CN116685855A - Protection switch device and method - Google Patents

Abstract

The invention relates to a method for protecting a circuit of a protection switching device, wherein: the mechanical disconnection contact element (MK) is connected in series with the electronic interruption Element (EU). The mechanically decoupled contact unit (MK) can be switched by opening the contacts to avoid a current flow or closing the contacts for a current flow in the electrical circuit. An electronic interrupt unit (EU) can be switched to a high impedance state of the switching element by the semiconductor-based switching element to avoid current flow or to a low impedance state of the switching element for current flow in the low voltage circuit. The current level in the low-voltage circuit is determined and, if the current level exceeds at least one current threshold, the avoidance of the current flow of the low-voltage circuit is initiated by means of a high-impedance switched electronic interrupt unit (EU). For a high-impedance or high-impedance switched electronic interruption unit (EU), the current level in the low-voltage circuit is continuously determined, and in the event of a first fault current threshold being exceeded, the contact opening of the mechanically decoupled contact unit (MK) is initiated.

Description

Protection switch device and method

Technical Field

The invention relates to the technical field of protection switching devices for low-voltage circuits with electronic interrupt units and to a method for protection switching devices for low-voltage circuits with electronic interrupt units.

Background

Low voltage refers to voltages up to 1000 volts ac or up to 1500 volts dc. The low voltage is in particular a voltage greater than a small voltage, which has a value of 50 volts ac or 120 volts dc.

A low voltage circuit or low voltage network or low voltage system refers to a circuit rated or nominal current up to 125 amps, more particularly up to 63 amps. A low-voltage circuit refers in particular to a circuit rated or rated up to 50, 40, 32, 25, 16 or 10 amperes. The current values mentioned refer in particular to the rated current, the nominal current or/and the off current, i.e. the maximum current that is normally conducted through the circuit, or the current that the circuit normally interrupts, for example by a protection device, such as a protection switching device or a line protection switch or a circuit breaker.

Line protection switches are known over-current protection devices for a long time, which are used in low-voltage circuits in electrical installation technology. The line protection switch protects the line from damage caused by heating due to excessive current and/or short circuits. The line protection switch may automatically shut down the circuit in case of overload and/or short circuit. The line protection switch is a fuse element that is not automatically reset. Unlike line protection switches, the current of the circuit breaker is set to be greater than 125 amps, and in some cases also starts from 63 amps. Therefore, the structure of the line protection switch is simpler and more elaborate. Line protection switches generally have the option of being fastened to so-called top hat rails (support rails, DIN rails, TH 35).

The circuit protection switch adopts an electromechanical structure. In the housing, they have mechanical switch contacts or operating current triggers for interrupting (triggering) the current. In general, bimetallic protection elements or bimetallic elements are used to trigger (interrupt) in the event of prolonged overcurrent (overcurrent protection) or thermal overload (overload protection). Electromagnetic triggers with coils are used for short-term triggering in the event of an overcurrent limit being exceeded or in the event of a short circuit (short-circuit protection). One or more arc extinguishing chambers or means for extinguishing arc are provided. Furthermore, a connection element for a conductor of the circuit to be protected is provided.

Protection switching devices with electronic interrupt units are relatively new developments. The protection switching device has a semiconductor-based electronic interrupt unit. That is, the current of the low voltage circuit is conducted through a semiconductor device or semiconductor switch that can interrupt the current or switch to conduct. Protection switching devices with electronic interrupt units also generally have mechanically separate contact systems, which in particular have a separate characteristic according to the relevant standards for the low-voltage circuit, wherein the contacts of the mechanically separate contact system are connected in series to the electronic interrupt unit, i.e. the current of the low-voltage circuit to be protected is conducted both through the mechanically separate contact system and through the electronic interrupt unit.

In semiconductor-based protection switching devices or solid state circuit breakers (Solid State Circuit Breaker, abbreviated to SSCB), the switching energy does not need to be converted into an arc as in mechanical switching devices, but rather into heat by means of additional circuits, energy absorbers. The shut-down energy here comprises the energy stored in the circuit, i.e. the energy stored in the network impedance, the line impedance or the load impedance (consumer impedance). In order to reduce the load on the energy absorber, the current flowing at the moment of switching off must be as low as possible. This also applies in the case of a short circuit. The current here rises very fast. By means of the rapid short-circuit detection, short-circuits can be found early, and excessive short-circuit currents are avoided. The semiconductor-based protection switching device interrupts the circuit in the region of μs with little delay in the sense of the switching-off process. No high currents occur and the load on the energy absorber of the semiconductor-based protection switching device is reduced. Known short circuit detection or shutdown criteria are typically based on the determination and evaluation of actual current values.

The invention relates to a low voltage ac circuit having an ac voltage, typically a sinusoidal ac voltage with a frequency f, typically 50 or 60 hertz (Hz), depending on time. The time dependence of the instantaneous voltage value u (t) of the alternating voltage is described by the following equation:

u(t)＝U*sin(2π*f*t)

Wherein:

instantaneous voltage value at u (t) =time t

U=amplitude of voltage (maximum value)

The harmonic alternating voltage can be represented by a rotation of a pointer, the length of which corresponds to the amplitude (U) of the voltage. Here, the instantaneous deflection is the projection of the pointer onto the coordinate system. The oscillation period corresponds to a complete rotation of the pointer and its full angle is 2Pi (2 Pi) or 360 °. The angular frequency is the rate of change of this rotating pointer phase angle. The angular frequency of harmonic oscillations is always 2pi times its frequency, namely:

ω=2pi×f=2pi/t=angular frequency of ac voltage (t=period duration of oscillation)

The description of angular frequency (ω) is generally preferred over frequency (f) because many vibration theory formulas can be more compactly represented by angular frequency due to the occurrence of trigonometric functions, which by definition have a period of 2pi:

u(t)＝u*sin(ωt)

in the case of angular frequencies that are not constant over time, the term instantaneous angular frequency is also used.

