EP0289778B1 - Load break switch - Google Patents

Abstract

A load isolator is proposed which is arranged in a multi-part housing (1), the said housing (1) consisting of a first, lower housing part (2), a second, upper housing part (3), a side part (4) and a top part (13). The first housing part (2) consists of a plurality of switching chambers (5), in which there are provided a switch pole and a bimetallic and/or magnetic release. The load isolator is switched off by means of a single release rod, which disconnects all the poles and is housed in the side part (4). The switching mechanism is located in the second housing part (3). In the top part (13), there are provided low-voltage h.r.c. fuse elements which are electrically connected in series with the switch poles. The switch handle (6) has a switching angle of 45 DEG and can be raised from the switched-off state and pivoted downwards. <IMAGE>

Description

The invention relates to a circuit breaker according to the preamble of claim 1. Such a circuit breaker is e.g. known from the brochure "Load-Disconnector Type LK" from ELEK GmbH, D-4000 Düsseldorf or from DE-U-8027369. There, a circuit breaker is described with a multi-part housing, which essentially consists of a first, lower housing part and a second, upper housing part. The lower part of the housing has individual chambers that are sealed off from one another and contain the switching poles. The upper part of the housing contains the switching mechanism and the switching slide of the circuit breaker. An operating handle is eccentrically attached to the switching mechanism at the front. The switching mechanism itself is designed as a torque circuit or snap-action circuit.

From DE-A-3402371 and DE-A-3402372 novel electrical switching elements are known as circuit breakers, which have a particularly pronounced ability to extinguish the arc when high currents are switched off. For this purpose, a special composite material is used, the manufacture and composition of which are known from US-A-4011426. For further details, reference is expressly made to the aforementioned writings. However, a circuit breaker containing the above switching elements has not been commercially available yet.

In many cases, a forced shutdown is required in addition to the switching function. This can be ensured, for example, by additional NH fuses connected in series with a power isolating switch mentioned above. These NH fuses are then intended for both overcurrent and short-circuit. As is well known, NH fuses may only be used by specialist staff Electricity plant to be replaced. This means that even with a small, brief overcurrent, the layperson cannot switch on again. In doing so, valuable working time is lost. The NH fuses must also be specially calculated for each of the above circuit breakers, for example with regard to their characteristics and their current profile. Another disadvantage is the spatially separate arrangement of the NH fuses, which in many cases are not adequately protected by a cover. In addition, only each individual supply line is monitored by the respective NH fuse, so that in the event of a fault on one supply line, the other supply lines are not switched off and are therefore still live.

The object of the invention is to create a circuit breaker of the type mentioned above, which enables a multi-pole disconnection by means of the aforementioned novel electrical switching elements, whereby a forced release, an all-pole disconnection and a compact design are to be achieved.

This object is achieved by the features of patent claim 1.

From FR-A-2516699 a disconnector is known which is housed in a basically two-part housing and in which a single release linkage is directly engaged with the switching mechanism. This release linkage is housed in a side part to the two housing parts, the largest surface of which covers at least the side wall of the lower housing part. The switch axis for the switch handle of the disconnector is also housed in the side panel.

The power isolating switch according to the invention has the enormous advantage that the advantages of the novel electrical switching element and a positive release with a magnetic and / or bimetallic release now come into their own with every switching pole. A single trigger link ensures fast and safe all-pole shutdown at overcurrent and short-circuit at all times. An advantage of the embodiment of the invention according to claims 2 and 3 is the modular structure of the switch housing. The individual housing parts are therefore much smaller than a one-piece housing, so that a considerably simpler and cheaper production is possible. Above all, can Now circuit breakers with basically any number of switching poles can be manufactured quickly and efficiently. According to claim 4, the circuit breaker according to the invention can also have an attachment with NH fuses connected in series with the switching poles. The NH fuses then only respond in the event of a quick short circuit and therefore serve as a current limiter. The bimetallic or magnetic triggers, on the other hand, respond in the event of overcurrent and short circuits, so that the switch-off is always guaranteed. In the event of a brief overcurrent, which statistically occurs twice as often as a short circuit, the layperson can therefore switch on again without having to call in specialist personnel.

