[0001] The invention relates to a lever for a disconnector comprising a handle part which is arranged to turn between a first position and a second position, whereby the lever for the disconnector is arranged to control contacts of the disconnector to be in an open position in the first handle part position and in a closed position in the second handle part position, and which handle part is provided with a position indicator and a lock latch wherewith the handle part may be locked into place the handle part remaining in the open position. The invention also relates to a disconnector.

[0002] The disconnector is a switching device by means of which an electric load may be disconnected from an electric circuit, when the disconnector is without current. The disconnector provides a visible opening space between the contacts of the disconnector. In regard to the above feature, it should be noted that at least in low-voltage switching devices a reliable indication of position is also allowable instead of a visible opening space.

[0003] The above-described function is necessary to be able to work safely on electric devices. Work of this kind includes, for example, maintenance of circuit-breakers in switching stations, when needed.

[0004] The term 'disconnector' is to be interpreted broadly in this connection. In this connection said term also covers, for instance, a switch disconnector, which is required to have a given switching and interrupting capacity and also properties required of a disconnector. In some contexts the above- described low-voltage switch disconnector is also known as a disconnecting switch.

[0005] The disconnector has to be furnished with a reliable position indicator. In addition, it is necessary to have a possibility of locking the disconnector to an open position. The open position refers here to a position in which the contacts of the disconnector are apart from one another, i.e. there is a visible opening space between the contacts. This feature is defined in standard IEC 60947-1 7.1 .7.

[0006] Use of switches as a disconnector requires that tests defined by standard IEC 60947-3 8.2.5.3.1 . be carried out in an acceptable manner. An option to lock the disconnector to the open position while the contacts are in the closed position, in other words, engaged with one another, is a non- allowable feature. When the disconnector contacts are welded in the closed position, in other words, in a position where they are engaged, the disconnector is controlled in the opening direction with a lever for the disconnector using a test force defined in standard IEC 60947-3 8.2.5.3.1 . During the control it is not allowable to lock the lever for the disconnector to the open position while the test force is active.

[0007] In general, the actuating moment of the disconnector lever of a switch used as disconnector has to be set relatively high in order to achieve a sufficient contact speed and hence a sufficient capacity of disconnecting in the required class. Reliable indication of a position and fulfilment of a locking option, in turn, require a relatively short lever. The above details as a whole contribute to the fact that the lever for the disconnector is excessively short for the actuating moment, i.e. it is difficult to readily control the disconnector lever.

[0008] The above stated details have resulted in development of a variety of different solutions so as to achieve a good end result. Examples include solutions disclosed in publications DE 42 06378 A1 , DE 44 39373 C1 , GB 2,279,810 A, US 6,797,903 B1 , US 6,969,813 B1 and US 2010/0294632 A1 .

[0009] A drawback with the above known solutions is that they are complex, which causes increased costs. Moreover, operating characteristics of the above prior art solutions are not so good as possible.

[0010] The object of the invention is to provide a lever for a disconnector and a disconnector by which the prior-art disadvantages can be eliminated. This is achieved by means of the lever for the diconnector and the disconnector in accordance with the invention. The lever for the disconnector of the invention is characterized in that the handle part is furnished with a detachable extension part that is arranged to prevent the use of a lock latch in the handle part during operation.

[0011] An advantage of the invention is above all its simplicity, which makes the adoption and use of the invention advantageous. The simple structure also results in high reliability of operation. A further advantage of the invention is that the invention may be applied in connection with all known disconnector levers in an advantageous manner. By means of the invention, the usability of the lever will be substantially improved over prior art, because the length of the lever is no longer a limiting factor for achieving a lockable disconnector feature. This appears to the operator in such a way that the disconnect- or is lighter to control than before and a possibility of locking errors is eliminated.

[0012] The invention will be explained in the following in more detail by means of application examples described in the attached drawing, in which

Figures 1 and 2 show schematically a disconnector which employs a first embodiment of the invention,

Figure 3 shows schematically a disconnector which employs a second embodiment of the invention,

Figures 4 to 6 show schematically a handle part in accordance with the embodiment of Figure 3,

Figures 7 and 8 show schematically a handle part in accordance with a third embodiment of the invention,

Figures 9 and 10 show schematically a disconnector which employs the handle part in accordance with Figures 7 and 8,

Figures 1 1 and 12 show an alternative implementation to the embodiment of Figures 1 to 6 and

Figures 13 to 16 show an alternative implementation to the embodiment of Figures 7 to 10.

