WO1997018571A2

WO1997018571A2 - Device for forcible separation of main supply lines in switching devices

Info

Publication number: WO1997018571A2
Application number: PCT/DE1996/002148
Authority: WO
Inventors: Gerhard Scholz
Original assignee: Aeg Niederspannungstechnik Gmbh
Priority date: 1995-11-16
Filing date: 1996-11-12
Publication date: 1997-05-22
Also published as: EP0804800B1; DE59606956D1; ATE201531T1; ES2159060T3; DK0804800T3; DE19542690A1; EP0804800A3; EP0804800A2; WO1997018571A3; GR3036359T3

Abstract

All switching devices which have the purpose of protecting people or objects from the harmful effects of electric current include at least triggering elements which trigger the appropriate switching mechanisms whenever predetermined threshold values are exceeded. This opens the main current contacts in the switching device, thus usually stopping current flow. However, such switching devices occasionally fail in an emergency situation because, for example, the trigger elements stick, the switching mechanisms jam, the contacts become welded together, or because of other faults. For such eventualities, a device is proposed for forcibly interrupting the appropriate mains or main current lines with a work storage unit. The latter produces a force along a pathway and is kept in an inactive state by a locking mechanism. The locking mechanism can easily be released by a trigger controlled by the switching device and the work storage unit can thus be freed to switch to its active state. A separator device driven by the work storage unit then forcibly separates the current lines. The device is especially suitable for incorporation in or combination with protective switches such as fault current protective switches, automatic cut-outs, bus protection switches, motor protection switches, power protection switches and the like.

Description

Description:

"Device for forcibly disconnecting power lines in switchgear"

All switching devices that are intended to protect people and / or property from the dangerous effects of electrical current, such as residual current circuit breakers, circuit breakers, main circuit breakers, motor circuit breakers, circuit breakers and the like, contain triggers that detect residual currents or overloads or short circuits and then trigger the switchgear when limit values are exceeded . The main current contacts of the switchgear then open, so that normally no harmful current can flow.

However, it happens that such switching devices fail in an emergency because, for example, their triggers stick, the switching mechanisms stick, the contacts are welded or other defects are present. In this case, the persons and / or things to be protected are at considerable risk, especially if a residual current circuit breaker fails.

From DE-A 42 11 079 an electrical fuse element, in particular a high-current fuse element, is already known, in which a current conductor connected to the circuit to be protected is destroyed if the current strength exceeds a threshold value. Here, the strength of the current flowing through the current conductor is determined by a current detection device which, after the threshold value has been exceeded, destroys the current conductor by means of an ignition pulse generating device and a pyrotechnically operated separating device. The aim of this arrangement is to replace the thin fuse wire which is customary in conventional fuses with a thicker current conductor in order to reduce the power loss. As a result, when the threshold value matched to the associated nominal current strength is reached, this current conductor cannot self-destruct through melting, but must be mechanically separated by a device.

In contrast, the invention is based on the object, in the event of failure of the switching devices mentioned at the outset, in particular for residual current circuit breakers, to provide a device for forcibly and very quickly disconnecting the associated mains or main power lines, so as to rule out a risk to people and / or things. This object is achieved by a device with the characterizing features of claim 1. Further developments and advantageous refinements of the invention are specified in the subclaims.

The device essentially has the following elements: a) a working memory from which a force can be made available via a path. Such working memories can be, for example:

• preloaded springs such as cylindrical coil springs, spiral or torsion springs.

• Accumulators in which a working medium is kept compressed, which provides a force via a path when expanded by means of a piston.

• Gas generators, such as those already used in airbag and belt tensioning systems. These generate a gas volume, which then uses a piston to provide a force over a path.

b) a locking mechanism which keeps the working memory in its inactive state with little effort. Such locks can be:

• Lever, toggle, ratchet or Riegeiges lock, as well as other means that are each positively effective.

• friction-locking mechanism.

c) a trigger that releases the locking mechanism and thus releases the working memory. Triggers can be:

• a preloaded spring that is held by a thin wire. This wire may have a predetermined breaking point and is held until it is melted by a current.

• A device that generates a movement of a body from electrical forces. This can be an electromagnet, but also the Coulomb force, the capacitor effect, the Johnsen-Rhabeck effect or the attempt by Elihu Thomson can generate the movement of the body.

