CN111200273A - Protective switching device for low-voltage circuits for detecting series fault arcs - Google Patents
Protective switching device for low-voltage circuits for detecting series fault arcs Download PDFInfo
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- CN111200273A CN111200273A CN201911117603.9A CN201911117603A CN111200273A CN 111200273 A CN111200273 A CN 111200273A CN 201911117603 A CN201911117603 A CN 201911117603A CN 111200273 A CN111200273 A CN 111200273A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3271—Testing of circuit interrupters, switches or circuit-breakers of high voltage or medium voltage devices
- G01R31/3275—Fault detection or status indication
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
- G01R31/2827—Testing of electronic protection circuits
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3277—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/54—Testing for continuity
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
- H02H1/0015—Using arc detectors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/04—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned
- H02H3/042—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned combined with means for locating the fault
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current additionally responsive to some other abnormal electrical conditions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
- H02H5/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to mechanical injury, e.g. rupture of line, breakage of earth connection
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention relates to a protective switching device for low-voltage circuits, in particular for detecting series fault arcs, wherein a current measurement is carried out by means of a measuring resistor, via which the current of a conductor of the low-voltage circuit is conducted in order to determine the magnitude of the current of the low-voltage circuit. The measuring resistor is connected with the measuring circuit through at least one wire-shaped connecting line. The measurement circuit is powered by a power supply. The connection of the measuring circuit connected to the wire-like connection line is connected to the output of the power supply via a pull-up resistor, so that a break in the wire-like connection line can be determined and signaled by the voltage at the input of the measuring circuit exceeding a first threshold value.
Description
Technical Field
The invention relates to a circuit breaker arrangement for low-voltage circuits, such as a fire switch or a line breaker, and to a method according to the invention for a circuit breaker arrangement for low-voltage circuits.
Background
Low voltage refers to voltages up to 1000 volts ac or up to 1500 volts dc. Low voltage means in particular a voltage greater than a low voltage having a value of 10 volts ac or 120 volts dc.
A low-voltage circuit or a low-voltage network or a low-voltage device is a circuit which measures current up to 125 amperes, in particular up to 63 amperes.
A fault arc refers to an arc that occurs in the event of a fault, i.e., an arc is formed as a result of a fault in the circuit. For example, due to poor clamping, malfunction or poor electrically conductive connections in the electrical circuit, for example in the junction box, switch or socket of a low-voltage circuit.
But not (disturbing) arcs, such as occur in the normal operation of the power grid, for example in switching or at the brushes of the electric machine.
A series fault arc is an arc which occurs in the current path of the circuit, i.e. the current flowing through the arc also flows, for example, through the load. That is, if current flows in an "almost interrupted" conductor, a so-called series fault arc may form at the point of interruption.
The fire switch is a relatively new type of protective device for electrical circuits or voltage networks, which is used to identify such fault arcs. The fire switch can be used in particular in a domestic installation, for example in a fuse box, in order to detect such faults and, in the event of a fault or if a fault-arc limit value is exceeded, to initiate an interruption of the circuit, to carry out an interruption itself or to output a fault-arc detection signal.
Line protection switches are well known overcurrent protection devices which are used in the electrical installation of low-voltage circuits. The line protection switch protects the line from damage due to heating caused by excessive current and/or short circuits. The line protection switch may automatically open the circuit in case of overload and/or short circuit. The line protection switch is a safety element which does not reset automatically.
With respect to line protection switches, power switches are set for currents greater than 125A, sometimes even from 63 amps. Therefore, the line protection switch is designed more simply and using a filament process.
Line circuit breakers are usually designed electromechanically and have a switching contact or an operating current trigger for interrupting the current flow
A bimetal protection element or bimetal element for triggering against long-lasting overcurrent or thermal overload; an electromagnetic trigger having a coil for short-time triggering when an overcurrent limit value is exceeded or in the event of a short circuit; and one or more arc extinguishing chambers or devices for extinguishing arcs. The line protection switch also has connection elements for the conductors of the circuit to be protected.
In principle, the line protection switch monitors the magnitude of the current in the circuit and interrupts the circuit if a current limit value or a current-time interval limit value is exceeded.
Fault current protection switches are also known. Fault current protection switches monitor the sum of the currents in the circuit to be protected, which sum is usually zero, and interrupt the circuit if a fault current limit or a difference current limit is exceeded, since there is usually a faulty and potentially life-threatening current outflow.
