DE102012219457A1 - Circuit breaker i.e. residual current circuit breaker, for use in installation system for detecting fault current during charging electric car, has control device actuating switch to open when fault current is detected with other switches - Google Patents

Abstract

The breaker has first- and second switches (2, 3) attached to power source conductors e.g. phase conductor (L) and neutral conductor (N). A third switch (5) is attached to a protective conductor (PE). Multiple detection units detect fault current in a system of the power source conductors and the protective conductor and produce a corresponding detection signal. A control device i.e. evaluation electronics (9), controls the switches depending on the detection signal. The control device actuates the third switch to open when the fault current is detected with the other opened switches. The detection units consist of a transmitter (1), a signal processing unit (7) and an amplifier (8). An independent claim is also included for a method for controlling a circuit breaker.

Description

The present invention relates to a protective switching device for detecting a fault current with a first power supply conductor to which a first switch is connected, a second power supply conductor to which a second switch is connected, and a protective conductor to which a third switch is connected. In addition, the protection switching device has a detection device for detecting a fault current in the system of the three conductors and for generating a corresponding detection signal. In addition, in the protection switching device, a control means for controlling the first, second and third switches in response to the detection signal is included. Moreover, the present invention relates to a method for controlling such a protective switching device.

Protection switching devices, eg. As residual current circuit breaker, serve to interrupt a circuit when a fault current occurs. Thus, for example, in a three-wire system with phase conductor, neutral conductor and protective conductor, the three-wire conductor system is disconnected, or corresponding switches are opened when a fault current is detected in the protective conductor. In particular, the protective conductor PE (Protected Earth) is switched in such situations.

The aim of devices with switched PE is to create the possibility of switching off a system or not switching it on in dangerous situations (eg L potential on PE cables due to incorrect wiring in the socket). This avoids that L potential lies on a metal housing of a consumer (eg body of an electric vehicle). If the metal housing were touched, then there would be the risk of an electric shock.

Below are some problems illustrated by the example of an electric vehicle as a consumer. In particular, a ground fault in the vehicle or a ground fault can occur via a person and the vehicle.

In the example below, an electrically powered motor vehicle is charged via a residual current circuit breaker and a socket. In this case, the earth fault can occur in the vehicle, with a fault current, for example, flows from a phase conductor in the protective conductor. In the event of a ground fault over the vehicle and the person, the fault current flows from the phase conductor or neutral conductor via the vehicle and a person to earth.

• 1. Einzelfehler a) Körperschluss (im Fahrzeug; z. B. Phasenleiter L auf PE); es erfolgt eine allpolige Abschaltung auch ohne Berührung, wodurch das Fahrzeug spannungsfrei wird. b) Betriebsmäßige Ableitströme (Kapazitäten gegen Karosserie) über das Fahrzeug und die Person; es erfolgt beispielsweise eine Auslösung des Fehlerstromschutzschalters (RCD) unterhalb von 7,5 mA; die Karosserie erhält PE-Potenzial und es fließt kein Körperstrom bei Berührung. c) L-Potenzial auf PE-Leitung (Falschanschluss L-N-L); es erfolgt eine allpolige Abschaltung bei Fehlerstrom, wodurch die Karosserie spannungsfrei bleibt und es höchstrelevant ist, dass der Schutzleiter PE geschaltet wird.
• 2. Doppelfehler
• 2.1 Erster Fehler: PE-Kontakt schließt nicht a) Als zweiter Fehler entsteht ein Körperschluss (im Fahrzeug, z. B. L auf PE); es erfolgt keine unmittelbare Reaktion und es ist kein Fehlerschutz über PE gegeben, aber ein Schutz bei direktem Berühren. b) Zweiter Fehler: Betriebsmäßige Ableitströme (Kapazitäten gegen Karosserie) über das Fahrzeug und die Person; es ist keine Abschaltung erforderlich, da der Differenzstrom zu gering ist; beispielsweise ist der Körperstrom über Kapazitäten < 3,5 mA (wegen der geringfügigen, geschalteten Potenzialdifferenz gegen Erde ist eine elektrische Durchströmung ohne Gefahr). c) Zweiter Fehler: L-Potenzial auf PE-Leitung (Falschanschluss L-N-L); es erfolgt eine allpolige Abschaltung bei Fehlerstrom, sodass die Karosserie spannungsfrei bleibt; dabei ist wiederum relevant, dass der Schutzleiter PE geschaltet wird.
• 2.2 Erster Fehler: L-Kontakt verschweißt a) Zweiter Fehler: Körperschluss (im Fahrzeug; z. B. L auf PE); es erfolgt ein Versuch des allpoligen Abschaltens, aber L bleibt geschlossen; somit bleibt die Spannung anliegen und es besteht Gefahr bei Berührung. b) Zweiter Fehler: Betriebsmäßige Ableitströme (Kapazitäten gegen Karosserie) über das Fahrzeug und die Person; es ist keine Abschaltung erforderlich, da ein zu geringer Differenzstrom herrscht; beispielsweise liegt die Karosserie auf PE-Potenzial und es kommt zu keinem Körperstrom bei Berührung. c) Zweiter Fehler: L-Potenzial auf PE-Leitung (Falschanschluss, z. B. L-N-L); es erfolgt ein Versuch des allpoligen Abschaltens bei Fehlerstrom, aber L bleibt geschlossen; die Karosserie ist hier spannungsfrei und es ist sehr relevant, dass der PE geschaltet wird.

