DE7835883U1 - Electrical safety device for the rapid disconnection of an electrical mains circuit - Google Patents

Description

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Augsburg, March 13, 1979 Official. File number: G 78 35 883.5

Westinghouse Electric Corporation, Westinghouse Building, Gateway Center, Pittsburgh, Pennsylvania 15222, V.St.A.

Device for the rapid disconnection of an electrical mains circuit

The innovation relates to a device for quick disconnection of a number of mains sockets containing and an electrical net circuit protected by a residual current circuit breaker through generation a fault current between a phase conductor and the earthed protective conductor or neutral conductor.

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Electrical emergency switches for interrupting electrical mains circuits in emergencies are often found in laboratories, Workshops, factories and commercial establishments application. These kill switches are usually big, noticeable ones red pushbutton switches that are placed in easily accessible places in case of an emergency to enable a quick power cut-off,

In known safety systems, the emergency switch is a pushbutton which is open in the idle state and via which, when actuated, the release coil of a safety switch protecting the circuit in question is excited. As a result, separate line connections must be made between the circuit breaker and each location at which an emergency switch is to be arranged. The cost and complexity of this additional network of pipelines, often result in actually less Notschalter

installed than would actually be desirable. In other cases it even happens that because of the cost and the complexity of the security system relies entirely on the installation of such a security system is waived.

Both in the electrical installations of industrial and commercial companies as well as in household installations

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is due to the technical connection conditions, safety regulations and other applicable to the power supply technical guidelines, in addition to overload protection, residual current protection is also required. The residual current protective devices are normally designed in such a way that they are already connected to the relevant electrical network Switch off the occurrence of fault currents, which very much

('are smaller than the tripping currents of the overload fuses. For example, residual current circuit breakers for household installations are often designed so that they already trip in the event of a fault current (earth fault current) of 5 mA.

The innovation is based on the task of designing a device of the type mentioned at the beginning so that a special one Safety line network is dispensable.

' This object is achieved according to the innovation in that the device is designed as a plug-in device that can be plugged into any mains socket, is shaped like a mains plug and has a plug contact arrangement corresponding to a mains plug, with a built-in, open, manually operated switch, the external electrical of which Connections are formed by the plug contacts.

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The device according to the innovation has the advantage that, in addition to the conductors of the relevant network circuit, which are already present No special safety lines required, can be plugged into any socket, portable and easily removed is changeable.

When the switch is closed, a connection y ) is established between the phase conductor and the earthed conductor. By switching on an appropriately dimensioned impedance, it is ensured that no short circuit occurs when the switch is closed; By operating the switch, a fault current is deliberately caused, which triggers the residual current circuit breaker assigned to the relevant circuit, the latter already present in most electrical installation systems and already mandatory for new systems.

In the case of mains sockets / mains plug systems with asymmetrical plug contact arrangement, i.e. with fixed, non-interchangeable Allocation of the individual plug contacts to the phase conductor contact and to the neutral conductor contact of the socket is sufficient j a simple switch between the phase conductor

assigned plug contact and the protective conductor contact of the connector is switched.

In the case of mains sockets / mains plug systems in which the plug contacts (for example in the German Schuko system) form a rotationally symmetrical arrangement and the two

Plug contacts for the phase and neutral during insertion comparable f "\ exchangeable contact in the phase conductor and the neutral conductor contact of the socket can be inserted, is a two pole

* Switch required, the one with the two

) Plug contacts for phase and zero and the other

■ connected to the protective conductor contact of the connector

is and therefore both plug contacts for Phase and zero simultaneously with the protective conductor contact

connects. This ensures that regardless of how the plug-in device is plugged into the socket, definitely a connection between phase conductors

and protective conductor is established, which has a fault current has the consequence.

For multi-phase circuits with multi-phase sockets a simple switch between any one of the various phase conductors assigned to it is sufficient Plug contacts and the protective conductor contact of the plug device is switched, as the residual current circuit breaker always triggers when between any phase and

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a fault current occurs on the protective conductor.

The innovation can also be used for single or multi-phase mains circuits that are located behind the residual current circuit breaker branch and in which the phase conductor protects each branch with its own overload protection is. By operating a device according to the innovation in any branch of the circuit, the entire Circuit to be switched off. This of course has the prerequisite that the overload protection of the relevant Circuit branch is switched on, so the phase conductor of the relevant branch of the circuit is live. Otherwise, no leakage current could occur when the device is operated be generated.

However, it may also be desirable to switch off the circuit in a branched and in its branches individually fused mains circuit from any branch of the circuit by means of a device according to the innovation to be able to trigger even if the overload protection of the relevant circuit branch is triggered and consequently the associated phase conductor is interrupted.