It is known to combine a line protection switch with a fault current protection switch by inserting a fault current module into the line protection switch. Furthermore, a combined line protection switch and fault current switch is also known as a Residual current operated circuit Breaker (Residual current circuit Breaker with over-current protection), abbreviated RCBO.
In particular, fire switches and more new types of electronic circuit protection switches use a measuring resistor for determining the magnitude of the current in a low-voltage circuit, the current of which is conducted via the measuring resistor in a single-phase low-voltage circuit with a phase line and a neutral line. The magnitude of the current in the low voltage circuit is determined from the voltage drop across the measuring resistor of known resistance value. For this purpose, at least one or two connecting lines are connected to the measuring resistor, said connecting lines leading to a measuring circuit, which may be part of the control unit, for example. The control unit analyzes the voltage drop, determines the magnitude of the current or its equivalent, compares it to a current limit value, and initiates an interruption of the circuit when the current limit value is exceeded. This can be achieved, for example, by the control unit. In a similar manner, the evaluation of the current (together with other monitored variables if necessary) can be used to detect (series) fault arcs, as in a fire switch, for example.
If the connecting line between the measuring resistor and the measuring circuit/control unit is damaged, the magnitude of the current cannot be determined, and thus a fault in the low-voltage circuit cannot be detected.
Disclosure of Invention
The object of the present invention is therefore to improve a protective switching device, for example a fire switch or a line protection switch, in particular for detecting series fault arcs or overcurrents, which allows the current level to be determined by means of a measuring resistor, in particular allows wire breakage detection of the connecting line between the measuring resistor and the measuring circuit/control unit.
This object is achieved by a circuit breaker arrangement having the features according to the invention or by a method according to the invention.
According to the invention, a circuit breaker device, for example a fire protection switch or/and a line protection switch, for a low-voltage circuit, for example a single-phase circuit, is provided, having:
a first input connection for a first conductor (e.g. a phase conductor) of the low-voltage circuit, which is connected to the first output connection by a first line,
a second input connection for a second conductor (e.g. a neutral conductor or a zero conductor) of the low-voltage circuit, which is connected to the second output connection by a second line,
a measuring resistor inserted into the first or second line, in particular into the phase line, for determining the magnitude of the current (I) of the low-voltage circuit,
a power supply which is connected on the input side to the first and second lines for supplying energy to a control unit, in particular for identifying a series fault arc or/and for identifying an overcurrent condition,
the control unit has a first and a second measuring terminal, which are connected to a measuring resistor.
According to the invention, the first or the second measuring terminal is connected to the output of the power supply via a pull-up resistor.
In particular, the measuring terminal connected to the terminal on the output connection side of the measuring resistor is connected to the output terminal of the power supply via a pull-up resistor.
The pull-up resistor is a resistor for defining and pulling up a potential. The potential can thus be set or pulled to a specific value. The pull-up resistor is also logically referred to as a pull-down resistor, which pulls the potential down, i.e., sets it to a "lower" level. In the event of a fault, a defined potential should be applied. The pull-up resistor is a "potential regulating resistor".
This has the advantage that in the event of a wire break (fault situation) of the connecting line between the measuring resistor and the measuring connection, the measuring connection is pulled to a potential which is higher (or lower) than the usual potential of the measuring resistor. Thus, a wire break is determined by a threshold comparison with a first threshold value and a signal is emitted if necessary.
The invention also provides an advantageous embodiment.
In an advantageous embodiment of the invention, the measuring resistor is connected via a wire-like connecting line to a measuring terminal, which is connected to the output of the power supply via a pull-up resistor.
A wire-like connection line refers to an electrical line in the form of a rigid wire or a flexible stranded wire, with or without insulation (lack of insulation), respectively.
Advantageously, the components can be arranged on a printed circuit board, to which the remaining components can be connected advantageously by connecting lines. The connecting line can thus advantageously be monitored.
In an advantageous embodiment of the invention, the power supply and control unit is arranged on a printed circuit board, which has at least one part of the first and second lines.
This has the particular advantage that a particularly good integration of the components comprising the line can be achieved.
In an advantageous embodiment of the invention, the measuring terminal, which is not connected to the output of the power supply via the pull-up resistor, is connected to the measuring resistor at least partially via a printed conductor of the printed circuit board.
This has the particular advantage that a further advantageous integration can be achieved, so that only wire-like connection lines which can be advantageously monitored by means of the invention are required for measuring the resistance.