An advantage of the embodiment according to claim 5 is the non-positive, releasable connection between the extension piece for the shift handle and the shift axis. Because of the triple graduated backdrop and the cam on the extension piece, the control handle must be raised and swiveled down (while switching off) before the cover of the top part of the housing can be removed and the NH fuses can be replaced. With a snap-on cover according to claim 6, the NH fuses are protected against contact. The lid can also only be removed with a tool, such as a screwdriver. The contact pieces are secured with the ribs according to claim 7 against rotation on the bottom of the attachment part. According to claim 8, the operational readiness of the circuit breaker is displayed in three ways: via a viewing window that enables marking of the switching mechanism, via the indicator of the NH fuses and via the switch position of the control handle. According to claim 9, the lid is sealed with the attachment part, so that unauthorized opening of the lid is prevented.

Fig. 1

das mehrteilige Gehäuse eines Leistungs-Trennschalters,

Fig. 2

eine Obenansicht des Leistungs-Trennschalters nach Fig. 1,

Fig. 3

das mehrteilige Gehäuse eines Leistungs-Trennschalters mit integrierten NH-Sicherungselementen,

Fig. 4

eine Seitenansicht einer Schaltkammer mit einem Schaltpol, einem Bimetall- und einem Magnet-Auslöser eines Leistungs-Trennschalters nach Fig. 3,

Fig. 5

teilweise einen Längsschnitt einer Kammer mit einem Schaltpol, einem Bimetall- und Magnet-Auslöser und einem Schaltgestänge des Leistungs-Trennschalters nach Fig. 3,

Fig. 6

einen Querschnitt durch den Seitenteil mit dem Auslösegestänge und der Schaltachse des Leistungs-Trennschalters,

Fig. 7

eine Obenansicht des Aufsatzteils für die NH-Sicherungselemente von dem Leistungs-Trennschalter nach Fig. 3,

Fig. 8

einen Querschnitt des Aufsatzteiles gemäss der Linie A-A in Fig. 7, und

Fig. 9

die Kennlinie des Leistungs-Trennschalters mit NH-Sicherungselementen.

Further advantages follow from the description below, where the invention is explained in more detail using an example shown in the drawing. It shows:

Fig. 1

the multi-part housing of a circuit breaker,

Fig. 2

2 shows a top view of the circuit breaker according to FIG. 1,

Fig. 3

the multi-part housing of a circuit breaker with integrated NH fuse elements,

Fig. 4

3 shows a side view of a switching chamber with a switching pole, a bimetal and a magnetic release of a circuit breaker according to FIG. 3,

Fig. 5

partially a longitudinal section of a chamber with a switching pole, a bimetallic and magnetic release and a switching linkage of the circuit breaker according to FIG. 3,

Fig. 6

a cross section through the side part with the release linkage and the switching axis of the circuit breaker,

Fig. 7

3 shows a top view of the top part for the NH fuse elements from the circuit breaker according to FIG. 3,

Fig. 8

a cross section of the attachment part along the line AA in Fig. 7, and

Fig. 9

the characteristic of the circuit breaker with NH fuse elements.

In the figures, the same reference numbers are used for the same elements.

In Fig. 1, the multi-part housing 1 of a circuit breaker with a first, lower housing part 2, a second, upper housing part 3 and a side part 4 is shown. The first housing part 2 consists of three individual switching combs 5, each of which contains a switching pole, a bimetal and a magnetic release. A switching mechanism with a switching slide is accommodated in the upper housing part 3. The switching mechanism is operated with a switching handle 6. A connection terminal 7 is provided on each of the two opposite sides of each switching chamber. An auxiliary contact 8 for remote interrogation of the switching mechanism is arranged at the top of the rear of the side part.

