Circuit breaker device and method
Patent Information
- Application Number
- EP2023797669
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-04
- Filing Date
- 2023-10-11
- Publication Date
- 2025-07-16
AI Technical Summary
Existing protective switching devices for low-voltage circuits lack flexibility and phase-specific control, as they typically operate all contacts simultaneously, which limits their ability to manage overcurrent conditions effectively in multi-phase circuits.
A protective switching device with a combination of mechanical and electronic components, allowing independent switching of phase conductors into high- or low-resistance states, and featuring current and voltage sensors to manage current flow selectively based on threshold values, enabling phase-specific intervention and enhanced flexibility.
This solution provides greater flexibility and safety in managing overcurrent conditions by allowing independent control of each phase conductor, reducing unnecessary power disruptions and enhancing the security of the electrical supply.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Protective switching device and procedure
[0003] The invention relates to the technical field of a protective switching device for a low-voltage circuit with electronic switches and a method for a protective switching device for a low-voltage circuit with electronic switches.
[0004] Low voltage refers to voltages of up to 1000 volts AC or up to 1500 volts DC. Low voltage refers in particular to voltages greater than extra-low voltage, with values of 50 volts AC or 120 volts DC.
[0005] The term low-voltage circuit, network or system refers to circuits with nominal or rated currents of up to 125 amperes, more specifically up to 63 amperes. The term low-voltage circuit particularly refers to circuits with nominal or rated currents of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values mentioned refer in particular to nominal, rated and / or breaking currents, i.e. the maximum current that is normally carried through the circuit or at which the electrical circuit is usually interrupted, for example by a protective device such as a protective switching device, circuit breaker or circuit breaker. The rated currents can be further staggered, from 0.5 A to 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.
[0006] Miniature circuit breakers are long-established overcurrent protection devices used in low-voltage electrical circuits. They protect cables from damage caused by overheating due to excessive current and / or short circuits. A miniature circuit breaker can automatically disconnect the circuit in the event of an overload and / or short circuit. A miniature circuit breaker is a non-self-resetting fuse element.
[0007] Unlike miniature circuit breakers, circuit breakers are designed for currents greater than 125 A, and in some cases even as low as 63 A. Miniature circuit breakers are therefore simpler and more delicate in design. Miniature circuit breakers typically have a mounting option for mounting on a so-called top-hat rail (support rail, DIN rail, TH35).
[0008] Miniature circuit breakers are electromechanical in design. They contain a mechanical switching contact or shunt release in a housing to interrupt (trip) the electrical current. A bimetallic protective element or bimetallic element is usually used to trip (interrupt) the circuit in the event of a prolonged overcurrent (overcurrent protection) or thermal overload (overload protection). An electromagnetic release with a coil is used for brief tripping when an overcurrent limit is exceeded or in the event of a short circuit (short-circuit protection). One or more arc quenching chambers or devices for arc quenching are provided. There are also connection elements for conductors of the electrical circuit to be protected.
[0009] Protective switching devices with an electronic interruption unit or an electronic switch are relatively new developments. These have a semiconductor-based electronic interruption unit / switch. This means that the electrical current flow in the low-voltage circuit is guided via semiconductor components or semiconductor switches, which interrupt the electrical current flow or can be switched to conduction. Protective switching devices with an electronic interruption unit / switch also often have a mechanical isolating contact unit, in particular with isolating properties in accordance with the relevant standards for low-voltage circuits, with the contacts of the mechanical isolating contact unit being connected in series to the electronic interruption unit / electronic switches, i.e.The current of the low-voltage circuit to be protected is conducted via both the mechanical isolating contact unit and the electronic interruption unit.
[0010] The present invention relates in particular to low-voltage alternating current circuits with an alternating voltage, usually with a time-dependent sinusoidal alternating voltage with the frequency f. The time dependence of the instantaneous voltage value u(t) of the alternating voltage is described by the equation: u(t) = U * sin (2n * f * t). Where: u(t) = instantaneous voltage value at time t
[0011] U = amplitude of the voltage
[0012] A harmonic alternating voltage can be represented by the rotation of a pointer whose length corresponds to the amplitude (U) of the voltage. The instantaneous deflection is the projection of the pointer onto a coordinate system. One oscillation period corresponds to one full rotation of the pointer, and its full angle is 2n (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 2n times its frequency, i.e.: w = 2n*f = 2n / T = angular frequency of the alternating voltage (T = period of the oscillation)
[0013] Often the angular frequency (w) is specified compared to the
[0014] Frequency (f) is preferred because many formulas of oscillation theory can be represented more compactly using the angular frequency due to the occurrence of trigonometric functions whose period is by definition 2n: u ( t ) = U * sin (wt)
[0015] In the case of angular frequencies that are not constant over time, the term instantaneous angular frequency is also used.
[0016] In the case of a sinusoidal, in particular temporally constant, alternating voltage, the time-dependent value of the angular velocity w and the time t corresponds to the time-dependent angle cp ( t ) , which is also referred to as the phase angle cp ( t ). This means that the phase angle cp ( t ) periodically passes through the range O...2n or 0°...360°. This means that the phase angle periodically assumes a value between 0 and 2n or 0° and 360° (cp = n* (0...2n) or cp = n* ( 0 °...360 ° ) , due to periodicity; in short: cp = O...2n or cp = 0°...360° ).
[0017] The instantaneous voltage value u(t) is therefore the instantaneous voltage value at time t, i.e., for a sinusoidal (periodic) alternating voltage, this refers to the voltage value at the phase angle cp (cp = 0...2n or cp = 0°...360°, of the respective period). The same applies to instantaneous current values i(t), etc.
[0018] The object of the present invention is to improve a protective switching device of the type mentioned above, in particular to demonstrate a new concept for a multi-phase protective switching device and to enable greater flexibility for a multi-phase protective switching device.
[0019] This object is achieved by a protective switching device having the features of patent claim 1, as well as by a method according to patent claim 17.
