EP2901466B1 - Dc power switch with a current direction independent arc extinguishing device - Google Patents

Description

The invention relates to a DC switch with a device for current direction independent arc extinguishing.

A well-known principle for extinguishing arcs in load disconnectors and circuit breakers for alternating currents is to drive an arc by means of its own magnetic field in a specially provided quenching chamber, where it is divided and cooled by the arrangement of quenching plates in several small arcs. This cooling causes a voltage increase, which ultimately leads to the shutdown of the stream. Helpful in this case is the natural zero crossing of the current at an applied AC voltage source.

The erasure of arcing when switching DC currents, however, is much more problematic, especially at high DC voltages of, for example, up to 1500 volts and relative to the rated current small (and dependent on the present switch geometry) currents such as about 5 ... 50A only a small Magnetic field of the arc predominates, which is usually not sufficient to drive the arc in a quenching chamber. Another problem is that there is no natural zero crossing in DC currents, which makes the elimination of arcs even more difficult.

In extreme cases, therefore, when switching a direct current an arc between the open contacts of a switch can remain, do not go out and destroy the switch under certain circumstances, especially damage the switch contacts. Other conventional protective devices such as circuit breakers also do not lead to the switching off of the current, as this is usually below the Rated current is, so there is an operating current for these protective devices, which prevents shutdown.

From the EP 2 061 053 A2 It is known in the manufacture of a switching device for DC applications to use the housing of a switching device for AC applications and adapt this housing with little effort for DC applications by being supplemented by a particular arranged on the outside of the housing permanent magnet. As a result, the DC switching capacity of conventional AC switching devices is substantially increased because arcs are moved away from contact points of the switching device in extinguishing chambers by the permanent magnetic field. As an advantage of the teaching of EP 2 061 053 A2 is also seen that not every separation distance and each extinguishing device needs to be assigned to each a single magnet, as is the case with known DC switching devices.

From the WO2012 / 076606A1 a switch is known, which is suitable for a polarity-independent multipolar DC operation and has at least two switching chambers. Each of the switching chambers has two extinguishing chambers with quenching plates for extinguishing arcs occurring in the respective switching chamber between contact areas. Two magnets generate a magnetic field in the region of the switching contacts of all switching chambers such that arcs are driven independently of the current direction in the arc in the direction of one of the extinguishing chambers of the switching chambers. This switch has a fast, reliable, and independent of the current direction erase behavior and therefore prevents polarization-induced installation errors and is suitable for applications where switches are required for both current directions.

r Further DC switches are from the DE1140997 B and US2010 / 126966 A1 known. The object of the present invention is to propose a further improved DC switch.

This object is solved by the subject matter of the independent claim. Further embodiments of the invention are the subject of the dependent claims.

An underlying idea of the present invention is to provide differently oriented magnetic fields for deflecting arcs resulting from the disconnection of a DC switch with a plurality of switching units. As a result, regardless of the current direction of the direct current to be switched, a deflection into extinguishing devices for extinguishing arcs is always effected. The arrangement of the means for generating the magnetic fields for deflecting arcs in quenching can be selected according to the invention so that arcs are deflected by generated magnetic fields in some switching units in erasing devices and other switching units opposite, for example, against a switching shaft of a DC switch. For example, deflecting arcs against rotating double breaker switching shafts from e.g. A thermoset of rotary double breakers used as switching units can cause an extension and simultaneous cooling of the arc, without the surrounding components are destroyed. Therefore, the inventive principle of aligning magnetic fields for deflecting arcs in switching units of a DC switch may result in the voltage increase desired to separate the DC and arc breaks, and thus also contribute to the separation of small and critical currents at high voltages, for example can occur in the initially described cases. In particular, when a fault current occurs, for example when using a DC switch in a photovoltaic system, which is opposite in its current direction to the operating current; can nevertheless be deleted by the present invention reliably occurring arcs, as is deleted according to the invention, regardless of the direction of current flow through a DC switch.

The arrangement and orientation of magnetic fields for deflecting arcs can be distributed in principle according to the invention in principle. The advantage is a uniform distribution as possible, so that in reversible current flow directions about similar extinguishing conditions are present and the switch can safely shut off the current flow regardless of polarity. Above all, the invention is suitable to use switching devices for AC applications by technically less expensive modifications for switching DC currents.

