EP1771870A1

EP1771870A1 - Breaker device for low voltage applications

Info

Publication number: EP1771870A1
Application number: EP05763086A
Authority: EP
Inventors: Michael Anheuser; Gerd Griepentrog; Reinhard Maier; Bernd Trautmann
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2004-07-27
Filing date: 2005-07-26
Publication date: 2007-04-11
Anticipated expiration: 2025-07-26
Also published as: EP1771870B1; DE102004036279A1; US7916442B2; US20090046403A1; CN1993790B; CN1993790A; WO2006010760A1

Abstract

In breaker devices an early short-circuit recognition is required and also a tripping of the contacts. According to the invention, the recognition of a short-circuit occurs so early that with consideration of the response time of the measuring probes and the unlocking mechanism (5, 6-8) by a suitable analysis algorithm the release of the moving contact (4) occurs before or at least at the time that the current-breaking forces correspond to the contact force. The contact force is hence compensated for and a rapid opening of the contacts (2, 4) can be achieved.

Description

description

Switchgear for low voltage applications

The invention relates to a switching device for low-voltage applications, with at least one fixed contact and at least one moving contact.

Switches for low-voltage applications are known for example from DE 10 05163 Cl, DE 44 25 330 Al or

EP 04 50 104 Bl known. They consist of at least one fixed contact and at least one moving contact with associated drive, which can be actuated either in particular electrically or else magnetically and can be activated by means of a specific algorithm. In DE 197 29 599 C1 tripping ^¬ criteria based on current (i) and current gradient (di / dt) are described, from which an advantageous Auswerte¬ algorithm is derived.

In conventional low-voltage circuit breakers, the opening of the main contacts is usually done via a mechanical switching mechanism. This can be activated manually at the actuating lever ^¬ - or automatically when this egg nen overcurrent detect by thermi¬ cal, magnetic or electronic trip. The proper times of the switching circuit are in the range of several ms, so that even in the case of larger short circuits, the existing electrodynamic forces from the current loop do not lead directly to the contact opening, but are initially directed only against the forces of the locked switching mechanism.

Electronic short-circuit releases can be equipped with a so-called "electromagnetic bypass", in order to cause rapid tripping at high short-circuit currents.

Up to now, an improved problem solving with the above-mentioned triggering chain has been sought, in that an additional pivot point has been created by an additional bearing, which, however, is provided with an additional bearing. additional springs or guides to temporarily stop the contact. Only with extreme currents can electrodynamic forces overcome these spring forces and bring about a temporary or final contact opening without the help of the switch lock.

When dimensioning the switching device, however, care must be taken to ensure that the short-circuit release unlocks the switch lock in the event of a malfunction. In individual cases, a different trigger chain can be selected.

After expiry of the dynamic processes, the main contacts remain open. Some devices also allow a temporary opening without a final forced opening through the lock.

On this basis, it is an object of the invention to provide a comparison with the prior art faster responsive switching device.

The object is achieved by a switching device with the features of claim 1. Further developments are specified in the subclaims.

With the invention, an improved switching device can re ^¬ alisieren. The invention-bearing idea is to use in the new switching device such a specific method for early detection of short-circuit, in which the imminent short circuit are detected early before reaching the currents necessary for contact separation. According to the invention, the proper times of the probes and the Entklinkungsme- mechanism can be considered.

For early detection of short circuits, methods are advantageously based on the evaluation of the current i and the

Current slope di / dt, ie locus method, in particular with application of so-called "tolerant loci (TOK)" used according to DE 197 29 599 C. However, other possible Method, for example traveling wave method.

In the invention, the detection of a short circuit by a suitable algorithm takes place so early that taking into account the proper times of the probes and the Entkklinkungsmechanismus the release of the moving contact before or at least at the time by the stromabheben ^¬ the forces correspond to the contact force ,

Within the scope of the invention, two device concepts are possible:

1) The short-circuit early detection (KFE) only affects the - any kind - trigger chain, opens early the lock and avoids re-accident of the contacts. The contact system is designed so that an intrinsically dynamic opening is possible. As a result, the release time of the lock is preferred, a bypass (electromechanical, pneumatic, electronic or similar) is not required. Nevertheless, the switch, e.g. in the selec- tivity case, act as an additional limiter without switching off.

