JPS6314434Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a protection device for a capacitor that is built into an explosion-proof capacitor.

In general, vapor-deposited electrode capacitors, unlike foil electrode capacitors, often do not have enough short-circuit current to operate the fuse or NFB even if the insulation breaks down. Therefore, as a means to prevent explosions caused by insulation breakdown, the expansion of the case caused by gas pressure is used to cut the metal pieces that make up the protective device built into the capacitor, thereby cutting off the power supply. . As shown in Fig. 1, this type of capacitor protection device, which has been generally used in the past, connects a metal piece 4 with a weak point 3 between a pair of insulating support plates 2 with a mounting bracket 1 attached to one end. It is composed of what was done. As shown in FIG. 2, the capacitor protection device is arranged near the opening of the case body 6 housing the capacitor element 5, and a lead wire 7 led out from the capacitor element 5 is connected to the metal piece 4. The metal piece 4 is connected to one end and the other end of the metal piece 4 is connected to an external terminal 10 fixed to the case top cover 9 via a lead wire 8, and is used as a component of an explosion-proof capacitor. However, the protection device configured as described above has a relatively weak cutting strength and can be sufficiently cut by the expansion of the case body 6, but after cutting, the distance between the metal pieces 4 is relatively short and the metal pieces 4 may be re-ignited or re-contacted especially in the case of high voltage applications. It is dangerous. In other words, abnormalities in these capacitors are generally accompanied by heat generation, and when the metal piece 4 breaks, the internal temperature is often high.If the capacitor operates under these conditions, the displacement of the case will become smaller as the temperature decreases. Even if there is no re-ignition or re-contact, or no heat generation, the generated gas is gradually absorbed by the oil and the displacement of the case becomes smaller, resulting in re-ignition or re-contact. In addition, with such a structure, even if the cutting distance is long, the cutting operation of the metal piece 4 is slow, so there is a risk that the arc during cutting will ignite the insulating oil and cause a re-ignition.

The present invention has been developed in view of the above-mentioned points, and by sandwiching at least both sides of the weak point for cutting of a metal piece to be connected and fixed between a pair of insulating rigid plates, the metal piece can be easily cut. It is an object of the present invention to provide a capacitor protection device that can reliably prevent re-ignition and re-contact after disconnection.

An embodiment of the present invention will be described below with reference to the drawings. That is, as shown in FIGS. 3 and 4, a pair of insulating rigid plates 12 and 13 for fixing the metal piece are arranged between a pair of mounting fittings 11, and the insulating rigid plates 12 and 1
3. Attach one end of each to each of the mounting brackets 11, and with a gap between the other ends of the metal piece fixing insulating rigid plates 12 and 13, attach one end to one of the metal piece fixing insulating rigid plates 12. A metal piece 15 having the other end located on the other insulating rigid plate 13 for fixing the metal piece and having a weak point 14 for cutting is provided. In this case, the cutting weak point 14 is arranged to avoid the gap between the insulating rigid plates 12 and 13. However, the metal piece 15
A pair of insulating rigid plates 16 and 17 for holding metal pieces are disposed on the upper surface with a space between them. In this case, similarly to the above, the weak point 14 for cutting of the metal piece 15 is located at a location other than the space provided between the insulating rigid plates 16 and 17 for holding the metal piece, and the metal piece 15 is attached to the insulating rigid plate for fixing the metal piece. 12, 13 and insulating rigid plates 16, 17 for holding metal pieces. In the figure, 18 is a fixing rivet.

According to the capacitor protection device configured as described above, the metal piece 15 is attached to the insulating rigid plate 1 for fixing the metal piece.
2, 13 and insulating rigid plates 16, 17 for holding metal pieces
Metal fragments 1 due to expansion of the case body due to dielectric breakdown due to the metal pieces being sandwiched between them.
5, and the metal piece 15 is not cut gradually as in the conventional structure, but the metal piece 15 is cut at the moment when a certain tension is reached. Therefore, the displacement of the case body is large, the cutting distance is large, the insulating oil is not carbonized due to arc generation during cutting, and the risk of re-ignition can be eliminated. Moreover, the weak point part 14 for cutting provided in the metal piece 15 is connected to the insulating rigid plate 13 for fixing the metal piece and the insulating rigid plate 17 for holding the metal piece.
When the metal piece 15 is cut, as shown in FIG. As such, one of the cutting locations is located between the metal piece fixing insulating rigid plate 13 and the metal piece holding insulating rigid plate 17, and is isolated from the other cutting location. Therefore, not only when the cutting distance of the metal piece itself is short, but also when the displacement of the case body after operation is small and the cutting distance is shortened, the risk of re-ignition or re-contact is completely eliminated, which is useful in high voltage fields. It has the advantage that the field of use can be expanded without any problems.

In the above embodiment, a pair of insulating rigid plates for holding metal pieces were used, but as shown in FIGS. 6 and 7, a pair of insulating rigid plates 191 for holding metal pieces were used.
The same effect can be obtained if the structure is such that at least the weak point 14 for cutting provided on the metal piece 15 is sandwiched between the insulating rigid plates 13 for holding the metal piece. In the drawings, parts that are the same as those in the above embodiment are designated by the same numbers, and explanations thereof are omitted. Furthermore, as the weak point for cutting provided in the metal piece, in the above embodiment, a cut-shaped weak point was exemplified and explained, but as shown in FIG. May be used.

As mentioned above, by creating a structure in which at least both sides of the weak point for cutting of the metal piece to be connected and fixed between a pair of insulating rigid plates are sandwiched between the insulating rigid plates, re-ignition and re-contact between the cut points can be ensured. It is possible to obtain a highly reliable capacitor protection device that can prevent

[Brief explanation of the drawing]

Figures 1 and 2 are related to a conventional example; Figure 1 is a perspective view showing a capacitor protection device;
3 to 5 are an embodiment of the present invention; FIG. 3 is a perspective view showing a capacitor protection device; and FIG. 4 is a capacitor protection device. Sectional view showing the device, No. 5
The figure is a sectional view showing the state of the capacitor protection device after operation, FIGS. 6 and 7 are sectional views showing capacitor protection devices according to other embodiments of the present invention, and FIG. 8 is the structure of the protection device. It is a perspective view showing a metal piece. 11... Mounting bracket, 12, 13... Insulating rigid plate for fixing metal piece, 14, 20... Weak point for cutting, 1
5, 21... Metal piece, 16, 17, 19... Insulating rigid plate for holding metal piece.

Claims (1)

[Scope of utility model registration request] A pair of mounting brackets, a pair of insulating rigid plates for fixing a metal piece attached with a space between the mounting brackets, a metal piece with a weak point for cutting fixed between the insulating rigid plates, and the metal piece. An insulating rigid plate for holding the metal piece is provided with one end fixed on one upper surface, and at least the weak point for cutting is sandwiched between the insulating rigid plate for fixing the metal piece and the insulating rigid plate for holding the metal piece. A protection device for capacitors featuring: