DE2606176A1 - Wound capacitor with safety interruptor - uses dielectric foil shrinkable by heat in longitudinal direction for contact breaking - Google Patents

Abstract

The wound capacitor has a shrinkable dielectric responsive to heat and thus interrupting an electric contact. The shrinking of the dielectric takes place in its longitudinal direction. In the capacitor roll cavity is provided an electric lead which is interrupted by the constriction of the foil windings round the cavity. Preferably the lead wire is clamped between two dished pressure elements. Alternately it may be mounted between two blade edges on opposite pressure elements which may be formed by dished diaphragms carrying the blades. The diaphragm edges may be connected in such manner, as to form a closed pressure box, through which the clamped lead wire extends. The cavity may contain a core tube of heat softened material.

Description

Electrical wound capacitor

with switch-off protection The invention relates to an electrical Winding capacitor with a shrinkable dielectric, in which by shrinking of the dielectric an electrical supply line is interrupted as a result of heating.

It is known that some dielectrics of electrical wound capacitors, in particular plastic films which have the property that they are heated when heated shrink. Such dielectric films can already achieve this property have received their manufacturing process, or they may have a separate one Are subjected to stretching treatment that gives the film such properties.

It is already known such properties of the Piel ei "-trikums of a wound capacitor to take advantage of excessive heating of the capacitor winding to interrupt an electrical supply.

For example, DT-AS 1 806 924 has a wound capacitor built into a GeIniuse known, its plastic film @@ e property has to become warm when heated pull together in the axial direction of the roll. The wrap will be in the home anchored in one place, while an electrical connection is anchored in a second place is anchored in the housing. If the wrap is excessively heated, it will shrink this in the axial direction, the contact between the assignment and the connection contact is interrupted. Such a switch-off protection can, however, only be used with capacitor windings can be used that are built into a housing.

From DT-OS 2 060 907 there is also an electrical winding capacitor Known with cut-off protection, in which a housing is not required. This Winding capacitor is also with a dielectric that can be shrunk in the axial direction and also has front contact layers. By shrinking the wrap in the axial direction when heated, the electrical contact is now within the front contact layer or interrupted between the front contact layer and a connecting conductor. Ilicabei the phenomenon is exploited that although the winding shrinks in the axial direction, a non-shrinking core tube arranged in the coil, however, retains its original Maintains length.

Because the forehead contact layer is relatively low by spraying Melting metals or metal alloys is produced and thereby conditioned on the one hand does not fall below a certain thickness and also off @@ ner consists of a porous layer of a ductile metal or a ductile metal alloy, is not reliably guaranteed that when moving the individual parts due to the effect of heat, there is a reliable interruption of the electrical contact entry. In addition, the shrinkage in the axial direction of the winding is not used, i.e. in the direction of the dielectric tape in which the tape is relatively narrow so that the absolute value of the shrinkage is only small.

The object of the present invention is to provide the known winding with to improve shrinkable dielectric and cut-off device in such a way that that a safe shutdown also takes place in the event of a lower exposure to heat.

In the case of an electrical wound capacitor, this task is carried out at the beginning mentioned type solved in that <lis dielectric in the longitudinal direction of the dielectric hand is shrinkable and that an electrical lead is arranged in the winding cavity which is interrupted by the narrowing of the winding cavity.

For such a fuse it is not necessary that the winding capacitor is built into a housing, nor that the winding end-to-end contacting layers at.

In a particularly advantageous embodiment of the invention the conductor arranged in the winding cavity is clamped between arched pressure members. I) these will be @@ in the shrinkage of the winding and thus the winding cavity compressed, whereby the electrical conductor firmly connected to them tore will.

In another embodiment of the invention, the two pressure members are provided with cutting edges through which the conductor stretched between them shrinks of the winding is cut.

The pressure members can preferably be designed as arched membranes be, a11 which the cutting edges are formed The pressure members designed as membranes with cutting edges can be designed according to the further embodiment of the invention, that they hilden a closed pressurized can through which the tensioned supply line runs. Such a pressurized can forms an independent fuse unit that acts on each Pressure responds. It can therefore also have one in the path of the condenser arranged @ liquid impregnation agent or a gas can be actuated. The pressurized can then does not necessarily have to be arranged in the winding cavity of the capacitor.

The use of cutting links to cut one in between taut electrical conductor in a fuse for electrical capacitors is known per se from tier DT-AS 1,295,071. I) place is only one of the intersecting links arranged on a membrane which forms part of the capacitor housing.

A core tube can also be arranged in the winding cavity, but must this consist of a material that softens when heated, so that the pressure of the winding can be propagated into the winding cavity, so that the arranged therein Head can be interrupted.