2) The short circuit (KS) early detection acts on the - any kind of - trip chain, opens the lock early and avoids re-accident of the contacts. Parallel a locking of the contacts is opened and the opening due to the inherent dynamics is possible. This will be the

Unlatching time of the lock preferred, a bypass is not needed. It is thus no welds occur, because the contacts in case of lifting always ge ^¬ opens - and limiting at a relatively low Abhe-.

In an advantageous embodiment of the invention, a change and simplification of the mechanical conditions on the switching device can be achieved in that - a possibly existing second pivot point in the mechanical contact system is eliminated and / or

- A decoupling of the triggering of the dynamic contact opening Kon¬ is achieved. Although a direct latching of the Be¬ wegtkontakte additionally provided in the invention, but the z. B. by ei¬ nen eddy current (= Thomson) drive can be unlatched quickly from the switch lock. After that are the current-lowering

Forces in full force and it can be a rapid opening of the con ^¬ tacts take place:

Further details and advantages of the invention will become apparent from the following description of exemplary Ausführungsbei¬ playing the drawing in conjunction with the patent claims. Show it

FIG. 1 is a schematic representation of the detail of the contact arrangement of a switching device;

Figure 2 is a graphical representation of the current waveform in a switching device according to Figure 1 and

FIG. 3 shows a flowchart to clarify the functional sequence of the switching device according to FIG. 1.

Switching devices of the prior art have a switching mechanism which is activated by the overcurrent or short-circuit current release. Thus, the contacts are opened against the closing acting Kon ^¬ tactile force, whereby a mechanical release chain is defined. At the latest with the opening of the contacts, a lift-off force between the contacts is created in equal measure.

Known switching devices suffer far less, is that it ranges Strom¬ or can give, in which the closing overall taught contact force is already compensated so far through the opening forces from the current loop that be ^¬ already a floating of the contacts arcing a ¬ sets before the triggers unlatch the lock.

The arrangement described below provides a remedy here:

FIG. 1 shows a fixed contact carrier 1 for a fixed contact 2, which has a moving contact carrier 3 is assigned for a moving contact 4. The moving contact ^¬ carrier 3 is pivotable about an axis I.

The moving contact 4 is assigned a pawl 5 and a toggle mechanism 6 with which the moving contact carrier 3 can be activated. The toggle lever 6 is articulated via a spring to the housing or another fixed reference points. The toggle mechanism 6 is actuated in FIG. 1 specifically by a Thomson drive 8, which is known and operates on the eddy current principle and is comparatively fast.

Furthermore, in FIG. 1 there is a unit 10 for short-circuit early detection (KFE). The KFE unit 10 advantageously works according to the locus method with the coordinates i and di / dt, for example according to the T_olerant G) rtsk_urve (TOK) method, for which the evaluation algorithm is described in detail in the above-mentioned DE 197 29 599 C, the disclosure of which is also the subject of the present application documents ("Incoperation by Reference"). This evaluation tealgorithmus is particularly suitable for this application and can gen including Vorstromereignisse berücksichti ^¬. The TOK evaluation algorithm is by software stored in Spei cher ^¬ an associated, not shown in Figure 1 micro controller.

Optionally, other can also quickly ar ^¬ beitende methods are used for early detection of short-circuit in the KFE 10th

In the figure 2, the time course during the switching process of

Contact arrangement according to Figure 1 shown as a graph: on the abscissa, the time t and on the ordinate of the zugehö ^¬ rige arc current i in arbitrary units aufgetra¬ conditions. The graph 21 shows the current profile when a short circuit occurs.