[0020] According to the invention, a protective switching device for protecting an electrical multi-phase low-voltage alternating current circuit with a neutral conductor, in particular a three-phase low-voltage alternating current circuit with a neutral conductor, is proposed, comprising:
[0021] - a housing with a first, second and third mains-side phase connection and a first, second and third load-side phase connection for a first, second and third phase conductor of the three-phase low-voltage AC circuit, a mains-side neutral conductor connection and a load-side neutral conductor connection for a neutral conductor of the low-voltage AC circuit,
[0022] - a first series circuit of a first mechanical phase contact and a first electronic switch, a second series circuit of a second mechanical phase contact and a second electronic switch, a third series circuit of a third mechanical phase contact and a third electronic switch, wherein the first series circuit electrically connects the first mains-side phase connection to the first load-side phase connection, the second series circuit electrically connects the second mains-side phase connection to the second load-side phase connection, and the third series circuit electrically connects the third mains-side phase connection to the third load-side phase connection,
[0023] - that the mains-side neutral conductor connection is connected to the load-side neutral conductor connection via a mechanical neutral conductor contact,
[0024] - that the mechanical phase contacts and the mechanical neutral contact can be switched together to open to prevent current flow or together to close to prevent current flow,
[0025] - that the electronic switches can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow or into a low-resistance state of the switching elements to allow current flow,
[0026] - that the protective switching device is designed in such a way that the first, second and third electronic switches can be switched independently of one another into a high-resistance or low-resistance state.
[0027] This has the advantage that the phase conductors can be switched to the high-impedance or low-impedance state independently of one another. Previous protective switching devices, particularly the widely used classic electromechanical protective switching devices (circuit breakers, power circuit breakers, residual current devices), do not offer this option, as their mechanical isolating contact unit opens or closes all contacts simultaneously (multi-pole devices).
[0028] This enables greater flexibility of a protective switching device and more flexible switching behavior.
[0029] Further advantageous embodiments of the invention are specified in the subclaims and in the exemplary embodiment.
[0030] In an advantageous embodiment of the invention, a current sensor unit is provided for each series circuit, for the respective determination of the current level of the respective phase conductor. In particular, instantaneous current values are determined and are available. This means that a first, second and third current sensor unit is provided. The first current sensor unit is provided in the first series circuit, the second current sensor unit in the second series circuit and the third current sensor unit in the third series circuit, for the respective determination of the current level of the first, second and third phase conductor, in particular such that instantaneous current values are available.
[0031] In an advantageous further development, a control unit is provided which is connected to the current sensor units, the mechanical contacts, and the electronic switches. The protective switching device is designed such that, upon exceeding at least a first current threshold value in a phase conductor, the relevant electronic switch initiates the prevention of a current flow in the relevant phase conductor, in particular for a first period of time.
[0032] This has the particular advantage that when a specified current threshold or a current-time threshold is exceeded (i.e., the current threshold is exceeded for a defined period of time), a selective interruption occurs only in the affected conductor(s). Current flow is still permitted in the other conductors (unaffected conductors) in a multi-phase low-voltage AC circuit.
[0033] By avoiding this for an initial period, the device can be switched back on or reduced to low resistance after the initial period, thus ensuring continued security of supply and allowing further testing to determine whether the current threshold has been exceeded. This can be achieved particularly advantageously by evaluating instantaneous current values.
[0034] In an advantageous embodiment of the invention, the first time period is less than 20 ms, in particular less than 10 ms.
[0035] This has the particular advantage that an interruption occurs for a half-wave or full-wave of the voltage or current in the AC circuit (in the example (20 ms, 10 ms) based on a mains frequency of 50 Hz), so that the electrical supply reliability is restored with the next full-wave or half-wave. In particular, after an interruption, the low-resistance can occur in the area of the next zero crossing (at the zero crossing, or in the range 1 ms before or after).
[0036] In an advantageous embodiment of the invention, the protective switching device is designed such that, when at least one second current threshold, in particular an effective value, is exceeded in at least one phase conductor (or two phase conductors, in particular in three phase conductors) for at least a first period of time, the current flow is prevented by opening the contacts. The second current threshold can advantageously be higher in magnitude than the first current threshold.
[0037] The first time period can be less than 100ms, 20ms, in particular less than 10ms.
[0038] This has the particular advantage that if one or more of the electronic switches remain faulty and the second current threshold is subsequently exceeded, the current flow in the low-voltage alternating current circuit is prevented and the safety in the circuit is thus increased.
[0039] In an advantageous embodiment of the invention, the mechanical neutral conductor contact can be opened or closed together with the phase contacts. In particular, the neutral conductor contact is closed before the phase contacts are closed, or (and) the neutral conductor contact is opened after the phase contacts are opened.
[0040] This has the particular advantage that the neutral conductor contact always opens and closes without current. This reduces contact wear and increases its service life. Furthermore, it prevents the occurrence of an arc when the neutral conductor contact opens.
[0041] In an advantageous embodiment of the invention, the mechanical phase contacts are part of a mechanical isolating contact unit that opens or closes the contacts together. In particular, the mechanical isolating contact unit has a handle accessible on the protective switching device for manual (user-operated) opening or closing of the phase contacts (of the mechanical isolating contact unit).
[0042] This has the particular advantage that a complete galvanic isolation of all phase conductors is achieved simultaneously, in contrast to a phase-related high-resistance electronic switch which prevents current flow. The handle enables compatible behavior with classic electromechanical protective switching devices. In an advantageous embodiment of the invention, the protective switching device is designed such that the mechanical isolating contact unit can be opened by the control unit, but not closed. In particular, closing of the mechanical isolating contact unit by the handle is only possible after release by the control unit.
[0043] This has the particular advantage of increasing the safety of the protective switching device, as the control unit cannot accidentally (faultily) close the contacts.
[0044] In an advantageous embodiment of the invention, the electronic switches are part of an electronic interruption unit, wherein the electronic switches can be switched independently of one another.
[0045] This has the particular advantage of providing a compact electronic interruption unit that combines the electronic switches, enabling a space-saving design and allowing synergy effects of components to be utilized.
[0046] In an advantageous embodiment of the invention, the electronic interruption unit / electronic switches have bidirectional dielectric strength. In particular, overvoltage protection is provided for the semiconductor-based switching elements.
