DE2153082C3 - Electronic contactor - Google Patents

Description

The invention relates to an electronic contactor, preferably for switching three-phase motors using thyristors or triacs as semiconductor switching elements.

Arrangements are known in which thyristors and / or bidirectional thyristors (Triacs) for switching AC or three-phase loads of all kinds, including switching Moloren, be used. In the known arrangements, it is common to use the semiconductor switching elements that are arranged as closed components in their own housing, in a suitable manner on base plates to assemble and interconnect that the desired properties of an electronic switching device be achieved. The base plates carrying the semiconductor components also usually serve as Cooling arrangements, since the heat generated during operation of the semiconductor components is dissipated got to.

The control of the semiconductor switching elements can in a known manner by pulse trains or by connecting the control electrode directly to & ° the network. These known designs therefore use existing components and deliver them each in an appropriate manner for the desired purpose. However, this technique is relatively expensive because several casings connected in series that are not functionally required can be used. In addition, in the known arrangements, the design of the semiconductor switching elements is not ideal adapted to the special operating conditions when switching motors. When operating squirrel cage motors the splitting device must carry 6 times the nominal current of the motor when the motor is switched on can, while in continuous operation only the rated current of the motor flows through the switching device Continuous operation the heating is essential. lower than in other common applications.

The invention is based on the object of building and designing an electronic contactor in such a way that the heat generated in the switching element when a motor is switched on is properly dissipated can be produced without, however, the arrangement being particularly expensive with regard to cooling

To achieve this, the semiconductor switching elements are directly on the ones in the line Connection lugs of the contactor attached and together with control means in a common pressed part encapsulated or encapsulated. The connection lugs of a contactor protrude outwards, and those of The heat transferred to the switching elements on these terminal lugs is dissipated directly to the outside. By housing together with the tax revenue in a common pressed or cast part, the molding or casting compound surrounding the switching elements also serves to dissipate heat, switching elements are created which are combined with a magnetic exciter part can be. Several switching elements with a common magnetic control part can be used can be assembled into a multi-pole contactor. As a control means for the semiconductor switching element a magnetically controlled reed contact is expediently present in the switching element, the is influenced by the magnetic exciter part. Thyristors are expediently used as semiconductor switching elements used with the same structure on similar fastening parts, so that the switching elements easily are interchangeable. Instead of the thyristors, a triac can also be used for each switching path. It is also useful to display the state of excitation of the magnet by means of the magnetic field Provide a moving tongue that is visible from the outside.

In the following, reference is made to the drawing, in which an embodiment of the invention is shown is.

F i g. 1 shows the structure of an electronic contactor, while in

F i g. 2 shows the associated circuit;

F i g. 3 shows the arrangement of the semiconductor switching elements on the terminal lugs.

In Fig. 1, 1 denotes a lower part, which has approaches 1.1, which are used to assemble the device. In this lower part there is a magnet bracket 2 with a U-shaped cross-section, which carries an excitation coil 3 through which a certain magnetic field strength can be generated via an air gap 4 between the legs of the magnet bracket 2. A reed contact 5 located in the vicinity can be switched on by the magnetic field strength. This reed contact controls, via a series resistor 6, the semiconductor switching elements 7 and 7 ', which in the exemplary embodiment are thyristors connected in anti-parallel. The semiconductor switching elements are attached to the connection lugs 8 and 8 ', care being taken that the connection lugs are in the line of the contactor. The connection lugs with the semiconductor switching

elements, as well as the reed contact used for control and any resistors, capacitors • etc. are cast or pressed in a block 9. Several of these can be placed on a lower magnet part 1 Blocks are attached side by side. s

According to the in F i g. The circuit of the contactor shown in FIG. 2, the two thyristors 7 and T are connected to the reed contact 5 and the resistor 6 via their control electrodes 10 and 10 '. In addition, the thyristors are connected in antiparaiiel and the connecting lugs 8 and 8 ', which serve both for heat and for current conduction, are indicated. A rectifier 11 or 11 'is connected in parallel to the control electrode and cathode of the thyristors, so that proper control of both thyristors by a single reed contact 5 is possible. A / C element is provided parallel to the entire arrangement, which consists of a capacitor 12 and a resistor 13 and attenuates any voltage peaks that may occur. The entire arrangement lies between a phase Ph of the network and the consumer V.

F i g. 3 shows the connecting lugs 8 and 8 'in plan view. The two connection lugs have the same Dimensions and are equipped with thyristors 7 and 7 ', which have the same structure. The thyristors are soldered with their anode sides on the connection lugs, while the cathodes 14 and 14 'over flexible connecting strips 15 and 15 'each with the opposite projection 16 and 16' of the connecting lugs 8 and 8 'are connected.

The advantage of the device according to the invention consists in the elimination of superfluous housings between the active elements and the connection parts as well as good heat dissipation via the connection lugs. The row arrangement on a lower part used for excitation enables easy combinability and interchangeability of the switching elements. Instead of the thyristors, triacs in such a switching element block can be accommodated.

For this purpose 2 sheets of drawings

Claims (6)

Patent claims: 1. Electronic contactor, preferably for switching three-phase motors using thyristors or triacs as semiconductor switching elements, characterized in that the semiconductor switching elements (7, T) are attached to the connecting lugs (8, 8 ') of the contactor lying in the line and are encased or encapsulated together with control means in a common pressing part (9). 2. Electronic contactor according to claim 1, characterized in that magnetically controlled reed contacts (5) are provided as control means for the semiconductor switching elements (7, T). 3. Electronic contactor according to claim 1 and 2, characterized in that one or more of the encapsulated or molded switching elements combined with a magnetic exciter part (2, 3) are. 4. Electronic contactor according to claim 1 to 3, characterized in that as semiconductor switching elements (7, T) thyristors with the same structure on similar connecting lugs (8, 8 ') are attached. 5. Electronic contactor according to claim 1 to 3, characterized in that the semiconductor switching elements Triacs are used. 6. Electronic contactor according to claim 1 to 5, characterized in that to display the state of excitation of the magnet, a tongue that is moved by the magnetic field and visible from the outside is provided is. 35