EP0193732A1 - Device for monitoring and controlling switching devices and combinations of switching devices - Google Patents

Abstract

Devices for monitoring and controlling switchgear to determine the required maintenance dates usually operate on a mechanical or time basis. Electronic devices are limited to counting the switching cycles and comparison with stored reference values. In order to achieve maintenance or inspection appropriate to the actual state of the switchgear, the events actually occurring and the instantaneous state of the switchgear are recorded by a multiplicity of sensors (1 to 13) and fed as signals to an evaluation logic (14) which carries out a correlation, an assessment and a comparison with stored behaviour patterns (16) and acts on an optical and/or acoustical indicating device (17) or makes a record in a scannable memory (15). <IMAGE>

Description

The invention relates to a device according to the preamble of claim 1.

With switchgear or switchgear and controlgear assemblies, it is often desirable to signal the time for required maintenance or inspection to the outside. Knowledge of z. 8. the contact erosion (main contact pieces or, in the case of multi-stage systems, also break contacts), the contact pressure, the condition of arcing chambers, and various mechanically stressed parts of particular interest for the reliability of a system.

So far, mechanical or electrical counting devices have been used with which the number of mechanical switching cycles is registered. Burn-up indicators for the contact pieces are also known, which are mechanically operated via levers or cables to be controlled; also the recording of the number of operating hours via clock counters.

Temperature recorders for the temperature / time behavior as well as safety circuits for fault messages, i. H. Notification of an unwanted switch triggering can be used.

A device for checking the operability of electrical switching devices is also known from DE-C2 27 27 378, in which the output current of a current transformer is used as the input variable of a switch-off current and switching piece erosion linking the function converter. The output variable of the converter is given to an accumulator by means of an auxiliary switch, the content of which forms a measure of the erosion of the switch pieces caused in previous operation. An electronic function memory (for example a ROM) is provided as the function converter, in which the burn-up is stored as a numerical value depending on the level of the current to be switched off. With each switch-off, the burn-up value corresponding to the instantaneous value of the current is taken for input into the summing memory. Furthermore, a comparison stage is provided which emits a signal when the sum of the burn-up values exceeds the predetermined target value. or inspections If maintenance work or repairs / are carried out according to a rigid scheme corresponding to the number of mechanical switching cycles or the number of operating hours, many other influencing variables inevitably remain unconsidered. When making recommendations for these maintenance intervals, switchgear manufacturers must therefore assume standardized operating conditions.

In fact, when using the switchgear, there are significant deviations from these assumptions. Then there are statements of reliability for preventive maintenance Setting with complete switchgear combinations (e.g. industrial plants, power plants) is very problematic. So z. B. only three power disconnections with the limit switching capacity cause the same contact erosion on the main contact pieces of a circuit breaker as five thousand disconnections in the rated current range of the device.

If the maintenance intervals are selected to be very small to achieve a high level of operational reliability, there may be an uneconomical use of materials and equipment with high maintenance costs.

Excessively long maintenance intervals are detrimental to operational reliability and can endanger people and the system and lead to considerable production downtimes when the system is down. Operating systems that are subject to the Emission Protection Ordinance are particularly challenged here.

The state of a switchgear or a switchgear combination between two maintenance appointments has so far largely remained unknown to the operator, and he also receives no notification of any excessive wear that would require immediate intervention.

The invention has for its object to develop a monitoring and control device with which it is possible or Inspection of the maintenance / flexible, to be carried out according to the actual requirements of the respective application, the current state of the switchgear or degree of wear and tear being recognizable during operation.

This object is achieved by the characterizing features of claim 1.

Developments of the invention are specified in the subclaims.

A number of advantages are associated with the device according to the invention. This means that no rigid switching number and measurement data or time intervals are required for maintenance, and those parameters are taken into account that influence the actual degree of wear of the switching devices. Furthermore, the material utilization is improved, revision dates can be better estimated and a statement is made as to whether an overhaul of the switchgear is still worthwhile. Finally, there is the possibility to save the previous history (already performed maintenance).

In the drawing, an embodiment according to the invention is shown.

• Fig. 1 das prinzipielle Abnutzungsverhalten eines Gerätes am Beispiel eines Diagrammes über die Abhängigkeit des Abnutzungsgrades von der Anzahl der Schaltspiele,
• Fig. 2 ein Blockschaltbild zur Erläuterung des Wirkungsprinzips und
• Fig. 3 ein Schaltbild für das Zusammenwirken eines Schaltgerätes mit der Überwachungs- und Kontrolleinrichtung.

It shows

• 1 shows the basic wear behavior of a device using the example of a diagram of the dependence of the degree of wear on the number of switching cycles,
• Fig. 2 is a block diagram for explaining the principle of action and
• Fig. 3 is a circuit diagram for the interaction of a switching device with the monitoring and control device.