• a stream that activates a fuel. d) a separation device that drives the separation of the lines driven by the working memory. The mains or main power lines can be separated by:

• Opening contacts

• Cutting lines

• Destruction of lines. The particular advantage of the device according to the invention is that it can be arranged in series directly in circuit breakers of the type mentioned above or as an additional device. In particular, the fault, overload or short-circuit currents are measured in the circuit breakers using suitable conventional current measuring systems and these measured values are also used by the device. If the measured values exceed a predetermined limit value and the respective circuit breaker does not switch off within a certain time, the mains or main power lines are disconnected using the device according to the invention. If the basic protective function of the switchgear, which is fundamentally present, fails for various reasons, the device simply and reliably interrupts the current-carrying lines within a certain non-hazardous time. This forced separation of the lines is normally a one-time and irreversible process, so that at least the circuit breaker or the switching device must then be replaced and the device reactivated.

The invention is explained in more detail below using various exemplary embodiments with reference to the drawing.

1 to 7 show the device only schematically, each with working memory,

Locking and triggering and the interaction of these assemblies, while in Fig. 8 to 15 possible forms of the separation device are also only shown schematically, a combination of these elements with the assemblies according to Fig. 1 to 7 being realized as desired in the sense of the invention can.

In the device according to FIG. 1, a spring accumulator is provided as the working memory, which interacts with a lifting lock and a fuse wire as a trigger. In this case, a compression spring 2 and above it a piston 3 with a plunger 3.1 are arranged in a pot-shaped housing 1, which represent the essential parts of the spring accumulator. The compression spring 2 can be compressed by means of a lever 4 mounted in the housing 1, which acts on the upper side of the piston 3, so that it is under spring tension. This prestressed position of the compression spring 2 (as already shown in FIG. 1) is reliably held by means of a fusible wire 5 engaging the lever 4 and anchored to the housing 1. Due to a relatively short lever arm for the point of engagement 4.1 of the lever, there is also a favorable transmission ratio, based on the fastening point of the fusible wire, which is accordingly made thin can. Despite sufficiently large forces and travel of the compression spring 2 and corresponding conditions on the piston 3 or plunger 3.1, such a thin fuse wire can be melted by a current in a very short time and the working movement of the plunger 3.1 can thus be initiated very quickly.

The function of the above-described assembly of the device is as follows: If the specified limit values of fault current, overload or short-circuit current are exceeded and the circuit breaker (not shown here) has not tripped within the required time, a triggering current is conducted to the fuse wire 5 by the measuring devices of the circuit breaker that will melt it. Immediately the lever 4 is released and under the action of the tensioned compression spring 2 the piston 3 with its plunger 3.1 swings upwards or away from the housing 1. With this plunger movement, mains or main power lines of the circuit breaker are then forcibly separated via the isolating devices according to FIGS. 8 to 15, which will be described in more detail below.

The device according to FIG. 2 is designed in a similar manner. Here, however, a tension spring 2 'is suspended in the cup-shaped housing 1 as a spring accumulator on the piston 3 or on the housing. The tension spring is tensioned via a toggle lever 4 'which engages in the area of the spring eyes and is arranged in the spring interior, as shown in FIG. 2. So that the toggle lever 4 'can maintain its almost extended position and thus the spring tension, it is also locked by a fuse wire 5. This is preferably attached at one end to the toggle joint and held at the other end on the outer surface of the housing and led out there. Another tension spring 6, whose direction of action and points of attack correspond approximately to the position of the fuse wire, supports the latter in its task. The tension spring 6 is considerably weaker than the tension spring 2 '. Nevertheless, the tension spring 6 relieves the fuse wire 5 considerably, so that it can be made much thinner than in the exemplary embodiment according to FIG. 1. Its mode of operation is also analogous here, that is, after the fuse wire 5 is destroyed by a trigger current, the tension spring drives 2 'the plunger 3.1 and this ultimately a separating device.

The device according to FIG. 3 is also designed with a toggle lever. Here again serves as a spring accumulator, a compression spring 2, which is braced by the toggle lever 4 'via the piston 3 against the bottom of the housing 1. The almost stretched location of the as a ratchet The toggle lever 4 'which engages above the piston and is supported on the upper side of the housing is again ensured by the fuse wire 5, which, together with a tension spring 6, also prevents the toggle lever from buckling here. This device also functions in the manner already described.

In Fig. 4 a device is shown which, in contrast to the previous arrangements, has a Riegeiges lock. For the rest, a compression spring 2 is arranged as a working memory in a pot-shaped housing 1, which is tensioned by the piston 3. In the plunger 3.1 there is a recess into which a bolt 7 engages, which is supported on the top of the housing 1 and thus blocks the plunger in the position shown. A fuse wire 5 also holds the bolt 7 in engagement with the plunger recess, while a tension spring 7.1 engaging the bolt attempts to unlock it against the holding force of the fuse wire.

