Protection switch device and method

Abstract

The invention relates to a protective switchgear (SG) for protecting a low-voltage circuit, wherein: - grid-side and load-side connections (LG, NG, LL, NL) for conductors of the low-voltage circuit are provided; - a mechanical disconnecting contact unit (MK) is provided, which has a closed state of contacts for current flow in the low-voltage circuit or an open state of contacts for galvanic disconnection in the low-voltage circuit for avoiding current flow; - an electronic interruption unit (EU) is provided, which is connected in series with the mechanical disconnecting contact unit (MK) on the circuit side and has a switching element for avoiding current flow via a semiconductor-based switching element. the high-resistance state of the switching element or the low-resistance state of the switching element for current flow in the low-voltage circuit, determining the size of the differential current of the conductors of the low-voltage circuit and, when a first differential current limit value or a first differential current-time limit value is exceeded, initiating the avoidance (VS) of current flow in the low-voltage circuit by the high-resistance state (EUh) of the switching element of the electronic interruption unit in the closed state (MKg) of the separation contacts, and, after the avoidance of current flow by the high-resistance state of the switching element of the electronic interruption unit and the closed state of the contacts, checking whether a second differential current limit value or a second differential current-time limit value is exceeded.

Description

Technical Field

[0001] The invention relates to the technical field of a protective switching device for a low-voltage circuit with an electronic interruption unit according to the preamble of claim 1 and a method for a protective switching device for a low-voltage circuit with an electronic interruption unit. Background Art

[0002] Low voltage refers to voltages up to 1000 V AC or 1500 V DC. Low voltage specifically refers to voltages greater than minimum voltage, which is 50 V AC or 120 V DC.

[0003] A low voltage circuit or a low voltage network or a low voltage system refers to a circuit with a rated current or a nominal current of up to 125 amperes, more particularly up to 63 amperes. A low voltage circuit refers in particular to a circuit with a rated current or a nominal current of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values ​​mentioned refer in particular to the rated current, the nominal current and / or the cut-off current, i.e. the maximum current that is conducted through the circuit under normal circumstances, or the current that is usually interrupted by the circuit, for example by a protective device, such as a protective switchgear or a line protection switch or a circuit breaker. The rated current can be further graded from 0.5A through 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A, 9A, 10A, etc. up to 16A.

[0004] Circuit breakers are overcurrent protection devices that have been known for a long time and are used in low-voltage circuits in electrical installation technology. Circuit breakers protect circuits from damage caused by overcurrent and / or short circuits. Circuit breakers can automatically switch off the circuit in the event of an overload and / or short circuit. Circuit breakers are non-automatically resettable fuse elements.

[0005] Unlike line circuit breakers, circuit breakers are designed for currents greater than 125 amperes, in some cases also starting at 63 amperes. The line circuit breaker is therefore simpler and more compact in design. Line circuit breakers usually have a mounting option for mounting on a so-called top hat rail (support rail, DIN rail, TH35).

[0006] According to the prior art, line protection switches adopt an electromechanical structure. In the housing, they have mechanical switch contacts or working current triggers for interrupting (triggering) the current. Usually, bimetallic protection elements or bimetallic elements are used to trigger (interrupt) in the case of long-term overcurrent (overcurrent protection) or thermal overload (overload protection). Electromagnetic triggers with coils are used to trigger for a short time when the overcurrent limit value is exceeded or a short circuit occurs (short-circuit protection). One or more arc extinguishing chambers or devices for arc extinguishing are provided. In addition, connection elements for conductors of the circuit to be protected are provided.

[0007] Residual current circuit breakers for circuits, in particular for low-voltage circuits or low-voltage devices, are generally known. Residual current circuit breakers are also called residual current devices (RCDs). Residual current circuit breakers determine the sum of the currents in the circuit (in general, the sum of the currents is zero) and interrupt the circuit when a differential current value, i.e. a sum of the currents that is not equal to zero, is exceeded (the sum of the currents exceeds a certain (differential) current value or a fault current value).

[0008] Almost all residual current circuit breakers known to date have a summation current transformer, whose primary winding is formed by the conductors of the circuit and whose secondary winding outputs a current sum which is used directly or indirectly to interrupt the circuit.

[0009] For this purpose, two or more conductors, usually the outgoing conductor and the return conductor or the outer conductor and the neutral conductor in a single-phase AC network, all three outer conductors or all three outer conductors and the neutral conductor in a three-phase AC network, are led through a current transformer, which usually has a ring-shaped core made of ferromagnetic material. Only the differential current in the conductors, i.e. the current that deviates from the outgoing current and the return current, is converted. The sum of the currents in the circuit is usually equal to zero. Therefore, a fault current can be detected.

[0010] If, for example, a current flows from the energy sink or the consumer to the ground, this is called a fault current in this context. A fault occurs, for example, when there is an electrical connection between the phase conductor of a circuit and the ground. This happens, for example, when a person touches a phase conductor. Part of the current then does not flow back as usual via the neutral conductor or zero conductor, but instead flows back via the person and the ground. This fault current can now be detected with the aid of a summing current transformer, since the sum of the incoming and return currents detected according to the values ​​is not equal to zero. By means of a relay or a holding magnet trigger For example, a relay or a holding magnet trigger connected to a mechanical device is used to interrupt the circuit, for example, to interrupt at least one, part or all of the lines. A residual current circuit breaker for collecting AC residual currents is generally known from DE 44 32643 A1.

[0011] The main functions of a residual current circuit breaker are to protect people from electric current (electric shock) and to protect equipment, machines or buildings from fire due to electrical insulation faults.

[0012] If a residual current circuit breaker or its summing current transformer is designed in such a way that the energy on the secondary side of the summing current transformer is sufficient to actuate a tripping unit or an interruption unit or a release, then such a residual current circuit breaker is said to be independent of the mains voltage.

[0013] If the triggering circuit requires or uses auxiliary energy, which is usually generated by a power supply provided in the residual current circuit breaker, then such a residual current circuit breaker is said to be grid-voltage-dependent. In other words, a grid-voltage-dependent residual current circuit breaker contains a power supply which is used for the energy supply for residual current detection (not independent of the grid voltage). For example, these power supplies are required for detecting residual currents in DC grids and DC / AC hybrid grids or in high-frequency circuits.

[0014] Protection switchgear with electronic interruption units are a relatively recent development. Protection switchgear has an electronic interruption unit based on semiconductors. That is, the current of the low-voltage circuit is conducted through a semiconductor device or a semiconductor switch, which can interrupt the current or switch to conduction. Protection switchgear with an electronic interruption unit also usually has a mechanical separation contact system, which has a separation characteristic in particular according to the relevant standards for low-voltage circuits, wherein the contacts of the mechanical separation contact system are connected in series to the electronic interruption unit, i.e. the current of the low-voltage circuit to be protected is conducted both through the mechanical separation contact system and through the electronic interruption unit.

[0015] The invention relates in particular to a low-voltage AC circuit having an AC voltage, which is usually a time-dependent sinusoidal AC voltage with a frequency f. The time dependence of the instantaneous voltage value u(t) of the AC voltage is described by the following equation:

[0016] u(t)=U*sin(2π*f*t).

[0017] in:

[0018] u(t) = instantaneous voltage value at time t

[0019] U = voltage amplitude

[0020] A harmonic AC voltage can be represented by the rotation of a pointer, the length of which corresponds to the amplitude of the voltage (U). Here, the instantaneous deflection is the projection of the pointer on the coordinate system. The oscillation period corresponds to a full rotation of the pointer, and its full angle is 2π (2Pi) or 360°. The angular frequency is the rate of change of the phase angle of this rotating pointer. The angular frequency of a harmonic oscillation is always 2π times its frequency, that is:

[0021] ω = 2π*f = 2π / T = angular frequency of the AC voltage (T = duration of the oscillation cycle)

[0022] The specification of angular frequency (ω) is usually preferred to frequency (f) because many vibration theory formulas can be expressed more compactly in terms of angular frequency due to the presence of trigonometric functions, which by definition have a period of 2π:

[0023] u(t)=U*sin(ωt)

[0024] In the case of an angular frequency that is not constant over time, the term instantaneous angular frequency is also used.