In Fig. 2 the same housing as in Fig. 1 is shown in top view. The connection terminals 7 are screw terminals 9 at the top for copper bars and cable lugs, and clamp terminals 10 at the bottom for unassembled cables. Instead of clamp clamps 10, cage clamps (not shown here) can also be used. For a rear, pluggable connection, plug connections instead of screw terminals 9 can be used. A viewing window 11 is provided on the upper housing part 3 in the middle at the bottom. A marking on the switching slide 27 is visible through the viewing window. This enables the switching status of the switching poles to be checked. On the housing part 3, a display strip 12 is provided on the right, so that the switching position of the control handle 6 is undoubtedly determined. The switching handle 6 makes an angle of 45 ° between the on and off position. This offers a much better handling than the usual switching angle of 90 °. The condition of the emergency stop is also optimally fulfilled. Incidentally, it should be noted that only these two switching angles are approved in accordance with regulations.

3 shows a multi-part housing 1 of a circuit breaker with integrated NH fuses. On the upper housing part 3 there is an attachment part 13 in which the NH fuses are individually contained in fuse chambers. A cuboid side chamber 14 of the attachment part 13 is located exactly above the side part 4. The side chamber 14 is an integral part of the attachment part 13. A snap-on cover 15 is attached to the attachment part 13 and is sealed by means of a sealed wire 16. The structure of the modular, multi-part housing 1 is very compact and forms a closed unit with little protruding edges.

As can be seen from FIGS. 1 and 3, the connecting terminals 7 are arranged as deeply as possible below, and are also secured against rotation using ribs or the like. The terminals with their connecting straps are robust. In this way, a simple and stable connection technology is provided.

FIG. 4 shows a side view - and partly a cross section - of the switching chamber 5 of the circuit breaker shown in FIG. 3, in which a switching pole 17, a bimetallic release 18 and a magnetic release 19 are accommodated. As already mentioned above, the switching pole 17 is described in detail in DE-A-340371 and DE-A-3402372, so that it will not be discussed further here. The switching pole 17 is held in its switched-off state by a compression spring 20. At the bottom, a first busbar 21 runs across the entire switching chamber 5, the left end of which is in contact with a screw connection 9 and the right end of which is in contact with the right contact of the switching pole 17. A second busbar 22 leads from the left contact of the switching pole 17 to an NH fuse (not shown here). A third busbar 23 leads from the NH fuse to the clamp terminal 10. An electrical insulation 24 is arranged between the first busbar 21 and the third busbar 23 so that there is no electrical flashover in the area of the right contact of the switching pole 17. The Bimetallic release 18 and the magnetic release act on a release lever 25 which is integrally connected to a release axis 26, which is coupled via a tongue and groove to a similar release axis in the adjacent switching chamber. The switching pole 17 is switched on via a switching mechanism with a switching slide 27 which acts on the right behind the switching pole 17. The switching chamber 5 is open on one side and has cutouts and slots for the switching carriage 27 at the top. The switching mechanism as such is described in detail in EP-B1-0 291 668. In the switching chamber 5, two cylindrical guides 28 are provided, through which screws are guided , with which the switching chambers 5 and the side part 4 are screwed together (see Fig. 1 and 3). The control chambers are attached congruently with transverse guides, ribs and grooves.
In the case of the circuit breaker according to FIG. 1, there are no NH fuses. The first busbar 21 is then connected to the left contact and the third busbar 23 to the right contact of the switching pole 17. The second busbar 22 and the insulation 24 are then omitted. As a result, the connections to the power disconnector with integrated NH fuses are interchanged. Otherwise, the structure is the same and therefore the same switching chambers 5 can be used.

Fig. 5 shows a switching chamber 5 and the side part 4 in longitudinal section. In addition to the elements shown in FIG. 4, a switching axis 29 and a release linkage 30 can be seen in the side part 4. This single release linkage 30 couples the release axis 26 common to all the switching poles 17 to the switching mechanism 31, so that when triggered by a single bimetal release 18 or magnetic release 19, all poles are switched off.

6 shows a side view of the side part 4. The switching axis 29 is rotatable by a holder 32 and a locking ring 33, but is not displaceable in the longitudinal direction. For this purpose, the locking ring 33 is screwed onto the switching shaft 29 with an Allen screw 34. The switching axis 29 is provided above the holder 32 with an annular edge 35 which rests on the holder 32. At the top, the switching axis 29 has a square blind hole 36, one corner of which is chamfered. With a shunt release 37, the circuit breaker can be operated remotely. An undervoltage release can also be used instead.