In the case of sinusoidal, in particular temporally constant, alternating voltages, the time-dependent value as a function of the angular velocity ω and the time t corresponds to the time-dependent angleThis angle is also called phase angle>That is, the phase anglePeriodically through a range of 0..2 pi.or 0..360 °. That is, the phase angle periodically assumes a value between 0 and 2pi or 0 and 360- >Or->Due to periodicity; abbreviated as: />Or->)。

The instantaneous voltage value u (t) thus refers to the instantaneous value of the voltage at the point in time t, i.e. in the case of a sinusoidal (periodic) alternating voltage, with respect to the phase angleThe value of the voltage (">Or->For the corresponding period).

Disclosure of Invention

The object of the present invention is to improve a protection switching device of the above-mentioned type, in particular to increase the safety of the protection switching device and the safety in the low-voltage circuit, in particular to avoid undesired currents caused by faults or ageing.

The above-mentioned problem is solved by a protection switching device having the features of claim 1 and by a method according to claim 15.

According to the invention, there is provided an (electronic) protection switching device for protecting a low-voltage circuit, in particular a low-voltage alternating-current circuit, having:

a housing with a first, in particular grid-side connection and a second, in particular load-side connection for conductors of the low-voltage circuit,

a mechanically separate contact unit connected in series with the electronic interruption unit,

wherein in particular a mechanically separate contact unit is associated with the (second) load-side joint, and an electronic interruption unit is associated with the (first) grid-side joint,

Wherein the mechanically separate contact unit can be switched by opening the contacts to avoid current flow or closing the contacts for current flow in the electrical circuit,

wherein the electronic interruption unit can be switched by means of the semiconductor-based switching element to a high impedance state of the switching element to avoid a current flow or to a low impedance state of the switching element for a current flow in the circuit,

a current sensor unit for determining the current magnitude of the low-voltage circuit (of the at least one conductor, in particular of the phase conductor) in order to obtain an instantaneous current value,

a control unit connected to the current sensor unit, the mechanically decoupled contact unit and the electronic interrupt unit,

wherein when the current magnitude exceeds at least one current threshold value, the avoidance of the current flow of the low-voltage circuit is initiated by a high-impedance switching of the electronic interrupt unit (EU),

wherein the protection switching device is designed such that for a high-impedance or high-impedance switched electronic interruption unit (i.e. when the electronic interruption unit should be in a high-impedance state) and the contact opening of the mechanically decoupled contact unit is initiated when the current in the low-voltage circuit exceeds a first fault current threshold.

It should be realized according to the invention that in the case of high-impedance or high-impedance switched electronic interrupt units, the avoidance of current flow in the circuit is safely realized. If, in spite of the presence of the high-impedance or high-impedance switched electronic interruption unit, a current exceeding the fault current threshold is determined in the low-voltage circuit, in particular in the phase conductor (in particular in the case of a two-pole protection switching device with a neutral conductor and a phase conductor), the galvanic isolation is initiated by opening the contacts of the mechanically separated contact unit for safety reasons.

The safety in the low-voltage circuit is thus increased by means of the safety protection switching device.

This has the special advantage that in case of (dangerous) residual currents or faulty electronic interruption units the circuit is opened, i.e. a higher safety is provided.

Advantageous embodiments of the invention are set forth in the dependent claims.

In an advantageous embodiment of the invention, the first connection is a network-side connection and the second connection is a load-side connection. The mechanically decoupled contact unit is associated with the load-side connection and the electronic interrupt unit is associated with the grid-side connection.

This has the particular advantage that a power supply for the protection switching device, in particular for the control unit, is provided. Furthermore, even in the case of a mechanically separated contact unit with a broken contact, the power supply of the protection switching device is available.

In an advantageous embodiment of the invention, a communication unit is provided which is connected to the control unit. The communication unit refers in particular to a wireless or wired or optical communication to a further protection switching device, a computer or an upper management system. The protection switching device is designed to signal information by means of the communication unit in the case of a high-impedance or high-impedance switched electronic interrupt unit and in the case of a current in the low-voltage circuit exceeding a first fault current threshold.

This has the particular advantage that such problems can be reported, so that measures can be taken to improve the safety again.

In an advantageous embodiment of the invention, a display unit is provided, which is connected to the control unit, in particular for displaying information on the protection switching device. The protection switching device is designed to display information in the event of a high-impedance or high-impedance switched electronic interrupt unit and in the event of a current in the low-voltage circuit exceeding a first fault current threshold.

This has the particular advantage that faulty behaviour is signaled on the protection switching device.

In an advantageous embodiment of the invention, the first fault current threshold is in the range of 30mA, 6mA or 300 mA. More particularly in the range 26 to 30mA, in particular in order to advantageously provide personnel protection, in particular in europe. More particularly in the range of 4 to 6mA, in particular in order to advantageously provide personnel protection, in particular in north america/the united states. More particularly in the range 290 to 300mA, in particular in order to advantageously ensure fire protection.

In an advantageous embodiment of the invention, the check whether the first fault current threshold is exceeded is performed only after a first time limit for the contact of the mechanically separated contact unit and for the high impedance of the electronic interruption unit. In particular after a first time limit of at least 50 μm, more in particular after 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1 ms.

This has the particular advantage that the checking is only performed after a non-critical time limit, in particular for personnel protection, and thus the switching behavior of the electronic interruption unit, in particular of an existing energy absorber or overvoltage protection element, is taken into account together in order to avoid false triggers or unnecessary interruptions caused by mechanically separated contact units.

In an advantageous embodiment of the invention, the first fault current threshold value must be exceeded for a first duration in order to cause the contact to open, the message to be signaled or the message to be displayed.

This has the particular advantage that short-term transients, in particular transients caused by switching behaviour of the electronic interruption unit, in particular of an existing energy absorber or overvoltage protection element, are not taken into account. False triggering or unnecessary interruption by mechanically separating the contact units is thereby avoided, so as not to limit the usability of the power supply and to ensure the safety of the power supply.