[0025] In the case of a sinusoidal, in particular temporally constant, alternating voltage, the time-dependent value corresponding to the angular velocity ω and the time t corresponds to the time-dependent angle This angle is also called the phase angle

[0026] That is, the phase angle Periodically passes through the range of 0...2π or 0°...360°. That is, the phase angle periodically takes on values ​​between 0 and 2π or 0° and 360° or Due to periodicity; abbreviations are: or

[0027] Therefore, the instantaneous voltage value u(t) refers to the instantaneous value of the voltage at the time point t, that is, in the case of a sinusoidal (periodic) alternating voltage, it refers to the phase angle The voltage value ( or for the corresponding period). Summary of the invention

[0028] The technical problem to be solved by the present invention is to improve a protective switchgear of the type mentioned at the outset, in particular to ensure protection against (fault) currents caused by personnel, while achieving power supply reliability or availability of electrical equipment, i.e. to achieve immunity against technically caused (fault) currents, which would lead to erroneous triggering of the protective switchgear. That is, on the one hand, personnel protection is ensured, and on the other hand, the power supply reliability of the low-voltage circuit is improved. Alternatively, a new concept is created for such a protective switchgear.

[0029] This object is achieved by a circuit breaker assembly having the features of claim 1 and by a method according to claim 12 .

[0030] According to the present invention, a protection switch device for protecting a low-voltage circuit, in particular a low-voltage AC circuit, is provided, the protection switch device comprising:

[0031] a housing having line-side and load-side connections for conductors of the low-voltage circuit,

[0032] a differential current sensor unit for determining the magnitude of a differential current of a conductor of a low-voltage circuit,

[0033] a mechanically disconnecting contact unit having a closed state of the contacts for current flow in the low-voltage circuit or an open state of the contacts for galvanic disconnection in the low-voltage circuit for preventing current flow,

[0034] The mechanically isolating contact unit can be operated and switched, in particular, by a mechanical handle, so that the opening of the contact for preventing the flow of current or the closing of the contact for the flow of current in the low-voltage circuit can be switched (by the handle), whereby (in particular) the galvanic separation in the low-voltage circuit can be switched;

[0035] In a mechanically separated contact unit, the opening of the contacts is also called release, and the closing of the contacts is called making-in;

[0036] an electronic interruption unit which is connected in series with the mechanically isolating contact unit on the circuit side and which, by means of a semiconductor-based switching element, has a high-resistance (in particular non-conductive) state of the switching element for preventing a current flow or a low-resistance state of the switching element for a current flow in the low-voltage circuit;

[0037] In the electronic interruption unit, the high-resistance (in particular non-conductive) state of the switching element (for the prevention of current flow) is also referred to as the off-state (process: off), and the low-resistance (conductive) state of the switching element (for current flow) is referred to as the on-state (process: on);

[0038] A control unit which is connected to the differential current sensor unit, the mechanical separation contact unit and the electronic interruption unit.

[0039] According to the invention, the protective switching device, in particular the control unit, is designed to initiate the prevention of a current flow in the low-voltage circuit when a first differential current limiting value or a first differential current-time limiting value is exceeded, by the high-resistance state of the switching element of the electronic interruption unit in the closed state of the disconnecting contacts. After the prevention of a current flow by the high-resistance state of the switching element of the electronic interruption unit and the closed state of the contacts, a check is performed to determine whether a second differential current limiting value or a second differential current-time limiting value has been exceeded.

[0040] This has the particular advantage that, after a faulty differential current event, for example due to a person touching a (phase) conductor (critical event) or due to a technically induced operating current (not critical for the person, i.e. a non-critical event) (e.g. due to a connected capacitor), an immediate avoidance of a current flow in the low-voltage circuit is initiated by the high-resistance state of the switching element of the electronic interruption unit.

[0041] Immediate prevention of the current flow means in particular that the electronic interruption unit becomes high-impedance within 10 ms, in particular 5 ms or 1 ms. (Today's residual current circuit breakers generally trigger after at least / more than 20 ms.)

[0042] After the avoidance of a current flow through the high-resistance state of the switching element of the electronic interruption unit and the closed state of the contacts, a check is performed to determine whether a second differential current limit value or a second differential current-time limit value has been exceeded, in order to further check whether a faulty differential current event is present and, if necessary, to differentiate between critical and non-critical events, in order to ensure personnel protection on the one hand and the availability of the device on the other.

[0043] Therefore, the state of the load-side connection can be further monitored for the presence of a differential current limit value or a differential current-time limit value. In the event of a change in state, further actions can be advantageously performed, for example according to an advantageous embodiment of the invention.

[0044] On the other hand, this provides a completely new operating concept of the protective switchgear, in which, in contrast to conventional residual current circuit breakers, for example, a check is also performed after the event of preventing the current flow.

[0045] Advantageous embodiments of the invention are specified in the dependent claims and in the exemplary embodiments.

[0046] Advantageously, only the mechanical disconnecting contact switch can be actuated by the mechanical handle. Switching on and off by means of the electronic disconnecting unit cannot be actuated (directly) on the device.

[0047] In an advantageous embodiment of the invention, the electronic interruption unit switches to the low-resistance state when a second differential current limit value or a second differential current-time limit value is not exceeded within a first time range (10ms ... 20ms ... 30ms ... 50ms ... 100ms ... 200ms ... 1s (any value is possible depending on the application)).

[0048] The first time range is, for example, a value in the range of 10 ms to 100 ms to 200 ms to 1 s. That is, when, for example, after exceeding the first differential current limit value or the first differential current-time limit value for 10 ms (15 ms) or 20 ms (25 ms, 30 ms, ..., 95 ms, 100 ms, ..., 1 s), the second differential current limit value or the second differential current-time limit value is not exceeded, the electronic interruption unit switches to the low-resistance state.

[0049] The first time range can be dependent in particular on the magnitude of the determined differential current (in particular its effective value), ie in the case of a larger differential current, the first time range is smaller.

[0050] This has the particular advantage that automatic reconnection takes place when an insignificant differential current limit value or differential current-time limit value is present, thereby achieving a high level of availability.

[0051] In an advantageous embodiment of the invention, the isolating contacts are opened when a second differential current limiting value or a second differential current-time limiting value is exceeded for a first period of time.

[0052] The first time period is, for example, in the range of 10 ms to 100 ms to 10 s. The first time period can in particular be less than 300 ms, 200 ms, 150 ms, 100 ms, 50 ms, 40 ms, 30 ms, 20 ms or 10 ms.

[0053] This has the particular advantage that a disconnection behavior similar to that achieved in conventional residual current circuit breakers, in which a galvanic separation is effected for personal protection, is achieved.

[0054] In an advantageous embodiment of the present invention, the electronic interruption unit switches to a low-resistance state when (after a certain period of time / first period of time and) the second differential current limit value or the second differential current-time limit value is not exceeded within a second time range (without exceeding).

[0055] The second time range may be a value within a range of 20 ms to 100 ms to 1 s to 10 s. The length of the second time range may correspond to the length of the first time range or be greater than the length of the first time range.

[0056] This has the particular advantage that automatic restarting takes place and thus a high availability of the energy supply is achieved.

[0057] In an advantageous embodiment of the present invention, a communication unit, in particular an input unit, is provided. The electronic interruption unit switches to a low-resistance state only when a response is made by means of the communication unit, in particular the input unit, when a second differential current limit value or a second differential current-time limit value is not exceeded within a second time range.

[0058] The second time range may be a value in the range of 20 ms to 100 ms to 1 s. The length of the second time range may correspond to the length of the first time range or be greater than the length of the first time range.

[0059] This has the particular advantage that reconnection is only possible after confirmation (acknowledgement) by the user, thus achieving a high degree of reliability.

[0060] In an advantageous embodiment of the invention, the mechanical isolating contact unit (MK) is associated with the load-side connection.

[0061] This has the particular advantage that an architecture is provided which supports the characteristics according to the invention of the protective switching device, since on the one hand the current flow is interrupted in the case of a high-resistance interruption unit, but via the closed contacts (on the load side) the check according to the invention can continue (with the aid of the load-side connection).

[0062] In an advantageous embodiment of the invention, the check on whether a second differential current limit value or a second differential current-time limit value is exceeded at the load-side connection is performed by switching at least one switching element, in particular two or all switching elements, of the electronic interruption unit to a low resistance, in particular for a first switch-on period.

