BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described and explained in greater detail below with reference to the exemplary embodiments that are illustrated in the figures, in which:
FIG. 1 shows an illustration of the handle of a switching device which has been switched on,
FIG. 2 shows an illustration of the handle of a switching device which has been tripped due to short circuit,
FIG. 3 shows an illustration of the handle of a switching device which has been tripped due to overload,
FIG. 4 shows an illustration of the handle of a switching device which has been switched off,
FIG. 5 shows a schematic illustration of the OFF state of the switching device,
FIG. 6 shows a schematic illustration of the ON state of the switching device,
FIG. 7 shows a schematic illustration of the disconnection of the switching device due to short circuit, and
FIG. 8 shows a schematic illustration of the disconnection of the switching device due to overload.
DETAILED DESCRIPTION OF INVENTION
FIGS. 1 to 4 show in each case a handle 4 of a switching device which is used for the protection of an electrical load, e.g. a motor, against short circuit or overload. The switching device can also be switched on or off manually by rotating the handle 4. In order to visually indicate the switch states—switched on or off—and the disconnection cause (short circuit or overload) of the switching device, a total of four positions 10, 11, 12 and 13 are provided for the handle 4. The four positions 10, 11, 12 and 13 represent respectively the ON state, the OFF state, the disconnection due to overload and the disconnection due to short circuit for the switching device. The first position 12 and the second position 13 of the handle 4 are situated between the third position 10 and fourth position 11, with the angle of rotation of the handle 4 between the third position 10, in which the handle indicates the ON position of the device, and the fourth position 11, in which the handle 4 indicates the OFF position, being 90°. Each position 10, 11, 12 and 13 is also depicted differently by a symbol (or inscription) for greater ease of identification.
If the handle 4 is rotated to the ON position 10 (FIG. 1), the switching device is switched on. Conversely, if the handle 4 is rotated to the OFF position 11 (FIG. 4), the switching device is switched off. In addition, the handle 4 can automatically move to position 12 or 13 and be locked or held there (FIGS. 3 and 2) if the switching device automatically disconnects due to overload or short circuit. If the switching device is disconnected, e.g. due to overload, the handle 4 moves from the ON position 10, past the position 13 which indicates tripping due to short circuit, to the position 12 and is locked in this position 12 in order to prevent a further rotation to the OFF position 11. It is therefore possible, using the handle 4 alone, clearly to indicate the disconnection causes of the switching device in addition to the ON and OFF state, without any need to use an additional component.
FIG. 5 shows the schematic construction of a switching device as cited above which has been switched off. The switching device has a first tripper 2 for overload protection and a second tripper 3 for short-circuit protection. The first tripper 2 is preferably a thermobimetal tripper with time delay, and the second tripper 3 is preferably an electromagnetic tripper without time delay and additionally having a coil 17 and an armature 16. Furthermore, the switching device has a switch latch 1 for mechanical activation of moving contacts 14 of the switching device and a handle 4 for activating the switch latch 1. The handle 4 has a toothed segment 6, and the switch latch 1 comprises a switch gearwheel 5 which is mounted on a fixed spindle and at least one connection lever 7. By virtue of a toothed segment 6 engaging in the switch gearwheel 5, the handle 4 is mechanically coupled to the switch latch 1. The switch latch 1 is mechanically coupled to the trippers 2 and 3 respectively via two levers 8 and 9. A spring 15 is provided in order to exercise a force on the lever 9, such that the switch latch 1 can activate the trippers 2 and 3 or the handle 4 by means of its mechanical movement, the reverse applying analogously.
If the handle 4 is rotated to the position 11, the handle 4 engages in the switch gearwheel 5 by means of the toothed segment 6 and rotates the switch gearwheel 5. As a result of the rotation of the switch gearwheel 5, the switch latch 1 can open the switching contacts 14. The switching device is consequently switched off, and at the same time the handle 4 indicates the OFF state of the switching device in the OFF position 11.
An identical switching device which is switched on is schematically illustrated in FIG. 6. If the handle 4 is rotated to the ON position 10, the handle 4 activates the switch latch 1 in the same way. The switching contacts 14 are closed in order to switch the switching device on again, while the handle 4 indicates the ON state of the switching device in the ON position 10.
In FIG. 7, the switching device has been disconnected due to a short circuit. In normal operation the lever 9 rests on the spring 15 and compresses the spring 15. In the case of a short circuit, the armature 16 plunges into the coil 17 of the tripper 3 and the lever 9 is consequently freed. The lever 9 is pressed against the handle 4 by the released spring force and locks the handle 4 in the position 13. At the same time the switching contacts 14 are opened via the switch latch 1. The switching device is thus disconnected and at the same time the handle 4 shows the disconnection cause as a short circuit in the position 13.
In FIG. 8, the switching device has been disconnected due to an overload. In the case of overload, the bimetal of the tripper 2 heats up. As a result of the deflection of the bimetal, the switch latch 1 is activated via the lever 8. The handle 4, which is coupled to the switch latch 1, is moved to the position 12 by means of said switch latch 1 and locked there. The switching contacts 14 are then open. The switching device is thus disconnected and the handle 4 shows the disconnection cause as overload in the position 12.