The interaction of the unit 10 for short-circuit detection is described in detail with reference to the flowchart of FIG (KFE) with specific evaluation algorithm with the Klinkenme ^¬ mechanism 5 on the one hand and the drive 6 for the Bewegkontakt 3 on the other hand apparent: After detection of the short circuit 'in the KFE 10 at time tl is on the one hand a signal to an actuator 5' for the give pawl 5 ge ^¬ takes place and on the other hand, the energization of the Thomson drive 8. to punk time t _2, the pawl 5 and the free Thomson drive 8 is actuated. With method step Sil, the opening of the contacts 2, 3 is now introduced at a point in time at which the moving contact 4 is free.

By acting on the contact system current forces the opening movement is advantageously accelerated. The current forces exceed the locking or contact forces at time t3. The contacts 2, 3 open faster in step S12. At time t ₄ , the contacts 2, 3 fully ^¬ constantly open. The arc then tears off at the appropriate time and the current i is extinguished.

The latter is represented by the temporal current curve i (t) according to FIG. 2, to which reference has already been made above. The graph of the graph 21 shows that after the response of the unit 10 for early detection of the short circuit at the time ti already at the time t ₂ triggering the pawl 5 of the switching device according to Figure 1. For ^¬ time point t3, the lifting forces are immediately effective opening, wherein at the time t _4, the contacts are open.

The time course of the current i of Figure 2 can be deduced that the early detection of the Kurschlussfalles in the

Short-circuit detection unit 10 allows a trigger ^¬ chain already then set in motion before the lift-off of the contact system is achieved. This allows the mechanical release chain to be started very early. The disadvantages of a slow mechanical release chain for opening the contacts can thus be compensated.

Now the release is not alone on the balance of the forces. The problem here is typically that in the prior art, the mechanical release chain is too slow to avoid accidental contact in the event of a short circuit. However, it is sufficient if the lock opens the contacts before they close again due to missing momentum.

In a switching device with an arrangement according to Figure 1 can thus be a faster opening of the switching contacts 2 and 4 than in conventional switching devices.

Overall, it is thus ensured that, taking into account the proper times of the measuring probes, the evaluation algorithm and the unlatching mechanism, the release of the moving contact takes place before or at least at the time at which the current-removing forces correspond to the contact force.

The arrangement described above in a switching device with ver ^¬ tiltable about an axis movable contact arrangement can also be transferred to switching devices with bridge contacts.

Claims

claims

1. Switching device for low-voltage applications, with at least one fixed contact and at least one moving contact, with a device for short-circuit detection and with an actuator for opening the contacts, the unit for Kurz¬ early detection early (10) works so fast that, taking into account the proper times the probes and the latching mechanism (5, 6 to 8) release the at least one moving contact (4) before or at least to the

Time (t ₂ ) takes place in which correspond by a current flow (i) resulting electrodynamic Abhebekräfte the contact force and wherein an evaluation algorithm considers the proper times of the probes and the Entklinkungsmechanismus (5, 6-8).

2. Switching device according to claim 1, characterized in that the unit (10) for short-circuit detection operates according to a locus method.

3. Switching device according to claim 2, characterized in that the locus method so-called. Tolerant loci (TOK method) used.

4. Switching device according to claim 4, characterized in that the TOK algorithm takes into account bias current events.

5. Switching device according to claim 1, characterized in that the Entklinkungsmechanismus a pawl (5) for Ver- / Entklin- kung of the at least one moving contact (4).

6. Switching device according to claim 5, characterized in that the pawl (5) directly from the unit (10) for short-circuit early detection is controlled

7. Switching device according to one of the preceding claims, da¬ characterized in that an eddy current drive (8) is present before ^¬ .

8. Switching device according to claim .., characterized in that the drive (8) via a toggle lever (6) on a contact ^¬ carrier (3) for the moving contact (4) acts.

9. Switching device according to one of the preceding claims, ^¬ characterized in that on the evaluation algorithm at the same time the actuator for opening the contacts (2, 4), in particular a separate actuator (5 ') for the pawl (5) and the drive (8) for the moving contact (4), are activated.

10. Switching device according to claim 9, characterized in that the evaluation algorithm takes into account the Abhe ^¬ bekräfte the contacts (2, 4) caused by the current.

11. Switching device according to claim 9, characterized in that the evaluation algorithm is stored in a memory of a microcontroller.