In an advantageous embodiment of the invention, the control unit has a measuring circuit, in particular a measuring circuit using an ASIC or an amplifier, to determine the magnitude of the current or its equivalent value as a function of the voltage drop across the measuring resistor.
This has the particular advantage that a compact and accurate implementation for determining the magnitude of the current and for monitoring the voltage is provided.
In an advantageous embodiment of the invention, the control unit has a microprocessor. The processor may be connected to the measuring circuit, in particular.
This has the particular advantage that digital analysis and programming can be implemented, whereby a large number of functions can be implemented and the limit values can be simply adjusted.
In an advantageous embodiment of the invention, a pressure limiting element is connected between the first and the second measuring nipple. This can be realized in particular in the form of one or two diodes. In particular in the case of two diodes, these two diodes can be connected in anti-parallel. As the diode, a silicon diode, a Z diode, or the like can be used.
This has the particular advantage that a voltage limitation of the measuring circuit/control unit is achieved, whereby damage due to excessively high voltages is avoided.
In an advantageous embodiment of the invention, the control unit is designed such that a series fault arc in the low-voltage circuit is determined and a fault arc detection signal, in particular an interruption of the low-voltage circuit, is output if a fault arc limit value is exceeded.
This has the particular advantage that a fault arc protection function including monitoring is achieved.
In an advantageous embodiment of the invention, the pull-up resistor has a resistance value of between 100 ohms and 10 megohms, in particular a resistance value of between 1 kohm and 1 megohm, more particularly a resistance value of between 10 kohm and 100 kohm, and includes values of 10 kohm and 100 kohm.
This has the particular advantage that there is a resistance value which causes less influence on the measurement result, but which nevertheless enables a pull-up function.
In an advantageous embodiment of the invention, the pull-up resistor has a resistance value which is at least 1000 times greater than the resistance value of the measuring resistor, in particular 10000 times, 100000 times, 1000000 times, 10000000 times or 100000000 times greater.
This has the particular advantage that there is also a resistance value which causes a smaller influence on the measurement result, but which nevertheless enables a pull-up function.
In an advantageous embodiment of the invention, the measuring resistor has a resistance value which is constant at least over a temperature range.
The temperature range refers to the temperature range of the application of the protective switching device. In particular, it refers to a temperature range of-25 ℃ to 70 ℃, 105 ℃ or 150 ℃.
A constant resistance value refers to a resistance value that varies only slightly. This is common in particular in measuring resistance. In particular, constant resistance refers to resistance having a temperature coefficient of up to 200ppm per kelvin, 150ppm per kelvin, 100ppm per kelvin, 75ppm per kelvin, and even better 50ppm per kelvin.
Alternatively or in particular to α (-80 … + 40). 10-6K-1Or α ═ 50 · 10-6K-1The temperature coefficient of (a).
This has the particular advantage that accurate and reproducible current measurements can be achieved in many application locations and under varying environmental conditions.
In an advantageous embodiment of the invention, the voltage drop across the measuring resistor is a voltage proportional to the current.
This has the particular advantage that, in particular, precise measurements can be achieved by means of the linear member.
In an advantageous embodiment of the invention, the measuring resistor has a bimetallic or bimetallic protective element.
This has the particular advantage that a particularly simple current measurement can be achieved, wherein additionally a thermoelectric overcurrent protection function can also be achieved.
In an advantageous embodiment of the invention, the bimetallic protection element is connected in series with the measuring resistor.
This has the particular advantage that particularly accurate current measurement and thermoelectric overcurrent protection functions can be realized.
In an advantageous embodiment of the invention, the wire break detection signal is output when it is detected that the input voltage at the measuring connection exceeds a first threshold value. In particular, in the presence of a wire break detection signal, an optical, electrical (switch contact) or acoustic signal is emitted.
This has the particular advantage that an alarm can be output in the event of a wire break.
In an advantageous embodiment of the invention, an interruption unit is provided for interrupting the low-voltage circuit, which interruption unit interrupts the low-voltage circuit, in particular in the presence of a wire breakage detection signal.
This has the particular advantage that the circuit is interrupted, i.e. protected, in the event of a wire break and subsequent lack of monitoring.
In an advantageous embodiment of the invention, the interruption unit is connected upstream of the input side of the power supply or/and has contacts for interrupting the first and/or second line.
This has the particular advantage that the protection switching device has no current in the event of a fault.
