Protection switch device and method

Abstract

The invention relates to a protective switching device for protecting a low-voltage circuit, comprising: a mechanical disconnecting contact unit which is connected in series to an electronic interrupting unit, the series circuit being connected, on one hand, to at least one network-side connection and, on the other hand, to at least one load-side connection; determining the magnitude of the current of the low-voltage circuit; starting the avoidance of the current flow of the low-voltage circuit when the current threshold value or / and the current-time threshold value are / is exceeded; determining a temperature on the connection terminal of the protection switching device; when a first temperature threshold is exceeded, the electronic interruption unit is switched into a high-resistance state of the switching element to avoid current flow, thereby avoiding overheating of the connection terminals of the protection switching device.

Description

Technical Field

[0001] The invention relates to the technical field of a protective switching device for a low-voltage circuit having an electronic interruption unit and a method for a protective switching device for a low-voltage circuit having 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 is a circuit with a rated or nominal current of up to 125 amperes, more particularly up to 63 amperes. A low-voltage circuit is particularly a circuit with a rated or nominal current of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values ​​mentioned are particularly the rated current, the nominal current and / or the cut-off current, i.e. the maximum current conducted through the circuit under normal circumstances, or the current which 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 0.5 A through 1 A, 2 A, 3 A, 4 A, 5 A, 6 A, 7 A, 8 A, 9 A, 10 A, etc. up to 16 A.

[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 the option of being mounted on a so-called top hat rail (support rail, DIN rail, TH35).

[0006] Line protection switches are electromechanical in 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 the conductors of the circuit to be protected are provided.

[0007] 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. In addition, protection switchgear with an electronic interruption unit usually has a mechanical separation contact unit, which has a separation characteristic in particular according to the relevant standards for low-voltage circuits, wherein the contacts of the mechanical separation contact unit 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 unit and through the electronic interruption unit.

[0008] The invention can be used both for low-voltage DC circuits and for low-voltage AC circuits. In particular, the invention relates to low-voltage AC circuits 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:

[0009] u(t)=U*sin(2π*f*t)

[0010] in:

[0011] u(t) = instantaneous voltage value at time t

[0012] U = voltage amplitude

[0013] 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:

[0014] ω = 2π*f = 2π / T = angular frequency of the AC voltage (T = duration of the oscillation cycle)

[0015] 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:

[0016] u(t)=U*sin(ωt)

[0017] In the case of an angular frequency that is not constant over time, the term instantaneous angular frequency is also used.

[0018] 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

[0019] That is, the phase angle Periodically passes through the range of 0...2π or 0°...360°. That is, the phase angle periodically assumes values ​​between 0 and 2π or 0° and 360° ( (0...2π) or (0°...360°), due to periodicity; abbreviated as: or ...360°).

[0020] 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 ...360° for the corresponding period). Summary of the invention

[0021] The object of the present invention is to improve a circuit breaker device of the type mentioned at the outset, in particular to avoid destruction, damage or inadmissible operating states (in particular inadmissible operating temperatures) of the circuit breaker device, in particular its connecting terminals.

[0022] The above-mentioned technical problem is solved by a protection switching device having the features according to the invention and by a method according to the invention.

[0023] According to the present invention, a protective switch device for protecting a low-voltage circuit, in particular a low-voltage AC circuit, is provided, wherein the protective switch device comprises:

[0024] a housing having at least two mains-side connections and at least one load-side connection, the at least two mains-side connections and the at least one load-side connection being for a low-voltage circuit,

[0025] the grid-side connection and the at least one load-side connection each have a connection terminal for connecting an external conductor of the low-voltage circuit to be protected (ie, outside the protective switching device) to the protective switching device,

[0026] a mechanically isolating contact unit which is connected in series with the electronic interruption unit, wherein the series circuit is connected on the one hand to one of the at least two network-side connections and on the other hand to at least one load-side connection,

[0027] - a mechanically separating contact unit capable of switching by opening at least one contact to prevent current flow or by closing at least one contact for current flow in the low-voltage circuit,

[0028] - the electronic interruption unit is capable of switching the switching element by means of a semiconductor-based switching element into a high-resistance state of the switching element to prevent current flow or into a low-resistance state of the switching element for current flow in the low-voltage circuit,

[0029] - a current sensor unit for determining the magnitude of the current in the low voltage circuit,

[0030] a control unit which is connected to the current sensor unit, the mechanical isolating contact unit and the electronic interruption unit, wherein, when the magnitude of the determined current exceeds a current limit value and / or a current-time limit value (i.e., when the current magnitude exists for a certain time), prevention of the current flow in the low-voltage circuit is initiated, in particular by a high-resistance state of a switching element of the electronic interruption unit.

[0031] According to the invention, a temperature sensor connected to the control unit is provided for determining the magnitude of the temperature. The temperature sensor is provided at (on) the connection terminal (or terminals) or in the region of the connection terminal (or terminals).

[0032] According to the invention, the protective switching device is designed such that when the determined temperature level (in the case of at least one connecting terminal) exceeds a first temperature threshold, the electronic interruption unit is switched to a high impedance state of the switching element to prevent current flow and thus to prevent overheating of the connecting terminal.

[0033] The high resistance state interrupts the current flow through the connection terminal(s) and therefore no more power loss occurs at the connection terminal, so that the connection terminal can cool down. Avoiding overheating means that the connection terminal or the protective switching device is kept within its permissible thermal limits or permissible (device) temperature.

[0034] This has the advantage that overheating of the connection terminal(s) or the protective switchgear is avoided. Thermal overload or thermal destruction can thus be avoided. Protection against equipment fires / fires in the sub-distribution system can be provided. Thus, power supply safety is provided. By avoiding the flow of current, heating of the protective switchgear is avoided and a safe state is established.

