connected. The phase of the control voltage U at the control voltage input 28 is fed via a first phase line 30a to an output 32a. A likewise on Control voltage input 28 connected neutral 34 for the control voltage U leads to a terminal 36. From the output 32a via a connecting line 38, the phase of the control voltage U to the emergency stop button 22 and from there back to an input 32b. Depending on the switching state of the emergency stop button 22 is thus at the input 32b, the control voltage U (button 22 closed) or no voltage (button 22 open). From the input 32b, another phase line 30b leads via a mechanical or electronic controllable switch 40 to the terminal 36. Phase line 30b and neutral conductor 34 are led from the terminal 36 to the motor starter 10.

If the control voltage U is applied to the terminal 36, the motor starter 10 closes and the motor 4 starts running. If the emergency stop button 22 is pressed or the switch 40 is opened, no control voltage is applied to the terminal 36, the motor starter 10 opens and the motor 4 stops.

The interface module 20 further includes a microprocessor 42 which actuates the switch 40 via a control line 44. In addition, a measuring device 46 is present in the interface module 20, which is connected to output 32a and input 32b via measuring lines 48. The measuring device 46 is also connected to the microprocessor 42, which in turn is connected to a communication interface 50, via which it communicates with the system controller 24.

The measuring device 46 determines the voltages U1 and U2 of the output 32a and the input 32b with respect to the neutral conductor 34 and / or the current I1 or I2 flowing to or coming from the emergency stop button 22. The corresponding measured quantities U1,2 or I1,2 are transmitted to the microprocessor 42 by the measuring device 46, which determines therefrom a parameter 52 for the connection line 38 and the emergency-off button 22, in the example its ohmic resistance.

Alternatively, the relevant measured values can also be transmitted to the system controller 24 and the parameter 52 can be determined there.

When installing the drive system 2, the connection line 38 is inadvertently selected too long. In the first system test, therefore, a resistance R1 from the voltages U1, U2 and the currents I1, I2 is determined as characteristic value 52, which is greater than a maximum value Rmax stored in the system control. The system controller 24 reports this error to a system operator, not shown, and the connecting line 38 is replaced by a correct length. When commissioning the drive system 2, the repeated measurement results in the resistance R2 as a characteristic.

After several years of operation, during which the resistance R2 between input 32a and output 32b is determined repeatedly, the resistance increases within a few days to a value R3. The deviation ΔR from R3 to R2 detected by the microprocessor 42 is greater than an allowable resistance deviation ΔRmax stored in the plant controller 24. The change in resistance indicates an imminent failure of the emergency stop button 22, probably because its contact resistance increases sharply. Within a few days, this would lead to a faulty, unintentional triggering or interrupting the emergency stop button 22 and thus to a standstill of the engine 4. Therefore, in a nocturnal production break, in which the engine 4 is stopped anyway, the emergency stop Button 22 replaced by a similar, but new.

Alternatively, the emergency stop button 22 may also be a limit switch. Since due to a failure of an operating sensor, not shown, the motor 4 moves to an end position, the limit switch triggers. The control voltage U drops at input 32b to 0V. The motor 4 is switched off, the remaining drive system 2 remains in operation. In particular, the microprocessor 42 notifies the system controller that the limit switch has triggered and the system is otherwise ready for operation, the plant standstill has thus been done by a correctly triggering limit switch.

Claims (13)

1. Control module (20) with interrupt function for an externally connectable electric circuit breaker (10), comprising:

   - a voltage input (28) for a control voltage (U),

   - an output (32a) carrying the control voltage (U) to which output an interrupter (22) can be connected,

   - an input (32b) to which the interrupter (22) can be connected to feed back the control voltage (U),

   - a terminal (36) for the circuit breaker (10), said terminal being connected to the input (32b),

   - a measuring unit (46) for measuring current (I1,2) and/or voltage (U1,2) at the input (32b) and at the output (32a)

   characterised in that

   - a control switch (40) for the circuit breaker (10) is connected between input (32b) and terminal (36).
2. Control module (20) according to claim 1, comprising an evaluating unit (42) for evaluating current (I1,2) and/or voltage (U1,2) for functional control of the interrupter (22).
3. Control module (20) according to claim 1 or 2, wherein the control voltage (U) is fed back from output (32) to the input (39) by means of an externally connected interrupter (22).
4. Control module (20) according to claim 3, wherein the interrupter (22) is an emergency stop switch or a limit switch.
5. Control module (20) according to one of the preceding claims, comprising a bus interface (50) to a plant control system (24).
6. Control module (20) according to one of the preceding claims wherein the circuit breaker (10) is that of a motor starter system.
7. Electrical protection system (6) comprising a control module (20) according to one of claims 1 to 6, an electric circuit breaker (10) externally connected to the control module (20), and an interrupter externally connected to the control module (20).
8. Method for operating a control module (20) according to one of the claims 1 to 7, wherein:

   - at the terminal (36), voltage (U) and current (I1,2) are generated for supplying the circuit breaker (10) during its operation,

   - the measuring unit (46) determines currents (I1,2) and/or voltages (U1,2) at the input (32b) and the output (32a),

   - with the interrupter (22) connected, the control module (20) transmits currents (I1,2) and/or voltages (U1,2) to an evaluating unit (42,24) for determining a characteristic value (R1-3) which correlates to the quality of the interrupter (22),

   - from currents (I1,2) and/or voltages (U1,2), the evaluating unit (42,24) determines a characteristic value (R1-3) which correlates to the quality of the interrupter (22).
9. Method according to claim 8, wherein

   - the evaluating unit (24,42) determines a current characteristic of the interrupter (22) as the characteristic value (R1-3).
10. Method according to claim 9, wherein

    - the evaluating unit (24,42) determines an ohmic resistance of the interrupter (22) as the characteristic value (R1-3).
11. Method according to one of the claims 8 to 10, wherein

    - given a characteristic value (R1-3) corresponding to a quality of low value, the interrupter (22) and/or a lead (38) running from the input (32b) and/or the output (32a) thereto is repaired.
12. Method according to one of the claims 8 to 11, wherein

    - given a characteristic value (R1-3) corresponding to a quality of low value, the circuit breaker (10) is switched off in controlled manner.
13. Method according to one of the claims 8 to 12, wherein the control module (20) is connected to a plant control system (24), wherein

    - currents (I1,2) and/or voltages (U1,2) and/or the characteristic value (R1-3) are transmitted to the plant control system (24) for further processing.

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