In an advantageous embodiment of the invention, the low-voltage circuit is a low-voltage ac circuit.
This has the particular advantage that the invention is particularly well suited for ac circuits.
In an advantageous embodiment of the invention, the protective switching device is a fire switch, a line protection switch, a power switch or a residual current circuit breaker. Alternatively, the protection switching device has a fire protection function, a line protection function or a fault current protection function.
This has the particular advantage that the invention can be used in particular in the mentioned devices for protecting circuits.
Furthermore, a parallel method for protecting a switching device for low-voltage circuits is claimed according to the invention,
wherein the current measurement is performed by means of a measuring resistance via which the current of the conductor of the low-voltage circuit is conducted to determine the magnitude of the current of the low-voltage circuit,
the measuring resistor is connected to the measuring circuit by at least one wire-like connection line,
-energizing the measurement circuit by means of a power supply.
According to the invention, the connection of the measuring circuit connected to the electrical wire-like connection line is connected to the output of the power supply via a pull-up resistor, so that a break in the electrical wire-like connection line can be determined and signaled by the voltage at the input of the measuring circuit exceeding a first threshold value.
In an advantageous embodiment of the invention, the signal is emitted by means of an optical display, an activation of a switching contact or/and an interruption circuit.
All the embodiments of the invention result in an improvement of the protective switching device.
Drawings
The described features, characteristics and advantages of the present invention as well as the manner of attaining them will become more apparent and the invention thereof will be better understood by reference to the following description of embodiments taken in conjunction with the accompanying drawings.
Herein, in the drawings:
figure 1 shows a first diagram for explaining the protective switching device of the invention,
figure 2 shows a second diagram for explaining the protection switching device of the invention,
fig. 3 shows a third illustration of the protective switching device for explaining the invention.
Detailed Description
Fig. 1 shows a schematic representation of a protective switching device SG for low-voltage circuits, for example a fire switch, a line protection switch or a combined fire switch/line protection switch, in particular for detecting series fault arcs, having:
a first input connection E1 for a first conductor L1 of the low-voltage circuit, which is connected to a first output connection a1 via a first line LT1,
a second input connection E2 for a second conductor N of the low-voltage circuit, which is connected to the second output connection a2 by a second line LT2,
a measuring resistor MR which can be inserted into the first or second line LT1, LT2, in the example according to FIG. 1 into the first line LT1, to determine the magnitude of the current of the low-voltage circuit,
a power supply NT, which is connected on the input side to the first and second lines LT1, LT2 for supplying energy to a control unit SE, which is designed in particular for detecting series fault arcs or/and overcurrents,
the control unit SE has first and second measuring terminals ME, MA, which are connected to the respective input-side terminal or output-side terminal of the measuring resistor MR.
In this example, a first measuring terminal ME is connected to the end of the first line LT1 on the input connection side; the second measuring terminal MA is connected to the end of the first line LT1 on the output connection side.
According to the invention, the first or second measuring terminal is connected to the output of the power supply NT via a pull-up resistor PR. In the example according to fig. 1, the second measuring terminal MA is connected to the output of the power supply NT via a pull-up resistor PR.
The control unit SE may have a measuring circuit MS and a microprocessor MCU, which are supplied with energy, for example, by a power supply NT, respectively.
Fig. 2 shows the arrangement according to fig. 1, with the difference that the measuring resistor MR is connected via a wire-like connecting line DVL to a measuring terminal which is connected via a pull-up resistor PR to the output of the power supply NT.
In this example, the second measuring terminal MA is connected to the terminal on the output connection side of the measuring resistor MR via a wire connection DVL.
The series resistor VR may also be connected before one or both measuring terminals; in this example, the second measuring terminal MA has a series resistance VR, so that the electrical wire-like connection DVL is connected to the second measuring terminal MA via the series resistance VR.
Furthermore, the power supply NT and the control unit SE are arranged on a printed circuit board LP having at least a part of the first and second lines LT1, LT 2. Furthermore, the measuring terminal, which is not connected to the output of the power supply NT via the pull-up resistor PR, is connected at least partially to the measuring resistor MR via the conductor track LB of the printed circuit board LP. In this example, the first measuring terminal ME is connected via a conductor track LB and a first line LT1 to a terminal on the input connection side of the measuring resistor MR, it also being possible for the first line LT1 to be embodied as a conductor track of a printed circuit board.