The invention now relates to a DC switch with a device for current-independent arc extinguishing comprising at least two interconnected switching units, each switching unit having at least one current path with a breaker gap and each current path at least two switching contact elements for forming the breaker gap, at least one arc quenching device, the one or more Current paths of the switching units is assigned, and one or more magnetic field generating means, each generated magnetic field associated with a breaker distance of different switching units and aligned so that its field lines are substantially transverse to the respective interruption distance, and wherein the deflection forces of at least two magnetic fields generated in a predetermined current flow direction through the current paths opposite to extending along the respective interruption distance arcs w so that at least one arc is deflected in the direction of the arc quenching device and another arc is deflected away from the arc quenching device. The devices for magnetic field generation may comprise, for example, electromagnets, permanent magnets and / or coil.

The switching units are rotary double breakers and an arc deflected away from the arc quenching device is directed to the switching shaft or a switching shaft segment of a double breaker. The switching shaft or the switching shaft segment can serve to cool a directed thereon arc so that it breaks off or goes out. A rotary double breaker has two interrupting paths, and the four switching contact element are each closed by a rotation separated, for example, two switching contact elements coupled to the switching shaft and thus movably mounted and two other switching contact element are fixed.

Each switching unit can each have at least one device for magnetic field generation. As a result, a separate magnetic field can be generated for each switching unit, as a function of the predetermined current flow direction through the at least current path of a switching unit For example, can be determined by appropriate adjustment of the magnetic field, in which direction a resulting arc is deflected.

Furthermore, provision can be made for approximately half of the switching units to have the deflecting forces of the magnetic fields generated by the devices for generating magnetic fields acting on arcs along the respective interrupting path such that the arcs are deflected in the direction of the arc quenching device in the predetermined direction of current flow through the current paths. and in the other switching units, the deflection forces of the magnetic fields generated by the magnetic field generating devices on extending along the respective interruption path arcing act so that the arcs are deflected in the direction of current flow direction through the current paths in the direction of parts of the switching units, which extinguishing the arcs favor.

The parts of the switching units, such as switching shaft segments or housing parts of the switching units, may be made of a material that causes cooling of an arc, in particular of a thermosetting plastic. It has been shown that a thermoset for cooling arcs is particularly well-suited without arcing damage to the thermoset occur.

If the devices for magnetic field generation have permanent magnets, this has the advantage that no separate supply of electrical energy is required for generating a magnetic field. In addition, the implementation with permanent magnets compared to electromagnets or coils is less expensive and less prone to failure.

The DC switch may be a four-phase AC switch, which is designed to switch direct current by appropriately interconnecting the individual switching units.

Further advantages and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

In the description, in the claims, in the abstract and in the drawings, the terms and associated reference numerals used in the list of reference numerals recited below are used.

• Fig. 1 ein Ausführungsbeispiel eines erfindungsgemäßen Lasttrennschalters für Gleichstrom mit vier Schalteinheiten und vier Einrichtungen zur Magnetfeldererzeugung;
• Fig. 2 eine Seitenansicht einer Schalteinheit des Lasttrennschalters von Fig. 1 ohne Magnetfelderzeugungseinrichtung und eines Lichtbogens zwischen Schaltkontakten der Einheit;
• Fig. 3 die in Fig. 2 gezeigte Schalteinheit mit Permanentmagneten zum Erzeugen eines Magnetfeldes zum Ablenken des Lichtbogens zwischen den Schaltkontakten abhängig von der Stromflussrichtung durch die Strombahnen der Schalteinheit; und
• Fig. 4 die in Fig. 3 gezeigte Schalteinheit mit Löschblechen zum Löschen eines zu den Löschblechen abgelenkten Lichtbogens.

The drawings show in

• Fig. 1 an embodiment of a DC circuit breaker according to the invention with four switching units and four means for magnetic field generation;
• Fig. 2 a side view of a switching unit of the circuit breaker of Fig. 1 without magnetic field generating device and an arc between switching contacts of the unit;
• Fig. 3 in the Fig. 2 shown switching unit with permanent magnets for generating a magnetic field for deflecting the arc between the switch contacts depending on the current flow direction through the current paths of the switching unit; and
• Fig. 4 in the Fig. 3 shown switching unit with quenching plates for deleting a deflected to the quenching arc.

In the following description, identical, functionally identical and functionally connected elements may be provided with the same reference numerals. Absolute values are given below by way of example only and are not to be construed as limiting the invention.

The in Fig. 1 shown in itself for the switching of 4-phase AC load switch 10 has four basically identical switching units 12, 14, 16 and 18 for each phase N, L1, L2 and L3. The switching units 12, 14, 16 and 18 used are rotary double breakers, each having two current paths and two interrupting paths, which are connected together in series, in order to achieve the required high total arc voltage and thus an externally applied, counteract driving network voltage and extinguish the power as soon as possible.