The following error cases can occur, whereby the protective conductor is always switched:

• 1. Single fault a) Physical closure (in the vehicle, eg phase conductor L to PE); There is an all-pole shutdown even without contact, whereby the vehicle is de-energized. b) operational leakage currents (capacities against bodywork) over the vehicle and the person; for example, the residual current circuit breaker (RCD) is tripped below 7.5 mA; the body gets PE potential and there is no body flow when touched. c) L potential on PE line (wrong connection LNL); There is an all-pole shutdown at fault current, whereby the body remains de-energized and it is hochstrelevant that the protective conductor PE is switched.
• 2nd double error
• 2.1 First fault: PE contact does not close a) The second fault is a physical fault (in the vehicle, eg L on PE); there is no immediate reaction and there is no error protection via PE, but protection by direct contact. b) Second error: operational leakage currents (capacities against bodywork) over the vehicle and the person; there is no shutdown required because the differential current is too low; For example, the body current is above capacities <3.5 mA (because of the small, switched potential difference to earth is an electrical flow without danger). c) Second error: L potential on PE line (wrong connection LNL); there is an all-pole shutdown at fault current, so that the body remains de-energized; In this case, it is again relevant that the protective conductor PE is switched.
• 2.2 First fault: L-contact welded a) Second fault: body closure (in the vehicle, eg L on PE); an attempt is made to disconnect all poles, but L remains closed; Thus, the voltage is applied and there is a risk of contact. b) Second error: operational leakage currents (capacities against bodywork) over the vehicle and the person; there is no shutdown required because there is too little differential current; For example, the body is at PE potential and there is no body flow when touched. c) Second error: L potential on PE line (wrong connection, eg LNL); an attempt is made to disconnect all poles at fault current, but L remains closed; The bodywork is de-energized and it is very relevant that the PE is switched.

The following is based on 1 the basic structure of a generic protection switching device (here residual current circuit breaker) explained. A three-wire power supply system has a phase conductor L, a neutral N and a protective conductor PE. The two power supply conductors L and N are through an annular core of a transformer 1 guided. The first power supply conductor, ie the phase conductor L, then leads to a first switch 2 , The second contact of the switch optionally leads to a consumer, not shown.

In addition, also the second power supply conductor, ie the neutral conductor N through the annular core of the transformer 1 to a second switch 3 guided. The further contact of the second switch 3 can also be led to a consumer.

The protective conductor PE is in a primary winding here around the core of the transformer 1 wound and leads to a third switch 5 , The second contact of the third switch 5 can also be led to the consumer.