In an advantageous embodiment of the invention, the first duration is dependent on the determined current level.

This has the particular advantage that a higher security is ensured. At high currents, triggering is rapid and at low currents, behavior can be observed for a longer period of time. Thus, the personnel safety is ensured, and the power supply safety is also ensured.

In an advantageous embodiment of the invention, the first duration is at least 50 μm, in particular greater than 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1ms.

Furthermore, the first duration may be up to 5ms.

This has the particular advantage that there is a specific duration.

In an advantageous embodiment of the invention, a voltage sensor unit is provided, which is connected to the control unit, for determining the voltage level at the electronic interruption unit, in particular at the conductor, in particular at the phase conductor. The voltage magnitude is compared to a voltage threshold and if the voltage threshold is exceeded, the check is suspended for a second duration of time if the first fault current threshold is exceeded.

The second duration may be less than 10ms.

The voltage threshold is greater than the magnitude of the (nominal) grid voltage of the low voltage circuit (and thus greater than 325 volts in a 230 volt grid).

In particular, the voltage threshold is higher than the voltage threshold of the elevated grid voltage. For example, the elevated grid voltage is a voltage that is more than 10% higher than the (nominal) magnitude of the grid voltage (for a 230 volt grid, the magnitude is about 325 volts, so the magnitude of the elevated grid voltage is about 360 volts).

In particular, the voltage threshold is smaller than the compressive strength of the semiconductor-based switching element (power semiconductor) used for the electronic interruption unit.

This has the particular advantage that (temporarily) ineffective grid conditions are taken into account, i.e. for example when a surge occurs or lightning hits the low-voltage circuit or a lightning produces a temporary overvoltage, which according to the invention is not taken into account.

Thus, the robustness of the protection switching device is improved without neglecting the safety.

In an advantageous embodiment of the invention, a single control element is provided on the protection switching device, in particular, with which a threshold value for the current threshold value or the current increase can be adjusted in order to adjust the threshold value for the overcurrent or short-circuit detection.

This has the particular advantage that the adjustment can be performed by means of a current threshold or by means of a current increase threshold or a current change threshold.

In an advantageous embodiment of the invention, the protection switching device is designed such that

The control unit has an analog first subunit and a digital second subunit. The first subunit has a current comparator, to which the instantaneous current value or current change value and at least one current threshold value or instantaneous current change threshold value are fed, in particular from the second Subunit (SED). The current threshold or current change threshold is provided phase-dependently by the second subunit according to a time profile of the voltage. This may enable a comparison of the instantaneous current value or instantaneous current change value with at least one current threshold or instantaneous current change threshold, the comparison being phase-dependent with respect to the time profile of the voltage. This allows to initiate an interruption of the low voltage circuit when exceeded.

This has the particular advantage of a simple implementation solution.

In an advantageous embodiment of the invention, the protection switching device is designed to provide a grid synchronization unit. The grid synchronization unit determines at least one phase angle of the voltage from the supplied instantaneous voltage valueAnd alternatively determining the magnitude (U) of the voltage. A threshold unit is provided, which is connected to the grid synchronization unit and possibly to the regulating element, in such a way that the phase angle of the voltage is used +.>The amplitude (U) of the voltage and in particular a set threshold value for the current threshold value or current increase determine the instantaneous current (change) threshold value. The instantaneous current (change) value is phase-dependently compared to an instantaneous current (change) threshold to determine initiation of the interrupt.

This has the particular advantage of a further simple implementation solution.

In an advantageous embodiment of the invention, the mechanically decoupled contact system is designed such that galvanic isolation, i.e. switching on (as opposed to switching off), with standard isolation characteristics is possible. Thus, a standard protection switching device is present.

A corresponding method for a protective switching device for a low-voltage circuit with an electronic (semiconductor-based) switching element is claimed according to the invention, which method has the same and further advantages.

In a method for protecting a low voltage circuit:

the mechanically separating contact unit is connected in series with the electronic interruption unit,

the mechanically separate contact unit can be switched by opening the contacts to avoid current flow or closing the contacts for current flow in the electrical circuit,

the electronic interruption unit may be switched by the semiconductor-based switching element to a high impedance state of the switching element to avoid a current flow or to a low impedance state of the switching element for a current flow in the low voltage circuit,

determining the current level in the low-voltage circuit and if the current level exceeds at least one current threshold (or current change threshold), initiating avoidance of current flow of the low-voltage circuit by switching the electronic interrupt unit with high impedance,

for high-impedance or high-impedance switched electronic interruption units, the current level in the low-voltage circuit (in particular in the phase conductors) is continued to be determined and, if a first fault current threshold is exceeded, the contact opening of the mechanically separated contact unit is initiated.

In an advantageous embodiment, the information is signaled when the first fault current threshold is exceeded.

In an advantageous embodiment, the check is performed after a first time limit if the first fault current threshold is exceeded, with a high impedance of the mechanically decoupled contact unit contact and the electronic interrupt unit.

In an advantageous embodiment, the first fault current threshold value must be exceeded for a first duration in order to cause the contact to open, the information to be signaled or the information to be displayed.

According to the invention, a corresponding computer program product is claimed. The computer program product comprises commands which, when the program is executed by the microcontroller (=microprocessor), lead to an improved safety of such a protection switching device or to a higher safety in a low-voltage circuit protected by the protection switching device, in particular to the avoidance of mechanically separated contact units performing a current flow in certain situations. The microcontroller (=microprocessor) is part of a protection switching device, in particular a control unit.

A corresponding computer-readable storage medium, on which a computer program product is stored, is claimed according to the invention.

A corresponding data carrier signal carrying the computer program product is claimed according to the invention.

All the embodiments, whether referring to claims 1 or 15 or to only a single feature or a combination of features of the claims, lead to an improvement of the protection switching device for increased safety.

Drawings

The described features, characteristics and advantages of the present invention, as well as the manner of attaining them, will become more apparent and the invention will be better understood in conjunction with the following description of embodiments taken in conjunction with the accompanying drawings.