[0063] This has the particular advantage that a simple possibility is provided for checking whether a second differential current limit value or a second differential current-time limit value is exceeded (on the load-side connection), since it is only necessary to switch the existing electronic interruption unit (briefly) to a low-resistance state in order to briefly generate a measuring current or a measuring voltage in order to check whether a differential current limit value or a differential current-time limit value is present and its magnitude.

[0064] The first switch-on period can be so short that there is no danger to persons.

[0065] In an advantageous embodiment of the invention, the check as to whether a second differential current limit value or a second differential current-time limit value is exceeded (on the load-side connection) is carried out by converting at least one switching element of the electronic interruption unit, in particular two or all switching elements, into a low resistance when the instantaneous value of the voltage magnitude is less than a first voltage threshold value.

[0066] The first voltage threshold is in particular less than 50 V or is the value of a (protective) undervoltage. The first voltage threshold is advantageously adjustable.

[0067] This has the particular advantage that voltages which are dangerous to humans are checked, so that reliability is provided both in the low-voltage circuit and also for the protective switching device.

[0068] For this purpose, a voltage sensor unit is advantageously provided which determines the magnitude of the voltage in the low-voltage circuit, in particular the voltage present at the mains-side connection.

[0069] In an advantageous embodiment of the invention, the switching element changes to high resistance again when the instantaneous value of the magnitude of the voltage is greater than a second voltage threshold value.

[0070] This in turn has the particular advantage that voltages which are dangerous to humans are checked, thereby providing reliability not only in the low-voltage circuit but also for the protective switching device. The magnitude of the second voltage threshold can correspond to the magnitude of the first voltage threshold.

[0071] In an advantageous embodiment of the invention, the check on whether a second differential current limit value or a second differential current-time limit value is exceeded (at the load-side connection) is performed by applying an auxiliary voltage which is less than the first voltage limit.

[0072] This in turn has the particular advantage that voltages which are dangerous to humans are checked by means of different solutions, so that reliability is provided both in the low-voltage circuit and also for the protective switching device.

[0073] Here, the magnitude of the first voltage limit may correspond to the magnitude of the first (or second) voltage threshold.

[0074] In an advantageous embodiment of the present invention, when a second differential current limit value or a second differential current-time limit value is exceeded, a check is performed at a first time interval, the first time interval being in particular 1, 3, 5, 10, 15, 30 seconds or 1, 5, 10 or 15 minutes, wherein in particular the check is performed at the first time interval after a first time period has elapsed.

[0075] This has the particular advantage that a periodic check is carried out over a relatively long period of time without a check function or a check routine being carried out continuously.

[0076] In an advantageous embodiment of the present invention, when (further) there is a second differential current limit value or a second differential current-time limit value exceeded, after the first time limit has passed, the mechanical separation contact unit is switched to the disconnected state of the separation contact. In particular, the first time limit is 15 minutes, 30 minutes, 1 hour, 8 hours, 24 hours, 36 hours or 48 hours. Any intermediate value is possible. The first time interval depends on the first time limit. That is, the first time interval is less than the first time limit.

[0077] This has the particular advantage that, after a first time limit has elapsed, a permanent or significant defect in the low-voltage circuit can be inferred and a safe state in the low-voltage circuit can be initiated by galvanic isolation.

[0078] According to the invention, a corresponding method for a protective switching device for a low-voltage circuit having electronic (semiconductor-based) switching elements is claimed, which has the same advantages and further advantages.

[0079] A protective switchgear is used for protecting a low-voltage circuit. In the method for protecting a protective switchgear:

[0080] - a network-side and a load-side connection for conductors of the low-voltage circuit is provided,

[0081] - a mechanically isolating contact unit is provided, which has a closed state of the contacts for current flow in the low-voltage circuit or an open state of the contacts for galvanic separation in the low-voltage circuit for preventing current flow,

[0082] - an electronic interruption unit is provided which is connected in series with the mechanical isolating contact unit on the circuit side and which, by means of a semiconductor-based switching element, has a high-resistance state of the switching element for preventing a current flow or a low-resistance state of the switching element for preventing a current flow in the low-voltage circuit,

[0083] - determining the magnitude of a differential current in a conductor of the low-voltage circuit and, when a first differential current limit value or a first differential current-time limit value is exceeded, initiating the prevention of a current flow in the low-voltage circuit by means of a high-resistance state of a switching element of the electronic interruption unit in the closed state of the separating contacts,

[0084] After the current flow has been prevented through the high-resistance state of the switching element of the electronic interruption unit and the closed state of the contacts, a check is performed to determine whether a second differential current limiting value or a second differential current-time limiting value has been exceeded.

[0085] In an advantageous embodiment of the method, it is possible to:

[0086] When a second differential current limit value or a second differential current-time limit value is not exceeded within a first time range (eg 20 ... 100 ms ... 1 s), the electronic interruption unit switches to a low-resistance state.

[0087] - opening the isolating contacts when a second differential current limit value or a second differential current time limit value is exceeded for a first time period, which is in particular less than 300 ms, 200 ms, 150 ms, 100 ms, 50 ms, 40 ms, 30 ms, 20 ms or 10 ms.

[0088] The electronic interruption unit switches to the low-resistance state only when an acknowledgement has been made if a second differential current limit value or a second differential current-time limit value is not exceeded within a second time range (eg 20 ... 100 ms ... 1 s).

[0089] a check (on the load-side connection) to determine whether a second differential current limit value or a second differential current-time limit value is exceeded is performed by switching at least one switching element, in particular two or all switching elements, of the electronic interruption unit to a low resistance, in particular for a first switch-on period.

[0090] - A check (on the load-side connection) as to whether a second differential current limit value or a second differential current-time limit value is exceeded is performed by converting at least one switching element, in particular two or all switching elements, of the electronic interruption unit into a low resistance when the instantaneous value of the voltage in terms of magnitude is less than a first voltage threshold value.

[0091] According to the invention, a corresponding computer program product for protecting a switching device is claimed. The computer program product comprises instructions which, when executed by a microcontroller, cause the microcontroller to check, according to any one of claims 1 to 17, whether a second differential current limit value or a second differential current-time limit value has been exceeded after the current flow through the high-impedance state of the switching element and the closed state of the contacts of the electronic interruption unit has been avoided.

[0092] The microcontroller is part of a protective switching device, in particular a control unit.

[0093] According to the invention, protection is claimed for a corresponding computer-readable storage medium on which a computer program product is stored.

[0094] According to the invention, a corresponding data carrier signal is claimed which transmits a computer program product.

[0095] All design schemes, not only in the form of dependent reference to claim 1 or 12, but also merely in the form of reference to individual features or feature combinations of the claims, and in particular in the form of device claims to be processed that reference independent method claims, achieve improvements in protective switchgear, in particular in terms of personnel safety and power supply reliability in low-voltage circuits, and provide a new and reliable scheme for protective switchgear. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] The described characteristics, features and advantages of the present invention and the implementation thereof will become clearer and more easily understood in conjunction with the following description of the embodiments, which are described in detail in conjunction with the accompanying drawings.

[0097] Here, in the accompanying drawings:

[0098] Figure 1 shows a first principle illustration of a protective switchgear,

[0099] Figure 2 A second principle diagram of a protective switchgear is shown,

[0100] Figures 3 to 8 A time sequence is shown for explaining the present invention. DETAILED DESCRIPTION

[0101] Figure 1 The diagram shows a circuit breaker device SG for protecting a low-voltage circuit, in particular a low-voltage AC circuit, which circuit breaker device SG has a housing GEH and has:

[0102] - grid-side connections, which in particular comprise a grid-side neutral conductor connection NG and a grid-side phase conductor connection LG,

[0103] - load-side connections, which in particular comprise a load-side neutral conductor connection NL and a load-side phase conductor connection LL;

[0104] - These connectors are designed for low voltage circuits;

[0105] - An energy source is usually connected to the grid-side connection / grid-side GRID,

[0106] - Electrical consumers are usually connected to the load-side connector / load-side LOAD;

[0107] a (two-pole) mechanically isolating contact unit MK having connection points APLL, APNL on the load side and connection points APLG, APNG on the grid side,

[0108] The connection point APNL on the load side is set for the neutral conductor, the connection point APLL on the load side is set for the phase conductor, the connection point APNG on the grid side is set for the neutral conductor, and the connection point APLG on the grid side is set for the phase conductor. The connection points APNL and APLL on the load side are connected to the neutral conductor connection and the phase conductor connections NL and LL on the load side, so that the opening of the contacts KKN and KKL for preventing the flow of current or the closing of the contacts KKN and KKL for the flow of current can be switched in the low-voltage circuit.