For this purpose, if the device is used in conjunction with residual current circuit breakers after the innovation

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should be, which also when a low resistance occurs Release the connection between the neutral conductor and the protective conductor, the switch on the one hand to the neutral conductor assigned plug contact and on the other hand connected to the protective conductor contact of the connector be. When actuated, the switch establishes a low-resistance connection between the neutral conductor and the protective ( conductor, which triggers the residual current circuit breaker.

Since considerable currents can flow even in the neutral conductor when there is a high load on the circuit, the plug-in device contains preferably a low-resistance impedance connected in series with the switch to limit the current.

■ The switch is advantageously a push button,

Some exemplary embodiments of a device serving as a safety device according to the innovation are described below will be described in more detail with reference to the accompanying drawings. It shows:

1 shows a safety device according to I.

Innovation for generating an error current I between phase and earth conductor,

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Pig. 2 a safety device according to

Innovation for the production of a low-resistance connection between the neutral conductor and protective conductor,

Fig. 3 shows a modification of the security

direction to Pig. I for socket / plug systems with rotationally symmetrical Plug contact arrangement, and

Fig. K shows a further development of a security

device according to Fig. 1 for a three-phase socket.

Fig. 1 shows an electrical network circuit 1 with three conductors, namely a phase conductor L, a Neutral conductor N and a grounded protective conductor G. The one on the left in the drawing to a power source (not shown) (feeding network) connected circuit 1 has a number of sockets 2 for plugging in the power plug electrical devices to be connected to; one of these sockets is shown as an example. The socket 2 has a contact 3 connected to the phase conductor L, a contact 4 connected to the neutral conductor N and a contact contact 5 connected to the earthed protective conductor.

Circuit 1 is through one between your feeding Mains and the first socket arranged residual current circuit breaker 6 secured, which has an opener 7 located in the phase line L. Occurs as a result of an earth fault a fault current occurs between the phase conductor L and earth and the fault current strength exceeds a specified limit value, the residual current circuit breaker 6 is triggered and by opening the contacts of the opener 7 is behind the Residual current circuit breaker · lying part of the circuit disconnected from the network.

The tripping current strength of the fault current at which the residual current circuit breaker 6 responds depends on the respective Use case. For example, to protect people against accidental contact, the residual current circuit breaker is designed in such a way that that a person who comes into contact with the phase conductor L and earth at the same time will not suffer any serious damage can. The tripping current is about 5 mA for this purpose. This tripping current is natural much smaller than the overload tripping current, since the Overload protection mainly to protect the conductors themselves from damage by overcurrents with currents in the area of a few amps or more.

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The illustrated safety device 10 is used to intentionally a fault current between the phase conductor L and Bring about earth. If the current strength of this fault current reaches the tripping current strength of the residual current circuit breaker 6, it triggers and thus disconnects the circuit from the mains.

The safety device 10 is designed as a plug-in device that is shaped like a mains plug, however, a switch 11 in the form of a push button with a push button 12 contains. The connector pins 13, 14 and the connector come by plugging into the associated contacts 3, 4 and 5 of the socket 2 with the Conductors L, N and G in connection, the switch 11 and a resistor 16 connected in series therewith are between the connector pins 13 and 15 connected, which are assigned to the phase conductor L and the protective conductor G, respectively. Accordingly is when the switch is pressed by pressing the push button 12 an electrical connection between the Pin 13 and pin 15 produced, and when the plug device 10 is plugged into the socket 2, flows then a fault current from the phase conductor L via the socket contact 3, the connector pin 13, the resistor 16,

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the switch 11, the connector pin 15 and the socket contact 5 to the grounded protective conductor G. The resistance value of the resistor 11 corresponds to the line voltage on the circuit 1 chosen so that the current strength of the resulting fault current is greater than the tripping current strength of the residual current circuit breaker 6 is. When the push button is pressed, the residual current circuit breaker 6 trips and disconnects

through circuit 1 or its downstream of the residual current circuit breaker lying part of the network.

For example, with an AC mains voltage of 115 V, the residual current circuit breaker 6 can be set to a tripping current of 5 mA so that a | Person is protected from more serious harm. With a dimensioning · | of the resistor 16 with a value of 10 k JX arises at A fault current of approx. 12 mA is applied when the push button is pressed. This fault current is sufficiently above the Tripping current of the residual current circuit breaker 6, but far below the overcurrent trip threshold at which there is a risk of damage to the conductors of circuit 1.

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By for the resistor 16 a resistance value is selected, the one with normal mains voltage well above the tripping current of the residual current circuit breaker If there is a lying fault current strength, one obtains a sufficiently large safety range which ensures that even in emergency situations in which the mains voltage is high can drop, a to trigger the residual current protection | (^ switch sets a sufficiently large fault current.