[0047] This has the particular advantage of being robust against overvoltages and of being able to switch off an inductive line circuit.
[0048] In an advantageous embodiment of the invention, the mechanical phase contacts are assigned to the load-side phase connections and the electronic switches are assigned to the mains-side phase connections.
[0049] This has the particular advantage of providing a convenient design that supports phase-related switching of the electronic switches and enables self-testing (in particular, self-testing of the electronic switches and the electronic interruption unit), even when the contacts are open. Furthermore, a power supply to the protective switching device is ensured, even when the contacts are open.
[0050] In an advantageous embodiment of the invention, a voltage sensor unit is provided between each phase conductor and the neutral conductor to determine the voltage level between the respective phase and neutral conductors, in particular to determine the instantaneous voltage values. The voltage sensor units are connected to the control unit.
[0051] In an advantageous further development of the embodiment, the protective switching device is designed such that when the control unit initiates a low-resistance event (in particular in the absence of an overcurrent event, ie when the first or second current threshold is not exceeded; e.g. when the user initiates a low-resistance event) of the (all) electronic switches, they become low-resistance one after the other at the respective zero crossing of the voltage (or at a voltage that is less than 50V, 25V, in particular less than 10V).
[0052] This has the particular advantage of reducing the switching load (and thus wear) on the electronic switch. Furthermore, it reduces network perturbations.
[0053] In an advantageous embodiment of the invention, the protective switching device is designed such that when the control unit initiates a high-impedance event (in particular in the absence of an overcurrent event, ie when the first or second current threshold is not exceeded; e.g. when the user initiates a high-impedance event), (all) electronic switches become high-impedance one after the other when the voltage crosses zero (or when the voltage is less than 50V, 25V, in particular less than 10V). This has the particular advantage that the system perturbations are reduced and the switching load in the switch is lower.
[0054] In an advantageous embodiment of the invention, a control unit is provided that is connected to the current sensor units, the voltage sensor units, the mechanical phase contacts, and the electronic switches. The protective switching device is designed such that when (at least) the first current threshold value in a conductor is exceeded, the relevant electronic switch initiates the prevention of current flow in the relevant conductor. At the next or subsequent zero crossing of the voltage, the electronic switch becomes low-resistance again to allow current flow.
[0055] This has the particular advantage that increased robustness against false triggering is achieved and thus increased electrical supply reliability is achieved.
[0056] In an advantageous embodiment of the invention for the three-phase low-voltage alternating current circuit, which advantageously provides a solution for a classic three-phase network, the protective switching device has at least the following switching states:
[0057] -all mechanical phase contacts open, all electronic switches high resistance,
[0058] - all mechanical phase contacts closed, all electronic switches low resistance,
[0059] - all mechanical phase contacts closed, all electronic switches high resistance,
[0060] - all mechanical phase contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance,
[0061] - all mechanical phase contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance,
[0062] - all mechanical phase contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance.
[0063] In a further advantageous embodiment of the invention for the three-phase low-voltage alternating current circuit, the protective switching device has at least the following switching states:
[0064] -all mechanical phase contacts open, all electronic switches high resistance,
[0065] - all mechanical phase contacts closed, all electronic switches low resistance,
[0066] - all mechanical phase contacts closed, all electronic switches high resistance,
[0067] - all mechanical phase contacts closed, the first and second electronic switch low resistance, the third electronic switch high resistance,
[0068] - all mechanical phase contacts closed, the first and third electronic switches low resistance, the second electronic switch high resistance,
[0069] - all mechanical phase contacts closed, the second and third electronic switches low resistance, the first electronic switch high resistance.
[0070] The two advantageous embodiments, or the combination of both, have the particular advantage of providing new switching states for a protective switching device, allowing for individual and more flexible response to overcurrent (short-circuit) conditions. This means that instead of switching off all phases, the response can be phase-specific, enabling greater supply reliability in the low-voltage circuit.
[0071] In a further advantageous embodiment of the invention, the protective switching device has at least the following switching state:
[0072] - all mechanical phase contacts are open, some of the electronic switches are low-resistance, the other part of the electronic switches are high-resistance, in particular one electronic switch is low-resistance and the other electronic switches are high-resistance, alternatively or additionally, in particular two electronic switches are low-resistance and the other electronic switch is high-resistance.
[0073] Alternatively or additionally, the protective switching device can have the following switching state:
[0074] - all mechanical phase contacts open, all electronic switches low resistance.
[0075] In particular, these switching states are provided when a measuring resistor is provided between each phase conductor and the neutral conductor. For this purpose, in one embodiment, a first measuring resistor is provided between the first phase conductor L1 and the neutral conductor N, a second measuring resistor is provided between the second phase conductor L2 and the neutral conductor N, and a third measuring resistor is provided between the third phase conductor L3 and the neutral conductor N.
[0076] These switching states are advantageous for testing whether the electronic switches can be switched on or off. This means that the electronic switches are briefly switched on with the mechanical phase contacts open in order to test their functionality (regarding their ability to switch on or off). A measuring current flows through the respective measuring resistors.
[0077] According to the invention, a corresponding method (method claims) for a protective switching device for a low-voltage circuit with electronic (semiconductor-based) switches / switching elements with the same and further advantages is claimed.
[0078] The method for a protective switching device (SG) for protecting a three-phase low voltage alternating current circuit with neutral conductor comprises:
[0079] - Series circuits of a mechanical phase contact and an electronic switch, each of which electrically connects a mains-side phase connection with a load-side phase connection,
[0080] - that a mains-side neutral conductor connection is connected to a load-side neutral conductor connection via a mechanical neutral conductor contact,
[0081] - that the mechanical contacts can be opened together to prevent current flow or closed together to allow current flow,
[0082] - that the electronic switches can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to avoid a current flow or a low-resistance state of the switching elements to allow current flow, that the electronic switches can be switched independently of one another into a high-resistance or low-resistance state in order to (advantageously) avoid or enable a phase-conductor-dependent current flow.