[0109] an electronic interruption unit EU, in particular a unipolar one (which in the case of a unipolar embodiment is in particular arranged in the phase conductor),

[0110] A grid-side connection point EUG is provided, which is electrically connected to a grid-side phase conductor connection LG, and

[0111] a load-side connection point EUL, which is electrically connected or connected to a grid-side connection point APLG of the mechanical disconnecting contact unit MK,

[0112] The electronic interruption unit EU has or can switch, via a semiconductor-based switching element (not shown) in the low-voltage circuit, a high-resistance state of the switching element for preventing a current flow or a low-resistance state of the switching element for a current flow,

[0113] - a differential current sensor unit ZCT, which is used to determine the magnitude of the differential current of the conductor of the low-voltage circuit, the differential current sensor unit ZCT being arranged in this example between the electronic interruption unit EU and the mechanical disconnection contact unit MK, which can alternatively be arranged (arranged) between the mechanical disconnection contact unit MK and the neutral conductor connection and the phase conductor connection NL, LL on the load side, and can also alternatively be arranged (arranged) between the electronic interruption unit EU and the connections NG, LG on the grid side. The differential current sensor unit ZCT determines the magnitude of the differential current of the conductor of the low-voltage circuit (to be protected) which is guided through the protective switchgear. In this example, in the case of a single-phase AC circuit, this is the neutral conductor and the phase conductor.

[0114] The differential current sensor unit ZCT may be a typical sum current transformer. The primary side of the sum current transformer is formed by the conductors of the low voltage circuit (in the example, the phase conductor and the neutral conductor). The secondary side of the sum current transformer is connected to the control unit SE.

[0115] a current sensor unit SI for determining the magnitude of the current of the low-voltage circuit, which current sensor unit SI is arranged in particular in a current path of a phase conductor or in a phase conductor current path,

[0116] a control unit SE which is connected to the differential current sensor unit ZCT, to the current sensor unit SI and to the mechanical isolating contact unit MK and the electronic interruption unit EU, wherein when a current limiting value and / or a current-time limiting value is exceeded, prevention of a current flow in the low-voltage circuit is initiated.

[0117] In this example, the mechanical disconnecting contact unit MK is arranged on the load side, and according to the invention, the electronic interruption unit EU is arranged on the grid side.

[0118] The grid side GRID with the energy source is normally under voltage. Electrical consumers are usually connected to the load side LOAD.

[0119] This has the advantage that there are no other (especially voltage-exposed) parts or components between the contacts of the mechanically isolating contact unit / the load-side connection point (APLL, APNL) of the mechanically isolating contact unit and the two load-side connections (LL, NL). Thus, due to this structure or construction, it can be ensured that when the contacts KKL, KKN are open, no voltage is present at the load-side connections LL, NL in any case. This increases the reliability of the protective device.

[0120] In contrast thereto, in other architectures in which the mechanically isolating contact unit is arranged on the network side, there is often a (non-galvanically isolating) electronics unit upstream of the connection on the load side.

[0121] According to the invention, the protection switchgear can be designed so that the magnitude of the voltage on the electronic interruption unit can be further determined. That is, the magnitude of the first voltage between the grid-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU can be determined or determined.

[0122] To this end, according to Figure 1 In the example of FIG. 4 , a first voltage sensor unit SU1 connected to the control unit SE is provided, which determines the magnitude of the voltage between the grid-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU.

[0123] Alternatively, when measuring the voltage via the first voltage sensor unit SU1, the voltage across the series circuit of the electronic interruption unit EU and the current sensor SI can also be determined, as in Figure 1 As shown in . The current sensor unit SI has a very small internal resistance, so that it has no influence or a negligible influence on the determination of the voltage magnitude.

[0124] Advantageously, a second voltage sensor unit SU2 can be provided which determines the magnitude of the voltage between the grid-side neutral conductor connection NG and the grid-side phase conductor connection LG.

[0125] The first voltage sensor unit can also be replaced by using two voltage measurements (before and after the electronic interruption unit). The voltage at the electronic interruption unit is determined by difference formation.

[0126] Thus, a second voltage sensor unit SU2 connected to the control unit SE can be provided, which determines the magnitude of a second voltage between the neutral conductor connection NG on the grid side and the phase conductor connection LG on the grid side. Furthermore, a third voltage sensor unit SU3 (not shown) connected to the control unit can be provided, which determines the magnitude of a third voltage between the neutral conductor connection NG on the grid side and the connection point EUL on the load side of the electronic interruption unit EU. The protective switchgear is designed such that the magnitude of a first voltage between the connection point EUG on the grid side and the connection point EUL on the load side of the electronic interruption unit EU is determined from the difference between the second voltage and the third voltage.

[0127] A measuring impedance ZM can be connected between the connection points APLG, APNG on the grid side of the mechanical separation contact unit MK. The measuring impedance ZM can be, for example, a resistor and / or a capacitor. The measuring impedance can also be an inductor. In particular, the measuring impedance can be a series circuit or a parallel circuit of a resistor and / or a capacitor and / or an inductor.

[0128] In accordance with Figure 1 In the example of , the electronic interruption unit EU is embodied as a single pole, in the present example in the phase conductor. In this case, the grid-side connection point APNG for the neutral conductor of the mechanically disconnecting contact unit MK is connected to the grid-side neutral conductor connection NG of the housing GEH. Figure 1 , which connection is conducted via a differential current sensor unit ZCT, for example its sum current transformer.

[0129] The protective switching device SG is advantageously designed in such a way that the contacts of the mechanical disconnecting contact unit MK can be opened by the control unit SE, but cannot be closed, as indicated by the arrow from the control unit SE to the mechanical disconnecting contact unit MK.

[0130] The mechanical separation contact unit MK can be operated by a mechanical handle HH on the protective switch device SG to switch the contacts KKL, KKN to be manually (manually) opened or closed. The mechanical handle HH indicates the switching state (open or closed) of the contacts of the mechanical separation contact unit MK on the protective switch device. In addition, the contact position (or the position of the handle, closed or open) can be transmitted to the control unit SE. For example, the contact position (or the position of the handle) can be determined with the aid of a sensor such as a position sensor. The contact position or the switching state can be transmitted to the control unit SE. The position sensor can be part of the mechanical separation contact unit MK. Alternatively, the position sensor can be an electronic first part (EPART, Figure 2 ) components. For example, a Hall sensor can be provided in the first electronic part (EPART), which detects and transmits the position of the contacts and / or the handle in a contactless manner.

[0131] The mechanical disconnecting contact unit MK is advantageously designed so that the contacts can only be closed (manually) by a mechanical handle after a release (Enable), in particular a release signal. This is also indicated by an arrow from the control unit SE to the mechanical disconnecting contact unit MK. That is, the contacts KKL, KKN of the mechanical disconnecting contact unit MK can only be closed by the handle HH when there is a release or a release signal (from the control unit). In the absence of a release or a release signal, the handle HH can be operated, but the contacts are not closed ("Dauerrutscher, continuous sliding").

[0132] The protection switchgear SG has an energy supply or power supply NT, for example a switching power supply. In particular, the energy supply / power supply NT is provided for the control unit SE, which is achieved by Figure 1 The connection between the energy supply device / power supply unit NT and the control unit SE is shown in FIG. The energy supply device / power supply unit NT is (on the other hand) connected to the neutral conductor connection NG on the grid side and to the phase conductor connection LG on the grid side. In the connection to the neutral conductor connection NG on the grid side (or / and the phase conductor connection LG), a fuse SS, in particular a blow-off fuse or a switch SCH ( Figure 2 ).

[0133] According to the invention, the power supply unit NT is normally continuously supplied with energy, in particular from a grid-side connection. If necessary, it is protected by a fuse SS or can be disconnected by a switch SCH.

[0134] The switch SCH / Sch can advantageously be designed in such a way that it can only be opened when the contacts are in the open state. This increases the reliability of the device, since the electronics (particularly the control unit) cannot be opened when the contacts are closed.

[0135] The purpose of the fuse SS is not only to protect the energy supply by means of the power supply unit NT, but also to be designed in two parts (see Figure 2 ) in order to protect the "electronic" first part EPART or in particular its entire unit (for example, in particular the control unit, the electronic interruption unit, the voltage sensor, the current sensor, (if necessary) the measuring impedance, etc.).