The resistor 16 is for the operation of the invention Safety device not absolutely necessary. However, its presence limits its size 'of the earth fault current that occurs when the

Push button sets so that cheap low power contacts for the switch 16 can be used. Instead of one A different impedance can also be selected to limit the current.

By designing the safety device as a plug-in device you get a number of advantages. The plug-in device can be plugged into any socket 2 in the circuit 1, and any number of sockets of this circuit with such safety devices can be plugged in be equipped. The cost of a plug

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Devices are much less than the cost of installing an emergency breaker of the prior art which requires separate wiring to connect to the trip coil of a circuit breaker. Further, if a time which is plugged into a socket I ^ an emergency switch, for example, at a remote location from the network required, the plug-in device 20 via a conventional extension _f ν cable, be connected to the network. In this way, the plug-in device can easily be brought to any location from which an emergency shutdown should be possible. In addition, the plug-in device can be carried by staff and used at any location with a socket,

Fig. 2 shows a branched network circuit la, the left in the drawing to a power source (supply network) is connected and having two phase conductors Ll and L2, a • ^ neutral conductor N and a protective earth conductor G. The circuit la is protected by a residual current circuit breaker 6a, which contains an NC contact 7 per phase. The neutral conductor N is grounded upstream of the residual current circuit breaker 6a and the protective conductor G is connected to the neutral conductor. Several branch circuits 21, 23, 25 branch off behind the residual current circuit breaker, each of which has a phase conductor L ',

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have a neutral conductor N ¹ and a protective conductor G ¹ , the neutral conductor N 'and the protective conductor G' of each branch circuit with the neutral conductor N and the protective conductor G and the phase conductor L ^{1 of} each branch circuit connected to one of the two phase conductors L1 and L2, respectively is protected by its own, single-pole overcurrent circuit breaker 22 or 24 or 26.

In the circuit shown in Fig. 2, the above

Embodiment of the safety device described with reference to FIG. 1 only trigger the residual current circuit breaker when the switch is actuated if the overcurrent circuit breaker 22 or 24 or 26 of the relevant branch circuit with which the safety device is connected by plugging it into a socket connected to it, is not switched off. Should the relevant overcurrent circuit breaker must be switched off, is the phase conductor of the relevant branch circuit de-energized and consequently, by actuating the embodiment of the safety device already described no residual current can be generated to trigger the residual current circuit breaker.

The safety device shown in FIG. 2 enables the residual current circuit breaker 6a to be triggered

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by actuating a safety device plugged into a socket 2 of any branch circuit 21, 23 or 25 10 even if the overcurrent circuit breaker in the phase conductor L 'of the branch circuit concerned is switched off is.

In the embodiment shown in FIG. 2 arrangement, the fault current protective switch comprises 6a additionally comprises means 20 for \ generating voltage pulses, which are transmitted via an exciter transformer 27 on the neutral conductor N. If a low-resistance connection is established between the neutral conductor N and earth behind the residual current circuit breaker, a circuit is closed so that pulse currents flow due to the voltage pulses induced in the neutral conductor. The residual current circuit breaker contains means that respond to this pulse

respond to currents and trigger the residual current circuit breaker immediately, so that when a low resistance occurs Connection between the neutral conductor and earth behind the residual current circuit breaker an opening of the NC contacts 7 and thus a separation of the entire circuit la from the feeding network takes place. This neutral earth fault protection is often used in residual current circuit breakers to ensure the safety and reliability of the residual current: ":" :!

Circuit breaker increase because, although a grounded

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The neutral conductor in itself does not pose a risk, an earth fault of the neutral conductor can reduce the sensitivity of the residual current circuit breaker for any fault currents that occur. A more detailed description of such residual current circuit breakers with neutral earth fault protection can be found, for example, in US Patents 3,959,693 and 3 611 035.

The safety device 10 shown in FIG. 2 is used to intentionally establish a ground fault in the neutral conductor, that is to say to establish a low-resistance connection between the neutral conductor and the protective conductor. For this purpose, the switch 11 of the plug device 10 in the embodiment according to FIG. 2 is connected between the plug pin 14, which interacts with the ^{socket contact 4 connected to the neutral conductor N 1} , and the plug contact 15, which is connected to the

® ■ conductor G ¹ connected socket contact 5 interacts. A low-resistance resistor 16a is connected in series with the switch 11 and has a value of l_ft, for example. Has. This resistance is not absolutely necessary for the operation of the safety device, but it is, when the branch circuit concerned is heavily loaded, a considerable current flows through the neutral conductor,

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advantageous for current limitation, as cheap low-voltage contacts to be used for the switch 11. Instead of one resistance, another resistance can of course also be used Impedance, for example a coil or a capacitor, is used to limit the current.