[0083] Advantageously, the level of the current of the respective series circuit is determined and, if at least a first current threshold value in a series circuit is exceeded, the avoidance of a current flow in the series circuit in question, in particular for a first period of time, is initiated by the electronic switch in question.
[0084] All embodiments, both in dependent form referring back to patent claim 1 or 17, and referring back only to individual features or combinations of features of patent claims, in particular also a reference of the pending arrangement claims to the independent method claim, bring about an improvement in a protective switching device, in particular an improvement in the safety of the electrical circuit, and provide a new concept for a protective switching device.
[0085] The described properties, features and advantages of this invention as well as the manner in which these are achieved will become clearer and more clearly understandable in connection with the following description of the embodiments, which are explained in more detail in connection with the drawing.
[0086] The drawing shows:
[0087] Figure 1 shows a first representation of a protective switching device,
[0088] Figure 2 shows a second representation of a protective switching device, Figure 3 shows a third representation of a protective switching device. Figure 1 shows an exemplary representation of a 4-pole protective switching device SG for protecting an electrical three-phase low-voltage alternating current circuit with a neutral conductor, comprising:
[0089] - a housing GEH with a first, second and third mains-side phase connection LG1, LG2, LG3 and a first, second and third load-side phase connection LL1, LL2, LL3, for the first, second and third phase conductors LI, L2, L3 of the low-voltage alternating current circuit, a mains-side neutral conductor connection NG and a load-side neutral conductor connection NL for a neutral conductor N of the low-voltage alternating current circuit, an energy source is usually connected to the mains side Grid, and a consumer is usually connected to the load side Load.
[0090] In the housing GEH :
[0091] - a first series circuit SS1 of a first mechanical phase contact K1 and a first electronic switch S1, a second series circuit SS2 of a second mechanical phase contact K2 and a second electronic switch S2, a third series circuit SS3 of a third mechanical phase contact K3 and a third electronic switch S3, wherein (inside the housing): the first series circuit SS1 electrically connects the first mains-side phase connection LG1 to the first load-side phase connection LL1, the second series circuit SS2 electrically connects the second mains-side phase connection LG2 to the second load-side phase connection LL2 and the third series circuit SS3 electrically connects the third mains-side phase connection LG3 to the third load-side phase connection LL3,
[0092] - the mains-side neutral conductor connection (NG) is connected to the load-side neutral conductor connection (NL) via a mechanical neutral conductor contact (KN),
[0093] - the mechanical phase contacts Kl, K2, K3 and the mechanical neutral conductor contact KN can be switched together, ie they are opened together to prevent a current flow or closed together to allow a current flow, ie the mechanical contacts are connected to each other via a mechanical coupling (e.g. switching shaft),
[0094] - the electronic switches SI, S2, S3 can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow or a low-resistance state of the switching elements to allow current flow.
[0095] According to the invention, the protective switching device is designed such that the first, second, and third electronic switches can be switched independently of one another to a high-impedance or low-impedance state. This means that the first, second, and third electronic switches are switched independently of one another to a high-impedance or low-impedance state. This is particularly useful in order to prevent or enable a phase-conductor-dependent current flow.
[0096] According to Figure 1, a first, second, and third current sensor unit SI1, SI2, SI3 are provided. The first current sensor unit SI1 is provided or arranged in the first series circuit SS1, the second current sensor unit SI2 is provided or arranged in the second series circuit SS2, and the third current sensor unit SI3 is provided or arranged in the third series circuit SS3, for respectively determining the magnitude of the current of the first, second, and third phase conductors, in particular for determining instantaneous current values.
[0097] The first mechanical phase contact Kl, the second mechanical phase contact K2 and the third mechanical phase contact K3 as well as the mechanical neutral conductor contact KN are, according to Figure 1, part of a mechanical isolating contact unit MK, which opens or closes the phase contacts Kl, K2, K3 and the neutral conductor contact KN together. The mechanical isolating contact unit MK can have a handle HH accessible on the protective switching device for manual (operated by a person) opening or closing of the contacts. The mechanical isolating contact unit MK corresponds, for example, to a classic unit, as is known from electromechanical protective switching devices (circuit breakers, power breakers) (although according to the invention without elements for overcurrent or short-circuit detection, such as bimetallic releases, etc.).
[0098] The protective switching device is in particular designed in such a way that the mechanical isolating contact unit MK can be opened but not closed by a control unit SE. In particular, the mechanical isolating contact unit MK can only be closed by the handle HH after release by the control unit SE. A release unit LC can be provided for this purpose. This means that the contacts can only be closed by the handle HH when release or a release signal (from the control unit) is present. Without release or the release signal, the handle HH can be operated, but the contacts cannot be closed ("continuous slipping").
[0099] The release unit LC can further be designed such that the contacts Kl, K2, K3, KN of the mechanical isolating contact unit MK can be opened by a control signal from the control unit SE, as indicated in Figure 1 by an arrow from the control unit SE to the release unit LC. According to Figure 1, the mechanical contacts Kl, K2, K3, KN are assigned to the load-side phase connections / the load side Load and the electronic switches SI, S2, S3 are assigned to the grid-side phase connections / grid side Grid.
[0100] The mains-side neutral conductor terminal NG is connected to the load-side neutral conductor terminal NL via the neutral conductor contact KN. In this example, an electronic interruption unit is not provided in the neutral conductor path in the protective device housing. This means that the neutral conductor connection between the mains-side neutral conductor terminal NG and the load-side neutral conductor terminal NL is free of electronic switches (electronic switch-free).
[0101] Specifically, the mechanical isolating contact unit MK can be designed such that the neutral conductor contact KN is closed before the phase contacts Kl, K2, K3 are closed. Similarly, the neutral conductor contact KN can be opened after the phase contacts Kl, K2, K3 are opened.
[0102] The first electronic switch S1, the second electronic switch S2 and the third electronic switch S3 can be part of an electronic interruption unit EU, wherein the electronic switches S1, S2, S3 can be switched independently of one another.