The operation of this device is carried out in the manner already described, that is, after the melting wire 5 has been smeared due to a tripping current, the spring 7.1 pulls the bolt out of the recess in the plunger 3.1. The inactive position of the working memory is thus eliminated and, under the action of the compression spring 2, the plunger 3.1 then shoots upwards and also drives a separating device for the forced separation of the power lines.

Furthermore, the device can be provided with a pressure accumulator as working memory, as shown by way of example in FIGS. 5 and 6. A working medium - preferably air - is kept compressed in the pressure accumulators and initially prevented from expanding by a locking mechanism.

5, a compressed working medium 8 is enclosed by the piston 3 in the housing 1, which is designed to be pressure-resistant. This is locked against the pressure of the working medium by means of a toggle lever 4 '- similar to the devices according to FIGS. 2 and 3, a fusible wire 5 likewise preventing the toggle lever from buckling. If the fuse wire is destroyed, the toggle lever releases the piston 3 and the compressed working medium 8 can expand, so that the plunger 3.1 moves away from the housing and actuates the separating device already mentioned. 6, in which a chamber of the housing 1 for receiving the compressed working medium 8 is closed by a valve 9. The valve, which is loaded by a compression spring 9.1 in the opening direction, is also held against this force by a fusible wire 5, so that the chamber remains tightly closed with the compressed working medium. A piston 3 with the tappet 3.1 is again arranged above the valve chamber. After the fuse wire 5 has been destroyed by a trigger current, the valve 9 opens under the action of the compression spring 9.1 and the working medium 8 can escape into the valve chamber. From there it flows under the bottom of the piston 3, which thus carries out the working stroke and again actuates a separating device with the plunger 3.1.

The device according to FIG. 7, in which the working memory is designed as a pyrotechnic gas generator and is automatic, that is to say without an actual locking mechanism, is in an inactive state. In this device, a fuel 8 'with a primer 8.1 is arranged in the housing 1 and enclosed by a gas-permeable wall 1.1 of the housing towards the piston 3. If a trigger current is applied to the primer, the fuel 8 'is activated and a gas volume is created. This flows under the bottom of the piston 3 and drives it together with the plunger 3.1 to actuate one of the separating devices described below.

8 to 15 separating devices of various types are shown. 8 contacts 10 and 11, which are connected in series in the course of a mains or main power line 12, are pressed together by spring force. A wedge-shaped insulating body 13 is arranged in front of the contacts and can be directly part of the plunger 3.1 of one of the working memories already described. In the case of a forced disconnection initiated by the trigger and the working memory, the insulating body 13 is immediately pressed between the contacts 10, 11 and opens them. The mains or main power line 12 is thus forcibly interrupted in the course of the corresponding circuit breaker, not shown.

9 shows two disconnecting devices by means of additional contacts 10 ', 11' or 10 ", 11", which can be opened in the course of the mains or main power line 12 and opened by the plunger 3.1 of the working memory. In Fig. 10 switching contacts 14, 15 are schematically shown by a circuit breaker, which are arranged in series with the line to be protected. If these switching contacts are welded in the event of a trip, for example, they are forced open by the plunger 3.1 of the working memory, which is also only indicated here. In this way, the mains or main power lines can be interrupted directly in the switching device.

Another form of separation device is shown in FIG. 11. Here, a contact sleeve 16 and a contact pin 17 are arranged in series with a line L1, which interlock and connect the two line ends to one another. The contact pin 17 also forms the tip of the plunger 3.1. If the piston of the working memory is moved so far in the direction of the arrow that it has pushed the contact pin 17 out of the contact sleeve 16 and the insulating part 3.1 'of the plunger is in the sleeve, the line L1 is interrupted.

Separating devices for several lines, which are similar in construction to FIG. 11, are shown schematically in FIGS. 12 / 12a and 13 respectively. The separating device according to FIG. 12 and its side view FIG. 12 a are enlarged in diameter on one Insulating part 3.1 'of the plunger two contact pairs 17' arranged at right angles, each working on the corresponding counter contacts 16 'of lines L1 and L2 on the circumference. By moving the plunger 3.1, as indicated by an arrow in FIG. 12a, the opposing contact pairs in the insulating part 3.1 'and the circumferential counter contacts come out of engagement, so that the lines L1 and L2 are interrupted.

13, three contact pairs for the lines L1, L2, L3 are arranged one behind the other in an axial direction around an insulating part 3.1 "of the plunger. If the plunger 3.1 is moved in the direction of the arrow shown, the contact pins arranged in the insulating part come 17 "out of engagement with the mating contacts 16" arranged on both sides thereof. The path of the plunger and thus also of the piston must be limited so that in the interrupted state there is a sufficient distance or offset between the contact pins 17 "in the insulating part and the mating contacts 16 "of the three lines remains. In this respect, the distances between the three contact pairs are only a schematic arrangement.