Furthermore, the control unit SE has a measuring circuit using an asic (asic) to determine the magnitude of the current or its equivalent value from the voltage drop over the measuring resistor MR. The ASIC is connected with the microprocessor MCU.
Furthermore, pressure limiting elements D1, D2 are connected between the first and second measuring connections. In the example according to fig. 2 are voltage limiting elements in the form of (one or) two diodes D1, D2. In the example, the two diodes D1, D2 are connected in anti-parallel for voltage limiting.
In the example according to fig. 2, the measuring resistor is embodied in the form of a bimetal or bimetal protection element BM, wherein, as shown in the example, the bimetal or bimetal protection element need not be located on the printed circuit board LP. The bimetallic or bimetallic protection element is arranged outside the printed circuit board LP and is connected on the output terminal side (a1) via a wire-like connection line (DVL) to a measuring terminal, in particular to a measuring terminal connected to the power supply NT via a pull-up resistor PR; in this example a second instrumented sub MA.
Furthermore, an interruption unit UE for interrupting the low voltage circuit is provided. The interruption unit can interrupt the low-voltage circuit, in particular in the presence of a wire-break detection signal. In the example according to fig. 2, the interruption unit UE is connected before the input side of the power supply NT. As shown in fig. 2, the interruption unit may have contacts for interrupting the first and/or second lines LT1, LT 2.
Fig. 3 shows the arrangement according to fig. 2, with the difference that the bimetallic protection element BM is connected in series with the measuring resistor MR. Here, the wire-like connection line DVL is installed at a connection point between the measuring resistor MR and the bimetal protection element BM.
In the example of fig. 3, the measuring circuit MS of the control unit SE is realized by using an amplifier AMP for determining the magnitude of the current or its equivalent value from the voltage drop over the measuring resistance MR.
The measuring resistor MR is connected on the other side via a line LT1 and a printed conductor LB to a first measuring input ME of the control unit SE or of the measuring circuit MS, which is exemplified by an amplifier AMP.
In this case, the measuring resistor MR and/or the bimetallic protection element BM may be arranged in whole or in part on the printed circuit board LP.
In one embodiment, the control unit SE is designed to determine a series fault arc in the low-voltage circuit and to output a fault arc detection signal if a fault arc limit value is exceeded, in particular to interrupt the low-voltage circuit by an interrupt unit UE which can also be arranged outside the housing of the protection switch device SG.
The measuring resistor MR advantageously has a resistance value in the milliohm range. For example in the range of 1 to 10 or 100 milliohms. The higher the measured current of the protective switching device, the lower the resistance value of the measuring resistor should be.
The pull-up resistor PR advantageously has a resistance value of between 100 ohms and 10 megohms, in particular between 1 kilohm and 1 megohm, more particularly between 10 kilohms and 100 kilohms or a value of between 1 megohm (including 10 kilohms and 100 kilohms or 1 megohm).
Pull-up resistor PR advantageously has a resistance value which is at least 1000 times the resistance value of measuring resistor MR, in particular 10000 times, 100000 times, 1000,000 times, 10000000 times or 100000000 times. The higher the value, the smaller the measurement error. On the other hand, a stable potential must be provided.
The voltage output by the power supply NT may be, for example, 3.3 volts. Silicon diodes can be used as voltage limiting elements, for example. Silicon diodes typically have a forward voltage of 0.7 volts. Upon recognition that the input voltage at the measuring connection exceeds a first threshold value, a wire breakage recognition signal is output. In this example, the first threshold may have a magnitude of 0.5 or 0.6 volts. The first threshold value should be lower than the voltage limit value of the voltage limiting element.
In the case of a wire break detection, for example, an optical (e.g., LED), electrical (on/off switch contacts) or/and acoustic signal is emitted.
The low voltage circuit may also be interrupted. Since monitoring is lost by wire breakage, a safety condition is created in the circuit.
Advantageously, the present invention may be embodied as a method.
The invention is explained again below, in other words. A measuring resistor (shunt) is used to measure the current (load current) of the low voltage circuit. In some cases, the connection to the measuring resistance may be damaged/destroyed. For example, if the measuring resistor is connected to an electric wire (wire-like connection wire), the electric wire may be broken. This type of fault cannot be identified. In the event of such a malfunction, the device cannot be put into use/damaged if there is no recognizable indication.