Due to the serial interconnection of the double breaker, the direction of current flow through the current paths is the same for each of the double breakers. By way of example, in the rotary double breaker 12 in FIG Fig. 1 the two current paths denoted by the reference numerals 20 and 22 and the two interruption paths by the reference numerals 24 and 26.

Each double interrupter 12, 14, 16 and 18 also includes a thermoswitch switching shaft segment 38 which is coupled to and rotates with a selector shaft (not shown) to disconnect the contacts 28, 30 and 29, 31 of the interrupter legs 24 and 26 or connect.

Fig. 2 shows a double breaker in a side view. Here it can be seen that the first flow path 20 has a first interrupter gap 24 with a lower fixed contact 28 and a contact piece with an upper loose contact 30. The switching piece with the upper loose contact 30 is coupled via a switching contact arm 40 with the switching shaft segment 38 and can be moved by a rotation of the segment 38, so that the interruption path 24 can be opened or closed. Accordingly, the second current path 22 has a second breaker gap 26 with an upper fixed contact 31 and a switching piece with a lower loose contact 29, which is also coupled via the switching contact arm 40 with the segment 38. The Loskontakte 29 and 30 are therefore moved synchronously over the switching shaft segment 38, so that the two interrupter lines 24 and 26 are opened and closed synchronously.

In order to extinguish arcs, two extinguishing chambers, each formed by packets with arc extinguishing plates 32 and 34, are arranged in each of the four double interrupters 12, 14, 16 and 18 in the area of the interrupter lines 24 and 26, respectively. The arc quenching plate packages 32 and 34 are in this case arranged so that they extinguish arcs, which are directed in a predetermined direction away from the thermoset switching shaft segment 38 in the quenching plates 32 and 34, respectively.

At the in Fig. 2 shown in side view double breaker is not deflected by a magnetic field arc 42 between the two contacts 29 and 31 shown.

For deflecting the arcs, each double interrupter 12, 14, 16 and 18 each has an array of permanent magnets 36 around at least one of their interrupter legs 24 and 26 (in FIGS Fig. 1 arrangements of permanent magnets 36 are shown only around the second interrupter lines 26, although permanent magnets could also be arranged around the first interrupter line 24). The arrangement of permanent magnets 36 generates a magnetic field in the region of the surrounding interrupting path 26, the field lines of which extend essentially transversely to the interruption path 26 that is surrounded. Furthermore, the magnetic fields of the permanent magnet assemblies are poled to produce at a given current flow direction through the current paths 20 and 22 on arcs deflecting forces that deflect the arcs in a predetermined direction, typically either to the arc splitter stack According to the invention, at least two of the generated magnetic fields are poled so that at operating current direction an arc occurring at a breaker distance to the arc quenching package 34 and an arc occurring at another interruption distance to the thermoset switching shaft segments 38th is distracted. As a result, regardless of the current flow direction, at least one arc is always deflected to the arc splitter stack 34 and another arc to the thermoset switching shaft segments 38.

At the in Fig. 1 illustrated load arrangement, the arrangement of the permanent magnets is now chosen so that in a current flow direction through the current paths of the double circuit breaker 12, 14, 16 and 18 in the operating current arcs through the permanent magnetic field at the first and second double breaker 12 and 14 in the respective arcing chamber and arcs at the other two double interrupters 16 and 18 opposite to the respective switching shaft segments made of thermoset of the double breaker 16 and 18 are deflected, as indicated by the bold arrows in Fig. 1 is indicated. The distraction arcing against the double breaker switch shaft segment made of thermosetting plastic that is rotating as it opens into the double breaker causes an extension and simultaneous cooling of the arc without destroying surrounding components. This leads to the desired voltage increase and thus also to the deletion of small and critical currents at high voltages. In Fig. 3 For example, in a double breaker shown in a side view, due to the arrangement of permanent magnets 36, a flex bend 44 deflected to the thermoset switching shaft segment 38 and an arc 46 deflected in the opposite direction are shown in the reverse current flow direction. Fig. 4 shows a double breaker in side view with arc quenching packs 32 and 34 and deflected arcs 44 and 46. It can clearly be seen how the arc 46 is directed into the arc splitter stack 34, from which it is cooled and interrupted. Similarly, the deflected to the thermoset switching shaft segment 38 Lichbogen 44 is cooled so that its resistance increases, resulting in the demolition of the arc 44.

If, for example, the current flow direction reverses when an error occurs, ie, the current paths are traversed counter to the predetermined operating current direction, arcs occurring when the interruption paths are opened become in the direction indicated by bold dotted arrows in FIG Fig. 1 distracted. In such a case arcs are thus deflected at the double breakers 16 and 18 in the respective extinguishing chambers and the double breakers 12 and 14 against the respective double breaker switching shaft segment made of duroplastic. The effect is the same as in the current flow direction in the operating current direction, since now the switching wave segments of the double interrupters 12 and 14 cause cooling of the directed and extended arcs on them.