[0035] The heating of the connecting terminals is essentially caused by the ohmic contact resistance that is always present, which together with the current (flowing through the connecting terminals) leads to electrical power loss and the associated heating at the connecting terminals.

[0036] The contact resistance of the connection terminal depends on various factors. For example, (typically) aging may already lead to an increase in the contact resistance. However, depending on the location of use (e.g. when used in an environment with harmful gases or sea air (salt-containing)), corrosion may increase, which also leads to an increase in the contact resistance.

[0037] In addition, incorrect installation can also be a cause, such as incorrect (and in particular too low) tightening torques in the case of screw connections or unmatched conductor cross sections in the case of plug connections (spring clamps), which can lead to an increase in the contact resistance. Loose connections, for example due to mechanical (over) stress, can also lead to an increase in the contact resistance at the connection terminal. However, simple contamination on the contact surface (for example due to incorrect handling during installation) can also lead to an increase in the contact resistance.

[0038] Other advantageous embodiments of the present invention are given in the exemplary embodiments.

[0039] In an advantageous embodiment of the present invention, at least one grid-side temperature sensor is provided for the grid-side connecting terminal for determining the magnitude of the temperature of the grid-side connecting terminal.

[0040] If, for example, two mains-side connecting terminals are adjacent to one another, a mains-side temperature sensor can advantageously be provided. The mains-side temperature sensor can then advantageously be arranged between the two connecting terminals.

[0041] In an advantageous embodiment of the invention, at least one load-side temperature sensor is provided for at least one load-side connecting terminal for determining the magnitude of the temperature of the at least one load-side connecting terminal.

[0042] In the case of two load-side connecting terminals, for example when the two load-side connecting terminals are adjacent to one another, a load-side temperature sensor can advantageously be provided. The load-side temperature sensor can then advantageously be arranged between the two connecting terminals.

[0043] In an advantageous embodiment of the invention, a temperature sensor (associated with the connection terminal) is provided for each connection terminal, in particular a current-carrying conductor of the low-voltage circuit, in order to determine the magnitude of the temperature of the respective connection terminal.

[0044] This has the particular advantage that individual (critical connecting terminals), important (current-carrying connecting terminals of the low-voltage circuit) or complete (all connecting terminals, possibly individual connecting terminals) monitoring of the temperature magnitude of the corresponding connecting terminals is possible. Thus, overheating of the monitored (multiple) connecting terminals or overheating due to the protective switchgear can be avoided. Thus, thermal overload or thermal damage can be avoided. Protection against equipment fires / fires can be provided in the sub-distribution system. By avoiding the flow of current, heating of the protective switchgear is avoided and a safe state is established.

[0045] In an advantageous embodiment of the invention, the mechanical disconnecting contact unit is associated with the load-side connection, and the electronic interruption unit (EU) is associated with the grid-side connection. In particular, the mechanical disconnecting contact unit can be operated by a mechanical handle to switch the opening of at least one contact or the closing of at least one contact.

[0046] This has the particular advantage that a structure for a protective switching device is provided in which the functionality of the protective switching device is provided even in the event of an open contact of the mechanically isolating contact unit.

[0047] In an advantageous design of the present invention, two grid-side connections and two load-side connections are provided, in particular, a grid-side neutral conductor connection, a grid-side phase conductor connection, a load-side neutral conductor connection and a load-side phase conductor connection are provided.

[0048] This has the particular advantage that a design for a two-pole circuit breaker device is provided, so that the phase conductor and the neutral conductor can be connected directly and, for example, an additional neutral conductor busbar can be omitted.

[0049] In an advantageous design of the present invention, in the case of a high-resistance state of the switching element at startup to avoid overheating, and when the magnitude of the determined temperature exceeds a higher second temperature threshold (i.e., the second temperature threshold is higher than the first temperature threshold), at least one contact of the mechanically separated contact unit is disconnected.

[0050] This has the particular advantage that an additional safety is provided in the protective switchgear. If, despite the activation of the high-resistance electronic interruption unit, there is still an increased heating, this can be attributed to the fact that the electronic interruption unit is not high-resistance or not high enough, and the (faulty) current flow leads to further heating of the connecting terminal(s). In this case, at least one contact of the mechanically separating contact unit opens in order to achieve galvanic separation and thus completely prevent current flow. Damage to the connecting terminal(s) / protective switchgear is avoided by this additional safety measure.

[0051] In an advantageous embodiment of the invention, the electronic interruption unit is switched to a low-resistance state (for current flow in the low-voltage circuit) when the switching element is in a high-resistance state to avoid overheating and the determined temperature is below a third temperature threshold value. The third temperature threshold value is lower than the first temperature threshold value.

[0052] This has the particular advantage that, after the connection terminals of the circuit breaker device have cooled, current can flow again. The circuit breaker device is therefore always in a safe operating state.

[0053] In an advantageous embodiment of the present invention, alternatively, in the case of a high-resistance state of the switching element to avoid overheating, and after a first time period has passed since the high-resistance state of the switching element (to avoid overheating) occurred, the electronic interruption unit can be switched to a low-resistance state (for current flow in the low-voltage circuit).

[0054] The first time period may be, for example, in the order of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes.

[0055] This has the particular advantage that a fixed cooling time (first time period) is achieved. After the connecting terminal(s) of the protection switching device have cooled, current flow is achieved again.

[0056] In an advantageous embodiment of the invention, at least one contact of the mechanically isolating contact unit is opened within a first time frame if a first number of changes to the high resistance state to avoid overheating (and back to the low resistance state) exceeds.