[0136] Alternatively, the measuring impedance ZM can be connected to the neutral conductor connection NG on the grid side via a fuse SS. Thus, a three-pole electronic unit or the first part of the electronics EPART ( Figure 2 ), for example as a module with three connections on the low-voltage circuit, namely a neutral conductor connection and two phase conductor connections. The electronic first part EPART can have further connections, in particular for control information or measurement information, for example for release signal Enable / enable, disconnection signal OEF, position information (of position unit POS) or / and a differential current signal (magnitude of the differential current) of the differential current sensor unit ZCT.

[0137] Electronic unit or the first part of the electronics EPART ( Figure 2 ) for example comprises an electronic interruption unit EU, a control unit SE, a power supply device NT (in particular including a fuse SS), a current sensor unit SI, an optional first voltage sensor unit SU1 and / or an optional second voltage sensor unit SU2.

[0138] With regard to the three connections on the low-voltage circuit of the first electronic part EPART, there is therefore the advantage that only the two phase conductor connections must have a high conductivity (several amperes for conducting the load current) and the neutral conductor connection must only have a (relatively) low conductivity (e.g. less than 1 A, a few milliamperes (depending on the energy requirement of the control unit)). This simplifies the construction and increases the reliability of the device, since in the event of a fault in the first electronic part EPART, no large short-circuit currents flow through these connections.

[0139] The low-voltage circuit can be a three-phase AC circuit with a neutral conductor and three phase conductors. For this purpose, the protective switchgear can be designed as a three-phase variant and, for example, have additional grid-side and load-side phase conductor connections. The contacts of the electronic interruption unit and the mechanical separation contact unit according to the invention are respectively arranged between these additional grid-side and load-side phase conductor connections in a similar manner. The individual conductors (three phase conductors L1, L2, L3, neutral conductor N) are led through the differential current unit ZCT.

[0140] Likewise, a current sensor unit and a voltage determination (for example by means of a first voltage sensor unit) may be provided.

[0141] High resistance refers to a state in which only a negligible current still flows. High resistance refers in particular to resistance values ​​greater than 1 kOhm, preferably greater than 10 kOhm, 100 kOhm, 1 MOhm, 10 MOhm, 100 MOhm, 1 kOhm or more.

[0142] Low resistance refers to the state in which a current value specified at the protective switching device can flow.

[0143] Low resistance refers in particular to resistance values ​​less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less.

[0144] Figure 2 Shown according to Figure 1 The difference is that the protective switching device is designed in two parts.

[0145] The circuit breaker device comprises an electronic first part EPART, for example on a circuit board / printed circuit board.

[0146] The first part EPART can have a control unit SE, a first voltage sensor unit SU1, a second voltage sensor unit SU2, a current sensor unit SI, an electronic interruption unit EU, and an energy supply device NT. In addition, the first part can have a fuse SS, a switch SCH, a measuring impedance ZM, a temperature sensor TEM (in particular for the electronic interruption unit EU), a communication unit COM, a display unit AE, and as a variant, a position sensor unit POS.

[0147] The first part of the electronics EPART has only three connectors for low voltage circuits:

[0148] a grid-side phase conductor connection LG as a first connection,

[0149] a (second) connection for or to a grid-side phase conductor connection point APLG of the mechanical disconnecting contact unit MK,

[0150] - A third connection EN for connection to the neutral conductor connection NG on the grid side.

[0151] The two connections: the connection LG for connecting to the phase conductor on the grid side and the connection for or connecting to the phase conductor connection point APLG on the grid side, have high conductivity, for example several amperes, greater than 10A / 16A (depending on the nominal current or rated current of the low-voltage circuit), in particular for carrying load currents also in the event of a short circuit or overload.

[0152] The third connection EN for connection to the neutral conductor connection NG on the grid side has a (relatively) low conductivity, for example less than 1 A, a few mA (depending on the energy requirement of the supplied unit, in particular in the electronic first part EPART). The third connection EN is designed with low conductivity in order to provide current for the power supply and for voltage measurement between the phase conductors and the neutral conductor of the low-voltage circuit. In particular, the third connection EN is protected by a fuse SS. This can be achieved by a fuse or a low-cost conductor track fuse (thin conductor tracks on the circuit board with corresponding length and thickness).

[0153] This has the particular advantage that the lower electrical conductivity in the line or at the third connection EN improves the safety against short circuits occurring within the electronic first part (EPART) (or (electronic) unit), for example on the power supply or control unit side.

[0154] This means that in the event of a failure or malfunction of an electronic component of a unit within the first electronic part EPART, no dangerous short-circuit current (supplied from the grid-side connections LG, NG) will occur, which could lead to a fire in the device.

[0155] This short-circuit current is supplied by the grid via the grid-side connection. The protection switch arranged upstream often has a much higher triggering current and supplies the low-voltage circuit arranged in parallel. Therefore, in the event of a fault in the protection switch device (protection switch device of the protected low-voltage circuit) and the protection switch arranged upstream triggers, the parallel circuit without fault will also be disconnected, thus avoiding this situation.

[0156] The communication unit COM can be a wireless communication unit in particular. The communication unit COM can have a (manual) input unit on the protective switch device for (manually) responding to the status on the protective switch device SG. The response can also be made (wired or and / or wirelessly) via the communication unit COM.

[0157] Furthermore, the communication unit COM may have a display function. A separate display unit may also be provided.

[0158] The protection switchgear comprises a second part MPART, in particular a mechanical one. The second part MPART can have a mechanical disconnecting contact unit MK, a handle HH, a release unit FG. In addition, the second part can have a position unit POS for reporting the position of the contacts of the mechanical disconnecting contact unit MK to a control unit and a (neutral conductor) connection. The second part MPART has a differential current sensor unit ZCT, such as a summation current transformer known, for example, from conventional fault current protection switches.

[0159] Further units not shown in detail may be provided.

[0160] The division into two parts advantageously makes it possible to realize a compact protection switching device according to the invention having a simplified construction.

[0161] When there is a release signal enable, the release unit / release function FG causes the release of the operation of the contacts of the mechanical separation contact unit by the handle HH. That is, only when there is a release signal enable (from the control unit SE) can the contacts KKL and KKN be closed by the handle. Otherwise, they cannot be closed (continuous sliding of the handle HH). The contacts remain in the disconnected position / switch state. In addition, when there is a disconnection signal OEF (from the control unit SE), the release unit FG can cause the disconnection of the contacts (the second function of the release unit FG). The release unit / release function FG then serves as a trigger unit for disconnecting the contacts of the mechanical separation contact unit MK.

[0162] Furthermore, the protective switching device SG, in particular the control unit SE, is designed to initiate the avoidance of a current flow in the low-voltage circuit, in particular to avoid a short-circuit current, when a current limit value or a current-time limit value is exceeded (i.e. when the current limit value is exceeded for a certain period of time). This is achieved in particular by switching the electronic interruption unit EU from a low-impedance state to a high-impedance state. The avoidance of a current flow in the low-voltage circuit is initiated, for example, by a first interruption signal sent from the control unit SE to the electronic interruption unit EU.

[0163] Alternatively or additionally, the mechanical isolating contact unit MK can be controlled by the control unit SE so as to initiate the avoidance of the current flow of the low-voltage circuit when a current limit value or a current-time limit value is exceeded. In this case, in particular, a galvanic disconnection is brought about if necessary. For example, the avoidance of the current flow of the low-voltage circuit or the initiation of a necessary galvanic interruption is carried out by a second interruption signal sent from the control unit SE to the mechanical isolating contact system MK.

[0164] The electronic interruption unit EU can have semiconductor elements, such as bipolar transistors, field effect transistors (FET), insulated gate bipolar transistors (IGBT), metal oxide field effect transistors (MOSFET) or other (self-commutated) power semiconductors. In particular, IGBTs and MOSFETs have low flow resistance. The high cut-off layer resistance and the good switching characteristics make it particularly suitable for use in the protection switching device according to the invention.

[0165] The mechanical disconnecting contact unit MK refers in particular to the disconnecting function (compliant with the standard) which is implemented by the disconnecting contact unit MK. The disconnecting function refers to the following:

[0166] - (voltage-dependent) minimum air gap (minimum distance between contacts) according to the standard,

[0167] - contact position indication for contacts of mechanically separated contact systems,

[0168] - Mechanically disconnecting contact system is always able to disconnect (disconnecting contact system cannot be blocked (especially by handle), free triggering).

