WO1999014779A1

WO1999014779A1 - Device for generating auxiliary energy for a trigger system, and operating mode

Info

Publication number: WO1999014779A1
Application number: PCT/DE1998/002774
Authority: WO
Inventors: Holger Hochgraef; Ulrich Baumgärtl; Wolfgang Röhl; Jeffery C. Mizener
Original assignee: Siemens Aktiengesellschaft
Priority date: 1997-09-16
Filing date: 1998-09-14
Publication date: 1999-03-25
Also published as: DE19843245A1; EP1016112A1; DE59802469D1; EP1016112B1

Abstract

The invention relates to a device designed to generate auxiliary energy intended for operating the trigger mechanism of a low voltage circuit-breaker. Said device presents a closing control in a mobile interrupter contact (1) as well as a generator (23) which is activated as a result of the interrupter contact closing (1). The generator (23), whether piezolelectric or otherwise, can be designed as an ending stop (33), which is used as a limit switch for the actuating device (7) when closing the interrupter contact (1). The output value appearing at the generator (23) is used, when power is supplied after a short circuit, as a signal for triggering the immediate activation of the voltage circuit-breaker.

Description

description

/ Arrangement for obtaining auxiliary energy for a trigger system and use of the same

The invention relates to an arrangement for obtaining auxiliary energy for operating a tripping system of a low-voltage circuit breaker, which has a spring-operated drive device for closing at least one movable switching contact and a releasable latching device for maintaining the closed state of the switching contact. wherein the trigger system comprises a trigger circuit for evaluating a current flowing through the switch contact on the basis of predetermined parameters and a switch device which can be activated by the trigger circuit for releasing the latching device by means of an actuating device for opening the switch contact.

An arrangement with these features corresponds to a commercial concept, as can be seen, for example, from EP 0 590 937 A2. Details of the mechanical part of a low-voltage circuit breaker for high switching capacities can be found, for example, in DE 44 16 088 Cl.

The auxiliary energy required to operate the trigger system can be provided according to two fundamentally different principles. One of these principles is the provision of an independent auxiliary energy source, ie a battery or a connection to an independent auxiliary network. Since batteries have a limited lifespan and an auxiliary network can fail, the operation of the release system according to this principle is often not considered to be sufficiently reliable. The further principle is that the auxiliary energy required to operate the tripping system is obtained from the same network in which the circuit breaker is located. As a rule, the currents flowing through the switching contacts of the circuit breaker are provided

Current transformers also used to keep the release system in operation and to feed the actuating device mentioned when the switch contacts are to be opened. In this case, the actuating device can either be acted upon directly by the secondary current of the current transformers, or a capacitor can be charged as an intermediate store by interposing a power supply device. Both arrangements differ in terms of their circuitry and the speed of response of the actuating device.

The invention has for its object to provide an arrangement for obtaining an auxiliary energy of the type mentioned, which is characterized by a particularly high level of reliability and at the same time requires only a small amount of circuitry.

According to the invention, this object is achieved in that, in order to provide the auxiliary energy, a generator designed as a mechanical-electrical converter is connected to the drive device and can inevitably be actuated when the switching contact closes.

The auxiliary energy is thus obtained from the mechanical kinetic energy of the circuit breaker. However, this does not mean that the circuit breaker has to be designed differently from a mechanical point of view than has hitherto been customary or required. Rather, the invention makes use of the fact that a not inconsiderable excess of mechanical drive energy is present in the circuit breaker. is there. This excess is necessary in order to bring about a safe switch-on with subsequent latching of the switching contacts in the closed position even with the greatest movement resistance. In the previously known circuit breakers, the excess drive energy is absorbed by energy-consuming buffers and mechanical locks in order to avoid that important components of the circuit breaker are damaged or destroyed as a result of the jerky termination of the drive movement. According to the invention, the excess drive energy is at least partially converted into electrical auxiliary energy for operating the release system and is thus used to advantage.

Different known generators are suitable for the purposes of the invention. In particular, a piezoelectric generator can be provided. This is particularly suitable if the auxiliary energy is to be obtained along a relatively small part of the drive path of the drive device.

Another suitable design of a generator is a magnetic-electrical generator. This can have the shape of a linear generator, for example, which is actuated at least along part of the drive path.

The known rotating generators of various designs are also suitable for the purposes of the invention.

The principle behind the generation of auxiliary energy according to the invention is that the duration of the energy production is relatively short. Since it may be desirable to keep the energy generated available over a longer period of time, it is advisable to connect an energy store between the generator and the trigger system. The previously known trigger systems have an electromagnet as the actuating device. To trigger the circuit breaker, the electromagnet is energized and a plunger is moved against the force of a return spring. In contrast, the following features can be provided according to a further embodiment of the invention:

the actuation device is designed as a piezoelectric actuator to be fed directly by the energy generated by the generator when the switching contact closes,

- The Verkl kungsemrichtung is designed such that it can be actuated by activating the actuator to maintain the closed state of the switching contact and

- The switching device is connected in parallel to the actuator as a bridging switch, which is to be closed by the release circuit in order to reset the actuator and release the locking device.