7 shows a top view of the attachment part 13 for the NH securing elements, which consists of the cuboid side chamber 14 and individual, sealed-off securing chambers 38. In the right fuse chamber 38 there is an NH fuse element 39 which is clamped in by contact pieces 40. The contact pieces are screwed against rotation on the bottom of the attachment part 13 by means of ribs 41. The other NH fuse elements 39 are not shown for the sake of a better overview. At the corners of the top part 13, cylindrical guides 42 are provided for screws. A tube 43 for the viewing window 11 (FIG. 2) is provided at the bottom of the attachment part 13 approximately in the middle, so that the marking on the switching slide 27 is visible. An extension piece 46 is mounted in the side chamber 14 and forms an extension of the control handle 6. On this extension piece 46 a cam 47 is attached, which is pressed by a compression spring 48 (dashed circle in Fig. 7) against a backdrop 45, which is stepped in three parts and is formed in wall parts of the side chamber 14.

FIG. 8 shows a cross section of the attachment part 13 along the line A-A in FIG. 7. The parallelepiped-shaped side chamber 14 has an inwardly standing edge 49 at the top. An annular edge 50 is provided on the extension piece 46 at about a fifth of the height. Between the two edges 49 and 50, the compression spring 48 is supported, which brings about a non-positive connection between the switching axis 29 and the extension piece 46. The extension piece 46 has a square extension 51 which corresponds exactly to the square blind hole 36. The extension piece 46 has a deep, square - not shown here - blind hole, into which the long square - not shown - axis of the control handle 6 is inserted. The blind hole and the axis both have the shape of a quadrilateral beveled in one corner. The axis of the control handle 6 is fixed in the extension piece 46 by means of an Allen screw 53.

The fuse chambers 38 are provided at the top with three slots 54, which are used to dissipate the heat from the NH fuse elements 39.

9 shows the characteristic of the circuit breaker (with a solid line) and the characteristics of the individual components (dashed lines). The circuit symbol 55 of the circuit breaker with an electric motor M connected downstream is shown at the top right. The circuit breaker with a three-pole disconnection consists of an NH fuse 56, a thermal overcurrent release (bimetal release) 57, a magnetic overcurrent release (magnetic release) 58 and a switch 59. The time is logarithmically plotted on the abscissa, in the upper third in minutes, below in seconds. The nominal switch current or nominal motor current is plotted logarithmically on the ordinate. Curve th is the characteristic of the bimetal release, curve m that of the magnetic release and curve NH that of the NH fuse. The takeover point - the intersection between the characteristic curves th and NH - is 8 times the nominal switch current (NAV on the ordinate). This means that the NH fuses have not yet responded and the circuit breaker can easily be switched on again. Below the ordinate it is specified in which area the bimetallic release (th), the magnetic release (m) or the NH fuse (NH) will first trigger the shutdown. Below is the range in which the switch (S) or the NH fuse switches off.

The circuit breaker with integrated NH fuse elements now works as follows:
The disconnector is switched on with the control handle 6. The switching carriage 27 (FIG. 4) is moved against the compression spring 20 until the switching mechanism 31 is latched. The compression springs 20 of the switching poles 17 thus form the restoring force of the switching mechanism 31. The current then runs from the screw terminal 9 (input terminal) via the first busbar 21 on the right to the switching pole 17, through the switching pole 17, from there via the second busbar 22 to the NH Fuse element 39 and via the third busbar 23 to the clamp terminal 10 (output terminal). Depending on whether there is an overcurrent or a short circuit, the bimetallic release 18 or the magnetic release 19 acts on the release lever 25 and triggers a free release or the NH fuse element 39 first interrupts the supply line and the magnetic release 19 subsequently switches off all poles . All-pole disconnection is thus guaranteed at all times.