[0057] The first time frame can be, for example, one hour, several hours, such as 3 hours, 5 hours, 6 hours, 10 hours, 12 hours, 18 hours, 24 hours (a day), several days, a week. For example, the number of changes can be changed from 2, 3, 4, ..., 10, ... 20 times.

[0058] This has the particular advantage that additional safety is achieved in the case of frequent temperature-induced changes to the high-resistance state (change from the low-resistance state to the high-resistance state), and at least one contact of the mechanically separating contact unit is opened in order to perform a galvanic separation and completely avoid the flow of heat-generating current. Thus, further changes of the electronic interruption unit to the high-resistance state (change to the high-resistance state and back to the low-resistance state) are avoided, and safety is established in the low-voltage circuit.

[0059] In an advantageous embodiment of the present invention, a communication unit connected to the control unit is provided. When a fourth temperature threshold is exceeded, a warning is issued by means of the communication unit. The fourth temperature threshold is advantageously smaller than the first temperature threshold.

[0060] The fourth temperature threshold may be, for example, 10, ..., 20, ..., 30, ..., 40 Kelvin less than the first temperature threshold.

[0061] This has the particular advantage that a notification is given when a temperature threshold value is reached, so that, for example or advantageously, a cause determination can be carried out before a shutdown due to overtemperature occurs.

[0062] Alternatively or additionally, the magnitude (or an equivalent value) of the temperature of the temperature sensor may be output (communicated) by means of the communication unit.

[0063] This has the particular advantage that (central) temperature monitoring of one or more protective switching devices is possible, so that corresponding measures can be taken in the event of a temperature increase.

[0064] In an advantageous embodiment of the invention, a display unit connected to the control unit is provided, which has a display device visible on the protective switchgear for displaying the magnitude of the temperature limit value (the first and / or the second and / or the third and / or the fourth temperature limit value) exceeded or / and the temperature as an alternative or in addition to the high-resistance or low-resistance state of the electronic interruption unit.

[0065] This has the particular advantage that a visualization of the temperature status is provided.

[0066] In an advantageous embodiment of the present invention, at least one contact of the mechanically isolating contact unit can be opened by the control unit but cannot be closed.

[0067] This has the particular advantage that a high level of safety of the protective switching device is provided, since the contacts cannot be closed erroneously (and not remotely, for example, by means of a communication signal) within the protective switching device.

[0068] In an advantageous embodiment of the present invention, at least one contact of the mechanically disconnecting contact unit has a release function. This can be a release function provided according to a standard. In particular, it is possible to disconnect at least one contact by the control unit even when the mechanical handle is locked, that is to say, for example, when the handle is locked in a closed contact state.

[0069] This has the particular advantage that a high level of safety and a particularly standard-compliant protective switchgear for low-voltage circuits is provided.By opening at least one contact, the current flow can be interrupted by the current at any time.

[0070] According to the invention, a corresponding method is claimed for a protective switching device for a low-voltage circuit having an electronic (semiconductor-based) switching element, which method has the same and other advantages.

[0071] A method for a protective switchgear for protecting a low voltage circuit, comprising:

[0072] a housing having at least two network-side connections and at least one load-side connection,

[0073] the grid-side connection and the at least one load-side connection each have a connection terminal for connecting an external conductor of the low-voltage circuit to be protected to the protective switching device,

[0074] a mechanically isolating contact unit which is connected in series with the electronic interruption unit, wherein the series circuit is connected on the one hand to one of the at least two network-side connections and on the other hand to at least one load-side connection,

[0075] - a mechanically separating contact unit can be switched by opening at least one contact to prevent current flow or by closing at least one contact for current flow in the low-voltage circuit,

[0076] - the electronic interruption unit is capable of switching the switching element by means of a semiconductor-based switching element into a high-resistance state of the switching element to prevent current flow or into a low-resistance state of the switching element for current flow in the low-voltage circuit,

[0077] - determining the magnitude of the current of the low-voltage circuit and, when a current limit value and / or a current-time limit value is exceeded, initiating the prevention of the current flow in the low-voltage circuit,

[0078] - determining the magnitude of the temperature at or in the region of at least one connecting terminal,

[0079] If the magnitude of the determined temperature exceeds a first temperature threshold value (in the case of at least one connecting terminal), the electronic interruption unit is switched into a high-resistance state of the switching element in order to prevent a current flow and thus to prevent overheating of the connecting terminal.

[0080] All design solutions, no matter individual features or feature combinations, improve the safety of the protective switchgear and provide a new solution for the protective switchgear. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The described characteristics, features and advantages of the present invention and the manner in which these characteristics, features and advantages are achieved will become clearer and more easily understood with reference to the following description of embodiments, which are explained in detail with reference to the accompanying drawings.

[0082] Here, in the accompanying drawings:

[0083] Figure 1A A first diagram showing a protective switchgear,

[0084] Figure 1B A second diagram showing a protective switchgear,

[0085] Figure 2 A first illustration of a graph is shown,

[0086] Figure 3 A second illustration of the diagram shows,

[0087] Figure 4 A third illustration of a diagram shows,

[0088] Figure 5 A fourth diagram of a graph is shown,

[0089] Figure 6 A fifth illustration of a diagram is shown. DETAILED DESCRIPTION

[0090] Figure 1A 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 has a housing GEH and has:

[0091] - a neutral conductor connection terminal NG on the grid side, a phase conductor connection terminal LG on the grid side, a neutral conductor connection terminal NL on the load side, and a phase conductor connection terminal LL on the load side for connecting an external conductor of the low-voltage circuit;

[0092] On the grid side Grid, for example, which has two grid-side connections, an energy source is usually connected.