In this configuration of the / arrangement, use is made of the property of the piezoelectric actuators that only an extremely small amount of energy is required to maintain their activated state. In the manner already mentioned, this can be taken from an energy store which absorbs that part of the energy generated by the generator which remains after the initial activation of the piezoelectric actuator. The actuator is deactivated by the bypass switch and its mechanical idle state is restored. As a result, the locking device is released.

According to a further embodiment of the invention, any influence of the generator provided on the sequence of movements of the drive device can be ruled out in that the generator is only part of a towards the end

of the switching contact effective end stop c, which is dimensioned for the absorption of a residual energy remaining after the switching contact has closed and the locking device has taken effect.

Piezoelectric generators and piezoelectric actuators are known in a number of different designs. For example, a piezoelectric generator is described in DE 34 24 339 AI and a piezoelectric actuation of a switching contact in DE 36 29 040 AI.

The circuit arrangements explained above can be improved further in that an AND gate is provided for linking a signal emitted by the trigger circuit for the occurrence of a short-circuit current and a signal of the generator, and for emitting an output signal when both signals occur in a temporal connection.

A circuit arrangement equipped with an AND element can advantageously be used to bring about an undelayed tripping of the circuit breaker by means of the output signal of the AND element if the circuit breaker is switched on to an already existing short circuit.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the figures.

Figure 1 shows schematically simplified the overall arrangement of a circuit breaker with a drive device and an arrangement for obtaining auxiliary energy.

FIG. 2 also schematically shows a first embodiment in which a release magnet is provided to release a locking device. A further exemplary embodiment is shown schematically in FIG. 3, in which a piezoelectric actuator interacts with the latching device.

An end stop designed as a generator for providing auxiliary energy is illustrated in FIG. 4.

In FIG. 1, a movable switch contact 1 and a stationary switch contact 2 interacting with it, with subsequent current conductors 3 and 4, are shown as part of a main current path as part of a low-voltage circuit breaker. Contrary to the simplified representation, conventional circuit breakers have three or four main current paths and are therefore provided with a corresponding multiple arrangement of the modules mentioned. The movable switch contact 1 is connected in an articulated manner to a pivotably mounted contact carrier 5, a contact force spring 6 being located between the contact carrier 5 and the movable switch contact 1. In order to transfer the movable switching contact 1 from the open position shown in FIG. 1 to the closed position (FIGS. 2 and 3), a drive device, designated as a whole as 7, is provided, which has a spring accumulator 10. The spring accumulator 10 is shown in its tensioned state, in which it is held by means of a locking rod 11. Also shown is a release magnet 12 which can be actuated in a known manner.

When the locking rod 11 is released, the movable switch contact 1 can be actuated by the spring accumulator 10 by means of a drive link 13 indicated by a dot-dash line. This is done via a switching linkage 15 and a latching device 16, which ensures that the movable switching contact 1 remains in its closed position. Taktkraftfeder 6 is also maintained a required contact force.

So that the circuit breaker can perform its protective functions, current transformer 17, whose secondary winding 20 provides a current signal that is applied to a trigger circuit 21, is attached to current conductor 3 of main current path e mentioned. This contains, in a known manner, analog or digital electronic circuits for evaluating the current signal present on the basis of predetermined parameters, in order to control an actuating device 22, which acts on the locking device 16, if necessary.

The auxiliary energy for operating the trigger circuit 21 and the actuating device 22 is generated by means of a generator 23 which is connected to the drive rod 13. This can be any generator of the type already known. The auxiliary power generated is kept available for a long period of time by being stored in a capacitor 24. Further details are explained below with reference to FIGS. 2 and 3.

In FIG. 2, only the main current path of the circuit breaker with the movable switching contact 1 in its closed position and the latching device and the tripping system are shown. The locking device 16 is shown as a locking bar with a locking lug 25, on the locking pin 26 which can be displaced by a release magnet 27 against the action of a return spring 30. A switching contact belonging to the trigger circuit 21 is shown as the switching device 31. Compared to the previously known circuit breakers, there is the difference that the tripping magnet 27 does not come from a separate auxiliary network or by means of the current transformer 17, but rather by means of the Generator 23 (Figure 1) generated and m operated in a capacitor 24 buffered energy.

In the further exemplary embodiment according to FIG. 3, the locking pin 26 is held in engagement with the locking lug 25 of the locking device 16 by a piezoelectric actuator 32. This takes place in that the actuator 32 is acted upon directly by the energy generated in the generator 23 and thus brings about the position of the locking pin 26 shown in FIG. 3. Subsequently, the actuator 32 requires only very little energy to maintain the position shown. The circuit breaker is drawn in that the switching device 31 contained in the opening circuit 21 is parallel to the actuator 32 and this is thus short-circuited when the switching device 31 is closed. This leads to the immediate resetting of the actuator 32 and the withdrawal of the locking pin 26 for the purpose of releasing the locking device 16.