[0013] Figures 1 to 2 show, in principle, a disconnector employing a disconnector lever in accordance with a first embodiment of the invention. The disconnector is generally denoted by reference numeral 1 . The disconnector 1 has a disconnector lever that comprises a handle part 2. Figure 3, in turn, is a general view of a disconnector which employs the disconnector lever in accordance with the second embodiment of the invention. The handle part 2 employed in the application of Figure 3 is shown in greater detail in Figures 4 to 6.

[0014] The handle part 2 of the disconnector lever is arranged to turn between a first position and a second position, whereby the disconnector lever is arranged to control the contacts of the disconnector 1 to be in an open position in the first position of the handle part 2, and in a closed position in the second position of the handle part 2. The handle part 2 is also furnished with a position indicator 3 and a lock latch 4, by means of which the handle part 2 may be locked into place the handle part remaining in the open position. Disconnector contacts are inside the disconnector 1 , so they are not visible in the figures. The position indicator may be provided in many different ways, for instance, the handle part may include a sign that moves, when turned, to a specific point, the whole handle part may serve as the position indicator, etc. [0015] The purpose of the lock latch 4 is to enable locking of the handle part to the open position. Locking may take place, for instance, by lifting the lock latch to the locking position and arranging a padlock, for instance, into an opening 6 of the latch. The principle of this situation is shown in Figure 5, for instance.

[0016] The structures and operations of the disconnector and the disconnector lever are self-evident to a person skilled in the art, so they are not described in greater detail in this connection. In this context, for generally known art, reference is made for instance to the publications cited as the prior art.

[0017] The basic idea of the invention is that in connection with a normal handle part 2 furnished with a lock latch 4 there is arranged a detachable extension part 5. The extension part 5 is locked into place in the handle part 2. The principle of this step is shown in Figures 4 to 6.

[0018] The extension part 5 may be arranged to form a one-sided handle, in other words a one-hand-operated lever, or a two-sided handle, i.e. a two-hand-operated lever. The one-hand-operated lever refers here to a handle type, in which a detachable extension part 5 is arranged to provide an extension only on one side of the pivoting axis of the handle part 2. The two-hand- operated lever, in turn, refers to an application, in which the detachable extension part 5 is arranged to provide an extension on both sides of the pivoting axis of the handle part 2.

[0019] An application of the invention employing the one-hand operation principle is shown in Figures 1 and 2. An application employing the two-hand operation principle is shown in Figures 3 to 6.

[0020] The extension part 5 prevents the lock latch 4 from being lifted during control, in other words, when the extension part 5 is mounted on the handle part 2 and the handle part is turned. The above feature appears clearly from Figures 4 to 6. Operation of this kind prevents locking during a switch control. For instance, in a situation, in which the disconnector contacts are engaged in the closed position and when the handle part is turned towards the open position, it is not even possible to try to lift the lock latch 4 for locking. After the control step, in other words in a situation, in which the control force no longer acts on the handle part, the extension part 5 may be withdrawn, whereby locking will be possible. This situation is shown, in principle, in Figure 5. [0021] The solution in accordance with the above-described principle enables a lockable disconnector feature for all known switch models. Moreover, usability is considerably improved over the known solutions, because the length of the handle part is no longer a limiting factor in providing a disconnector feature. This feature appears in such a way that the control is lighter than in previous solutions and a locking possibility is eliminated.

[0022] The basic idea of the invention may be modified in a variety of ways. Figures 1 to 6 show an application, the basic principle of which is that the detachable extension part 5 is arranged for mounting on the handle part 2. In this application, in the situation of the figures, the extension part may be pressed, for instance, on the handle part 2, as shown in Figures 4 to 6. It should be noted, however, that the application, in which the extension part 5 is arranged on the handle part 2, may also be provided such that, in the situation of the figures, the extension part is horizontally slipped onto the handle part 2.

[0023] Figures 7 to 10 show an application whose basic idea is that the detachable extension part 5 is arranged to surround, at least partly, the handle part 2. The same reference numerals are used in Figures 7 to 10 as in Figures 1 to 6 to refer to the corresponding parts.