[0093] Electrical consumers (energy absorbers) are usually connected to the load side Load, which has, for example, two load-side connections (of course, only one load-side connection can be provided, preferably for the phase conductor L);

[0094] a (two-pole) mechanically disconnecting contact unit MK having connection points APLL, APNL on the load side and connection points APLG, APNG on the grid side,

[0095] A connection point APNL on the load side is set for the neutral conductor, a connection point APLL on the load side is set for the phase conductor, a connection point APNG on the grid side is set for the neutral conductor, and a 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 terminal and the phase conductor connection terminals NL and LL on the load side, so that the opening of the contacts KKN and KKL can be switched to avoid current flow or the closing of the contacts for current flow in the low-voltage circuit.

[0096] The mechanical disconnecting contact unit can also be designed as a single-pole mechanical disconnecting contact unit, ie with one contact, wherein the contact KKL is preferably arranged in the phase conductor L without providing a neutral conductor N passing through the protective switchgear SG.

[0097] 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 L,

[0098] A grid-side connection point EUG is provided, which is electrically connected to a grid-side phase conductor connection terminal LG, and

[0099] 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,

[0100] The electronic interruption unit has a high-resistance state of the switching element to prevent current flow or a low-resistance state of the switching element for current flow in the low-voltage circuit by means of a semiconductor-based switching element,

[0101] a current sensor unit SI for determining the magnitude of the current of the low-voltage circuit, which current sensor unit is arranged in particular in the phase conductor L,

[0102] - a control unit SE which is connected to the current sensor unit SI, the mechanical isolating contact unit MK and the electronic interruption unit EU, wherein when a current limit value and / or a current-time limit value is exceeded, the prevention of a current flow in the low-voltage circuit is initiated, preferably by a high-impedance state of the electronic interruption unit EU.

[0103] According to the invention, the protection switchgear SG is designed such that at least one temperature sensor connected to the control unit SE is provided for determining the magnitude of the temperature. The at least one temperature sensor is arranged at or in the region of the connection terminal.

[0104] In accordance with Figure 1A In the example:

[0105] The grid-side neutral conductor connection terminal NG has a first grid-side temperature sensor TNG (=grid-side neutral conductor temperature sensor TNG),

[0106] The grid-side phase conductor connection LG has a second grid-side temperature sensor TLG (=grid-side phase conductor temperature sensor TLG),

[0107] The load-side neutral conductor connection terminal NL has a load-side first temperature sensor TNL (=load-side neutral conductor temperature sensor TNL),

[0108] The load-side phase conductor connection LL has a second load-side temperature sensor TLL (=load-side phase conductor temperature sensor TLL).

[0109] The mentioned temperature sensors are each connected to a control unit SE.

[0110] According to the present invention, the protection switch device SG is designed so that when the temperature of (at least) one of the above-mentioned temperature sensors of the connecting terminal) exceeds a first temperature threshold, the electronic interruption unit EU is switched to a high impedance state of the switching element to avoid current flow, thereby avoiding overheating of the connecting terminal of the protection switch device.

[0111] Furthermore, a first voltage sensor unit SUA connected to the control unit SE can be provided, which determines the magnitude of the voltage of the low-voltage circuit, in particular the instantaneous value of the magnitude of the voltage, in particular at the grid-side connecting terminals LG, NG, in particular between the grid-side neutral conductor connecting terminal NG and the grid-side phase conductor connecting terminal LG. Advantageously, the electronic interruption unit EU is switched into the low-resistance state when the value of the instantaneous value of the magnitude of the voltage falls below a first voltage limit, in particular less than or equal to 50 volts (or 25 volts or 10 volts).

[0112] Typically, the mechanical disconnecting contact unit MK and the electronic interruption unit EU form a series circuit. The series circuit is connected to at least one mains-side connection on the one hand and to at least one load-side connection on the other hand. The mechanical disconnecting contact unit MK can advantageously be associated with the load-side connection and the electronic interruption unit EU can be associated with the mains-side connection, as in Figure 1A The mechanical disconnecting contact unit MK can be operated by a mechanical handle HH in order to switch the opening of the contacts or the closing of the contacts, as in conventional line protection switches or miniature circuit breakers (MCBs).

[0113] The control unit SE can have a microcontroller (microcontroller unit).

[0114] In accordance with Figure 1A In the example of , the electronic interruption unit EU is embodied as a single pole, in this example in the phase conductor. In this case, the grid-side connection point APNG for the neutral conductor of the mechanical disconnecting contact unit MK is connected to the grid-side neutral conductor connection terminal NG of the housing GEH. In a single-pole variant of the protective switchgear SG, this connection can be omitted, and the neutral conductor contact KKN of the mechanical disconnecting contact unit can also be omitted.

[0115] 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.

[0116] The mechanical disconnecting contact unit MK can be operated by a mechanical handle HH on the protective switchgear SG to manually (manually) open or close the switching contacts KKL, KKN. The mechanical handle HH (in the unlocked state) (particularly through the mechanical connection between the contact and the handle) indicates the switching state (open or closed) of the contacts of the mechanical disconnecting contact unit MK on the protective switchgear.

[0117] The mechanical disconnecting contact unit MK is advantageously designed so that the contacts can only be closed (manually) by a mechanical handle after release (Enable), in particular a release signal. 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 release signal (from the control unit SE). In the absence of a release or release signal, the handle HH can be operated, but the contacts cannot be closed ("continuous slippage").