In the drawings herein:

figure 1 shows a first illustration of a protection switching device,

figure 2 shows a second illustration of the protection switching device,

figure 3 shows a third illustration of the protection switching device,

fig. 4 shows a first embodiment of the protection switching device.

Detailed Description

Fig. 1 shows a schematic representation of a protection switching device SG for protecting a low-voltage circuit, having a housing GEH, having:

the first connections L1, N1 of the conductors for the low-voltage circuit, in particular the network-side connections EQ, in particular the energy source-side connections, of the protection switch unit SG, and the second connections L2, N2 of the connections ES (consumer-side connections), in particular the load-side connections (in the case of passive loads), of the protection switch unit SG, wherein in particular the phase-conductor-side connections L1, L2 and the neutral-conductor-side connections N1, N2 can be provided;

the load-side connection may have a passive load (load) and/or an active load ((additional) energy source), or a load that is both passive and active in time sequence, for example;

A- (optional) first voltage sensor or first voltage sensor unit SU for determining the voltage level of the voltage circuit, thereby providing an instantaneous voltage value (phase-dependent voltage value) DU,

a current sensor or current sensor unit SI for determining the current level of the circuit to obtain an instantaneous (phase angle dependent) current value DI,

an electronic interruption unit EU which, by means of the semiconductor-based switching element having or being switchable to a high-impedance state of the switching element for interrupting and a low-impedance state of the switching element for a current flow in the low-voltage circuit,

mechanically separating the contact elements MK, which can be switched by opening the contacts to avoid a current flow or closing the contacts for a current flow in the electrical circuit,

a control unit SE connected to the (optional) first voltage sensor unit SUI, the current sensor unit SI and the electronic interrupt unit EU;

the control unit SE may:

* Implemented with digital circuitry, for example with a microprocessor (=microcontroller); the microprocessor may also include an analog portion;

* May be implemented using digital circuitry having analog circuitry portions.

The protection switch SG, in particular the control unit SE, is designed to initiate the avoidance of the current flow of the low-voltage circuit by switching the electronic interrupt unit EU with high impedance when the current level exceeds at least one current threshold value,

Such that in the case of a high-impedance or high-impedance switched electronic interrupt unit EU and in the case of a current in the low-voltage circuit exceeding a first fault current threshold, the contact opening of the mechanical disconnection contact unit MK is initiated.

Upon detection of a short circuit, in particular a load side (ES) short circuit, the electronic interrupt unit EU switches from a low impedance state to a high impedance state to interrupt the low voltage circuit, wherein the process has a trigger time from a short circuit event to the high impedance state. This may be achieved by continuously adjusting the current threshold. Thus, there may be a (periodic) instantaneous current (change) threshold, which depends on the voltage magnitude or the (periodic) time profile of the determined instantaneous voltage value.

The instantaneous current (change) threshold may be continuous or may exist phase angle by phase angle.

Here, the instantaneous current (change) threshold may be every single phase angle, phase angle range(s), e.g. every 2 °, or phase angle part (part of a phase angle), e.g. every 0.5 ° or 0.1 °. In particular, a resolution of 1 ° to 5 ° (which corresponds to a sampling rate of 3.5 to 20 kHz) is particularly advantageous.

The instantaneous current (change) value is phase-dependently compared to an instantaneous current (change) threshold. In case the absolute value exceeds the instantaneous current (change) threshold, for example by means of a first interrupt signal TRIP from the control unit SE to the electronic interrupt unit EU, an interruption of the low voltage circuit is initiated, as shown in fig. 1.

According to fig. 1, the electronic interrupt unit EU is drawn as a square in two conductors. In a first variant, this means that neither conductor is interrupted. At least one conductor, in particular the active conductor or the phase conductor, has a semiconductor-based switching element. The neutral conductor may be switchless, i.e. without semiconductor-based switching elements. That is, the neutral conductor is directly connected, i.e. does not become high impedance. That is, only one monopole (of the phase conductor) is interrupted. If a further active conductor/phase conductor is provided, in a second variant of the electronic interruption unit EU the phase conductor has a semiconductor-based switching element. The neutral conductor is directly connected, i.e. does not become high impedance. For example for a three-phase ac circuit.

In a third variant of the electronic interruption unit EU, the neutral conductor may also have a semiconductor-based switching element, i.e. both conductors become high-impedance when the electronic interruption unit EU is interrupted.

The electron interruption unit EU may have a semiconductor device such as a bipolar transistor, a Field Effect Transistor (FET), an Insulated Gate Bipolar Transistor (IGBT), a metal oxide layer field effect transistor (MOSFET), or other (self-commutating) power semiconductors. In particular, IGBTs and MOSFETs are particularly suitable for the protection switching device according to the invention due to their low on-resistance, high junction resistance and good switching behaviour.

The protection switching device SG has a mechanically separate contact unit MK (= mechanisches Trennkontaktsystem MK), in particular for galvanic isolation of the electrical circuit, in particular for standard-oriented switching on (with respect to switching off) of the electrical circuit, according to a standard having standard-oriented isolation properties. The mechanically decoupled contact element MK can be connected to the control unit SE, as shown in fig. 1, so that the control unit SE can initiate a galvanic isolation of the circuit.

In particular, further evaluations may be carried out which lead to galvanic isolation if other criteria are met. For example, it is possible to provide for an overcurrent detection, for example, in the control unit SE, when an overcurrent, i.e. when a current exceeding a current-time limit value, is applied for a certain time, i.e. when a certain energy threshold value, is exceeded, the control unit interrupting the circuit based on semiconductors or/and the current.

Alternatively or additionally, galvanic isolation may also be initiated, for example, in the event of a short circuit being detected.

The activation of the current interruption of the low-voltage circuit is carried out, for example, by a further second interrupt signal TRIPG, which is sent from the control unit SE to the mechanically separate contact system MK, as shown in fig. 1.