NH fuse elements are replaced as follows:
First, by means of the control handle 6 - by pivoting the control handle downwards (FIG. 2) - the power isolating switch is switched off. In the switched-off state, the cam 47 is above the second stage of the link 45, so that the control handle 6 can be raised against the pressure of the compression spring 48 (FIG. 8). The square extension 51 is then disengaged from the shift axis 29, so that the shift handle 6 can be pivoted further down. The third stage of the backdrop 45 prevents the control handle 6 from being pivoted further. Since a corner of the extension 51 and the blind hole 36 are chamfered, the extension 51 does not fit into the blind hole 36 in this position. The extension 51 does not jump back into the blind hole 36 until it is pivoted back into the switch-off position.

Claims (9)

1. Isolating switch with a multipart casing (1), which essentially has a first, lower casing part (2) and a second, upper casing part (3), the first casing part (2) comprising individual switching chambers (5) with in each case one switching pole (17) and the second casing part (3) contains a switching mechanism (31) with a switching slide (27), the switching mechanism (31) being operable by a control handle (6) located outside the casing (1), characterized in that for each switching pole (17) a magnetic (19) and/or bimetallic release (18) is provided in the switching chamber (5), a single release rod (30) is provided for all magnetic (19) and/or bimetallic releases (18), which is housed in a side part (4) to the two casing parts (2, 3), whose largest surface at least covers the side wall of the first casing part (2), the release rod (30) being in direct engagement with the switching mechanism (31) and an operating shaft (29) is provided for the control handle (6) and which is also housed in the side part (4).
2. Isolating switch according to claim 1, characterized in that the switching chambers (5) are homogeneous and open on one side, so that there is in each case only a single side wall between the switching poles(17), one of the outer switching poles (17) being covered by the side part (4) and in that the switching chambers (5) and the side part (4) are screwed together to form a fixed unit.
3. Isolating switch according to claims 1 or 2, characterized in that the side part (4) is parallelepipedic and open on one side, the open side being covered by a side cover and that the side part (4) has a mounting support (32) for the operating shaft (29), the latter being provided with a screwed on locking ring (33) in such a way that the operating shaft (29) is mounted in rotary manner, but is not longitudinally displaceable.
4. Isolating switch according to claim 3, characterized in that for each switching pole (17) is provided an electric NH fuse element (39) connected in series and that the NH fuse elements (39) are located in an attachment part (13) having partitioned safety chambers (38) fixed to the second casing part (3) and laterally alongside the said chambers (38) there is a side chamber (14), which contains an extension piece (46) for the control handle (6).
5. Isolating switch according to claim 4, characterized in that at the top the operating shaft (29) has a square blind hole (36) with a chamfer in a corner and that at the bottom the extension piece (46) has a corresponding square prolongation (51), that an extension piece (46) in the lower area has an annular rim (50) and the side chamber (14) has at the top a wall part (49), and a compression spring (48) is located between said rim (50) and the wall part (49), that in the wall parts of the side chambers (14) is provided a stepped link (45), that at the same point the extension piece (46) has a cam (47), that the extension piece (46) is provided with a deep, annular blind hole and the control handle (6) has a corresponding angular spindle, the control handle (6) being inserted in the blind hole and firmly connected by means of a screw (53) to the extension piece (46) and in such a way that the extension piece (46) is frictionally connected to the operating shaft, the operating handle (6), together with the extension piece (46), being disengageable from the operating shaft (29) and pivotable in only one direction.
6. Isolating switch according to claims 4 or 5, characterized in that the attachment part (13) is provided with a snap cover (15), so that the latter can only be removed by means of a tool.
7. Isolating switch according to one of the claims 4 to 6, characterized in that the bottom of the attachment part (13) is provided with ribs (41) for the contact pieces (40), so that the latter can be fixed in turning-prevented manner on the bottom.
8. Isolating switch according to claims 6 or 7, characterized in that a tube (43) is provided in the attachment part (13) and a corresponding opening in the second casing part (3), that the cover (15) has an inspection window (11) at a corresponding point and that the switching slide (27) of the switching mechanism (31) has a marking, so that the switching state of the switching slide (27) is always indicated.
9. Isolating switch according to one of the claims 6 to 8, characterized in that the snap-on cover (15) and the attachment part (13) are sealed by means of a sealing wire (16).

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