DE7718990U1 - ELECTRIC CAPACITOR WITH A SHUT-OFF DEVICE - Google Patents

Description

• t

The innovation concerns an electrical capacitor with a disconnection device, in particular a regenerative capacitor built into a housing.

When operating capacitors can be due to overload or changes occur in the capacitor that can lead to an explosion of the capacitor. Dielectric breakdowns in the case of metal foil capacitors, for example, lead to permanent short circuits with local ones Overheating and explosive gas development. With the so-called self-healing capacitors Dielectric breakdowns do not cause an electrical short circuit because of the local evaporation of the thin, vapor-deposited metal coating. While in the first Pail a fuse connected upstream of the capacitor coil responds and therefore the Prevented explosion, capacitors with a self-healing effect do not show a current increase in the event of a breakdown. In this Pail a fuse must respond to the rise in pressure in the condenser.

Such overpressure safeguards are in DT-PS 1 289 584 and DT-PS 1 295 071, in which a lead wire to the capacitor winding is interrupted by tearing or shearing can be if the expandable housing due to an impermissible internal pressure through a by a Gas development caused by breakdown extends beyond a certain level.

But it is also permissible according to most safety regulations, that the two winding lead wires remain lead or are short-circuited until an external circuit fuse is triggered by a developing overpressure and has switched off the capacitor. DT-OS 1 764 858 reveals a switch-off device for an in a regenerative capacitor built into a housing, with a barometric pressure cell in the housing in the event of an impermissible Internal pressure causes the external connection lines to short-circuit.

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The innovation is based on the task of a regenerative Specify capacitor of the type mentioned above, a simple and reliably operating disconnection device.

This object is achieved in that a movable plastic part with a first contact at the Formation of an overpressure against a fixed plastic part is pressed with a second contact and short-circuits the outer connection elements of the capacitor.

The advantages achieved with the innovation are in particular that with the proposed disconnection device reliable short-circuit soot protection for regenerable capacitors is created, which is simple in structure and therefore does not entail any significant increase in the cost of the capacitor.

Further advantageous details of the innovation are given below on the basis of an exemplary embodiment illustrated in the drawing described in more detail.

The capacitor shown in cross section in the figure consists of a coil 1 of two wound one on top of the other Plastic foils with vapor-deposited, burn-out thin metal coverings. The capacitor winding 1 is applied to a winding core 2 in such a way that the winding core 2 with its upper End 3 protrudes from the capacitor winding 1.

The capacitor winding 1 with the winding core 2 is located in a plastic housing 4, which has a continuous at the bottom or has an interrupted nose 5 on which the roll 1 rests with the outer edge of its lower winding contact 6. The winding 1 is held on the upper winding contact 7 by a plastic ring 8, which is in a groove 9 in the plastic housing 4- is fixed.

A movable plastic rope sits on this plastic ring 8 10 with rivet bushings 11, 12. This movable plastic part 10 has the shape of a downwardly open cylinder, the outer cylindrical surface adjoining the inner wall of the plastic housing 4 tightly. For better sealing and for the greatest possible elimination of friction between

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seeing these touching surfaces is suggested one mineral oil suitable as an impregnating agent for the wrap 1 can also be used.

At a certain distance above the movable plastic part 10 is a flat plastic part 13 with a rivet leadthrough 14 and a bore 15 in a further groove 16 in the plastic housing 4. The plastic housing 4 is over the plastic part 15 with a plastic potting 17 airtight locked. In this plastic potting 17, two outer connection elements 18, 19 are embedded, which via lines 20, 21 are connected to the loose contacts 6, 7. The ones below Winding contact 6 with the outer connection element 18 connecting Line 20 is through the high winding core 2 and the rivet bushings 11, 14 of the movable and the fixed Plastic part 10, 13 out, while the upper Winding contact 7 with the outer connection element 19 connecting Line 21 through the rivet bushing 12 of the movable plastic partly 10 and through the bore 15 of the fixed plastic partly 13 runs. So that the movable plastic part, the lower condenser space with the winding 1 is largely airtight completes, the two rivet bushings 11, 12 of the movable plastic part 10 after the implementation of the Lines 20, 21 soldered shut. The rivet feedthrough 14 of the fixed Plastic part 13 can also be soldered, while the bore 15 is preferably through a foam stopper 22 for the plastic potting 17 is closed. The The extent to which the upper end 3 of the winding core 2 protrudes from the capacitor winding 1 depends on the permissible safety distance the line 20 from the upper winding contact 7.

The movable plastic part 10 and the fixed plastic part 13 have as part of the rivet bushings 12, 14 the necessary for the functioning of the short-circuit protection Contacts 23, 24, while a further part of the rivet leadthrough 12 is designed as a spring 25 and the movable plastic part 10 resiliently on the plastic ring 8 holds.

Now becomes an explosive one due to condenser penetrations Overpressure in the lower condenser part, which is largely sealed off by the movable plastic part 10, with the

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- ■ Eonäensatorwickel 1 caused, so the movable Runst-

i · fabric part 10 upwards against the fixed plastic part j 'is pressed, creating a short circuit between the two

■ Contacts 23, 24 before reaching the critical explosion pressure

j is produced. A further increase in pressure in the condenser can

I did not occur because this short circuit firstly reduces the voltage on the

I turns capacitor winding 1 to WuIl and the explosion

]> ■ interrupts the dissolving process and, secondly, a backup in

I can respond to the external circuit.

1 The proposed disconnection device thus provides a

j | Reliable short-circuit protection for regenerative capacitors which is simple in structure, among other things, the capacitor is not significantly more expensive.

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Claims (1)

• f f I · · I · * I • I · tttt ■ * ·! ·· · * It t Lioentia - Patent-Verwaltungs-Gmbl-I 6000 ffrankfurt / Main 70, QU ieodor ^ Stern-Kai 1 N 75/14 3/6/1977 - PS-N-Gh / rh Electrial capacitor with a cut-off device; Sohutz claim ^ Electricx ¹ capacitor with a disconnection device, in particular a regenerable capacitor built into a housing, characterized in that a movable plastic part (10) with a first contact (23) when an overpressure is formed against a stationary plastic part (13) with a second contact (24) is printed and the outer connection elements (18, 19) of the capacitor short-circuited. 7718990 10/6/77