[0103] The electronic interruption unit / electronic switches can have bidirectional dielectric strength. Overvoltage protection is specifically provided for the semiconductor-based switching elements to limit the voltages and thus protect the semiconductor-based switching elements.
[0104] A control unit SE is provided (as already partially mentioned) which is connected to the current sensor units Sil, SI2, SI3, the mechanical contacts Kl, K2, K3, KN or the mechanical isolating contact unit MK (as shown in Figure 1) and the electronic switches SI, S2, S3.
[0105] The current sensor units Sil, SI2, SI3 each determine the current level of their respective conductor, so that instantaneous current values are available.
[0106] If at least a first current threshold value, in particular an instantaneous value of the current, is exceeded in a conductor, the current flow in the respective conductor is prevented by the electronic switch becoming highly resistive.
[0107] The high-impedance state can occur, in particular, for an initial period of time. After the initial period of time, the electronic switch in question can return to a low-impedance state. The initial period of time can, in particular, be less than 20 ms, especially less than 10 ms (specifically referring to a 50 Hz low-voltage AC circuit).
[0108] The low-resistance switching can occur alternatively or additionally, particularly at the next zero crossing, or before or after the zero crossing of the voltage. (All three options: at the zero crossing, before the zero crossing, or after the zero crossing (for example, within one millisecond / 1 ms) - are possible, or when the value falls below a voltage threshold, in particular 50 V, 25 V, or 10 V.)
[0109] The protective switching device can be designed such that, upon exceeding a second current threshold, which can in particular be an effective value, in at least one phase conductor (or two phase conductors, in particular in three phase conductors), a current flow prevention is initiated by opening the contacts for at least a first period of time. The first period of time is less than 100 ms, 10 ms, or more specifically, 1 ms.
[0110] The second current threshold value can advantageously be greater or smaller than the first current threshold value.
[0111] A differential current sensor unit ZCT can be provided, as shown in Figure 1, for example, for detecting differential currents in the low-voltage AC circuit, as is known, for example, from residual current circuit breakers. The differential current sensor unit ZCT is connected to the control unit SE.
[0112] In the example shown in Figure 1, the current sensor units Sil, SI2, SI3 are arranged between the mains-side terminals LG1, LG2, LG3 of the series circuit of the electronic switches SI, S2, S3 and the mechanical phase contacts Kl, K2, K3. Specifically, between the mains-side terminals LG1, LG2, LG3 and the electronic switches SI, S2, S3. The current sensor units Sil, SI2, SI3 can also be arranged differently, for example, between the electronic switches SI, S2, S3 and the mechanical phase contacts Kl, K2, K3. The same applies to the differential current sensor unit.
[0113] Figure 2 shows a representation according to Figure 1, with the following differences.
[0114] On the one hand, a power supply NT, such as a power supply unit, is provided to supply power to the protective switching device SG, in particular the control unit SE.
[0115] In this example, the NT power supply is connected to the phase conductors LI, L2, L3, and the neutral conductor N. It can also be connected to only some of the conductors (at least two) for the power supply. In this example, the NT power supply is also connected to the control unit SE, which supplies the power to the control unit.
[0116] On the other hand, the control unit SE is combined with the electronic switches SI, S2, S3 and the current sensor units Sil, SI2, SI3, as shown in Figure 2.
[0117] Furthermore, a voltage sensor unit is provided between each phase conductor and the neutral conductor. A first voltage sensor unit SUI is provided between the first phase conductor LI and the neutral conductor N, a second voltage sensor unit SU2 is provided between the second phase conductor L2 and the neutral conductor N, and a third voltage sensor unit SU3 is provided between the third phase conductor L3 and the neutral conductor N. These units are used to determine the voltage level between the respective phase and neutral conductors, in particular to determine the instantaneous voltage values. The voltage sensor units SUI, SU2, and SU3 are connected to the control unit SE.
[0118] In the case of a low-resistance switch initiated by the control unit SE, the electronic switches SI, S2, S3, for example:
[0119] - become low-resistance in the case of a user-initiated or
[0120] - in the event of a low-resistance event initiated by the protective switching device, especially in the absence of an overcurrent event (i.e. if the first or second current threshold is not exceeded), e.g. if an internal checking function (for internal checking) of the protective switching device initiates a low-resistance event,
[0121] => advantageously, the electronic switches can become low-resistance one after the other at the respective zero crossing of the voltage (e.g. in the vicinity of the voltage zero crossing, defined by a voltage below the absolute value of e.g. 50 V, 25 V or 10 V).
[0122] In the case of a high-impedance signal initiated by the control unit SE, the electronic switches SI, S2, S3, for example:
[0123] - become high-impedance when initiated by the user or
[0124] - in the event of a high-resistance event initiated by the protective switching device, especially in the absence of an overcurrent event (i.e. if the first or second current threshold is not exceeded), e.g. if an internal checking function (for internal checking) of the protective switching device initiates a high-resistance event,
[0125] => advantageously, the electronic switches can become high-resistance one after the other at the respective zero crossing of the voltage (e.g. near the zero crossing of the voltage, defined by a voltage below the absolute value of e.g. 50 V, 25 V or 10 V).
[0126] For this purpose, the voltage sensor units SUI, SU2, SU3 are, as already mentioned, connected to the control unit SE, which is further connected to the current sensor units S1, SI2, SI3, the mechanical phase contacts K1, K2, K3 (or mechanical isolating contact unit MK) and the electronic switches (S1, S2, S3). The protective switching device can also advantageously be designed such that when at least a first current threshold value (specifically the instantaneous current value) in a conductor is exceeded, the corresponding electronic switch initiates the prevention of current flow in the respective conductor. At the next or next but one zero crossing of the voltage, the electronic switch becomes low-resistance again in order to allow current flow.
[0127] This can be done several times until a certain number of repetitions is exceeded. Then: a) all electronic switches become high-impedance, or (and) b) the contacts open (galvanic isolation).
