Electrical transmission or interconnection systems – Switching systems
Reexamination Certificate
2002-05-08
2004-05-11
Toatley, Jr., Gregory J. (Department: 2836)
Electrical transmission or interconnection systems
Switching systems
Reexamination Certificate
active
06734580
ABSTRACT:
TECHNICAL FIELD
The invention relates to a switching rocker for a fused switch unit.
BACKGROUND OF THE INVENTION
Fused switch units such as these, as well as switching rockers used in them, in whose fuse plugs fuse links can be inserted, are used in a wide range of embodiments in both private and commercial buildings, in particular in buildings in which machines are electrically operated. It is also possible to use such fused switch units and components such as the switching rocker directly on or in machine elements or housings, for electrical protection of electrically operated machines.
A fused switch unit having a switching rocker of this generic type is known, for example, from DE 34 06 815 C2. Fused switch units such as these are used to interrupt the circuit of, and hence the electrical supply to, machines and appliances automatically when the current intensity or the power in the circuit exceeds a specific, fixed value. In order to match these values to the circumstances, in particular to the electrical machines and appliances as well as external requirements, for example safety requirements, fuse links which have different characteristic values can be inserted into the fused switch units, or into the fuse plug.
The purpose of these fused switch units is to reliably manually interrupt the circuit, in particular when it is necessary to carry out repairs to the electrical appliances and machines. To do this, the switching rocker which contains the fuse plug together with the corresponding fuse link, and which is mounted in a housing of the fused switch unit such that it can pivot between a switched-on position and a switched-off position, is moved to its switched-off position.
Since the fuse links which are used in a fused switch unit are generally fuses of the type that blow by melting, which may be blown defectively or by an excessively high load, it is advantageous to monitor the serviceability of the fuse link by means of a monitoring apparatus. The monitoring of the serviceability of the fuse link should be understood as meaning both the monitoring of any defects which may be present in the fuse link itself and monitoring for any defect in the contact with the fuse link in a main circuit of the fused switch unit.
A monitoring circuit for this purpose is known, which bridges the input and the output of the fused switch unit, in parallel with the main circuit passing through the fuse link, via a very high-impedance connection. A lamp is normally integrated as the monitoring indication in the monitoring circuit.
A significant current flows through the very high-impedance monitoring circuit only when the low-impedance connection in the main circuit is interrupted, for example by the blowing of the fuse link. Other monitoring systems are also possible, but these are all based on an interruption in the main circuit causing visible changes to occur in the monitoring circuit, which are indicated by means of a monitoring indication. One problem in this context is the position of the monitoring indication.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a low-cost fused switch unit having a long-life monitoring indication, which is arranged such that a simple structural design, in particular a compact design of the fused switch unit, is possible, with the monitoring indication being intended to supply the operator with information which cannot be misunderstood.
The object is achieved by a switching rocker for a fused switch unit as claimed herein, and by a fused switch unit as claimed herein.
According to the invention, the arrangement of the indication in the switching rocker results in the indication being integrated very well in the structural design of the fused switch unit, without requiring any additional space. The indication can be integrated in the switching rocker, so that it is protected from the outside and damage is avoided.
Furthermore, the switching rocker is a part which is subject to considerably less wear than the fuse plug. The life to be expected for the monitoring indication is thus noticeably increased in comparison to accommodation in the fuse plug.
Furthermore, it is feasible to design the fuse link and the fuse plug as a unit, so that different fuse plugs must be made available and interchanged, depending on the application. Since the monitoring indication is arranged in the switching rocker and not in a part subject to wear or in a part which can be lost or needs to be replaced regularly, this reduces the overall costs of the fused switch unit.
In comparison to positioning of the monitoring indication in the housing of the fused switch unit, positioning in the switching rocker has, in particular, the advantage that the fused switch unit can be designed to be more compact. Installation in the housing would necessitate an increase in the height of the housing above the area of the switching rocker, in order to accommodate the monitoring indications in the housing. If the monitoring indication were arranged at the side in the housing, this would mean that the fused switch unit would have greater dimensions in this direction and, furthermore, that disadvantages would have to be accepted with regard to installation of the fused switch unit, since further areas of the fused switch unit need to be visible, that is to say they must not be covered by other elements. An installation of the fused switch unit in which only the minimal area around the operating grip of the switching rocker is visible is highly desirable, on the other hand, in particular for visual reasons, as well.
Furthermore, an arrangement of the monitoring indication in the housing means that it is visible not only when the switching rocker is in the switched-on position, but also when it is in the switched-off position. Since, for safety reasons, the monitoring circuit must be interrupted in the switched-off position, the monitoring indication in principle does not illuminate in the switched-off position, to be precise irrespective of the serviceability of the fuse link. It is thus possible, in particular, for an untrained operator to be irritated by the unilluminated monitoring indication in conjunction with an interrupted circuit in the switched-off position, possibly unnecessarily replacing serviceable parts, in particular a serviceable fuse link. Such-an irritation to the operator is avoided by the arrangement according to the invention, when the monitoring indication is not externally visible in the switched-off position.
In one preferred embodiment, the monitoring indication is arranged in an inner area of the switching rocker.
The monitoring indication is thus protected, so that no damage can occur, irrespective of whether this is due to external action by the operator or by contact with other parts of the fused switch unit.
The indication is in this case preferably arranged behind a transparent window, or else the switching rocker is produced at least partially from transparent material, behind which the monitoring indication can be seen from the outside.
It should be stressed that the arrangement in the inner area of the switching rocker is not intended to adversely affect the capability to replace the monitoring indication, and, in particular, the window mentioned above or area elements of the switching rocker, for example, can be opened in order, when necessary, to allow access to the monitoring indication. However, since the monitoring indications generally have an extremely long life and the time for which they are switched on and which governs the life is short, such replacement processes are necessary only extremely rarely, and the capability to replace the monitoring indication can thus also be dispensed with, in favor of simpler construction.
It is advantageous to arrange the monitoring indication in the vicinity of an operating grip, in particular on that side of the switching rocker which faces the switched-off position. Thus, when the switching rocker is in the switched-on position, the monitoring indication is in a central, easily visible
Toatley , Jr. Gregory J.
Wood, Philipps, Katz, Clark & Mortimer
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