Via a secondary coil 6 which also surround the annular core of the transformer 6 is wound, a fault current signal becomes a signal conditioning unit 7 guided. An amplifier connected to it 8th amplifies the signal for a transmitter 9 , The evaluation electronics 9 in turn, each represents a switching signal for the first switch 2 , the second switch 3 and the third switch 5 in response to the fault current signal. As a detection device for the fault current so the specially arranged on the conductors L, N and PE transformer 1 together with the signal conditioning unit 7 and the amplifier 8th be seen. The output signal of the amplifier 8th Accordingly, a detection signal would be that of the transmitter 9 , which represents a control device here, is provided to the three switches 2 . 3 and 5 to control.

Due to the switched protective conductor PE, however, possible error situations arise in which - coming back to the above example of charging an electric vehicle - when touching the body leakage currents to earth occur, but usually pose no threat, since they are <3.5 mA , However, these currents are perceptible and may be unpleasant. It would therefore be desirable to keep away even such leakage currents from the consumer.

The object of the present invention is thus to provide a protective switching device with which the protection of persons can be improved, for example when charging an electric vehicle. In addition, a corresponding control method for protective switching devices is to be provided.

• – einem ersten Stromversorgungsleiter, an den ein erster Schalter angeschlossen ist,
• – einem zweiten Stromversorgungsleiter, an den ein zweiter Schalter angeschlossen ist,
• – einem Schutzleiter, an den ein dritter Schalter angeschlossen ist,
• – einer Erfassungseinrichtung zum Erfassen eines Fehlerstroms in dem System der drei Leiter: erster Stromversorgungsleiter, zweiter Stromversorgungsleiter und Schutzleiter, und zum Erzeugen eines entsprechenden Erfassungssignals, sowie
• – einer Steuereinrichtung zum Steuern des ersten, zweiten und dritten Schalters in Abhängigkeit von dem Erfassungssignal, wobei
• – die Steuereinrichtung dazu ausgebildet ist, den dritten Schalter nur dann zum Öffnen anzusteuern, wenn bei geöffnetem ersten Schalter und bei geöffnetem zweiten Schalter der Fehlerstrom erfasst wird.

According to the invention, this object is achieved by a protective switching device for detecting a fault current

• A first power supply conductor to which a first switch is connected,
• A second power supply conductor to which a second switch is connected,
• A protective conductor to which a third switch is connected,
• - Detection means for detecting a fault current in the system of the three conductors: first power supply conductor, second power supply conductor and protective conductor, and for generating a corresponding detection signal, and
• - A control device for controlling the first, second and third switches in response to the detection signal, wherein
• - The control device is adapted to control the third switch only to open when the fault current is detected when the first switch is open and when the second switch is open.

• – Erfassen eines Fehlerstroms in dem System der drei Leiter: erster Stromversorgungsleiter, zweiter Stromversorgungsleiter und Schutzleiter, und Erzeugen eines entsprechenden Erfassungssignals, sowie
• – Steuern des ersten, zweiten und dritten Schalters in Abhängigkeit von dem Erfassungssignal, wobei
• – der dritte Schalter nur dann zum Öffnen angesteuert wird, wenn bei geöffnetem ersten Schalter und bei geöffnetem zweiten Schalter der Fehlerstrom erfasst wird.

Moreover, according to the present invention, there is provided a method of controlling a protection switching device having a first power supply conductor to which a first switch is connected, a second power supply conductor to which a second switch is connected, and a protective conductor to which a third switch is connected , by

• Detecting a fault current in the system of the three conductors: first power supply conductor, second power supply conductor and protective conductor, and generating a corresponding detection signal, and
• - Controlling the first, second and third switches in response to the detection signal, wherein
• - The third switch is actuated to open only when the fault current is detected when the first switch is open and when the second switch is open.

Advantageously, therefore, a known protection switching device is developed to the effect that the control device opens the third switch on the protective conductor only when a fault current is detected, for example, the phase conductor L and the second switch open, for example, at the neutral N with open first switch. Thus, the case of a so-called "dangerous PE" in which the protective conductor PE is at L potential can be eliminated promptly.

Preferably, with the detection device, a current strength of the fault current can be detected and, if the current strength exceeds a predetermined threshold, a corresponding one Detection signal for the control device for opening the third switch can be generated. Thus, for example, if the current strength of the fault current remains below 7.5 mA, the third switch for the protective conductor remain closed, so that, for example, capacitive leakage currents flow off via the protective conductor. Thus, leakage currents can be prevented from touching the body persons.