[0128] Figure 3 shows a representation similar to Figure 2, with the difference that a measuring resistor is provided between each phase conductor and the neutral conductor. For this purpose, a first measuring resistor RI (or measuring impedance) is provided between the first phase conductor LI and the neutral conductor N, a second measuring resistor R2 (or measuring impedance) is provided between the second phase conductor L2 and the neutral conductor N, and a third measuring resistor R3 (or measuring impedance) is provided between the third phase conductor L3 and the neutral conductor N.
[0129] The switching behavior of the electronic switches SI, S2, S3 can be checked using the measuring resistors RI, R2, R3 (which can also be designed as measuring impedances, i.e. as resistance / capacitance and / or inductance combinations), for example by briefly switching on (ps, ms or less than a second range) the electronic switches with open contacts, whereby a measuring current corresponding to the measuring resistance (the measuring impedance) is provided and verifiable (at the respective instantaneous voltage values). This can be done by briefly switching on an electronic switch in order to generate a measuring current across the respective measuring resistor between the phase and neutral conductors. Alternatively or additionally, this can also be done by briefly switching on two electronic switches in order to generate a measuring current across two phase conductors (two measuring resistors).
[0130] The (optional) differential current sensor unit ZCT is not provided in this example (but could also be provided).
[0131] High-resistance refers to a state in which only a negligible current flows. In particular, high-resistance refers to resistance values greater than 1 kiloohm, preferably greater than 10 kiloohms, 100 kiloohms, 1 megaohm, 10 megaohms, 100 megaohms, 1 gigaohm, or greater.
[0132] Low-resistance refers to a condition in which the current value specified on the protective device could flow. Specifically, low-resistance refers to resistance values less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm, or less.
[0133] The electronic switches SI, S2, S3 or the electronic interruption unit EU can have semiconductor components such as bipolar transistors, field-effect transistors (FETs), isolated gate bipolar transistors (IGBTs), metal oxide layer field-effect transistors (MOSFETs) or other (self-commutated) power semiconductors. IGBTs and MOSFETs in particular are particularly well suited for the electronic switches (as semiconductor-based switching elements) due to their low forward resistances, high junction resistances and good switching behavior. The protective switching device according to the invention therefore contains electronic and mechanical components. The sensible arrangement of all required components for safe operation is one point. Furthermore, a number of switching combinations are possible by combining electronic switches and mechanical contacts.
[0134] In this example, the protective switching device has four mains-side and four load-side connections. The device contains a 4-pole mechanical isolating contact system. The contacts are mechanically coupled and can only be opened or closed together.
[0135] An electronic switch is located in series with the mechanical contact in the phase conductors. Unlike the mechanical contacts, these switches are switched on or off independently of each other. Furthermore, a current sensor unit is provided in the phase conductors (not in the neutral conductor N).
[0136] A conventional three-pole or four-pole protective device today (essentially) has only two switching states: On or Off.
[0137] According to the invention, in the example for a four-pole (e.g. for 3-phase conductors and a neutral conductor) protective switching device, further switching states are proposed, see the following table.
[0138] In addition to the switching states known today, Off (OFF) and On (ON), there are other states such as Standby, Hybrid 1, 2, 3, Hybrid 12, 13, 23. Furthermore, test states (Test 1, Test 2, Test 3, optionally Test 4) are available for the electronic switches.
[0139] The new hybrid switching modes allow the protective switching device to react differently to specific load or fault conditions than before. It can therefore be advantageous to switch only one or two of the included electronic switches to the high-impedance (off) state in a specific fault condition. When switching loads on and off, it can also be advantageous to perform a switching sequence in which only one or two of the included electronic switches are switched on at certain times.
[0140] Switching on can be achieved, for example, by switching on the electronic switches one after the other at the zero crossing of the voltage (i.e. not at the same time, but at staggered times, e.g. at the respective zero crossing of the voltage of the respective phase / phase conductor (which are, for example, phase-shifted by 120°).
[0141] A switch-off process could also proceed in an analogous manner.
[0142] This allows reduced network perturbations and the switching load in the switching device (especially in the electronic switch) to be reduced.
[0143] Overcurrent events (current threshold exceeded) can be handled per phase / phase conductor. This also protects the electronic switches from overload.
[0144] Likewise, phases can be switched off (high impedance) for a short time, for example for testing purposes.
[0145] The number of hybrid states or hybrid states occurring in a unit of time can be counted and if a limit is exceeded, all electronic switches can become high-resistance (or ( / and) the mechanical contacts can be opened).
[0146] For single-phase consumers, higher availability can be provided (fault only on one phase, switching off only one phase, continuing operation of the other phases).
[0147] The protective switching device therefore has at least the following switching states in one variant:
[0148] -(1) all mechanical contacts open, all electronic switches high resistance,
[0149] -(2) all mechanical contacts closed, all electronic switches low resistance,
[0150] -(3) all mechanical contacts closed, all electronic switches high resistance,
[0151] -(4) all mechanical contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance,
[0152] -(5) all mechanical contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance,
[0153] -(6) all mechanical contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance.
[0154] In a further variant, the protective switching device therefore has at least the following switching states:
[0155] -(1) all mechanical contacts open, all electronic switches high resistance,
[0156] -(2) all mechanical contacts closed, all electronic switches low resistance,
[0157] -(3) all mechanical contacts closed, all electronic switches high resistance,
[0158] -(7) all mechanical contacts closed, the first and second electronic switches low resistance, the third electronic switch high resistance,
[0159] -(8) all mechanical contacts closed, the first and third electronic switches low resistance, the second electronic switch high resistance,
[0160] -(9) all mechanical contacts closed, the second and third electronic switches low resistance, the first electronic switch high resistance.
[0161] In a further variant, the protective switching device therefore has the following switching states:
[0162] -(1) all mechanical contacts open, all electronic switches high resistance,
[0163] -(2) all mechanical contacts closed, all electronic switches low resistance,
[0164] -(3) all mechanical contacts closed, all electronic switches high resistance,
[0165] -(4) all mechanical contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance,
[0166] -(5) all mechanical contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance, -(6) all mechanical contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance,
[0167] -(7) all mechanical contacts closed, the first and second electronic switches low resistance, the third electronic switch high resistance,
[0168] -(8) all mechanical contacts closed, the first and third electronic switches low resistance, the second electronic switch high resistance,
[0169] -(9) all mechanical contacts closed, the second and third electronic switches low resistance, the first electronic switch high resistance.