[0169] In this context, the DIN EN 60947 and IEC 60947 series of standards are relevant in the context of the present invention with regard to the function of the separator and its properties, to which reference is hereby made.

[0170] The protective switchgear can be designed as a top-hat rail-mountable protective switchgear SG with two-pole connections (L, N), for example, with a width of 1TE, 1.5TE or 2TE. In electrical installations and in switch cabinet structures, the width of built-in devices such as protective switchgear, line protection switches, fault current protection switches, etc. is given in pitch units (abbreviated as TE). The width of one pitch unit is ~18mm. According to the DIN 43880:1988-12 standard, the built-in width of the device should be between 17.5 and 18.0mm, or calculated by multiplying this dimension by 0.5 or an integer multiple thereof, that is: kx 0.5x18mm or kx 0.5x17.5mm (where k=1, 2, 3, ...). Therefore, according to the prior art, a single-pole line protection switch has, for example, a width of 1TE. The built-in electrical installation distribution board is based on DIN 43871 "Installationskleinverteiler für bis 63A (small installation switchboard for built-in devices up to 63A)" matches the width of the pitch unit, such as the support rail / top hat rail.

[0171] According to the invention, the protective switchgear SG, in particular the control unit SE, is designed to initiate the prevention of current flow in the low-voltage circuit by the high-resistance state of the switching element of the electronic interruption unit in the closed state of the separation contacts when a first differential current limit value or a first differential current-time limit value is exceeded. The first differential current limit value or the first differential current-time limit value can be a limit value according to a relevant standard such as DIN EN 61008-1. For example, in Europe, in a 230-volt low-voltage circuit, this is 30 mA for personnel protection; in North America, this is 6 mA for personnel protection and 300 mA (230 volt effective value) for fire protection.

[0172] After the current flow has been prevented through the high-resistance state of the switching element of the electronic interruption unit and the closed state of the contacts, a check is performed to determine whether a second differential current limiting value or a second differential current-time limiting value has been exceeded.

[0173] The magnitude of the second differential current limit value or the second differential current-time limit value can correspond to the magnitude of the first differential current limit value or the first differential current-time limit value. However, according to the present invention, the magnitude of the second differential current limit value or the second differential current-time limit value is advantageously smaller than the magnitude of the first differential current limit value or the first differential current-time limit value.

[0174] The magnitude of the second differential current limit value or the second differential current-time limit value advantageously corresponds to the value that complies with the standard, but has a smaller magnitude resulting from the inspection. If, for example, the inspection is carried out with a small voltage, in particular a small protective voltage, a smaller differential current is also obtained. That is, the magnitude of the second differential current limit value or the second differential current-time limit value is determined by the magnitude of the voltage during the inspection. The higher the voltage, the greater the magnitude of the second differential current limit value or the second differential current-time limit value. If, for example, a grid voltage of a low-voltage circuit of 230 volts is used for the inspection (for a short time), the magnitude of the second differential current limit value or the second differential current-time limit value corresponds to the magnitude of the first differential current limit value or the first differential current-time limit value.

[0175] According to the invention, a check on whether (the connection on the load side) exceeds a second differential current limit value or a second differential current-time limit value can be performed by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit (EU) to a low resistance, in particular to a low resistance for a first switch-on duration.

[0176] The first switch-on period can be determined such that the effective value of the voltage present at the load connection (determined over a network cycle) does not exceed 50 V. That is, the instantaneous value of the voltage can be greater than 50 V for a short time, but the effective value of the voltage determined over a network cycle is less than 50 V. The first switch-on period is therefore always less than 20 ms, in particular less than 10 ms, in particular less than 1 ms.

[0177] The check (on the load-side connection) as to whether a second differential current limit value or a second differential current-time limit value is exceeded can be performed (with respect to the AC voltage) by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit (EU) to a low resistance when the instantaneous value of the voltage in terms of magnitude is less than the first voltage threshold value. The electronic interruption unit can be switched on for a short time, that is, the semiconductor-based switching element is switched to a low resistance for a short time. Here, short time means that the instantaneous voltage value u(t) of the AC voltage does not exceed a specific first switch-on duration ED1 of a specific value, for example 50 volts. Thus, for example, the AC voltage can be switched on (the electronic interruption unit EU changes to a low resistance) at the zero crossing (0°) of the AC voltage for approximately 444 μs / before 8°, that is, before the instantaneous voltage value reaches a maximum of 50 volts.

[0178] Alternatively, it can also be switched on at approximately -8° (relative to the zero crossing of the AC voltage), pass the zero crossing, and be switched off again at +8°, ​​that is, for approximately 888 μs. That is, the switch-on time period is less than 1 ms, in particular less than 0.9 ms, in particular approximately 0.8 ms (or half thereof, depending on the switch-on time point).

[0179] By briefly switching on the electronic interruption unit, a reduced (test) voltage is applied to the load-side connection (load connection). The effective value of this test voltage depends on the existing mains voltage and the first switch-on duration ED1 and is always less than the existing mains voltage. In this case, the first switch-on duration or the first voltage threshold is selected such that the effective value of the test voltage (applied to the mains-side connection) is less than 50 V. It is thus possible to reliably check whether a second differential current limit value or a second differential current-time limit value is exceeded.

[0180] In the present example, the second differential current limit value or the second differential current-time limit value is adapted to a voltage of up to 50 volts. The reduction of the second differential current limit value compared to the first differential current limit value corresponds to the same ratio as the reduction of the test voltage relative to the nominal grid voltage. That is, for example, in the case of a test voltage of 50 V effective value and a nominal grid voltage of 230 V, the second differential current limit value is reduced by 50 / 230. For example, from 30 mA (as the first differential current limit value), 30 mA*50 / 230=6.5 mA (as the second differential current limit value) is obtained.

[0181] That is to say, the second differential current limit value is smaller than the first differential current limit value.

[0182] Alternatively or additionally, in the event that the instantaneous value in terms of the magnitude of the voltage is greater than a second voltage threshold value (eg 50 Volts), the switching element can become high-impedance again.

[0183] Alternatively, at least one electrical parameter on the load-side connection can be checked by applying an auxiliary voltage, in particular a pulsed DC voltage, which is less than a first voltage limit. The first voltage limit can be a (limit) value of a protective low voltage or correspond to a voltage threshold. According to the invention, no dangerous voltage is present on the load-side connection either.

[0184] The first voltage limit may be 50 volts, for example.

[0185] If the second differential current limit value or the second differential current-time limit value is not exceeded within the first time range ZB1 , the electronic interruption unit EU can be switched to the low-resistance state.

[0186] (Alternatively, the check can be performed until the second differential current limit value or the second differential current-time limit value is exceeded. The electronic interruption unit is then switched to the low-resistance state.)

[0187] In contrast, if the second differential current limiting value or the second differential current time limiting value is exceeded for the first time period ZS1 , the disconnecting contacts can be opened (galvanic disconnection as in conventional residual current circuit breakers).

[0188] In this case, the value of the first time period can correspond to the value of the first time range, that is, after the first time period (=first time range) has passed, the contacts of the mechanically separating contact unit can be opened. The first time period can also have different values. In this case, the first time period can, for example, have a time period according to a standard for conventional residual current protection / for conventional residual current circuit breakers. Reference is made to the DIN EN 61008-1 standard Fehlerstrom- / Differenzstrom-Schutzschalter ohne eingebauten (RCCBs)fürHausinstallationen und für Anwendungen, insbesondere Teil 1: AllgemeineAnforderungen (Residual current / differential current circuit breakers (RCCB) without built-in overcurrent protection for domestic installations and similar applications, in particular Part 1: General requirements), which is included here by reference. For example, it can be derived from this standard that a 30mA residual current circuit breaker (RCD) must be triggered within 300ms at the nominal fault current (30mA). It must be triggered within 150ms at 2 times the nominal fault current (60mA). It must be triggered within 40ms at 5 times or more of the nominal fault current.

[0189] For example, the first time period can be less than 300ms, 150ms, 100ms, 40ms, 30ms, 20ms or 10ms. Thus, a behavior according to the standard or better can be provided, wherein, for example, an interruption is necessary only after 300ms. According to the invention, a check can be performed in advance to determine whether a differential current limit value or a differential current-time limit value is exceeded, without, for example, violating the standard. Thus, a higher power supply reliability can be achieved, in particular in the case of non-critical faults.