According to Fig. 1, the principle is assumed to measure critical sizes in the new state of various wear parts, i.e. 0% wear corresponds to 100% expected service life (here switching cycles). The respective wear is determined by numerous measurements over the number of operations. Characteristic curves (linear, degressive or progressive) are obtained as a function of the degree of wear depending on the number of switching operations. By extrapolation up to the wear limit (corresponding to the end of the service life) taking into account the scatter band, the remaining switching number to be expected is concluded. A reversal of meaning is also possible.

The empirically determined characteristics of the wear behavior of the different wear parts are fixed memory as a function, digitized with scatter band, as a family of curves with various parameters or multidimensionally as a reference map, possibly with its own computer program.

FIG. 2 shows a schematic representation of the measured variables detected by sensors, the changes of which are monitored, evaluated directly or determined indirectly by linking dependent data.

In a preferred embodiment, it is provided that after completion of the switching device or the switching device combination, all status memories are reset to zero and only the date of manufacture is entered in a non-volatile read-only memory.

By means of sensors 1 to 13, degrees of wear and tear or states of wear and conditions deviating from normal behavior are recorded directly or calculated indirectly by linking analog data using a separate software program. All of the information obtained in this way is processed in a core element 14, a microprocessor, and the result is stored in the state memory 15 (changeable, interrogable read-only memory).

So z. B. sensors 1 to 13 are used to record the following circuit or wear conditions: sensor 1 for the switching cycles N (number), sensor 2 the operating time t / a (long-term / date), sensor 3 temperature 1 of the current path, sensor 4 Temperature A 2 of the environment, sensors 5 to 7 for overcurrents Z1 to Z3, sensor 8 for switching / operating voltage U, sensor 9 for voltage drop Δ U or earth fault R _EI sensor 10 for current steepness di / dt, sensor 11 for contact erosion S ( indirect), sensor 12 for the contact erosion ΔS (direct) and sensor 13 for the time constant T.

The contact erosion can be determined directly via displacement or angle measuring sensors, via optical position signals or magnetic proximity sensors. Or indirectly by linking the analog data influencing the erosion, such as current level, switching voltage, cos ϕ, number of switching operations and switching instant (with alternating current), also current steepness di / dt or the time constant T = L / R (with direct current) in a separate one Program and comparison with the empirically determined data stored in a map.

From the time of commissioning, all wear-relevant events are recorded, evaluated to different extents depending on the level of influence and summed up as fictitious "number of wear cycles" and entered separately in state memories 15. This is followed by a comparison with the reference values specified in the reference map memory 16, by extrapolation to the wear limit, the remaining number of switching operations or the current overall state is determined.

This status information is analog / quasianalog with LED, LCD or corresponding signal devices 17 or digital via a segment display z. B. LCD segment display directly on the switchgear or combination. Suitable signal lines 18 are provided, e.g. B. data bus, fiber optic link, this information can also be given to higher-level monitoring service or alarm systems.

In a larger system (e.g. power plants, industrial operation, ship, etc.), this status information can be used to immediately identify whether the switchgear / combination needs to be serviced at this or only at the next revision.

The query of the current state is even more meaningful with a test case 19 or a computer which communicates with the microprocessor 14 via a bus connection 20 or via the telephone network by means of an acoustic coupler. Leave with it interrogate the "wear switching numbers" entered in the status memories 15 so that it can be seen, if necessary, which wear event led to the acute maintenance indication; whether z. B. increased contact erosion or the high number of mechanical switching operations are the cause (a kind of self-diagnosis). If the sensors for short-circuit and overload detection are switched, z. B. determine whether the contact erosion was caused by a few short-circuit shutdowns or by frequent overload circuits.

If a switchgear and controlgear assembly is monitored, it can be seen which switchgear and controlgear in a system is particularly stressed.

A significant advantage results from maintenance without a test case if the display field (e.g. 8th segment display) on the switching device as the query menu field 21, i. H. Selection of the various status memories 15 by pressing a key and displaying the content on this display field, is formed (dialog traffic).

This results in a very inexpensive, time-saving selective maintenance, in which only the work that is really required is carried out.

After the maintenance work has been carried out, the corresponding status memory 15 is then reset, depending on the expansion stage, either on the device itself by means of a button or when using the test case 19 via the data bus 20. It is also possible to permanently enter the number and extent of the maintenance that has been carried out in the status memory 15, and thus to query the history of this switching device during each maintenance.

If shorter maintenance intervals are required due to special operating conditions, the status memories 15 can also be reset step by step to the required level.