It is essential for a current-direction-independent arc quenching that at least two of the magnetic fields generated by the arrangements of permanent magnets 36 in the region of the interruption paths of the individual double breakers cause an opposite deflection of arcs.

In principle, the arrangement of the permanent magnets 36 can also be distributed in any other way. The permanent magnet arrangements should only possible be evenly distributed, so in reversible current flow direction similar extinguishing conditions are present and the device thus polarity-independent switching off the current flow safely.

The remaining 4 contact points corresponding to the first breaker section 24 of the double breakers 12, 14, 16 and 18 are in the in Fig. 1 This has the consequence that an arc with small currents at the contact points 28 and 30 by the above-described and too small magnetic interaction between the contact points stops and is neither driven in the direction arc quenching package 32 nor against the thermoset switching shaft segment 38. Almost the entire extinguishing work we thus taken in the small, critical streams of the contact points 29 and 31 of the second breaker route 26, which are equipped with permanent magnets 36.

At higher currents (> 50A up to overload, eg 4 times the rated current), as many quenching chambers as possible are required for arc quenching (high energy contents). Since at such high currents between the contacts 28 and 30 resulting arcs are driven without permanent magnets 36 from the electromagnetic interactions in the quenching chamber or arc quenching package 32 are (no matter in which direction) always 6 extinguishing chambers (+ 2 arcs , which run against the switching shafts), which is sufficient to extinguish the arc.

reference numeral

10

Switch disconnector for DC

12

first rotary double breaker

14

second rotary double breaker

16

third rotary double breaker

18

fourth rotary double breaker

20

first current path

22

second current path

24

first breaker route

26

second breaker route

28

fixed contact

29

Contact with loose contact

30

Contact with loose contact

31

fixed contact

32

Arc-quenching sheet package

34

Arc-quenching sheet package

36

permanent magnet

38

Thermoset switching shaft segment

40

Switch contact arm

42

undeflected arc

44

deflected to the thermoset switching shaft segment Lichbogen

46

Arc deflected to arc splitter stack

Claims (6)

1. Direct current switch (10) comprising a device configured for arc extinction independent of current direction, the direct current switch comprising at least two interconnected switch units (12, 14, 16, 18), wherein each switch unit has at least one current path (20, 22) including an interruption surface (24, 26), and each current path comprises at least two switch contact elements (28, 30) configured to form the interruption surface (24),
   at least one arc extinction device (32, 34) associated with one or more current paths of the switch units; and
   one or more magnetic field generation devices (36), wherein each generated magnetic field is assigned to an interruption surface of a different one of the switch units and oriented such that its field lines run substantially transversely to the respective interruption surface, and wherein at a predetermined direction of current flow, deflection forces of at least two generated magnetic fields act through current paths counter to arcs extending in a longitudinal direction of the respective interruption surface, such that at least one arc is deflected towards the arc extinction device and a further arc is deflected away from the arc extinction device,
   characterized in that
   the switch units are rotatory double interrupters, and an arc deflected away from the arc extinction device is directed onto a selector shaft or a selector shaft segment of a double interrupter (38).
2. Direct current switch according to claim 1,
   characterized in that
   each switch unit (12, 14, 16, 18) comprises at least one magnetic field generation device (36).
3. Direct current switch according to claim 2,
   characterized in that
   in the case of approximately half of the switch units (12, 14), the deflection forces of the magnetic fields generated by the magnetic field generation devices act on arcs extending in the longitudinal direction of the respective interruption surface such that, at the predetermined direction of current flow through the current paths, the arcs are deflected towards the arc extinction device, and, in the case of the remaining switch units (16, 18), the deflection forces of the magnetic fields generated by the magnetic field generation devices act on arcs extending in the longitudinal direction of the respective interruption surface such that, at the predetermined direction of current flow through the current paths, the arcs are deflected towards parts of the switch units which facilitate extinction of the arcs.
4. Direct current switch according to claim 1, 2 or 3,
   characterized in that
   parts of the switch unit, for example selector shaft segments or housing components of the switch units, are made from a material which brings about a cooling of the arc, and in particular are made from a duroplast material.
5. Direct current switch according to any of the preceding claims,
   characterized in that
   the magnetic field generation devices comprise permanent magnets.
6. Direct current switch according to any of the preceding claims,
   characterized in that
   the direct current switch is a four-phase alternating current switch configured to switch direct currents using corresponding interconnection of the individual switch units.

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