[0170] Consequently, in one variant, the protective switching device still has at least some (or all) of the following switching states:
[0171] -(10) all mechanical contacts open, the first electronic switch low resistance, the second electronic switch and the third electronic switch high resistance,
[0172] -(11) all mechanical contacts open, the second electronic switch low resistance, the first electronic switch and the third electronic switch high resistance,
[0173] -(12) all mechanical contacts open, the third electronic switch low resistance, the first electronic switch and the second electronic switch high resistance,
[0174] -(13) all mechanical phase contacts open, the first, second and third electronic switches low resistance.
[0175] The protective switching device can therefore furthermore, as an example in a variant, have at least one (or all) of the following switching states:
[0176] -(14) all mechanical contacts open, the first electronic switch and the second electronic switch low resistance, the third electronic switch high resistance,
[0177] -(15) all mechanical contacts open, the second electronic switch and the third electronic switch low resistance, the first electronic switch high resistance,
[0178] -(16) all mechanical contacts open, the first electronic switch and the third electronic switch low resistance, the second electronic switch high resistance.
[0179] In general, the protective switching device is characterized, for example, by at least the following new switching state:
[0180] - all mechanical contacts closed, some of the electronic switches are low-resistance, the other part of the electronic switches are high-resistance.
[0181] The term mechanical contact or mechanical isolating contact unit MK refers in particular to a (standard-compliant) isolating function implemented by the isolating contact unit MK. The isolating function includes the following points: - minimum air gap according to the standard (minimum distance between the contacts), - contact position indicator of the contacts of the mechanical isolating contact unit, - actuation / interruption of the contacts of the mechanical isolating contact unit (by the control unit) is always possible (no (permanent) blocking of the contacts in the closed state by the handle is possible).
[0182] The minimum clearance between the contacts of the isolating contact unit is essentially voltage-dependent. Other parameters include the degree of contamination, the type of field (homogeneous, inhomogeneous), and the air pressure or altitude above sea level.
[0183] There are corresponding regulations and standards for these minimum clearances and creepage distances. These regulations specify, for example, the minimum clearance for an inhomogeneous and a homogeneous (ideal) electric field in the case of air for impulse voltage resistance, depending on the degree of pollution. The impulse voltage resistance is the resistance when a corresponding impulse voltage is applied. The isolating contact unit or protective switching device only has an isolating function (isolating property) if this minimum length (minimum distance) is present. For the purposes of the invention, the DIN EN 60947 and IEC 60947 series of standards are relevant for the isolating function and its properties, and reference is made here to this.
[0184] The isolating contact unit is advantageously characterized by a minimum clearance between the open isolating contacts in the open position (open position, open contacts) depending on the rated impulse withstand voltage and the degree of pollution. The minimum clearance is, in particular, between 0.01 mm and 14 mm (at least). In particular, the minimum clearance is advantageously between 0.01 mm at 0.33 kV and 14 mm at 12 kV, especially for pollution degree 1 and especially for inhomogeneous fields.
[0185] Advantageously, the minimum air distance can have the following values:
[0186] E DIN EN 60947-1 (VDE 0660-100): 2018-06
[0187] Table 13 - Minimum clearances
[0188] The pollution levels and field types correspond to those defined in the standards. This advantageously allows for a standard-compliant protective switching device dimensioned according to the rated impulse withstand voltage.
[0189] In particular, the term mechanical isolating contact unit does not refer to a relay contact.
[0190] Although the invention has been illustrated and described in detail by the embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the scope of the invention.
Claims
Patent claims 1. Protective switching device (SG) for protecting an electrical three-phase low-voltage alternating current circuit with neutral conductor, comprising: - a housing (GEH) with a first, second and third mains-side phase connection (LG1, LG2, LG3) and a first, second and third load-side phase connection (LL1, LL2, LL3) for a first, second and third phase conductor (LI, L2, L3) of the low-voltage AC circuit, a mains-side neutral conductor connection (NG) and a load-side neutral conductor connection (NL) for a neutral conductor (N) of the low-voltage AC circuit, - a first series circuit (SSI) of a first mechanical phase contact (K1) and a first electronic switch (S1), a second series circuit (SS2) of a second mechanical phase contact (K2) and a second electronic switch (S2), a third series circuit (SS3) of a third mechanical phase contact (K3) and a third electronic switch (S3), wherein the first series circuit (SSI) electrically connects the first mains-side phase connection (LG1) to the first load-side phase connection (LL1), the second series circuit (SS2) electrically connects the second mains-side phase connection (LG2) to the second load-side phase connection (LL2), and the third series circuit (SS3) electrically connects the third mains-side phase connection (LG3) to the third load-side phase connection (LL3), - that the mains-side neutral conductor connection (NG) is connected to the load-side neutral conductor connection (NL) via a mechanical neutral conductor contact (KN), - that the mechanical phase contacts (Kl, K2, K3) and the mechanical neutral conductor contact (KN) can be switched together to open in order to prevent a current flow or together to close in order to prevent a current flow, - that the electronic switches (SI, S2, S3) are semiconductor-based switching elements can be switched into a high-resistance state of the switching elements to prevent current flow or a low-resistance state of the switching elements to allow current flow, - that the protective switching device is designed such that the first, second and third electronic switches can be switched independently of one another into a high-resistance or low-resistance state.
2. Protective switching device (SG) according to claim 1, characterized in that a first, second and third current sensor unit (Sil, SI2, SI3) is provided, that the first current sensor unit (Sil) is provided in the first series circuit (SS1), the second current sensor unit (SI2) in the second series circuit (SS2) and the third current sensor unit (SI3) in the third series circuit (SS3), for respectively determining the level of the current of the first, second and third phase conductors, in particular in such a way that instantaneous current values are available.