[0024] In the application of Figures 7 to 10, a locking plate 7 in the extension part 5 passes below the handle part 2, when the extension part 5 is arranged in the handle part 2. This situation is shown in Figure 8.

[0025] Figures 7 to 8 show, in principle, a handle part 2 and an extension part 5 of this application and Figures 9 to 10 show correspondingly a disconnector that is furnished with a disconnector lever employing the application of Figures 7 to 8.

[0026] In the embodiment of Figures 7 to 10 the extension part 5 is slipped horizontally onto the handle part in the situation of the figures. The above mentioned detail shows clearly in Figures 7 and 8.

[0027] The invention may be used in connection with various disconnectors. In case of a solution where several switches are superimposed, i.e. if a so-called transfer switch structure is concerned, the invention may be applied, in principle, in the following manner.

[0028] If the structure includes, for instance, two switches in superposition, in connection with said structure the actuating moment is at least double in comparison with a single switch. In a reliable testing of indication of position a test force is three times the normal actuating moment. In that case an approximately sextuple force is exerted on a single switch. In many cases the switch structure does not stand said force, but the control mechanism of the switch breaks down, and consequently, the indication of position may be erroneous. A situation of this kind is not allowable, because it may lead to serious hazards. The importance of the indication of position becomes apparent in connection with the above-mentioned stacked solutions, since, even though low-voltage modules generally have a transparent window, in the stacked solutions the window of a lower switch cannot be seen. Because opened contacts of a lower switch cannot be verified visually in this structure, the importance of a position indicator is high.

[0029] With reference to the above, the invention may be applied in such a manner that hazards may be eliminated also in situations referred to above. Such applications of the invention are shown in Figures 1 1 to 16. The application of Figures 1 1 to 12 is based on the application of Figures 1 to 6, in other words on the application, in which the extension part 5 is attached from above onto the handle part 2. The application of Figures 13 to 16, in turn, is based on the application of Figures 7 to 10, in other words, on the application, in which the extension part 5 is horizontally slipped onto the handle part 2.

[0030] In the applications of Figures 1 1 to 12, and correspondingly of Figures 13 to 16, the actuating moment being normal, the extension part 5 in the handle part 2 keeps in place, because the extension part 5 is locked to the handle part as stated above. When the actuating moment sufficiently exceeds the normal actuating moment, for instance because of the engagement of the contacts, the extension part becomes detached before the switch is broken. At the same time the indication of position is also retained.

[0031] In the application of Figures 1 1 to 12 the above described detachment of the extension part at a given, predetermined torsion force is achieved by the structure and shape of the extension part edges 8, 9 serving as locking means. Additionally, it is possible to select the material used in manufacturing the extension part such that correct operation will be obtained.

[0032] In the example of Figures 1 1 to 12 the locking means are provided by edges 8, 9. This is not the only option, however, but it is possible to form the locking means in some other manner, for instance, by providing surfaces in the upper surface of the handle part and mating surfaces in the lower surface of the extension part, which surfaces interlock when the extension part is pressed onto the handle part. [0033] In the example of Figures 13 to 16 the above-described detachment of the handle part 5 is implemented by providing at least one weakening point 10 in the locking plate 7. In the example of Figures 13 to 16 the weakening point is provided by means of two weakening grooves, as appears from Figure 15. Naturally, it is also possible to use only one weakening groove, etc. As the normal actuating moment is sufficiently exceeded the weakening points give in and the locking plate detaches, whereby the extension part 5 detaches before the switch will break down. Also in this application the indication of position will be retained. Also in this application the detachment of the extension part 5 at the right time is provided by a specific construction of locking, in other words, by furnishing the locking element with weakening points. Selection of the material of which the extension part is manufactured also contributes to the detachment of the extension part at the right time.

[0034] By the above-described applications it is possible to prevent a switch breakage, and at the same time to retain reliable indication of position in specific structures, for instance, in connection with the above-mentioned transfer switch solutions.

[0035] The invention is described above by means of a few application examples. The application examples are not, however, intended to limit the invention in any way, but the invention may be varied freely within the scope of the claims. Thus, the extension part, for instance, need not be exactly as shown in the figures, but other solutions are also possible, in other words, the shapes and dimensions may be modified freely according to a specific need.