[0118] The protective switchgear SG has an energy supply device NT (not shown), for example a power supply unit. In particular, the energy supply device NT is provided for the control unit SE. The energy supply device NT is connected, for example, to a neutral conductor connection terminal NG on the grid side and to a phase conductor connection terminal LG on the grid side. In the connection to the neutral conductor connection terminal NG on the grid side (or / and the phase conductor connection terminal LG), a fuse SS, in particular a blown fuse or / and a switch can advantageously be provided.

[0119] In the case of a purely single-pole circuit breaker device, the energy supply is effected via an external energy source / another connection.

[0120] 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.

[0121] Low resistance refers to a state in which a given current value can flow in the protective switching device. 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.

[0122] In a first variant, the mechanical disconnecting contact unit MK can be interrupted unipolarly. That is, only one conductor (one of two / multiple conductors), in particular an active conductor or a phase conductor, is interrupted, that is to say with a mechanical contact. The neutral conductor is thus contactless, that is to say the neutral conductor is directly connected.

[0123] In a second variant of the mechanical disconnecting contact unit MK, the neutral conductor also has a mechanical contact (two-pole interruption), as shown in FIG. 1 .

[0124] The mechanical disconnecting contact unit MK refers in particular to the disconnecting function (compliant with standards) which is implemented by the disconnecting contact unit MK. The disconnecting function is defined as the following:

[0125] - According to the standard minimum air distance (minimum distance of contacts),

[0126] - (mechanical) contact position indication of the contacts of a mechanically separated contact unit,

[0127] A free triggering or release function, ie an operation for interrupting the mechanical separation of the contacts of the contact unit by means of a handle or a control unit, is always possible, so that it is not possible to (permanently) lock the contacts in the closed state by means of the handle.

[0128] In particular, a free-release or release function means that at least one contact can be opened by the control unit even if the mechanical handle (for example in the switched-on state) is blocked.

[0129] Furthermore, the standard disconnect function can include the ability to lock the disconnect contact unit or the handle in the switched-on or switched-off state.

[0130] As regards the minimum air distance between the contacts of the separating contact system, this minimum air distance depends essentially on the voltage. Other parameters are the degree of contamination, the type of field (homogeneous, inhomogeneous) and the air pressure or the height above the standard zero point.

[0131] There are corresponding regulations or standards for this minimum air distance or creepage distance. These regulations, for example, stipulate the minimum air distance in air for the impulse withstand voltage, which is used for inhomogeneous and uniform (ideal) electric fields depending on the degree of pollution. The impulse withstand voltage is the strength that can be withstood when a corresponding impulse voltage is applied. Only when this minimum length (minimum distance) exists does the separating contact unit or the protective switch device have a separating function (separator characteristic).

[0132] In this context, in the context of the present invention, with regard to the function of the separator and its characteristics, in particular the standard series DIN EN 60947 or IEC 60947 are relevant, to which reference is hereby made.

[0133] The disconnect contact system is advantageously characterized by a minimum air distance of the disconnected contacts in the off position (open position, open contacts), depending on the rated impulse withstand voltage and the degree of contamination. The minimum air distance is in particular between (minimum) 0.01 mm and 14 mm.

[0134] Particularly advantageously, the minimum air distance is between 0.01 mm at 0.33 kV and 14 mm at 12 kV, in particular for pollution degree 1 and in particular for inhomogeneous fields.

[0135] Advantageously, the minimum air distance may have the following values:

[0136] E DIN EN 60947-1 (VDE 0660-100): 2018-06

[0137] Table 13 - Minimum air distances

[0138]

[0139] The degree of pollution and the field type correspond to the degree of pollution and the field type defined in the standard. This advantageously makes it possible to achieve a standard-compliant circuit breaker device that is dimensioned according to the rated surge voltage resistance.

[0140] Mechanically isolating contact units do not in particular refer to relay contacts.

[0141] The circuit breaker device can have a (in particular wireless / cordless) communication unit COM which is connected to the control unit SE or is part of the control unit SE.

[0142] When the fourth temperature threshold is exceeded, a warning may be issued by means of the communication unit COM. Alternatively or additionally, the magnitude of the temperature may be output (communicated) by means of the communication unit COM. For the grid side Grid or (and) the load side Load, an output or communication of exceeding the temperature limit value or (and) the temperature magnitude may be performed. Alternatively or additionally, for each temperature sensor, an output or communication of exceeding the temperature limit value or (and) the temperature magnitude may be performed.

[0143] In addition, a display unit AE can be provided. The display unit AE can be designed as a combined display and input unit. The display unit AE (display and input unit) is connected to the control unit SE or is part of the control unit SE. The display unit has a display device visible on the protective switch device, in particular for displaying the high resistance or low resistance state of the electronic interruption unit EU. As an alternative or supplement to displaying the temperature limit value (first or / and second or / and third or / and fourth temperature limit value) or (and) the temperature magnitude. For the grid side Grid or (and) the load side Load, the temperature limit value or (and) the temperature magnitude can be displayed. Alternatively or additionally, for each temperature sensor, the temperature limit value or (and) the temperature magnitude can be displayed.

[0144] The protective switching device SG operates, for example, in principle in the following manner: when the contacts of the mechanically separating contact unit are closed and the electronic interruption unit has a low resistance,

[0145] - if the determined current exceeds a first current value, in particular if the first current value is exceeded for a first time limit, the electronic interruption unit EU becomes high-resistance and the mechanical separation contact unit MK remains closed, or / and

[0146] - (or / and) if the determined current exceeds a second, higher current value, in particular if the second, higher current value is exceeded for a second time limit, the electronic interruption unit EU becomes high-resistance and the mechanical separation contact unit MK opens, or / and

[0147] If the determined current exceeds a third, still higher, current value, the electronic interruption unit becomes high-resistance and the mechanical isolating contact unit MK opens.