When the switch 11 is actuated by pressing the push button 12, an electrical connection is established between the plug pins 14 and 15, so that when the plug device 10 is plugged into a socket 2, due to the voltage pulses induced in the neutral conductor N, corresponding pulse currents via the branch circuit. Neutral conductor N ', the socket contact 4, the plug pin 14, the switch 11, the resistor 16a, the plug pin 15, the socket protective conductor contact 5 and the protective conductor can flow. These pulse currents are detected by the residual current circuit breaker, ) which then trips and disconnects the entire circuit la from the mains,

Those described above with reference to Figs Embodiments are tailored to mains sockets / mains plug systems with a plug contact arrangement in which the three plug contacts due to their different

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Shape and its non-rotationally symmetrical arrangement when plugged in cannot be interchanged with the phase conductor contact or the Neutral conductor contact or the protective conductor contact of the socket are assigned, so that of the connector pins a certain plug pin clearly corresponds to the phase conductor and another certain plug pin clearly corresponds to the neutral conductor assigned.

For socket / plug systems with a rotationally symmetrical plug contact arrangement and identical shape of the two Phase and zero assigned plug contacts, for example in the German Schuko system, the plug safely leaves in Insert two different positions into the socket, namely rotated by 180 ° against each other, so that of the two plug contacts provided for phase and zero, depending on how the plug is inserted into the socket of one of these two plug contacts with the phase conductor and the other of these two plug contacts comes into contact with the neutral conductor, this respective connector contact assignment by reversed insertion of the plug is interchangeable.

When realizing a plug / socket system of this type in connection with sockets

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using the safety device of the above based on Fig. 1 described basic type, in which, when actuated, a fault current between the phase conductor and the neutral is generated, care must therefore be taken that regardless of the type of plugging the safety device, which in turn is designed as a plug-in device, is definitely connected to the socket is established between the phase conductor and the neutral conductor.

Fig. 3 shows a safety device 40 in connection with a German Schuko socket 32. The socket has two symmetrically arranged contacts 33 and 34 the same shape, which are connected to the phase conductor L and the neutral conductor N. It also has the socket two electrically interconnected earthing contact springs 35 which are connected to the protective conductor G.

Correspondingly, the plug device 40 has two plug pins 43 and 44 which are inserted into the socket contacts 33 and 34 can be plugged in, and two protective conductor contacts 45, when plugged in with the contact springs 35 of the socket cooperate. So that now when the push button 12 of the connector 40 is actuated, a fault current between

Phase and protective conductor can be generated regardless of whether when plugging in the connector 40, the connector pin 43 with the contact 33 and the connector pin 44 with the contact 34 or, with the reverse insertion, the connector pin 43 with the contact 34 and the connector pin 44 with the contact 33 comes into contact with the socket 32, the plug device 40 contains two interconnected and ( \ jointly actuatable switches 11a and 11b, which are each connected on the one hand to the protective conductor contact 45 and on the other hand to the connector pin 43 or the connector pin 44 and each with a current limiting resistor 46a and 46b are connected in series.

Fig. 4 shows a safety device for generating a fault current, which in a three-phase socket of a Three-phase circuit can be plugged in,

The three-phase socket 52 has four contacts 53, 54, 55 and 56, which are connected to the neutral conductor N and the three phase conductors R, S and T are connected, and a protective conductor contact 57, which is connected to the protective conductor G. Guide lugs 58 prevent incorrect insertion of a plug.

The safety device 60, which is designed as a plug-in device, has four plug pins 63, 64, 65 and 66, which

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the NuIleiterkontakt 53 or, the three phase conductor contacts

^ 5k, 55 and 56 are assigned to the socket, and one

1 protective conductor contact pin 67. Since it is used to trigger the

1 residual current circuit breaker is sufficient to generate a residual current

I between any phase and the protective conductor

I generate, the connector 60 contains a switch 61, the pin with the protective conductor contact 67 and one of the

■■ 'pin three plugs assigned to the three phases, namely

|. for example the connector pin assigned to phase R.

I and connected to a current limiting resistor 62 in

' Is connected in series.

Claims (3)

Protection claims 1. Device for quick disconnection of a number of mains sockets and containing a residual current circuit breaker Protected electrical network circuit by generating a fault current between a phase conductor and the earthed protective conductor or neutral conductor, characterized in that the device can be used as an option in each any plug-in power socket, shaped like a power plug and corresponding to a power plug A plug-in device (10; 40; 60) having a plug-in contact arrangement with a built-in, manually-operable one that is open in the idle state Switch (11; 11a, 11b; 6l) is formed, the external electrical connections of which through the plug contacts (13, 15; 43, 44, 45; 64, 65, 66, 67) are formed. 2, device according to claim 1, characterized in that the switch (11; Ha, Hb; 6l) is a push button. 3. Apparatus according to claim 1 or 2 _3, characterized in that the switch (Ha ₃ Hb) is a two-pole switch.