According to the invention, a so-called pull-up resistor having a much higher resistance than the measuring resistance is added at the input of the control unit/measuring circuit or current trimming circuit. The effect of the pull-up resistance can be neglected when the measuring resistance is connected to the measuring circuit. When the connection to the measuring resistor is interrupted, the voltage over the measuring circuit will be very high, corresponding or proportional to the output voltage of the power supply (possibly proportional to the voltage divider with the pull-up resistor, that is to say the voltage decreases). Such high and constant voltages, in particular direct voltages, can be picked up by the measuring circuit or by a microprocessor MCU connected at the output of the measuring circuit.
A wire breakage recognition signal can be output.
The measuring resistance may be a bimetal. The measuring circuit may be an analog circuit with a resistor, an operational amplifier circuit or a fully integrated collating IC, such as an ASIC.
A possible embodiment of the invention is to use it in a fire switch for detecting series fault arcs. Furthermore, the use is made in line circuit breakers or combined fire switches/line circuit breakers, for example in housings with a width of 1 TE.
In the case of a pure line protection switch, the measuring resistor can be implemented as a bimetal of the line protection switch.
In the case of the fire-fighting switch function, the control unit or the measuring circuit can be designed as an ASIC for the fault arc identification function (including amplification and possibly offset addition).
The invention can also be used for measuring energy. Here, an amplifier Amp is used. Here, the power supply can generate and output an accurate reference voltage Vref to the amplifier, so that an accurate current measurement for energy determination can be achieved.
In this case in particular, the amplifier can be supplied with a negative voltage V-in addition to the positive voltage V +, in order to accurately measure the negative component of the current/load current.
In the amplifier, a reference voltage Vref, which is, for example, half the supply voltage of the power supply, is added to the output signal, so that the measurement can be realized or improved by the microprocessor MCU.
The invention can realize identifying the damaged device and sending out a signal. Otherwise, the device may be damaged without indication. This improves the overall safety level. The invention can be implemented simply by means of an additional resistor.
Although the invention has been illustrated and described in detail by way of example, the invention is not limited to the examples disclosed and other variants can be derived therefrom by those skilled in the art without departing from the scope of protection of the invention.
Claims (21)
1. A protection switching device for low-voltage circuits, in particular for identifying series fault arcs, having:
-a first input connection (E1) for a first conductor (L1) of the low-voltage circuit, which is connected to a first output connection (A1) by a first line (LT1),
-a second input connection (E2) for a second conductor (N) of the low-voltage circuit, which is connected to a second output connection (A2) by a second line (LT2),
-a Measuring Resistance (MR) inserted in the first or second line (LT1, LT2) to determine the magnitude of the current of the low voltage circuit,
a power supply (NT) which is connected on the input side to the first and second lines (LT1, LT2) for supplying energy to a control unit (SE), in particular for detecting series fault arcs,
-the control unit (SE) has a first and a second measuring connection, which are connected to the Measuring Resistor (MR),
it is characterized in that the preparation method is characterized in that,
the first or second measuring terminal is connected to the output of the power supply (NT) via a pull-up resistor (PR).
2. Protection switch device according to claim 1, characterized in that said Measuring Resistor (MR) is connected to said measuring terminal by a wire-like connection line (DVL), said measuring terminal being connected to the output of said power supply (NT) via said pull-up resistor (PR).
3. Protection switching device according to claim 1 or 2, characterized in that the power supply (NT) and the control unit (SE) are arranged on a printed circuit board (LP) having at least a part of the first and second line (LT1, LT 2).
4. Protection switching device according to claim 2 or 3, characterized in that a measuring tap not connected via the pull-up resistor (PR) with an output of the power supply (NT) is connected at least partially via a printed conductor (LB) of the printed circuit board (LP) with the Measuring Resistor (MR).
5. Protection switching device according to claim 1, 2, 3 or 4, characterized in that the control unit (SE) has a measuring circuit (MS), in particular a measuring circuit (MS) using an ASIC (ASICA) or an Amplifier (AMP), to determine the magnitude of the current or its equivalent from the voltage drop over the Measuring Resistance (MR).
6. Protection switching device according to any one of the preceding claims, characterized in that the control unit (SE) has a Microprocessor (MCU).
7. Protection switching device according to any one of the preceding claims, characterized in that a voltage limiting element (D1, D2), in particular in the form of one or two diodes (D1, D2), is connected between the first and second measuring terminals, wherein in particular in the case of two diodes the two diodes are connected anti-parallel.