The direct signal flow of some critical state parameters, which have a "striking" effect when predetermined limits are exceeded, is remarkable, represented by a double arrow. E.g. exceeds If the temperature of the switching device current path (sensors collar 6) in relation to the flowing current significantly exceeds a predetermined value, an alarm 22, 23, 24 graded according to urgency can be given via an alarm evaluation level or the switching device 25 can be switched off immediately. This case could e.g. B. occur with broken or loosened screw or solder connections in the current path. Since this fault would not be noticed by the usual overcurrent releases, the device could fail completely.

The monitoring device can preferably be implemented in various configuration levels and comfort classes, which are characterized by the number of input channels (sensor inputs), type of measurement value linkage (direct or indirect determination), and ease of use (LED line, menu field, test case or acoustic coupler connection and dialage techniques such as touch screen, light pen, measurement or window technology).

In one embodiment, interfaces are provided which enable interaction with other external protection systems, such as fire and smoke detectors, arcing fault monitors, current rise detection systems, object protection fault alarm systems, etc.

If the discrete modules are combined in terms of hardware or highly integrated, this module can also be integrated as a functional unit in other devices or monitoring and protection systems. This is especially true when not only individual switchgear, but entire switchgear combinations (definition according to VDE and IEC) must be monitored.

The following components are provided in the circuit arrangement according to FIG. 3 for monitoring a switching device 25:

A power supply unit 26 is used for infeed from the voltage network L1, L2, L3 or via current transformers or with both infeeds, which can be selected via bridges 27. An accumulator 28 is provided for the buffered operation of a clock with a date or the core element 14 (microprocessor), in which all information converges and is processed. The program for the microprocessor 14 and a reference map are permanently stored in a read-only memory 29 and the current state of the switching device is stored in a state memory 15. The data content of the memory 15 can be changed, but cannot be lost in the event of a power failure. It is also possible to combine the two read-only memories in a common component 30, since the content of the memory 29 can also be stored in a changeable read-only memory.

At 31, a clock is labeled with the date. This function can also be implemented by the microprocessor 14. However, continuous operation must be ensured, for example by buffering the supply voltage.

An LED line 17 is provided to display the current switching device status. It is also possible to use a 7-segment or an alphanumeric display with LED or LCD. A special bus connection 18 can be provided for reporting the switching device status to a higher-level monitoring, service or maintenance station.

A button 32 for resetting the status memory 15 is only required if a bus connection is not available. As an alternative to voltage sensors 34, the operating voltage or voltage type used can be entered in stages with a switch 33. Another switch 35 is used to select the map. The voltage sensor 34 can consist of one or three sensors for determining the switch voltage present. A rough one is enough here Classification e.g. B. 600 V or 1000 U network.

Current sensors 36 are used to detect the individual phase currents or - in the case of direct current - the flowing current. If necessary, they can be used to determine the cos ϕ from current and voltage or, in the case of direct current, the current steepness di / dt.

Temperature sensors 3 and 4 are e.g. B. in the vicinity of the contact pieces for detecting the temperature of the current path or. arranged to detect the ambient temperature of the switch.

An auxiliary contact 1 or another type of sensor detects the switching cycles and a sensor 12 as a displacement sensor, light barrier or angle of rotation sensor determines the contact erosion directly.

• - Anzahl der mechanischen Schaltspiele durch Hilfskontakt 1. Wenn uP-Pufferung gewählt wird, kann diese Bewertung alle Schaltspiele erfassen, sonst nur die, die bei anstehender Versorgungsspannung stattfinden.
• - Anzahl der elektrischen Schaltspiele durch Hilfskontakt 1 und Strommeßwertgeber 36.
• - Betriebsstunden durch Uhr 31 mit Datum.
• - Lagerzeit durch Uhr 31 mit Datum.
• - Zustand der Lagerfette des Schaltgerätes 25 indirekt durch Bewertung der Betriebszeit, Lagerzeit, Anzahl der Schaltspiele und Umgebungstemperaturgeber. Bei Pufferung von uP und Temperaturgeber lässt sich auch die Lagertemperatur mitbewerten.
• - Zustand der Schaltkontakte (z. B. Abbrand) indirekt durch Bewertung von
• . Anzahl der elektrischen Schaltspiele
• . Anzahl der Nennstromabschaltungen
• . Anzahl der Überstromabschaltungen Z1(1 x I_E), Z2 (2 x I_E) und Z3 (15 x I_E) (Sensoren 5, 6, 7 der Fig. 2)
• . Höhe der jeweiligen Abschaltleistung durch Einbeziehung der Schaltspannung und des cos ϕ
• . Höhe der jeweiligen Einschaltleistung
• . Kontaktabbrand indirekt über die Bewertung von Strom und Temperatur der jeweiligen Strombahn
• - Zustand der Schaltkontakte (z. B. Abbrand)
• - Direkt durch Änderungsmessung des Winkels oder weges oder der Position von Teilen.
• - Zustand der Lichtbogenlöschkammern indirekte Bewertung wie bei Schaltkontakten, jedoch ohne Kontaktabbrand.
• - Zustand der Schaltmechanik indirekt durch Bewertung vom Zustand der Schaltkontakte (erbrachte Ein/Ausschaltleistung) sowie den Zustand der Lagerfette (Betriebszeit, Lagerzeit, Temperatur, Anzahl der Schaltspiele)
• - Weitere Hardware-Sensoren sind denkbar und würden die Genauigkeit der Bewertung wesentlich erhöhen. Beispielsweise lässt sich der Kontaktabbrand auch über Winkel- oder Weggeber direkt erfassen, so daß man nicht auf die oben angeführte indirekte Bewertung angewiesen ist. Ebenso könnten geeignete Sensoren (z. B. Optik) das Lagerspiel der Schaltmechanik, die Position bzw. die Positionsänderungen verschleißbestimmender Teile überwachen.