In one embodiment, the detection device comprises a transformer with an annular core, through which the two power supply conductors and backwards the protective conductor are guided. Thus, a fault current can be detected in the usual way.

The protection switching device may further be configured such that the third switch is opened within a predetermined period of time after an occurrence or detection of the fault current. This is especially necessary for high fault currents in order to exclude a hazard to persons.

Specifically, the predetermined period of time may be such that the opening of the third switch is within the range AC3 of 20 of the Standard IEC 60479-1 he follows. As a result, health damage to persons can be avoided with high certainty.

Specifically, the protection switching device may be configured so that the third switch is closed immediately when the fault current is no longer detected by the detection device. As a result, the consumer (eg the vehicle or its body) is put back to the protective conductor as quickly as possible so that it becomes potential-free.

With the above-mentioned developments of the protective switching device can be mutatis mutandis further develop the inventive method.

In particular, however, an installation system can also be equipped with a protective switching device mentioned above.

Such an installation system can be, for example, a building installation system or even a charging station for electric vehicles.

The present invention will now be explained in more detail with reference to the accompanying drawings, in which:

1 a residual current circuit breaker according to the prior art with switchable protective conductor;

2 one to a residual current circuit breaker according to 1 connected defective consumers;

3 the circuit of 2 with open switches of power supply conductors;

4 the circuit of 3 with additionally opened switch of protective conductor PE and

5 one over the state of the circuit of 3 unchanged state with eliminated fault current.

The embodiments described in more detail below represent preferred embodiments of the present invention.

That on the basis of 2 to 5 Example explained is based on the known circuit arrangement of 1 , With regard to the detailed description, reference is therefore made to the explanations 1 directed.

In 2 is an initial state of a load connected via the residual current circuit breaker to a single-phase supply network (not shown) 10 played. The three switches 2 . 3 and 5 are closed, so the consumer 10 is electrically connected directly to the first power supply conductor, here the phase conductor L, and the second power supply conductor, here the neutral conductor N, and the protective conductor PE of the protective switching device. In the original initial state is the consumer 10 not yet defective, so that the circuit breaker (here residual current circuit breaker) does not have the cause, their switches 2 . 3 . 5 controlled by the evaluation electronics 9 to open.

In the closed state the switch 2 . 3 . 5 now an error occurs 11 (see the above-mentioned error cases), which is symbolic in the consumer 10 is drawn. The detection device in the present example including the transformer 1 , the signal conditioning unit 7 and the amplifier 8th detects a corresponding fault current and generates a corresponding detection signal for the control device (here the transmitter 9 ), which the switches 2 . 3 and 5 controls. The detection signal causes the evaluation 9 to the first and second power supply conductors L, N according to 3 from the consumer 10 to disconnect by the first switch 2 and the second switch 3 be opened. The protective conductor PE remains temporarily on the third switch 5 connected to the consumer. First, it is assumed that the error has occurred on the consumer side with correct wiring. Wiring errors such as the case that the protective conductor is at L potential ("dangerous PE"), are to be regarded as comparatively rare error cases. For this reason, here is a staggered shutdown of the contacts realized by just the first switch of the power supply conductor are opened, while the switch for the protective conductor initially still remains closed. If necessary, then the third switch 5 opened for the protective conductor. For this purpose, the fault current is based on the state of 3 further monitored.

Is in spite of disconnected L and N contacts, ie open switch 2 and 3 , furthermore detected a fault current, is also the third switch 5 opened at the protective conductor PE.

It is then assumed that the error case "dangerous PE" is present, in which the protective conductor PE is at L potential. This is in 4 graphically illustrated. In particular, it can be seen that now all the switches 2 . 3 and 5 are open. Is, however, after opening the two switches 2 and 3 , ie after the interruption of the phase conductor L and the neutral conductor N no more fault current before, so the switch remains 5 according to 5 closed and the protective conductor PE is as desired at ground potential. The protective conductor therefore continues to fulfill its intended purpose and protects, for example, against the occurrence of the error case mentioned at the beginning 2.1 b).