[0148] The electronic interruption unit EU can have a further interruption unit-side temperature sensor TSE. The functionality provided by this interruption unit-side temperature sensor can be similar to the connection terminal-side temperature sensor(s) (TLG, TNG, TLL, TNL, TG, TL).

[0149] Figure 1B Shown according to Figure 1A The diagram of the protective switchgear is different in that

[0150] Only one grid-side temperature sensor TG is provided for (for example two) grid-side connecting terminals. It is used to determine the magnitude of the temperature of the grid-side connecting terminal. The grid-side temperature sensor TG is advantageously arranged between (advantageously adjacent) grid-side connecting terminals NG, LG.

[0151] Only one load-side temperature sensor is provided for (for example two) load-side connecting terminals. It is used to determine the magnitude of the temperature of the load-side connecting terminal. The load-side temperature sensor TL is advantageously arranged between (advantageously adjacent) load-side connecting terminals NL, LL.

[0152] The grid-side temperature sensor TG and the load-side temperature sensor TL are respectively connected to the control unit SE.

[0153] Function or work similar to Figure 1A or the functions or working methods described below.

[0154] Figure 2 A diagram or a diagram of a first coordinate system is shown, in which the magnitude of the current I of the low-voltage circuit is plotted on the horizontal axis (abscissa) and the temperature T of one of the temperature sensors (on the connection terminal side) is plotted on the vertical axis (ordinate). TS size.

[0155] The figure shows the (corresponding) temperature T of the temperature sensor TS A curve that changes with the magnitude of the current I in the low-voltage circuit.

[0156] It is assumed here that the heating at the connection terminal depends on the magnitude of the current I through the low-voltage circuit of the protective switchgear (the protective switchgear is to protect the low-voltage circuit). As the magnitude of the current I increases, the temperature of the connection terminal increases. Therefore, the temperature T of the protective switchgear determined by the temperature sensor TSThe temperature increases monotonically with the current. (In addition to the current, the ambient temperature also affects the heat generation in the protection switchgear. To simplify the diagram, this is Figure 2 Not shown.)

[0157] according to Figure 2 , different temperature thresholds are shown: a first temperature threshold 1.SW (100°C in the example), a second temperature threshold 2.SW (110°C in the example), and a third temperature threshold 3.SW (80°C in the example).

[0158] Figure 3 Shown according to Figure 2 , except that three interrelated diagrams are shown, wherein the time t is plotted on the horizontal axis (abscissa).

[0159] exist Figure 3 In the upper region of the graph, the temperature T of the (selected) temperature sensor is plotted. TS The magnitude of changes with time t. A first temperature threshold 1.SW and a third temperature threshold 3.SW are shown.

[0160] exist Figure 3 In the middle region of , the change in the magnitude of the current I over time t is plotted.

[0161] exist Figure 3 In the lower region of FIG. , the switching state of the electronic interruption unit EU is plotted over time t. The low-resistance state of the electronic interruption unit EU is represented by on. The high-resistance state of the electronic interruption unit EU is represented by off.

[0162] For example, a (constant) current I or a current I having a constant effective value of a first magnitude flows for a certain time ( Figure 3 Center). A corresponding heating occurs at the connection terminals. Temperature / determined temperature T of the temperature sensor TS The magnitude of increases until it reaches the first temperature threshold 1.SW( Figure 3 upper part).

[0163] When a first temperature threshold 1.SW (in the example 100° C.) is reached or exceeded, the electronic interruption unit EU switches to the high-resistance state off (of the switching element) to prevent a current flow, at a first time t1 ( Figure 3 Thus, further heating and overheating of the connection terminals (and damage associated therewith) are avoided.

[0164] The protection switch device and the connection terminals can cool down. At the second time t2, the third temperature threshold 3.SW is reached or fallen below, in the example 80°C. When the third temperature threshold 3.SW is reached or fallen below, the electronic interruption unit (again) (at the second time t2) switches to the low-resistance state on (for current flow in the low-voltage circuit) ( Figure 3 The current I can flow again (from the second time point t2) ( Figure 3 middle). Possibly, the temperature can be raised again ( Figure 3 upper part).

[0165] The third temperature threshold is lower than the first temperature threshold.

[0166] Alternatively or additionally, instead of the third temperature threshold 3.SW, a first time period may be waited for from the occurrence of the high impedance state of the switching element. After the first time period has passed from the occurrence of the high impedance state of the electronic interruption unit, the electronic interruption unit is switched to the low impedance state (not shown).

[0167] If the changeover between the high resistance state for avoiding overheating and the return to the low resistance state is too frequent, at least one contact of the mechanical separation contact unit MK is disconnected. That is, in the case where the changeover (switching) between the high resistance state for avoiding overheating and the return to the low resistance state exceeds a first number, at least one contact of the mechanical separation contact unit MK is disconnected within a first time frame.

[0168] Figure 4 Shown according to Figure 3 , except that a fourth graph is shown, which is associated with the three above graphs.

[0169] The fourth chart is Figure 4 The change of the switching state of the mechanical isolation contact unit MK over time t is shown in the lowermost area of ​​. The closed state of at least one contact of the mechanical isolation contact unit MK is marked as closed. The open state of at least one contact of the mechanical isolation contact unit MK is marked as open.

[0170] In addition, Figure 4 A first temperature threshold value 1.SW and a second temperature threshold value 2.SW are shown in the upper region of FIG.