[0190] Depending on the application, the first time period ZS1 can have a value in the range of 10 ms to 10 s, in particular 10 ms to 40 ms or 40 ms to 150 ms or 150 ms to 300 ms or 1 s to 10 s, for example.

[0191] The protection switch device SG may have a communication unit COM, in particular an input unit. When a second differential current limit value or a second differential current-time limit value is not exceeded within a second time range (for example, a value within the range of 20ms ... 100ms ... 1s ... 10s ... 100s), the electronic interruption unit EU is switched to a low-resistance state only when (for example, an operator, a user) responds Q1 with the aid of the communication unit COM, in particular the input unit. The communication unit (input unit) may have an input element on the housing of the protection switch device. Alternatively or additionally, the communication unit may also have a wired (for example, electrical, optical) or wireless (for example, radio, optical) input possibility. The communication unit (input unit) may also have a display function.

[0192] Alternatively or additionally, after the first time period ZS1 has elapsed, the electronic interruption unit EU may be switched to the low-resistance state (EUn) again when it is determined that the second differential current limit value or the second differential current-time limit value is not exceeded for a duration of the (first (or) second) time range. Furthermore, after the first time period ZS1 has elapsed, before the electronic interruption unit EU is switched to the low-resistance state (EUn) again, a (needed) fault-free response (Q1) may be performed.

[0193] The circuit breaker device SG, in particular the control unit SE, can have a microcontroller (=microprocessor) on which runs a computer program product containing instructions which, when the program is executed by the microcontroller, cause the microcontroller to carry out checks on the circuit breaker device (as described above and below).

[0194] The computer program product can advantageously be stored on a computer-readable storage medium; for example a USB stick, a CD-ROM or the like; in order to be able to upgrade to an extended version, for example.

[0195] Alternatively, the computer program product can also advantageously be transmitted via a data carrier signal.

[0196] The control unit SE can:

[0197] * implemented by means of digital circuits, for example by means of a (further) microprocessor; the (further) microprocessor may also contain analog parts;

[0198] *Implemented using digital circuits with analog circuit portions.

[0199] exist Figures 3 to 8 A part of the above-mentioned time sequence is shown by way of example in FIG. Figures 3 to 8 A time axis t is shown respectively, on which the aforementioned specific time points are plotted, and further items of evaluation of the first differential current limit value or the first differential current-time limit value DSG1 or the second differential current limit value or the second differential current-time limit value DSG2 are plotted, and further states of the mechanical separation contact unit MK and the electronic interruption unit EU are plotted.

[0200] Figure 3 The point in time VS at which the current flow is avoided due to the exceeding of the first differential current limit value or the first differential current-time limit value DSG1 is shown. Before the point in time VS at which the current flow is avoided, the mechanical separation contact unit MK is in the closed state MKg of the contacts, and the electronic interruption unit EU is in the low-resistance state EUn of the switching element for the current flow in the low-voltage circuit. After the avoidance VS of the current flow, the mechanical separation contact unit MK continues to be in the closed state MKg of the contacts (for potential repeated current flow / in order to enable the current flow to be realized again quickly), and the electronic interruption unit EU is in the high-resistance state EUh of the switching element for avoiding the current flow. After the avoidance VS of the current flow, a check is performed to determine whether (at the load-side connection) the second differential current limit value or the second differential current-time limit value DSG2 is exceeded.

[0201] Figure 4 Shown according to Figure 3 , but with the following differences.

[0202] After the occurrence of current flow avoidance VS and the subsequent (at any subsequent time point) not exceeding the second differential current limit value SB or the second differential current-time limit value DSG2 (i.e. when the second differential current limit value or the second differential current-time limit value DSG2 is within the rated range), the electronic interruption unit EU switches to the low-resistance state EUn, in particular when there is no more than the second differential current limit value SB or the second differential current-time limit value DSG2 within the first time range ZB1, such as Figure 4Drawn in .

[0203] The first time frame ZB1 can be very short (ie, can be switched on again almost immediately), which can also be set in time in relation to reliability.

[0204] Whether the second differential current limit value or the second differential current-time limit value DSG2 is exceeded is checked until there is no longer an exceedance (SB). This check can be continued until the electronic interruption unit EU switches to the low-resistance state EUn (ZB1). Subsequently, the first differential current limit value or the first differential current-time limit value DSG1 is checked again.

[0205] In this case, the mechanically separating contact unit MK has the closed state MKg of the (separating) contacts during the entire period of time.

[0206] Figure 5 Shown according to Figure 3 , with the difference that after the avoidance of current flow VS, and when there is a second differential current limit value US or a second differential current-time limit value DSG2 that is exceeded for a first time period ZS1, the contacts (MKo) of the mechanical separation contact unit are opened, the first time period ZS1 being in particular less than 300ms, 150ms, 40ms, 30ms, 20ms or 10ms. In this example, the electronic interruption unit EU (since the current flow is avoided VS) remains in the high-resistance state EUh.

[0207] Figure 6 Shown according to Figure 5 , the difference is that after the avoidance of the current flow VS, the US second differential current limit value or the second differential current-time limit value DSG2 is not exceeded immediately, but at a later time point, but still before (passing) the first time range ZB1 (i.e. before the electronic interruption unit EU becomes low resistance). When the US second differential current limit value or the second differential current-time limit value DSG2 is exceeded for the first time period ZS1, the contact MKo of the mechanical separation contact unit MK is opened (after the first time period ZS1).

[0208] That is, there may be a switch that exceeds (US) / does not exceed the second differential current limit value SB or the second differential current-time limit value DSG2. When the second differential current limit value or the second differential current-time limit value DSG2 is exceeded for the first time period ZS1, the contact MKo of the mechanical separation contact unit MK is opened.

[0209] Figure 7 Shown according to Figure 4, with the difference that, after the occurrence of current flow avoidance VS and the subsequent not exceeding the second differential current limit value SB or the second differential current-time limit value DSG2 (i.e. when the second differential current limit value or the second differential current-time limit value DSG2 is within the rated range, wherein this should in particular be done before the first time period ZS1 has passed, i.e. before the contacts are opened), when there is not more than the second differential current limit value SB or the second differential current-time limit value DSG2 within the second time range ZB2 (the second time range ZB2 can correspond to the first time range ZB1) and a response (Q1) is made (with the help of the communication unit COM, in particular the input unit), the electronic interruption unit EU switches to the low-resistance state EUn.

[0210] Whether the second differential current limit value or the second differential current-time limit value DSG2 is exceeded is checked until there is no longer an exceedance (SB), or / and the second time range has passed, or / and a response is given. That is, the check for whether the second differential current limit value or the second differential current-time limit value DSG2 is exceeded can continue until the electronic interruption unit EU switches to the low-resistance state EUn (in this example Q1). Subsequently, the first differential current limit value or the first differential current-time limit value DSG1 is checked again.

[0211] In this case, the mechanically separating contact unit MK has the closed state MKg of the (separating) contacts during the entire period of time.

[0212] Figure 8 Shown according to Figure 5 or Figure 6 , the difference is that, when the second differential current limit value US or the second differential current-time limit value DSG2 is exceeded and the first time period ZS1 has passed, the contacts of the mechanical separation contact unit do not open, i.e. remain closed. In addition, after the first time period ZS1 has passed, a check is performed at a first time interval ZA1 (i.e. not always) to determine whether the second differential current limit value US or the second differential current-time limit value (DSG2) has been exceeded.

[0213] Furthermore, if a second differential current limit value US or a second differential current-time limit value DSG2 is further exceeded after the first time limit ZG1 (at least if it is not exceeded within the first or second time range ZB1 , ZB2 ), the mechanical isolating contact unit MK switches to the open state MKo of the contacts.

[0214] That is, after the first time period ZS1 has passed, the check is performed at the first time interval ZA1 until the first time limit ZG1 is reached. After the first time limit ZG1 has passed, if there is still a second differential current limit value US or a second differential current-time limit value DSG2, the mechanical separation contact unit MK is switched to the open state MKo. The electronic interruption unit EU (since the self-current flow is avoided VS) remains in the high-resistance state EUh.

[0215] In a similar manner, other behaviors or methods are combinable by those skilled in the art.

