Patent Application
20180053605
The disclosure relates to a contact slide unit for a switching unit, wherein the contact slide unit has a contact slide with a moving contact piece guided therein, one side of which the moving contact piece is acted on by a contact load spring.
Switching units, (e.g., circuit breakers), are used inter alia for safe disconnection in the event of a short circuit and thus protect consumers and installations. Furthermore, electrical or mechanical switching units are suitable for the operationally dependent, manual switching of consumers and for the safe isolation of an installation from the electrical grid in the event of maintenance work or changes to the installation. Electrical switching units may be operated electromagnetically.
In other words, such switching units are electrical switching devices, which are high quality in technical terms with integrated protection for motors, lines, transformers, and generators. They are used at service facilities with a relatively low switching frequency. In addition to short-circuit protection, such switching units are also suitable for overload protection.
In the event of a short circuit, an electrical switching unit disconnects an electrical installation safely. Thus, this electrical switching unit provides safety protection from overload. Any conductor through which current is flowing is heated to a greater or lesser extent. The heating is in this case dependent on the ratio of the current intensity to the conductor cross section, known as the current density. The current density should not become too great because otherwise the conductor insulation may be scorched by excessive heating and possibly a fire may be triggered.
Circuit breakers have two tripping mechanisms, which act independently of one another for overload and short-circuit protection. Both releases are connected in series. In the event of a short circuit, an electromagnetic release, which acts virtually without any delay in time, performs the function of protection. In the event of a short circuit, the electromagnetic release unlatches a switching mechanism of the circuit breaker without any delay. A switching armature isolates the switching piece before the short-circuit current may reach its maximum value.
In circuit breakers having a high switching capacity (ICU up to 100 kA at a rated current of IN=100 A), high short circuits occur, with the result that in turn large magnetic forces arise between the moving switching piece and the fixed switching piece. These are, for the one part, current-loop forces between the fixed switching pieces and the moving switching pieces and, for the other part, the much greater current constriction forces between the silver contacts. These two forces have the effect that, in the event of a short circuit, the moving switching piece is thrown suddenly counter to the resulting spring force thereof and strikes the impact domes in the lower part.
Furthermore, the abovementioned current constriction forces between the silver contacts do not act centrally in the middle of the contacts but decentrally further toward the periphery of the contacts. In addition to the opening force in the direction of the impact domes in the lower part, the moving switching piece therefore experiences a torque, which may result in rotation of the moving switching piece about the longitudinal axis. The striking of the impact domes, too, may have the effect, given an unfavorable position of the moving switching piece, that an undesired torque is again initiated.
Under extreme load it is occasionally possible for the moving switching piece to exploit its design-determined degrees of freedom, and, as a result of the initiated torques, for it either to become wedged in the contact slide or to rotate so far that regular contacting between the contacts of the moving switching piece and the fixed switching piece is no longer possible. In any case, reliable operation of the circuit breaker is no longer provided.
Known contact slides of these switching units frequently have two guide systems, namely an internal guide system and an external guide system. The external guide system is used when the switching operation, (e.g., the switch-on or switch-off operation), takes place via a switching mechanism of the switching unit. In this case, no bridge rotator occurs.
The internal guide system is used in the event of a short circuit when the switching operation is performed via a switching armature, (e.g., a plunger), of the switching unit. In other words, in the event of disconnection on account of a short circuit, the moving switching piece runs ahead of the contact slide along the internal guide system, rebounds at impact faces in what is referred to as the lower part of the switching unit and flies back along the internal guide system again. In this case, the moving switching piece flies in the opposite direction to the switching armature or the plunger of the switching unit. In this case, it is possible for the moving switching piece and the plunger to meet one another outside their center lines, and this may lead to rotation of the moving switching piece about its longitudinal axis.
If the moving switching piece remains in the rotated state, when the switching unit is next switched on, the contacts, (e.g., silver contacts of the moving switching piece and the fixed contacts of the switching unit), no longer meet one another, with the result that failure phenomena occur. In other words, a switching piece that remains in a rotated position is disadvantageous because the switching unit is then no longer usable. A non-functioning switching piece and a non-functioning switching unit are disadvantageous for the electrical consumers and the installation in which the switching unit is installed.
Accordingly, the object of the present disclosure is to create a contact slide unit for a switching unit, which is configured such that bridge rotators of the switching piece are avoided, and to specify a method for assembling this contact slide unit.
The scope of the present disclosure is defined solely by the appended claims and is not affected to any degree by the statements within this summary. The present embodiments may obviate one or more of the drawbacks or limitations in the related art.
This object is achieved by a contact slide unit, which has a contact slide with a moving contact piece guided therein, one side of which contact piece is acted on by a contact load spring. In this case, the moving contact piece is mounted in a turn gap between two turns of the contact load spring.
The contact load spring may have an enlarged turn gap, in which the moving contact piece is mounted. As a result, the moving contact piece is mounted in the contact load spring in a form-fitting manner. In conjunction with the guide faces integrated in the contact slide, the applied turns of the contact load spring above and below the moving contact piece provide protection against rotations.
A further advantage of this concept is that it is not necessary to deviate from the original assembly process of the switching unit, in particular of the circuit breaker. The bridge only has to be inserted into the contact load spring before it is fitted with the contact slide. The modifications include a minor modification to the contact slide, correction of the stamped bridge geometry, and adjustment of the contact load spring geometry.
If the bridge is thrown downward by the current constriction forces and current-loop forces, the bridge is now held securely in position by way of its form-fitting position in the contact load spring, even when a torque acts on the bridge as a result of eccentric force introduction. Thus, tipping or tilting of the bridge in the contact slide is no longer possible.