According to the invention, in the case of a high-impedance electronic interrupt unit EU or a high-impedance switched electronic interrupt unit EU, i.e. when the electronic interrupt unit EU is to be in a high-impedance state, and in particular when the current in the low-voltage circuit detected by the current sensor SI exceeds a first fault current threshold, a galvanic isolation is initiated. Depending on the field of application of the protection switching device, the first current threshold value may be on the order of 4 to 6mA, in particular at 5mA or 6mA. The first current threshold may be in the range 25mA to 32mA, in particular at 28mA, 29mA or 30mA, in particular for european personnel protection. The third threshold may be in the range of 290mA to 300mA, particularly for fire protection. Each of the edge values and intermediate values mentioned are disclosed.

According to the invention, the current determination in this case is performed with a current sensor unit SI. No additional sensor, such as a sum current transformer, is required, which is used, for example, for fault current protection switches. Nevertheless, a (further) sum current transformer may be provided in the protection switching device.

With the present invention, fault currents are detected and disconnected in case of defective or not completely high impedance of the interrupt cells. According to the invention, this is done in a conductor (phase conductor) with a current sensor unit.

In a further advantageous embodiment, in the event of a determined current level exceeding the second current threshold value, an interruption of the electrical circuit can be initiated, in particular by mechanically separating the contact system.

The second current threshold corresponds to, for example, a standard-compliant current (time) limit value, i.e., an I (t) characteristic of the solid-state circuit breaker, for example, according to standard IEC 60947 or IEC 60898. The person skilled in the art selects the chosen current (time) limit value according to the current application.

In a further advantageous embodiment, in the event of an interruption of the low-voltage circuit initiated by the electronic interruption unit and in the event of a current in the low-voltage circuit exceeding a third current threshold value for a second duration, the interruption of the low-voltage circuit can be initiated by the mechanically decoupled contact system, for example, in order to cause the interruption by the mechanically decoupled contact system in the event of a failure of the high impedance of the electronic interruption unit and thus of the interruption of the low-voltage circuit. Thereby advantageously increasing the operational reliability. This procedure can be advantageously displayed on the protection switching device.

The third current threshold and the second time period correspond, for example, to current-time limit values which meet a standard, i.e. I-t characteristic curves of solid-state circuit breakers, for example according to standard IEC 60947 or IEC 60898. The person skilled in the art selects the chosen current-time limit value according to the current application.

In a first variant, the mechanically decoupled contact system MK can be interrupted monopolarly. That is, only one of the two conductors, in particular the active conductor or the phase conductor, is interrupted, i.e. has mechanical contacts. Thus, the neutral conductor is contactless, i.e. the neutral conductor is directly connected.

If further active conductors/phase conductors are provided, in a second variant the phase conductors have mechanical contacts of a mechanically separate contact system. In a second variant, the neutral conductor is directly connected. For example for a three-phase ac circuit.

In a third variant of the mechanically decoupled contact system MK, the neutral conductor likewise has a mechanical contact, as shown in fig. 1.

The mechanical disconnection contact system MK is in particular a (standard) disconnection function, which is achieved by the disconnection contact system MK. The separation function refers to the following points:

according to a standard minimum air distance (minimum distance of contacts),

a contact position indication of the contacts of the mechanically decoupled contact system,

actuation of the mechanically decoupled contact system is always possible (without latching of the decoupled contact system).

Regarding the minimum air distance between the contacts of the split contact system, this minimum air distance is substantially dependent on the voltage. Other parameters are the degree of contamination, the field type (uniform, non-uniform) and the air pressure or the height above the standard zero.

There is a corresponding provision or standard for this minimum air distance or creepage distance. These regulations define, for example, in air, for impact pressure strength, a minimum air distance, which is used for non-uniform and uniform (ideal) electric fields, depending on the degree of pollution. The impact pressure resistance is a strength that can be endured when a corresponding impact voltage is applied. Only in the presence of this minimum length (minimum distance) the disconnection contact system or the protection switching device has a disconnection function (disconnection characteristic).

In the sense of the present invention, the standard series DIN EN 60947 or IEC 60947 are relevant for the separator function and its characteristics, which are hereby incorporated by reference.

The separate contact system is advantageously characterized by a minimum air distance of the open separate contacts in the off position (open position, open contacts) depending on the rated impact pressure strength and the degree of contamination. The minimum air distance is in particular between (minimum) 0.01mm and 14 mm. It is particularly advantageous if the minimum air distance is between 0.01mm at 0.33kV and 14mm at 12kV, in particular for a pollution level of 1 and in particular for inhomogeneous fields.

Advantageously, the minimum air distance may have the following value:

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

TABLE 13 minimum air distance

The contamination level and field type correspond to those defined in the standard. A standard protection switching device dimensioned according to the rated impact pressure resistance can thus advantageously be realized.

Fig. 2 shows the illustration according to fig. 1 with further detailed design and differences. In the example according to fig. 2, the mechanical disconnection contact element MK is associated with the load-side second connection L2, N2 or the load-side/consumer-side ES. The electronic interruption unit EU is associated with a first connection L1, N1 of a connection EQ on the grid side, in particular on the energy source side. That is, the series circuit of the mechanical disconnection contact element MK and the electronic disconnection unit EU connecting the first and second terminals is exchanged with respect to fig. 1. According to fig. 2, the mechanical disconnection contact element MK is associated with a load-side connection, and the electronic disconnection unit EU is associated with a grid-side connection. The power supply of the protection switching device can advantageously be provided by a grid-side connection. Typically the protection switching device is powered in this way.

According to fig. 2, the control unit SE has two subunits, a preferably analog first subunit SEA and a preferably digital second subunit SED. The first subunit SEA has a (current) comparator CI here. On the one hand, the instantaneous current (change) value DI of the current sensor SI is fed to the current comparator. On the other hand, the instantaneous current (change) threshold SWI is fed from the second subunit SED to the current comparator CI.

The current comparator CI compares the instantaneous current (variation) value DI with an instantaneous current (variation) threshold SWI and, as mentioned, when exceeded, outputs a first current interruption signal TI to initiate interruption of the low-voltage circuit.