[0171] For example, a (constant) current I of a first magnitude flows for a certain period of time ( Figure 4 Center). Corresponding heating occurs at the connection terminals. Temperature in the protective switchgear / temperature determined by the temperature sensor T TS The magnitude of increases until it reaches the first temperature threshold 1.SW( Figure 4 upper part).

[0172] When a first temperature threshold 1.SW (in the example 100° C.) is reached or exceeded, the electronic interruption unit EU switches to the high-resistance state off (of the switching element) to prevent a current flow, at a first time t1 ( Figure 4 lower part).

[0173] Current decreases ( Figure 4 middle).

[0174] If now the temperature continues to rise despite the electronic interruption unit EU switching to high resistance, for example because the electronic interruption unit EU is defective (i.e. the high resistance state is activated, but for example does not function or does not function completely) and a (small) current flows, then when the second temperature threshold 2.SW (110° C. in the example) is reached or exceeded, at least one contact of the mechanical separation contact unit MK opens ( Figure 4 bottom), at a third time point t3.

[0175] The second temperature threshold 2.SW is higher than the first temperature threshold 1.SW.

[0176] Figure 5 Shown according to Figure 3 The difference is that in Figure 5 The output of a warning Warn. as a function of time t is shown in the middle region of .

[0177] also, Figure 5 The upper area of ​​shows a first temperature threshold 1.SW and a fourth temperature threshold 4.SW. When the fourth temperature threshold is exceeded at a fourth time point t4, a warning Warn. is issued by means of the communication unit COM (wirelessly / wiredly). For example, it is output to a superior management system. Alternatively or additionally, the warning can be displayed, for example, using a display unit AE. The fourth temperature threshold is less than the first temperature threshold.

[0178] The electronic interruption unit EU remains in the low-resistance state on.

[0179] Alternatively or additionally, the magnitude of the temperature can be output (wirelessly / wiredly) by means of the communication unit COM. For example, to a higher-level management system. Alternatively or additionally, the magnitude of the temperature can be displayed, for example, using a display unit AE.

[0180] Figure 6 Shown according to Figure 5 The difference is that the time offset (time delay) t V That is, when the fourth temperature threshold 4.SW is exceeded at the fourth time point t4, no warning Warn. is issued, but Figure 6As shown, the warning Warn. is issued only at the fifth time point t5. Thus, for example, a warning based on a short-term heating caused by a short-term increase in starting current or switching current can be avoided. TS If the temperature drops below the fourth temperature threshold 4.SW again, no warning Warn. is issued.

[0181] Time offset (time delay) t V In the range of 1 second, ..., 5 seconds, ...10 seconds, ...1 minute.

[0182] Hereinafter, in other words, the present invention is explained again.

[0183] In electrical (sub)distribution systems there are a number of different protection and switching devices which are interconnected via corresponding lines. When designing such subdistribution systems, thermal considerations and calculations must also be made, since losses occur in the subdistribution systems due to ohmic losses in the conductors and electrical operating devices. The subdistribution systems thus heat up. Currently, thermal overloads are prevented by corresponding (over)dimensioning (according to standards, guidelines or regulations).

[0184] In addition to the thermal design of electrical sub-distribution systems mentioned above, electrical connection points (connection terminals) often lead to thermal overloads and fires. This can be caused by incorrect commissioning (contamination, incorrect tightening torque of screw connections, loose connection terminals) or by aging (corrosion).

[0185] Today, both installing companies and insurance companies stipulate that a visual inspection by a qualified electrician is carried out. However, in this case, it is possible that not every faulty terminal point will be found.

[0186] According to the invention, temperature measurements are performed at (selected / multiple) connecting terminals of the protective switchgear. The temperature measuring device and other device components are connected to a control unit so that a corresponding algorithm can shut down the device before dangerous temperatures are generated at the connection points / connecting terminals, in order to protect the device / sub-distribution system from dangerous fires.

[0187] Modern electronic protection and switching devices use electronic switching elements (power semiconductors) in the main current path. If a critical temperature is reached, a high-resistance state is initiated. As a result, current can no longer flow through the protection switching device and through the connection terminals, and the connection terminals (and the sub-distribution system) cool down.

[0188] Furthermore, a corresponding message can be issued for warning.

[0189] Since no current flows through the device any more, the connection terminals and the device cool down again. After falling below a certain temperature, the device can automatically switch to a low-resistance state for current flow (hysteresis).

[0190] Depending on the device configuration, instead of the low-resistance state, opening of the contacts of the mechanically separated contact unit can also be initiated. Automatic reclosing after cooling is then not possible. Manual reclosing of the contacts is required.

[0191] 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, comprising: a housing (GEH) having at least two grid-side connections and at least one load-side connection, the grid-side connection and the at least one load-side connection each have a connection terminal for connecting an external conductor of the low-voltage circuit to be protected to the protective switching device, a mechanical isolating contact unit (MK) which is connected in series with the electronic interruption unit (EU), wherein the series circuit is connected on the one hand to one of the at least two network-side connections and on the other hand to the at least one load-side connection, - the mechanically separating contact unit (MK) is switchable by opening at least one contact to prevent current flow or by closing at least one contact for current flow in the low-voltage circuit, the electronic interruption unit (EU) is capable of switching via a semiconductor-based switching element to a high-resistance state of the switching element to prevent a current flow or to a low-resistance state of the switching element for a current flow in the low-voltage circuit, - a current sensor unit (SI) for determining the magnitude of the current of the low-voltage circuit, - a control unit (SE) connected to the current sensor unit (SI), the mechanical separation contact unit (MK) and the electronic interruption unit (EU), wherein: When the determined magnitude of the current exceeds a current limiting value and / or a current-time limiting value, preventing the current flow in the low-voltage circuit is initiated, - providing at least one temperature sensor connected to the control unit for determining the temperature, - the at least one temperature sensor is arranged at or in the region of the connection terminal, The protective switching device is designed to switch the electronic interruption unit (EU) into a high-resistance state of the switching element to prevent a current flow and thus to prevent overheating of the connecting terminal when the temperature exceeds a first temperature threshold value (1.SW).