In a particularly advantageous configuration, provision may be made for the turns of the contact load spring above the moving contact piece to be guided by a contour in the contact slide. The guides that are integrated into the contact slide serve to receive the turns of the contact load spring, which are arranged above the moving switching piece, that is to say on the side of the contact pads. Rotation protection is achieved by way of the form-fitting mounting of the moving contact piece in the contact load spring and by way of the contour, which engages with the turns of the contact load spring above the moving contact piece.
In one development of this concept, the contour in the contact slide is arranged in a conically tapering manner. The conical tapering of the contour thus provides that the turns above the moving contact piece of the contact load spring are received and guided securely.
In a further specific development of the concept, provision may be made for the turns of the contact load spring above the moving contact piece to be formed with a narrowing diameter. In this way, the turns of the contact load spring above the moving contact piece, which turns taper with a narrowing diameter, enclose the, e.g., conically tapering guide of the contact slide with some play.
In one configuration, one technical development of the concept may include a spacer being formed in the contact load spring between the last turn on the bottom side of the moving contact piece and the first turn on the top side of the moving contact piece. The spacer allows a somewhat enlarged turn gap to be formed in the contact load spring, with the result that the moving switching piece may be positioned in a simple way between the last turn on the bottom side of the moving contact piece and the first turn on the top side of the moving contact piece.
In a further specific development of this concept, provision may be made for the spacer to be level with the longitudinal edge of the moving contact piece. Forming the spacer to be level with the longitudinal edge of the moving contact piece allows the moving contact piece to be inserted easily into the contact spring and leads to the moving contact piece being mounted in a virtually stress-free manner between the last turn on the bottom side and the first turn on the top side.
In a specific configuration, the moving contact piece may have opposing projections. The projections were previously embodied to be semi-concentric and in the present disclosure are designed in the form of a quarter-concentric projection. In this way, the spacer may be positioned in the recess obtained as a result on the moving contact piece.
Provision may also be made for the contact slide to be used in a circuit breaker.
The object of the present disclosure is also achieved by a method for assembling a contact slide unit for a switching unit, having a contact slide with a moving contact piece guided therein, one side of which the contact piece is acted on by a contact load spring, including inserting the moving contact piece into a turn gap in the contact load spring; and fitting the structural unit including the current moving contact piece with the contact load spring in the contact slide.
The contact slide unit for a switching unit has a contact slide with a moving contact piece guided therein. The contact slide may be U-shaped with a central region, which has four side edges, a top side and a bottom side, and two lateral guides arranged opposite one another. The lateral guides lead into the central region and may have, at the end regions opposite to the central region, small feet, which serve as a support surface for the moving contact piece. A conically tapering contour may be arranged on the inner side of the central region of the contact slide, the contour proceeding from the top side in the direction of the moving contact piece.
The top side of the moving contact piece has a contact pad on each side next to the contact slide. The bottom side of the moving contact piece is mounted on a contact load spring. The last turn of the contact load spring below the moving contact piece transitions into a spacer, which may be level with the moving contact piece. The spacer transitions into the first turn of the contact load spring on the top side of the moving contact piece. As a result, the moving contact piece is mounted or clamped in a turn gap in the contact load spring. The turns above the moving contact piece may be formed with a narrowing diameter. The conically formed contour, for example, engages with the turns above the moving contact piece with the result that the turns are fixed and guided.
The contact slide unit is characterized in that the moving contact piece assumes a form-fitting position in the contact load spring and is securely held in the horizontal position, even after switching processes. Even in the case of eccentric introduction of the current constriction forces and current-loop forces, which act on the moving contact piece in the event of a short circuit and throw it in the lower part counter to the impact, the moving contact piece is effectively guided by the contact load spring. Tipping or even tilting of the moving contact piece is therefore no longer possible and a secure contact connection between the fixed switching piece and the moving contact piece is provided, even after a short circuit.
Further advantages and embodiments of the disclosure are explained in more detail in the following text with reference to an exemplary embodiment and with reference to the drawing, in which, schematically:
The top side 6 of the moving contact piece 2 has a contact pad 7 on each side next to the contact slide 1. The bottom side 8 of the moving contact piece 2 is mounted on a contact load spring 9. The last turn of the contact load spring 9 below the moving contact piece 2 transitions into a spacer 10, which may be level with the moving contact piece 2. The spacer 10 transitions into the first turn of the contact load spring 9 on the top side 6 of the moving contact piece 2. Accordingly, the moving contact piece 2 is mounted or clamped in a turn gap of the contact load spring 9. The turns above the moving contact piece 2 may be formed with a narrowing diameter. The conically formed contour 5, for example, engages with the turn above the moving contact piece 2 with the result that the turns are fixed and guided.
The contact slide unit is characterized in that a possibility has been found whereby the moving contact piece is positioned in a rotationally secure manner by way of a simple modification to the geometry of the contact load spring. No additional parts are required for this. The assembly processes may also proceed as previously.
Although the disclosure has been illustrated and described in detail by the exemplary embodiments, the disclosure is not restricted by the disclosed examples and the person skilled in the art may derive other variations from this without departing from the scope of protection of the disclosure. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.
It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present disclosure. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent, and that such new combinations are to be understood as forming a part of the present specification.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15158551.0 | Mar 2015 | EP | regional |
The present patent document is a §371 nationalization of PCT Application Serial Number PCT/EP2015/075426, filed Nov. 2, 2015, designating the United States, which is hereby incorporated by reference, and this patent document also claims the benefit of EP 15158551.0, filed Mar. 11, 2015, which is also hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/075426 | 11/2/2015 | WO | 00 |