The power interruption signal TI may be fed to a logic unit LG which combines it with other interruption signals and provides a first interruption signal TRIP to an electronic interruption unit EU for semiconductor-based or high-impedance interruption.

In one embodiment, the current comparator CI registers the instantaneous threshold SWI so that these values are always available.

Wherein the instantaneous current (change) threshold SWI is synchronized with the time profile of the instantaneous voltage value (time profile of the voltage). Thus, for small instantaneous voltages (e.g., phase angles of sinusoidal alternating voltages of-30 ° to 0 ° to 30 °), a small instantaneous current (variation) threshold SWI is used (or present), and for high instantaneous voltages (e.g., phase angles of sinusoidal alternating voltages of 60 ° to 90 ° to 120 °), a large current (variation) threshold SWI is used (or present), so that the triggering time is largely independent of the phase angle of the voltage, so that the triggering time is lower than the first threshold in time.

The instantaneous current (variation) value/current value DI is also fed to the second subunit SED. In a preferred embodiment, the instantaneous current value DI is digitized there by an analog-to-digital converter ADC and fed to the microprocessor CPU. The microprocessor performs a determination or calculation of the instantaneous current (change) threshold SWI. The instantaneous current (change) threshold SWI determined by the second subunit SED or in particular by the microprocessor CPU is fed again to the first subunit SEA, in particular to the current comparator CI, to perform the above-mentioned comparison.

The instantaneous current (change) threshold SWI may advantageously be determined in the second subunit SED digitally or at a slower processing speed relative to a continuous comparison of the instantaneous current (change) value DI in the first subunit SEA with the instantaneous current (change) threshold SWI.

In an advantageous embodiment of the invention, the first subunit SEA can have a voltage comparator CU. On the one hand, the instantaneous voltage value DU of the voltage sensor SU is fed to the voltage comparator. On the other hand, the instantaneous voltage threshold SWU is fed from the second subunit SED to the voltage comparator CU.

The voltage comparator CU compares the instantaneous voltage value DU with an instantaneous voltage threshold SWU and sends a voltage interruption signal TU when exceeding or falling below or range checking to initiate interruption of the low voltage circuit.

The voltage interrupt signal TU may be fed to a logic unit LG which combines it with a (further) interrupt signal and sends a first interrupt signal TRIP to the electronic interrupt unit EU for semiconductor-based interrupts or high impedance interrupts.

In one embodiment, the voltage comparator CU registers the instantaneous threshold SWU so that these values are always available.

In this embodiment, the instantaneous voltage value DU can also be fed to the second subunit SED. In a further preferred embodiment, the instantaneous voltage value DU is digitized there by an analog-to-digital converter ADC and fed to the microprocessor CPU. The microprocessor performs the determination or calculation of the instantaneous voltage threshold SWU. The instantaneous voltage threshold SWU determined by the second subunit SED or in particular by the microprocessor CPU is again fed to the first subunit SEA, in particular to the voltage comparator CU, to perform the above-mentioned comparison.

In this case, the instantaneous voltage threshold SWU can advantageously be determined in the second subunit SED digitally or at a slower processing speed, which is a slower processing speed relative to the continuous comparison of the instantaneous voltage value DU and the instantaneous voltage threshold SWU in the first subunit SEA.

According to a further embodiment, a second interrupt signal TRIPG can be sent from the second subunit SED of the control unit SE, in particular from the microprocessor CPU, to the mechanical disconnection contact system MK for current interruption of the circuit, as shown in fig. 2.

The design of the control unit with an analog first subunit and a digital second subunit has the particular advantage that an efficient architecture exists. The simulated first subunit can make a very fast comparison of the instantaneous value and the threshold value, making a fast short-circuit detection possible. The second subunit may perform threshold calculations or adjustments independent of short circuit detection without having to perform as quickly as detection. For example, the threshold may be cached for fast comparison. The threshold does not need to be constantly adjusted.

In addition, by means of a combination of a current value or a current variation value and a voltage value, a higher evaluation reliability can also be achieved.

According to the invention, the protection switching device is designed such that in the case of a high-impedance switched electronic interrupt unit EU, the current is further monitored. This can be achieved by adjusting the current threshold SWI. That is, the current threshold SWI is then set to the first fault current threshold. That is, the current value DI is then compared with a (lower) current threshold SWI (first fault current threshold, e.g. 30 mA). Alternatively, for this case, the current value may also be evaluated by the digital second subunit SED.

In case the first fault current threshold is exceeded, the contact opening of the mechanically decoupled contact unit (MK) is initiated (either via a further connection from the first subunit SEA or its (current) comparator CI [ not drawn ], or via the second subunit SED).

Fig. 3 shows a diagram according to fig. 1 and 2. A series circuit of a mechanically separate contact unit MK and an electronic breaking unit EU, which electrically connects the first and the second connector, is provided according to fig. 2, the first connector L1, N1 being a grid-side connector and the second connector L2, N2 being a load-side connector, wherein the mechanically separate contact unit MK is associated with the load-side connector and the electronic breaking unit EU is associated with the grid-side connector. The control unit SE is denoted by a first subunit SEA and a second subunit SED.

Fig. 3 shows the difference that a second voltage sensor unit SU2 is provided, which is connected to the control unit, for determining the voltage level across the electronic interrupt unit. The second voltage sensor unit SU2 determines the voltage level over the electronic interruption unit of the conductor of the electronic interruption unit. In the example (preferably) in a phase conductor.

The voltage magnitude is compared to a voltage threshold and, if the voltage threshold is exceeded, a check is suspended for a second duration of time if the first fault current threshold is exceeded.

The second duration is less than 10ms.

The voltage threshold is greater than the magnitude of the grid voltage of the low voltage circuit, in particular greater than the magnitude of the boosted (e.g. + 10%) grid voltage, in particular greater than 10% of the grid voltage magnitude relative to the grid voltage magnitude.