8. Protection switching device according to one of the preceding claims, characterized in that the control unit (SE) is designed such that a series fault arc in the low-voltage circuit is determined and a fault arc identification signal is output, in particular the low-voltage circuit is interrupted, when a fault arc limit value is exceeded.
9. Protection switching device according to any of the preceding claims, characterized in that the pull-up resistance (PR) has a resistance value between 100 and 10 mohms, in particular between 1 kilo-ohm and 1 mohms, more particularly between 10 and 100 kilo-ohms and comprises values of 10 and 100 kilo-ohms.
10. Protection switch device according to one of claims 1 to 8, characterized in that the pull-up resistance (PR) has a resistance value which is at least 1000 times the resistance value of the Measuring Resistance (MR), in particular 10000 times, 100000 times, 1000000 times, 10000000 times or 100000000 times.
11. Protection switch device according to any one of the preceding claims, characterized in that the Measuring Resistor (MR) has a resistance value which is constant at least over a temperature range.
12. Protection switching device according to any one of the preceding claims, characterized in that the voltage drop over the Measuring Resistance (MR) is a voltage proportional to the current.
13. Protection switch device according to one of claims 1 to 10, characterized in that the Measuring Resistor (MR) has a bimetallic or bimetallic protection element (BM).
14. The protection switch device according to any one of claims 1 to 12, characterized in that a bimetallic protection element (BM) is connected in series with the Measuring Resistor (MR).
15. Protection switching device according to one of the preceding claims, characterized in that upon recognition that the input voltage at the measuring connection exceeds a first threshold value, a wire break recognition signal is output,
in particular, in the presence of a wire break recognition signal, an optical, electrical or acoustic signal is emitted.
16. Protection switching device according to claim 15, characterized in that an interruption Unit (UE) is provided for interrupting the low voltage circuit, which interruption unit interrupts the low voltage circuit, in particular in the presence of a wire break identification signal.
17. Protection switching device according to claim 16, characterized in that the interruption Unit (UE) is connected before the input side of the power supply (NT) or/and
having contacts for interrupting the first and/or second line.
18. A protection switching device according to any one of the preceding claims, characterized in that the low-voltage circuit is a low-voltage ac circuit.
19. Protection switching device according to any one of the preceding claims, characterized in that the protection switching device is a fire switch, a line protection switch, a power switch or a fault current protection switch, or the protection switching device has a fire protection function, a line protection function or a fault current protection function.
20. A method for protecting a switching device against low-voltage circuits, in particular for identifying series fault arcs,
-wherein a current measurement is performed by means of a Measuring Resistance (MR) via which the current of the conductor of the low voltage circuit is conducted to determine the magnitude of the current of the low voltage circuit,
-the Measuring Resistance (MR) is connected to a measuring circuit (MS) by means of at least one electrical wire-like connection line (DVL),
-energizing the measurement circuit (MS) by means of a power supply,
it is characterized in that the preparation method is characterized in that,
the terminal of the measuring circuit (MS) connected to the wire-like connection line (DVL) is connected to the output of the power supply (NT) via a pull-up resistor (PR), so that a break in the wire-like connection line (DVL) can be determined and signaled by the voltage at the input of the measuring circuit (MS) exceeding a first threshold value.
21. The method according to claim 20, characterized in that the signal is emitted by means of an optical display, activation of a switch contact or/and interruption of the low-voltage circuit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102018219692.3 | 2018-11-16 | ||
| DE102018219692.3A DE102018219692A1 (en) | 2018-11-16 | 2018-11-16 | Protective switching device for a low-voltage circuit for the detection of serial arcing faults |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111200273A true CN111200273A (en) | 2020-05-26 |
| CN111200273B CN111200273B (en) | 2022-11-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911117603.9A Active CN111200273B (en) | 2018-11-16 | 2019-11-15 | Protective switching device for low-voltage circuits for detecting series fault arcs |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN111200273B (en) |
| DE (1) | DE102018219692A1 (en) |
| GB (1) | GB2580206B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102020216429B4 (en) * | 2020-12-21 | 2022-12-29 | Siemens Aktiengesellschaft | Protective switching device and method |
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Also Published As
| Publication number | Publication date |
|---|---|
| DE102018219692A1 (en) | 2020-05-20 |
| GB201915728D0 (en) | 2019-12-11 |
| CN111200273B (en) | 2022-11-25 |
| GB2580206B (en) | 2021-10-27 |
| GB2580206A (en) | 2020-07-15 |
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