The shutdown, ie the all-pole shutdown by opening the three switches 2 . 3 and 5 or the teilpolige shutdown by opening only the switch 2 and 3 , preferably takes place within the predetermined switch-off time of the respective product standard. In any case, the shutdown but at the latest within the range AC3 the Standard IEC 60479-1 . 20 respectively.

In the examples of 1 to 5 each concrete residual current circuit breaker are shown. The inventive principle of staggered shutdown can also be applied to any other protective switching devices that detect a fault current. In addition, the above examples always refer to a single-phase system with protective conductor. However, the staggered shutdown according to the invention can also be used for any multi-phase system, in particular a three-phase system. In the three-phase system, the three phases and the neutral conductor are then interrupted, for example with four switches. If then then still a residual current flows, and the protective conductor is interrupted by another switch.

In general, therefore, not all contacts are opened directly when errors occur, but at first only the power supply lines or contacts. Only when the error persists will the PE contact be opened as well. This behavior provides increased protection, as the protective conductor is switched only in exceptional error situations. To shut down, the appropriate default times are preferably observed.

LIST OF REFERENCE NUMBERS

L

phase conductor

N

neutral

PE

protective conductor

1

exchangers

2

first switch

3

second switch

5

third switch

6

secondary coil

7

Signal conditioning unit

8th

amplifier

9

evaluation

10

consumer

11

error

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Standard IEC 60479-1 [0019]
• Standard IEC 60479-1 [0036]

Claims (10)

Protective switching device for detecting a fault current with - a first power supply conductor (L), to which a first switch ( 2 ), - a second power supply conductor (N) to which a second switch ( 3 ), - a protective conductor (PE) to which a third switch ( 5 ), - a detection device ( 1 . 7 . 8th ) for detecting a fault current in the system of the three conductors: first power supply conductor (L), second power supply conductor (N) and protective conductor (PE), and for generating a corresponding detection signal, and - a control device ( 9 ) for controlling the first, second and third switches in dependence on the detection signal, characterized in that - the control device ( 9 ) is adapted to the third switch ( 5 ) to open only when opened with the first switch ( 2 ) and with the second switch open ( 3 ) the fault current is detected. Protective switching device according to claim 1, wherein the detection device ( 1 . 7 . 8th ) a current strength of the fault current detectable and if the current exceeds a predetermined threshold, a corresponding detection signal for the control device ( 9 ) for opening the third switch ( 5 ) is producible. Protective switching device according to claim 1 or 2, wherein the detection means comprises a transformer with an annular core through which the two power supply conductors (L, N) and the protective conductor (PE) are guided. Protective switching device according to one of the preceding claims, which is designed such that the third switch ( 5 ) is opened within a predetermined period of time after occurrence or detection of the fault current. Protective switching device according to claim 4, wherein the predetermined period of time is dimensioned so that the opening of the third switch ( 5 ) within the range AC3 of 20 Standard IBC 60479-1. Protective switching device according to one of the preceding claims, designed such that the third switch ( 5 ) is closed immediately when the fault current from the detection device ( 1 . 7 . 8th ) is no longer recorded. Installation system with a protective switching device according to one of the preceding claims. Method for controlling a protective switching device, comprising a first power supply conductor (L) to which a first switch ( 2 ), a second power supply conductor (N) to which a second switch is connected ( 3 ), and a protective conductor (PE) to which a third switch ( 5 ) by detecting a fault current in the system of the three conductors: first power supply conductor (L), second power supply conductor (N) and protective conductor (PE), and generating a corresponding detection signal, and controlling the first, second and third Switch in response to the detection signal, characterized in that - the third switch ( 5 ) is only activated for opening when, when the first switch is open ( 2 ) and with the second switch open ( 3 ) the fault current is detected. The method of claim 8, wherein the third switch ( 5 ) is opened within a predetermined period of time after occurrence or detection of the fault current. Method according to claim 8 or 9, wherein the third switch ( 5 ) is closed immediately when the fault current from the detection device ( 1 . 7 . 8th ) is no longer recorded.

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