The voltage threshold should be selected to be smaller than the compressive strength of the semiconductor-based switching element used in the electronic break unit EU. A communication unit (not shown) connected to the control unit SE may be provided on the protection switching device. Such as a communication module with WLAN possibilities. The protection switching device is designed such that in the case of a high-impedance or high-impedance switched electronic interrupt unit EU and in the case of a current in the low-voltage circuit exceeding a first fault current threshold, information is signaled by means of the communication unit.

On the protective switching device, a display unit (not shown in the figure) with information display, such as LEDs, segmented displays, etc., can be provided, which is connected to the control unit SE. The protection switching device is designed such that information is displayed in the event of a high-impedance or high-impedance switched electronic interrupt unit EU and in the event of a current in the low-voltage circuit exceeding a first fault current threshold.

According to the invention, in the case of a high impedance of the contact-making and electronic interruption units EU of the mechanically separated contact unit MK, a check can be performed after a first time limit (i.e. the first time limit is suspended in time) whether the first fault current threshold is exceeded, in particular after a first time limit of at least 50 μm, more particularly after 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1ms.

According to the invention, exceeding the first fault current threshold can only be continued for a first duration to cause the contacts to open, the information to be signaled or the information to be displayed. The first duration may depend on the determined current magnitude. The first duration may be at least 50 μm, in particular greater than 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1ms. The first duration is at most 5ms.

The control of the monitoring may be at least partly implemented by software or firmware, i.e. a computer program product, for the control unit or the second subunit or the microcontroller (=microprocessor) thereof.

Fig. 4 shows a further embodiment or variant according to fig. 1, 2 and 3. Fig. 4 shows a part of a simple variant of the preferably analog first subunit SEAE and a part of an alternative variant of the preferably digital second subunit SEDE.

A part of the simple variant of the first subunit SEAE has a current comparator CIE, to which an instantaneous current value DI, in particular its absolute value, and an instantaneous current threshold SWI, in particular an instantaneous current threshold SWI which is likewise dependent on the absolute value, are fed. The current comparator CIE in this example directly outputs a first interrupt signal TRIP for interrupting the low voltage circuit, similar to the previous figures. The absolute value formation may be performed by one or other units not shown.

Part of the alternative variant of the second subunit SEDE has a grid synchronization unit NSE. The (analog) instantaneous voltage value DU is fed to the grid-synchronous unit. The grid synchronization unit NSE determines the phase angle of the voltage from the fed (analog) instantaneous voltage value DU The instantaneous voltage value is, for example, a sinusoidal alternating voltage of the low-voltage circuit.

Alternatively, the amplitude U and the desired time value of the voltage UE and the desired value of the voltage UE may be additionally determined.

Here, the desired value of the voltage UE is a filtered or regenerated or generated equivalent instantaneous voltage value DU.

Phase angle of voltage DUThe (and the desired value or amplitude U of the voltage UE) may be determined, for example, by a so-called phase locked loop or Phase Locked Loop, abbreviated PLL. A PLL is an electronic circuit arrangement that influences the phase of a variable oscillator and the frequency associated therewith by means of a closed-loop control loop such that the phase deviation between an externally periodic reference signal (instantaneous voltage value) and the oscillator or a signal derived therefrom is as constant as possible. The phase locked loop may also be programmed as software (within the framework of a computer program product) of a microcontroller.

Thus, among other things, the phase angle of the fed grid voltage is determinedThe fundamental frequency and its amplitude, i.e. the determined voltage value, i.e. the (undisturbed or filtered) desired value of the (grid) voltage as well.

Phase angle determined by grid synchronization unit NSE(and possibly the amplitude U and/or the desired time value of the voltage UE) is fed to the threshold unit SWE. The threshold unit SWE may have a (scaled) curve of the (phase-dependent) instantaneous current threshold SWI. For example, in the case of a sinusoidal alternating voltage of a low voltage circuit, a (nearly) sinusoidal current threshold curve, i.e. a sinusoidal curve in magnitude of the instantaneous current threshold SWI over a phase angle of 0 ° to 360 ° or period duration (or (corresponding) time).

The protection switching device SG can have in particular only one actuating element. With this adjusting element, in particular with the only one adjusting element on the protection switch SG, a threshold value of the current threshold value or of the current increase can be set. Alternatively, the limit value of the current threshold may also be fixedly set or programmed.

According to the invention, the current threshold curve is then scaled as a function of the limit value of the current threshold set by means of the adjusting element. For example, the magnitude (i.e., maximum) of the current threshold curve may be scaled with the margin value of the current threshold.

By the phase angle of the voltage in the threshold unit SWEFrom this threshold unit, the instantaneous current threshold SWI can be sent to the current comparator CIE in synchronization with the instantaneous current value DI, so that a phase-dependent (phase angle-dependent) comparison can be made between the instantaneous current value DI and the instantaneous current threshold SWI.

The current threshold value can also be stored (scaled) in a table, wherein this value is adjusted if necessary.

In order to operate normally and to avoid a current flow of the low-voltage circuit by checking whether the current level exceeds at least one current threshold value, a control unit according to the invention, in particular a control unit having two subunits, can be used in order to switch the electronic interrupt unit with high impedance. The current threshold may be fixed or may be adjusted according to the invention (instantaneous current threshold).

For current detection of the high-impedance or high-impedance switched electronic interrupt unit EU only a (fixed) first fault current threshold is required. Only a part of the control unit according to the invention is needed here. Detection may also be performed by other means.