The supply line to be interrupted preferably consists of a metal strip.

It can also be advantageous if the supply line is known per se Way has a predetermined breaking point.

The invention is to be described in more detail with reference to the figures.

FIG. 1 shows the capacitor winding before and after the shrinking process; FIG. 2 shows the tear-off protection arranged in the winding cavity before and after the Activity; FIG. 3 shows the cutting device arranged in the Wichel cavity before and after actuation-; FIG. 4 shows the cutting device designed as a pressurized can before and after actuation.

In dcii Figures la and 1b are cross sections of capacitor windings with a longitudinally shrinkable l) dielectric tape. The capacitor winding 1 has a winding cavity 2. Figure 1a shows the state of the winding before . r shrinkage and figure lb the state of the roll after shrinkage. One recognises from Figure 1b that the winding has contracted radially and the winding cavity 2 has been significantly reduced in size.

An electrical lead is arranged in the winding cavity, which leads through the narrowing of the winding cavity is interrupted. In Figure 2 are cross sections represented by such an arrangement in which in the winding cavity 2 a lead wire 3 is arranged tensioned between two arched pressure members 4 and 5. At 6 and 7, the pressure members are mechanically firmly connected to the supply line. The pressure links 4 and 5 can consist of strips of flexible material such as sheet metal or Plastic strips. Figure 2a shows the state before the deformation of the roll Shrink. If the winding cavity 2 has narrowed due to the heating, like This is shown in Figure 2b, the two pressure members 4 and 5 are pressed together so that the connection points 6 and 7 have moved away from each other. Through this the supply line 3 stretched between them is torn.

Another embodiment of the invention is shown in FIG. There the two pressure members 4 and 5 are provided with suitable cutting edges 8 and 9, which are arranged so that the supply line 3 arranged therebetween during shrinking of the roll is cut. Figure 3a shows the state after the response Fuse, the supply line 3 being cut by the cutting edges 8 and 9. The cutting edges 8 and 9 are preferably on the corresponding pressure members 4 and 5 molded.

It can also be useful to use the two pressure members 4 and 5 as To form membranes that can be shaped so that they are a closed pressure cell form. Imine such a pressure cell is shown in section in Figures 4a and b. The two membranes 10 and 11 with internally molded cutting edges 8 and 9 form together a closed pressure cell in which the supply line 3 is arranged under tension. en a Pressure is exerted on the two membranes 10 and 11, as shown in FIG. 4b is, through the cutting edges 8 and 9, the supply line stretched between the membranes 3 cut up. To be able to exert pressure on the pressure cell, it is in Winding cavity of the winding capacitor arranged.

However, such a pressurized can speaks not only to the pressure of a shrinking one Wraps on but also on the pressure by a liquid impregnating agent that can be present in the housing of a built-in wound capacitor.

In this case, the pressurized cell can also be located elsewhere than in the winding cavity be arranged.

IJm a light one despite a sufficient cross-section for the current conduction To achieve separation of the supply line, it is expediently designed as a metal strip.

The supply line to be cut can expediently still in itself known way be provided with a predetermined breaking point le to ensure that the separation takes place at a predetermined point.

8 claims 2 sheets of drawings

Claims (8)

Claims 1.) Electrical wound capacitor with a shrinkable Dielectric in which, as a result of warming due to shrinkage of the dielectric, an electrical Nontakt is interrupted, that J u r c b g e k e n n -z e i c h n e t that the Dielcktrikun is shrinkable in the longitudinal direction of the dielectric tape and that in the winding cavity an electrical lead is arranged through the narrowing of the winding cavity is interrupted. 2.) Electrical wound capacitor according to claim 1, characterized in that that the supply line arranged in the winding cavity between two arched pressure members is clamped. 3.) Electrical wound capacitor according to claim 1, characterized in that that the supply line arranged in the winding cavity is arranged between two cutting edges which are arranged on opposite pressure members. 4.) Electrical wound capacitor according to claim 3, characterized in that that the pressure members are designed as arched membranes to which the cutting edges are molded. 5.) Electrical wound capacitor according to claim 4, characterized in that that the membranes lie on top of one another with their edges and a closed pressure cell form through which the tensioned supply line runs. 6.) Electrical wound capacitor according to claim 1 to 5, characterized characterized in that in the winding cavity a core tube made of a softening when heated Material is arranged. 7.) Electrical wound capacitor according to claim 1 to 6, characterized characterized in that the lead consists of a metal band. 8.) Electrical wound capacitor according to claim 1 to 7, characterized characterized in that the lead has a predetermined breaking point.