[0216] According to the invention, advantageously, a check is performed to determine whether a second differential current limit value or a second differential current-time limit value DSG2 is exceeded by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit EU to a low resistance for a first switch-on duration ED1. That is, the high-resistance state EUh of the electronic interruption unit EU depicted in the figures does not refer to a continuous high-resistance state, but rather to a short-term low resistance of the electronic interruption unit EU (for a first switch-on duration ED1). In this case, the first switch-on duration ED1 is, for example, very short (compared to other times), so that this does not conflict with the illustration according to the figures and the basic mode of operation.

[0217] Although the present invention has been illustrated and described in detail through embodiments, the present invention is not limited to the disclosed examples and those skilled in the art may derive other variations therefrom without departing from the protection scope of the present invention.

Claims

1. A protection switch device (SG) for protecting a low voltage circuit, the protection switch device comprising: a housing having line-side and load-side connections (LG, NG, LL, NL) for conductors of the low-voltage circuit, a differential current sensor unit (ZCT) for determining the magnitude of a differential current of a conductor of the low-voltage circuit, a mechanically disconnecting contact unit (MK) having a closed state (MKg) of contacts for current flow in the low-voltage circuit or an open state (MKo) of contacts for galvanic disconnection in the low-voltage circuit for preventing current flow, an electronic interruption unit (EU) which is connected in series with the mechanically isolating contact unit (MK) on the circuit side and which, by means of a semiconductor-based switching element, has a high-resistance state (EUh) of the switching element for preventing a current flow or a low-resistance state (EUn) of the switching element for a current flow in the low-voltage circuit, - a control unit (SE) connected to the differential current sensor unit (ZCT), the mechanical separation contact unit (MK) and the electronic interruption unit (EU), It is characterized in that in, The protective switching device (SG), in particular the control unit (SE), is designed to initiate the prevention (VS) of a current flow in the low-voltage circuit by means of a high-impedance state (EUh) of a switching element of the electronic interruption unit in the closed state (MKg) of the disconnecting contacts when a first differential current limiting value or a first differential current-time limiting value (DSG1) is exceeded, After the current flow is prevented (VS) through the high-impedance state of the switching element and the closed state of the contacts of the electronic interruption unit, a check is performed to determine whether a second differential current limiting value or a second differential current-time limiting value (DSG2) is exceeded.

2. The protective switchgear (SG) according to claim 1, It is characterized in that The electronic interruption unit (EU) switches to the low-resistance state when the second differential current limit value or the second differential current-time limit value (DSG2) is not exceeded (SB) within a first time range (ZB1), the first time range being in particular less than 200 ms, 100 ms, 50 ms, 30 ms, 20 ms or 10 ms.

3. The protective switchgear (SG) according to claim 1 or 2, It is characterized in that The contact (MKo) is opened when the second differential current limit value or the second differential current time limit value (DSG2) is exceeded (US) for a first time period (ZS1), which is in particular less than 300 ms, 150 ms, 40 ms, 30 ms, 20 ms or 10 ms.

4. A protective switchgear (SG) according to claim 1, 2 or 3, It is characterized in that A communication unit COM, in particular an input unit, is provided, and the electronic interruption unit (EU) is switched to a low-resistance state only when a response (Q1) is made with the aid of the communication unit (COM), in particular the input unit, when the second differential current limit value or the second differential current-time limit value (DSG2) is not exceeded (SB) within a second time range (ZB2), and the second time range is in particular less than 5s, 3s, 1s, 500ms, 250ms, 100ms.

5. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The mechanically isolating contact unit (MK) is associated with the load-side connections (LL, NL).

6. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that A check on whether a second differential current limit value or a second differential current-time limit value (DSG2) is exceeded is performed by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit (EU) to a low resistance, in particular for a first switch-on duration (ED1), in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms or 1 ms.

7. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The check as to whether the second differential current limit value or the second differential current-time limit value (DSG2) is exceeded is performed by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit (EU) to a low resistance when the instantaneous value of the voltage in terms of magnitude is less than a first voltage threshold value.

8. Protection switchgear (SG) according to claim 6 or 7, It is characterized in that When the instantaneous value in terms of the magnitude of the voltage is greater than the second voltage threshold, the switching element becomes high-impedance again.

9. A protective switchgear (SG) according to any one of claims 1 to 5, It is characterized in that A check to determine whether a second differential current limiting value or a second differential current-time limiting value (DSG2) is exceeded is performed by applying an auxiliary voltage that is less than the first voltage limit.

10. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that When a second differential current limit value or a second differential current-time limit value (DSG2) is exceeded (US), a check is performed at a first time interval (ZA1), which is in particular 1, 3, 5, 10, 15, 30 seconds or 1, 5, 10 or 15 minutes, wherein in particular the check is performed at the first time interval (ZA1) after a first time period (ZS1) has elapsed.

11. The protective switchgear (SG) according to claim 10, It is characterized in that If (further) a second differential current limit value or a second differential current-time limit value (DSG2) is exceeded (US), the mechanical separation contact unit (MK) switches to the open state (MKo) of the contacts after a first time limit (ZG1) has elapsed, In particular, the first time limit is 15 min, 30 min, 1 h, 8 h, 24 h, 36 h or 48 h.

12. A method for a protective switchgear (SG), the protective switchgear being used for protecting a low voltage circuit, in which method, - grid-side and load-side connections (LG, NG, LL, NL) for conductors of the low-voltage circuit are provided, - a mechanically disconnecting contact unit (MK) is provided, which has a closed state (MKg) of contacts for current flow in the low-voltage circuit or an open state (MKo) of contacts for galvanic disconnection in the low-voltage circuit for preventing current flow, - an electronic interruption unit (EU) is provided, which is connected in series with the mechanical separation contact unit (MK) on the circuit side and has a high-resistance state (EUh) of the switching element for preventing a current flow or a low-resistance state (EUn) of the switching element for a current flow in the low-voltage circuit via a semiconductor-based switching element, - determining the magnitude of a differential current of a conductor of the low-voltage circuit and, when a first differential current limit value or a first differential current-time limit value (DSG1) is exceeded, initiating the prevention of a current flow in the low-voltage circuit by means of a high-impedance state (EUh) of a switching element of the electronic interruption unit in a closed state (MKg) of the contacts, After the current flow is prevented via the high impedance state (EUh) of the switching element and the closed state (MKg) of the contacts of the electronic interruption unit (EU), a check is performed to determine whether a second differential current limit value or a second differential current-time limit value (DSG2) is exceeded.

13. The method according to claim 12, It is characterized in that The electronic interruption unit (EU) switches to the low-resistance state (EUn) when the second differential current limit value or the second differential current-time limit value (DSG2) is not exceeded (SB) within a first time range (ZB1).

14. The method according to claim 12 or 13, It is characterized in that The contact (MKo) is opened when the second differential current limiting value or second differential current time limiting value (DSG2) is exceeded for a first time period (ZS1), which is in particular less than 300 ms, 150 ms, 40 ms, 30 ms, 20 ms or 10 ms.

15. The method according to claim 12, 13 or 14, It is characterized in that The electronic interruption unit (EU) switches to the low-resistance state only when an acknowledgement (Q1) has been made, if the second differential current limit value or the second differential current-time limit value (DSG2) is not exceeded within a second time range (ZB2).

16. The method according to claim 12, 13, 14 or 15, It is characterized in that A check on whether a second differential current limit value or a second differential current-time limit value (DSG2) is exceeded is performed by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit (EU) to a low resistance, in particular for a first switch-on duration (ED1), in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms or 1 ms.

17. The method according to claim 12, 13, 14, 15 or 16, It is characterized in that The check as to whether the second differential current limit value or the second differential current-time limit value (DSG2) is exceeded is performed by changing at least one switching element, in particular two or all switching elements, of the electronic interruption unit (EU) to a low resistance when the instantaneous value of the voltage in terms of magnitude is less than a first voltage threshold value.

18. A computer program product, comprising instructions which, when executed by a microcontroller, cause the microcontroller to check whether a second differential current limit value or a second differential current-time limit value is exceeded after avoiding a current flow through a high-resistance state of a switching element and a closed state of contacts of an electronic interruption unit according to any one of claims 1 to 17.

19. A computer-readable storage medium having stored thereon the computer program product according to claim 18.

20. A data carrier signal transmitting a computer program product according to claim 18.

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