3. Protective switching device (SG) according to one of the preceding claims, characterized in that the first mechanical phase contact (Kl), the second mechanical phase contact (K2), the third mechanical phase contact (K3) and the mechanical neutral conductor contact (KN) are part of a mechanical isolating contact unit (MK) which opens or closes the phase contacts together, in particular that the neutral conductor contact (KN) is closed before the phase contacts (Kl, K2, K3) are closed or the neutral conductor contact is opened after the phase contacts (Kl, K2, K3) are opened.
4. Protective switching device (SG) according to claim 3, characterized in that the mechanical isolating contact unit (MK) has a The protective switching device has an accessible handle (HH) for manually opening or closing the contacts.
5. Protective switching device (SG) according to one of the preceding claims, characterized in that the first electronic switch (S1), the second electronic switch (S2) and the third electronic switch (S3) are part of an electronic interruption unit (EU), wherein the electronic switches can be switched independently of one another.
6. Protective switching device (SG) according to one of the preceding claims, characterized in that the mechanical phase contacts (Kl, K2, K3) are assigned to the load-side phase connections and the electronic switches (SI, S2, S3) are assigned to the mains-side phase connections.
7. Protective switching device (SG) according to one of the preceding claims, characterized in that a control unit (SE) is provided which is connected to the current sensor units (S11, SI2, SI3), the mechanical contacts and the electronic switches (SI, S2, S3), that the protective switching device is designed in such a way that when at least a first current threshold value in a phase conductor is exceeded, avoidance of a current flow in the phase conductor in question, in particular for a first period of time, is initiated by the electronic switch in question.
8. Protective switching device (SG) according to claim 7, characterized in that the first time period is less than 20 ms, in particular less than 10 ms.
9. Protective switching device (SG) according to claim 7 or 8, characterized in that the protective switching device is designed such that when at least one second current threshold value is exceeded in at least one phase conductor, in particular for at least a first period of time, avoidance of a current flow is initiated by opening the contacts.
10. Protective switching device (SG) according to one of the preceding claims 7 to 9, characterized in that a voltage sensor unit (SUI, SU2, SU3) is provided between each phase conductor and the neutral conductor, for determining the level of the voltage between the respective phase and neutral conductor, in particular the instantaneous voltage values, that the voltage sensor units (SUI, SU2, SU3) are connected to the control unit (SE).
11. Protective switching device (SG) according to claim 10, characterized in that when the electronic switches (SI, S2, S3) become low-impedance initiated by the control unit (SE), they become low-impedance one after the other at the respective zero crossing of the voltage.
12. Protective switching device (SG) according to claim 10 or 11, characterized in that when the electronic switches (SI, S2, S3) become high-impedance initiated by the control unit (SE), they become high-impedance one after the other at the respective zero crossing of the voltage.
13. Protective switching device (SG) according to one of the claims 10 to 12, characterized in that a control unit (SE) is provided which is connected to the current sensor units (Sil, SI2, SI3), the Voltage sensor units, the mechanical phase contacts (Kl, K2, K3) and the electronic switches (S1, S2, S3) are connected, that the protective switching device is designed in such a way that when at least a first current threshold value in a conductor is exceeded, avoidance of a current flow in the conductor in question is initiated by the electronic switch in question, that at the next or next but one zero crossing of the voltage the electronic switch becomes low-resistance again in order to enable a current flow. 14 . Protective switching device (SG) according to one of the preceding claims, characterized in that the protective switching device has at least the following switching states: -all mechanical contacts open, all electronic switches high resistance, - all mechanical contacts closed, all electronic switches low resistance, - all mechanical contacts closed, all electronic switches high resistance, - all mechanical contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance, - all mechanical contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance, - all mechanical contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance, in particular that the protective switching device has the following switching state: - all mechanical phase contacts open, at least one electronic switch low resistance.
15. Protective switching device (SG) according to one of the preceding claims, characterized in that the protective switching device has at least the following switching states: -all mechanical contacts open, all electronic switches high resistance, - all mechanical contacts closed, all electronic switches low resistance, - all mechanical contacts closed, all electronic switches high resistance, - all mechanical contacts closed, the first and second electronic switches low resistance, the third electronic switch high resistance, - all mechanical contacts closed, the first and third electronic switches low resistance, the second electronic switch high resistance, - all mechanical contacts closed, the second and third electronic switches are low-resistance, the first electronic switch is high-resistance. 16 . Protective switching device (SG) according to one of the preceding claims, characterized in that the protective switching device has the following switching states: -all mechanical contacts open, all electronic switches high resistance, - all mechanical contacts closed, all electronic switches low resistance, - all mechanical contacts closed, all electronic switches high resistance, - all mechanical contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance, - all mechanical contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance, - all mechanical contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance, - all mechanical contacts closed, the first and second electronic switches low resistance, the third electronic switch high resistance, - all mechanical contacts closed, the first and third electronic switches low resistance, the second electronic switch high resistance, - all mechanical contacts closed, the second and third electronic switches are low-resistance, the first electronic switch is high-resistance.
17. Method for a protective switching device (SG) for protecting an electrical three-phase low voltage alternating current circuit with neutral conductor, comprising: - Series circuits of a mechanical phase contact (Kl, K2, K3) and an electronic switch (SI, S2, S3), each series circuit electrically connecting a mains-side phase connection (LG1, LG2, LG3) with a load-side phase connection (LL1, LL2, LL3), - that a mains-side neutral conductor connection (NG) is connected to a load-side neutral conductor connection (NL) via a mechanical neutral conductor contact (KN), - that the mechanical contacts (Kl, K2, K3, KN) can be opened together to prevent current flow or closed together to allow current flow, - that the electronic switches ( SI , S2 , S3 ) can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to avoid a current flow or a low-resistance state of the switching elements to allow current flow, that the electronic switches can be switched independently of one another into a high-resistance or low-resistance state to avoid or allow a phase-conductor-dependent current flow.
18. Method according to claim 17, characterized in that the level of the current of the respective series circuit is determined and, if at least a first current threshold value in a series circuit is exceeded, avoidance of a current flow in the series circuit in question, in particular for a first period of time, is initiated by the electronic switch in question.