2. The protective switchgear (SG) according to claim 1, It is characterized in that The mechanical disconnecting contact unit (MK) is associated with the load-side connection and the electronic interruption unit (EU) is associated with the grid-side connection.

3. The protective switchgear (SG) according to claim 1 or 2, It is characterized in that Two grid-side connections and two load-side connections are provided.

4. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that In the case of an activated high-impedance state of the switching element of the electronic interruption unit (EU) to avoid overheating and when a second, higher temperature threshold (2.SW) is exceeded, at least one contact of the mechanically separating contact unit (MK) is opened.

5. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that In the case of a high-resistance state of the switching element of the electronic interruption unit (EU) to avoid overheating, and when the temperature falls below a third temperature threshold (3.SW), the electronic interruption unit (EU) is switched to a low-resistance state.

6. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The third temperature threshold is lower than the first temperature threshold.

7. A protective switchgear (SG) according to any one of claims 1 to 4, It is characterized in that In the case of a high-resistance state of the switching element to avoid overheating and in the case of a first time period elapsing since the occurrence of the high-resistance state of the switching element to avoid overheating, the electronic interruption unit is switched into a low-resistance state.

8. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that In case a first number of changes to a high impedance state to avoid overheating is exceeded, at least one contact of the mechanically disconnecting contact unit (MK) is opened within a first time frame.

9. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that A communication unit (COM) is provided which is connected to the control unit (SE).

10. The protective switchgear (SG) according to claim 9, It is characterized in that When a fourth temperature threshold value (4.SW) is exceeded, a warning is output by means of the communication unit (COM).

11. Protection switchgear (SG) according to claim 9 or 10, It is characterized in that The temperature (T TS ) or equivalent.

12. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that At least one contact of the mechanically disconnecting contact unit (MK) can be opened by the control unit (SE), but cannot be closed.

13. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The mechanically disconnecting contact unit (MK) can be operated by a mechanical handle (HH) in order to switch the at least one contact open or the at least one contact closed.

14. The protective switchgear (SG) according to claim 13, It is characterized in that At least one contact of the mechanical separation contact unit (MK) has a release function, so that even if the mechanical handle (HH) is locked, the at least one contact is disconnected by the control unit (SE).

15. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that At least one grid-side temperature sensor is provided for the grid-side connection terminal to determine the temperature of the grid-side connection terminal.

16. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that At least one load-side temperature sensor is provided for the at least one load-side connection terminal, so as to determine the temperature of the at least one load-side connection terminal.

17. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that A temperature sensor is provided for each connection terminal, in particular a current-carrying conductor of a low-voltage circuit, in order to determine the magnitude of the temperature of the respective connection terminal.

18. A method for a protective switchgear (SG) for protecting a low voltage circuit, comprising: a housing (GEH) having at least two grid-side connections and at least one load-side connection, the grid-side connection and the at least one load-side connection each have a connection terminal for connecting an external conductor of the low-voltage circuit to be protected to the protective switching device, a mechanical isolating contact unit (MK) which is connected in series with the electronic interruption unit (EU), wherein the series circuit is connected on the one hand to at least one mains-side connection and on the other hand to the at least one load-side connection, - the mechanically separating contact unit (MK) is switchable by opening at least one contact to prevent current flow or by closing at least one contact for current flow in the low-voltage circuit, the electronic interruption unit (EU) is capable of switching via a semiconductor-based switching element to a high-resistance state of the switching element to prevent a current flow or to a low-resistance state of the switching element for a current flow in the low-voltage circuit, - determining the magnitude of the current (I) of the low voltage circuit, - the prevention of the flow of current in the low-voltage circuit when a current limit value and / or a current-time limit value is exceeded, - determining a temperature (T TS ), - at the temperature (T TS ) exceeds a first temperature threshold (1.SW), the electronic interruption unit (EU) is switched to a high-resistance state of the switching element to prevent current flow, thereby preventing overheating of the connecting terminal.

19. The method according to claim 18, It is characterized in that In the case of an activated high-impedance state of the switching element to avoid overheating, and when a second, higher temperature threshold value (2.SW) is exceeded, at least one contact of the mechanically separating contact unit (MK) is opened.

20. The method according to claim 18 or 19, It is characterized in that In the case of a high-resistance state of the switching element to avoid overheating, and below a third temperature threshold (3.SW), the electronic interruption unit (EU) is switched to a low-resistance state, In particular, the third temperature threshold (3.SW) is smaller than the first temperature threshold (1.SW).

21. The method according to claim 18 or 19, It is characterized in that In the case of a high-resistance state of the switching element to avoid overheating and in the case of a first time period elapsing since the occurrence of the high-resistance state of the switching element to avoid overheating, the electronic interruption unit is switched into the low-resistance state.

22. The method according to claim 18, 19, 20 or 21, It is characterized in that In case a first number of changes to a high impedance state to avoid overheating is exceeded, at least one contact of the mechanically disconnecting contact unit (MK) is opened within a first time frame.

23. The method according to claim 18, 19, 20, 21 or 22, It is characterized in that When the fourth temperature threshold (4.SW) is exceeded, a warning (Warn.) is issued.

24. The method of claim 18, 19, 20, 21, 22 or 23, It is characterized in that Output the temperature (T TS ) or equivalent.

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