Although the invention has been illustrated and described in detail with reference to specific embodiments, the invention is not limited to the examples disclosed and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (21)

1. A protection switching device (SG) for protecting a low voltage circuit, having:

a housing (GEH) having a first connection (L1, N1) and a second connection (L2, N2) for conductors of a low-voltage circuit,

a series circuit of a mechanically separate contact unit (MK) and an electronic interrupt unit (EU), said series circuit electrically connecting the first and the second terminal,

wherein the mechanically decoupled contact unit (MK) can be switched by opening the contacts to avoid current flow or closing the contacts for current flow in the low-voltage circuit,

wherein the electronic interruption unit (EU) is capable of switching to a high impedance state of the switching element by means of a semiconductor-based switching element to avoid a current flow or to a low impedance state of the switching element for a current flow in a low-voltage circuit,

A current sensor unit (SI) for determining a current magnitude of the electrical circuit to obtain an instantaneous current value,

a control unit (SE) which is connected to the current sensor unit (SI), the mechanical disconnection contact unit (MK) and the electronic interruption unit (EU),

wherein when the current magnitude exceeds at least one current threshold value, the avoidance of the current flow of the low-voltage circuit is initiated by a high-impedance switching of the electronic interrupt unit (EU),

-wherein the protection switching device is designed such that in case of a high-impedance or high-impedance switched electronic interruption unit (EU) and in case of a current in the low-voltage circuit exceeding a first fault current threshold, the contact opening of the mechanically separated contact unit (MK) is initiated.

2. Protection switching device (SG) according to claim 1, characterized in that,

the first connection (L1, N1) is a connection on the grid side and the second connection (L2, N2) is a connection on the load side,

the mechanical disconnection contact element (MK) is associated with a load-side connection and the electronic disconnection unit (EU) is associated with a grid-side connection.

3. Protection switching device (SG) according to any of the preceding claims, characterized in that,

A communication unit is provided which is connected to the control unit (SE),

the protection switching device is designed such that in the case of a high-impedance or high-impedance switched electronic interrupt unit (EU) and in the case of a current in the low-voltage circuit exceeding a first fault current threshold, information is signaled by means of the communication unit.

4. Protection switching device (SG) according to any of the preceding claims, characterized in that,

a display unit connected to the control unit (SE) is arranged on the protection switch device, the display unit has information display,

the protection switching device is designed such that information is displayed in the event of a high-impedance or high-impedance switched electronic interrupt unit (EU) and in the event of a current in the low-voltage circuit exceeding a first fault current threshold.

5. Protection switching device (SG) according to any of the preceding claims, characterized in that,

the first fault current threshold is in the range of 30mA, 6mA or 300mA, more particularly in the range of 26 to 30mA, 4 to 6mA or 290 to 300 mA.

6. Protection switching device (SG) according to any of the preceding claims, characterized in that,

In the case of a contact-on of the mechanically decoupled contact unit (MK) and a high impedance of the electronic interrupt unit (EU), a check is performed after a first time limit as to whether a first fault current threshold is exceeded,

in particular after a first time limit of at least 50 μm, more in particular after 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1ms.

7. Protection switching device (SG) according to any of the preceding claims, characterized in that,

exceeding the first fault current threshold must last for a first duration in order to cause the contacts to open, the information to be signaled, or the information to be displayed.

8. Protection switching device (SG) according to claim 7, characterized in that,

the first duration depends on the determined current magnitude.

9. Protection switching device (SG) according to claim 7 or 8, characterized in that,

the first duration is at least 50 μm, in particular greater than 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 950 μm or 1ms.

10. Protection switching device (SG) according to claim 7, 8 or 9, characterized in that,

the first duration does not exceed 5ms.

11. Protection switching device (SG) according to any of the preceding claims, characterized in that,

providing a second voltage sensor unit (SU 2) connected to the control unit for determining the voltage level over the electronic interruption unit of the conductor,

the voltage magnitude is compared to a voltage threshold and, if the voltage threshold is exceeded, a check is suspended for a second duration of time if the first fault current threshold is exceeded.

12. Protection switching device (SG) according to claim 11, characterized in that,

the second duration is less than 10ms.

13. Protection switching device (SG) according to claim 11 or 12, characterized in that,

the voltage threshold is greater than the amplitude of the mains voltage of the low-voltage circuit, in particular greater than the amplitude of the elevated mains voltage,

in particular, the magnitude of the elevated grid voltage relative to the grid voltage is a voltage that is more than 10% higher than the magnitude of the grid voltage.

14. Protection switching device (SG) according to claim 11, 12 or 13, characterized in that,

The voltage threshold is smaller than the compressive strength of the semiconductor-based switching element used in the electronic interruption unit (EU).

15. A method for protecting low voltage circuitry for a protection switching device, wherein:

the mechanical disconnection contact element (MK) is connected in series with the electronic interruption Element (EU),

the mechanically decoupled contact unit (MK) can be switched by opening the contacts to avoid current flow or closing the contacts for current flow in the electrical circuit,

the electronic interruption unit (EU) is capable of switching to a high impedance state of the switching element by means of a semiconductor-based switching element to avoid a current flow or to a low impedance state of the switching element for a current flow in the electrical circuit,

determining the current level in the low-voltage circuit and, if the current level exceeds at least one current threshold, initiating avoidance of the current flow of the low-voltage circuit by means of a high-impedance switched electronic interrupt unit (EU),

-for a high-impedance or high-impedance switched electronic interruption unit (EU), continuing to determine the current level in the low-voltage circuit and, in case a first fault current threshold is exceeded, initiating the contact opening of the mechanically decoupled contact unit (MK).

16. The method of claim 15, wherein the step of determining the position of the probe is performed,

signaling information if the first fault current threshold is exceeded.

17. The method according to claim 15 or 16, wherein,

in the event of a contact-on of the mechanically decoupled contact unit (MK) and a high impedance of the electronic interruption unit (EU), a check is performed after a first time limit as to whether the first fault current threshold is exceeded.

18. The method of claim 15, 16 or 17, wherein,

exceeding the first fault current threshold must last for a first duration in order to cause the contacts to open, the information to be signaled, or the information to be displayed.

19. A computer program product comprising commands which, when a program is executed by a microcontroller, cause the microcontroller to support, in particular to perform, the method steps of the protection switching device according to any one of claims 1 to 18.

20. A computer readable storage medium on which the computer program product of claim 19 is stored.

21. A data carrier signal carrying the computer program product according to claim 19.