14 and 15 are separating devices in which the lines are irreversibly interrupted. 14 is a line schematically 12, which has a predetermined breaking point 12.1. The predetermined breaking point is arranged such that it comes to lie opposite the end face of the plunger 3.1. As soon as the piston of the working memory is moved in the direction of the arrow shown, the plunger 3.1, with its forehead designed as an insulating part, opens the line 12 at the predetermined breaking point and forcibly separates it.

In the arrangement according to FIG. 15, the line 12 has a uniform cross-section throughout, whereas the tip of the plunger 3.1 is designed like a knife. The plunger directed at right angles to the line also cuts the line 12 with the knife edge during a piston movement that is driven by the main memory. With such an arrangement, the forces and paths of the working memory available must of course be matched to the cross section and the required shear forces of the line 12.

8, 14 and 15 each show only the mechanical separation from a line. If several lines are disconnected at the same time, a corresponding number of disconnection devices must be provided and the drives of the working memory distributed over these disconnection points. In addition, the working memory and separation devices should be coordinated with one another in a sensible manner.

Claims

Claims:

1. Device for the forced disconnection of mains or main power lines (12, L1.L2) in switching devices, in particular in the case of residual current circuit breakers, characterized by the following features:

• The device has a working memory (2, 2 ', 8, 8'), which provides a force along a path;

• the working memory (2, 2 ', 8, 8') is kept in an inactive state by means of a locking mechanism (4, 4 ', 7);

The locking mechanism (4, 4 ', 7) can be released with little effort and the working memory (2, 2', 8, 8 ') can be released via a trigger (5, 6, 7.1, 9.1) controlled by the residual current of the residual current protective holder, so that it changes from the inactive to its active state;

• A separating device (3.1, 13) driven by the main memory (2, 2 ', 8, 8') causes the mains or main power lines (12, L1, L2) to be disconnected in the active state.

2. Apparatus according to claim 1, characterized in that main memory in the form of springs (2, 2 ') or pressure accumulators (8) or gas generators (8') as a drive for the forced separation of the lines (12, L1, L2) are used.

3. Apparatus according to claim 1, characterized in that locking mechanism in the form of levers (4) or toggle levers (4 ') or ratchet or latch lock (7) the working memory (2, 2', 8, 8 ') until it is triggered in keep inactive state.

4. The device according to claim 1, characterized in that the trigger has a biased spring (6, 7.1, 9.1), which is held by a thin, optionally provided with a predetermined breaking point wire (5) until the wire through one Forced separation initiating current is melted.

5. The device according to claim 1, characterized in that the trigger is in principle designed as an electromagnet or other body moved due to electrical effects.

6. The device according to claim 1, characterized in that the forced separation is brought about by opening contacts (10/11, 14/15, 16/17) or cutting or destroying lines (12) in the separating device.

7. Device according to one of claims 1 to 6, characterized in that with a working memory (2, 2 ', 8, 8') separation devices for the simultaneous forced separation of one or more lines (L1, L2, L3), for example the phase conductor and the neutral conductor, are driven.

8. Device according to one of claims 1 to 7, characterized in that the separating device for the mains or main power lines (12, L1, L2) is arranged within the switching device.

9. Device according to one of claims 1 to 7, characterized in that the separating device for the mains or main power lines (12, L1, L2) is located in an additional housing arranged in series with the switching device.

10. Device according to one of claims 6 to 9, characterized in that the separating device is provided with a wedge-shaped insulating body (13) which can be inserted between two contacts (10, 11) of the mains or main power lines (12) (Fig. 8th).

11. The device according to one of claims 6 to 9, characterized in that the separating device (3.1) has a knife, preferably an insulated knife, with which the mains or main power lines (12) can be cut (Fig. 15).

12. Device according to one of claims 6 to 9, characterized in that a predetermined breaking point (12.1) in the mains or main power lines (12) can be opened with an insulated plunger (3.1) arranged in the separating device (Fig. 14).

13. Device according to one of claims 6 to 9, characterized in that the separating device (3.1) has a in the network of the main power lines (L1, L2, L3) arranged, from a contact sleeve (16) pull-out contact pin (17) (Fig . 11, 12, 13).

14. Device according to one of claims 6 to 9, characterized in that the existing switch contacts (14, 15) of the circuit breaker by means of the separating device (3.1) can be opened for the forced disconnection of the mains or main power lines (Fig. 10).

15. Device according to one of claims 6 to 9, characterized in that the separating device (3.1) as a contact of a second contact point (10 ', 1 1' or 10 ", 11") formed in the mains or main power lines (12) is (Fig. 9).