The following events or states of the three-pole switching device 25 can be evaluated with components:

• - Number of mechanical switching cycles through auxiliary contact 1. If uP buffering is selected, this evaluation can record all switching cycles, otherwise only those that take place when the supply voltage is present.
• - Number of electrical switching cycles through auxiliary contact 1 and current sensor 36.
• - Hours of operation through clock 31 with date.
• - Storage time by clock 31 with date.
• - Condition of the bearing greases of the switching device 25 indirectly by evaluating the operating time, storage time, number of switching cycles and ambient temperature sensor. If the uP and temperature sensor are buffered, the storage temperature can also be evaluated.
• - Condition of the switching contacts (e.g. erosion) indirectly by evaluating
• . Number of electrical switching cycles
• . Number of nominal current shutdowns
• . Number of overcurrent shutdowns Z1 (1 x I _E ), Z2 (2 x I _E ) and Z3 (15 x I _E ) (sensors 5, 6, 7 of FIG. 2)
• . Amount of the respective breaking capacity by including the switching voltage and the cos ϕ
• . Amount of the respective switch-on power
• . Contact erosion indirectly via the evaluation of current and temperature of the respective current path
• - State of the switching contacts (e.g. erosion)
• - Directly by measuring changes in the angle or path or the position of parts.
• - State of the arc quenching chambers indirect evaluation as for switch contacts, but without contact erosion.
• - State of the switching mechanism indirectly by evaluating the state of the switching contacts (provided on / off switching power) and the condition of the bearing greases (operating time, storage time, temperature, number of switching cycles)
• - Additional hardware sensors are conceivable and would significantly increase the accuracy of the evaluation. For example, the contact erosion can also be recorded directly via angle or displacement sensors, so that one is not dependent on the indirect evaluation mentioned above. Suitable sensors (e.g. optics) could also monitor the bearing play of the switching mechanism, the position or the position changes of wear-determining parts.

Claims (12)

1. Monitoring and control device for electrical switchgear and switchgear and controlgear assemblies for obtaining flexible maintenance and inspection times using electronic read-only memories, signal signals being derived by comparing current switchgear data with stored reference values, characterized in that a plurality of sensors (1-13) are provided is, which record the actually occurring events and the current state of the switching device (25) or the switching device combination and feed them as signals to an evaluation logic (14), which undertakes a linkage, evaluation and comparison with stored behavior patterns and an optical and / or acoustic Display device (17) acted upon. 2. Device according to claim 1, characterized in that a microprocessor serves as the evaluation logic (14), to which a changeable, interrogable read-only memory (15) (state memory) is connected for storing the result obtained from the information. 3. Device according to claim 1, characterized in that the display device (17) is directly associated with the switching device (25) or the switching device combination. 4. Device according to claim 1, characterized in that the display of the switching device status via a data bus in a higher-level monitoring station. 5. Device according to one of claims 1, 3 or 4, characterized in that an alarm (22, 23, 24) graded according to urgency is optionally output with the display in the case of a critical switching device state. 6. Device according to claim 1, characterized in that a transportable test device (19) (test case) via a data bus (20) can be connected to the evaluation logic (14). 7. Device according to claims 3 and 4, characterized in that a display device permitting dialogue traffic is provided on the switching device (25). 8. Device according to claim 7, characterized in that the display device is designed as a query menu field (21), screen with light pen, touch screen screen or screen with mouse operation. 9. Device according to one of claims 1, 3 to 6, characterized in that an LED line or an LCD display serves as the display device. 10. The device according to claim 1, characterized in that an acoustic coupler can be connected to the evaluation logic (14), with which data can be called up via the telephone network. 11. The device according to claim 1, characterized in that the linkage and evaluation on the switching device (25) or within the switching device combination can be carried out. 12. The device according to claim 1, characterized in that the linking and evaluation is carried out outside the switching device (25).

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