As an example of the arrangement of a generator for generating the auxiliary energy, FIG. 4 shows an end stop 33 which is supported on a wall 34 of the circuit breaker in a relatively stationary manner. The end stop 33 has a housing 35 in which there is an arrangement of piezoelectric generators 36. Em plunger 37 serves to introduce kinetic energy into the piezoelectric generators 36. This is done by means of a pivotable lever 40, which can be part of the drive rod 13 m FIG. 1. An arrow 41 indicates the transfer of the lever 40 from a rest position m to the switch-on position shown in dashed lines. Obviously, the end stop 33 is equally suitable for absorbing a linear movement and converting a residual mechanical energy into an auxiliary electrical energy. An AND gate 42, to which two input signals can be fed, is shown in dashed lines in FIG. One of the input signals is provided by the trigger circuit 21 when a short circuit current flows through the main circuit of the power switch (current conductors 3 and 4) and is accordingly referred to below as a short circuit signal. The further input signal of the AND gate 42 is taken from the generator 23 for auxiliary energy and thus arises when the circuit breaker is switched on. This input signal is referred to below as the switch-on signal and is associated with the occurrence of auxiliary energy at the generator 23, but does not represent the auxiliary energy itself. The switch-on signal is thus obtained by means of the generator 23 with practically no reduction in the yield of energy.

An output signal output by the AND gate 42 when the switch-on signal and the short-circuit signal occur together is supplied to the actuating device 22 in order to release the latching device 16 without delay.

In the event of a short circuit, the AND gate 42 enables the circuit breaker to behave differently, depending on whether the short circuit occurs when the circuit breaker is switched on or whether the circuit breaker is switched on to an existing short circuit. In the latter case, it is namely advantageous to trigger the circuit breaker without delay in order to limit damage to the circuit breaker itself and the associated switchgear or the associated consumer as far as possible. In contrast, it is usually necessary to delay tripping if a short circuit occurs with the circuit breaker open. This delay, which is caused by the trip circuit, serves to ensure the desired selectivity in systems with several circuit breakers connected in series. len so that only faulty power supplies are switched off. The delayed triggering becomes effective in the arrangement according to FIG. 1 if only the short-circuit signal occurs and therefore no output signal is output by the AND gate 42.

The described use of the mechanical-electrical converter 23 both for obtaining auxiliary energy for operating a trigger circuit and for emitting a switch-on signal for an instantaneous triggering when switched on for a short circuit represents an advantageous combination. In contrast, the older one DE patent application 198 06 345.8 evaluates a voltage signal associated with the vibration of the circuit breaker when it is switched on. Obtaining a switch-on signal suitable for further processing, however, requires a certain amount of circuitry, which is individual for each type, size and type of installation of a circuit breaker, since the time course, amplitude and frequency of a voltage, such as that caused by a vibration when a line is switched on switch occurs on an electromagnetic component, can be very different.

Claims

claims

1. Arrangement for obtaining auxiliary energy for operating a trigger system of a low-voltage circuit breaker, which has a spring-operated drive device (7) for closing at least one movable switching contact (1) and a releasable locking device (16) for maintaining the closed state of the switching contact ( 1), the trigger system having a trigger circuit (21) for evaluating a current flowing via the switch contact (1)

Current based on specified parameters and a switching device (31) which can be activated by the trigger circuit (21) for releasing the locking device (16) by means of an actuating device (22) for the purpose of opening the switching contact (1), characterized in that for providing the auxiliary energy with the drive device ( 7) a generator (23) designed as a mechanical-electrical converter is connected and can inevitably be actuated when the switching contact (1) closes.

2. Arrangement according to claim 1, d a d u r c h g e k e n n e z e i c h n e t that the generator is designed as a piezoelectric generator (36).

3. Arrangement according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the generator is designed as a magnet-electric generator.

4. Arrangement according to claim 1, characterized in that the generator is designed as a rotating generator.

5. Arrangement according to one of claims 2 to 4, so that an energy store (24) is connected between the generator and the triggering system.

6. Arrangement according to one of claims 2 to 5, g e k e n n z e i c h n e t d u r c h the following features:

- The actuating device (22) contains a piezoelectric actuator (32) to be fed directly by the energy generated by the generator when the switching contact closes,

- The latching device (16) is designed such that it can be actuated by activating the actuator (32) to maintain the closed state of the switching contact (1),

- The switching device is connected in parallel to the actuator (32) as a bridging switch, which is to be closed by the trigger circuit (21) for resetting the actuator (32) and releasing the latching device (16).

7. Arrangement according to one of claims 2 to 5, dadurchgekennnzeichne t that the generator (36) is part of an end stop (33) effective only towards the end of a closing movement of the switching contact (1), which for receiving a after closing the switching contact ( 1) and the effectiveness of the latching device (16) remaining residual energy

8. Arrangement according to one of the preceding claims, characterized in that an AND gate (42) for linking a signal emitted by the trigger circuit (21) for the occurrence of a short-circuit current and a signal of the generator (23, 36)) and for delivering an output signal when both signals occur in a temporal connection.

9. Use of the arrangement according to claim 8 for bringing about an instantaneous tripping of the circuit breaker by means of the output signal of the AND gate (42) when the circuit breaker is switched on to an already existing short circuit.