JPS6059732B2 - Protection device for rod-shaped capacitors - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a so-called cane-shaped capacitor in which a container with a flexible wall containing a capacitor element is filled with insulating oil, and in particular, an internal abnormality is detected and promptly protected. It is.

In general, capacitors impregnated with insulating oil and having a sealed structure have a large capacity, for example, a single unit capacity of 500 KVA to 2000 KVA, in order to adjust the expansion and contraction of the insulating oil due to temperature changes.
KVA's one stores the capacitor element inside the tank,
A so-called tank-type condenser has been put into practical use, in which an oil volume adjustment device that expands and contracts in response to pressure changes is provided at the top of the tank.

On the other hand, for small capacity, for example ■KVA to 300KVA, the capacitor element is housed in a container with a flexible wall, and the expansion and contraction of the insulating oil is adjusted by the displacement of the flexible wall of the container. has been put into practical use. However, when an abnormality occurs inside these capacitors, the insulating oil is decomposed due to the arc generated by the abnormality, gas is generated, the internal pressure increases, the capacitor container is destroyed, and sometimes explosions, fires, etc. It may lead to secondary accidents.

In order to prevent such accidents, in capacitor equipment that includes large-capacity tank-type capacitors, a discharge coil with a secondary winding, an isolation transformer, A well-known voltage differential relay system that includes a relay or the like is used.

However, several small cane-shaped capacitors with small unit capacitance...
For capacitor equipment consisting of dozens or even hundreds of capacitors, if the voltage differential relay method described above is adopted, the circuit configuration will become extremely complicated, and the cost will increase. This method has not been adopted due to poor detection sensitivity, and currently, safety valves made of rupture discs that rupture when the internal pressure of the container rises above a certain level are installed, and flexible walls of the container are installed. However, in the case of the former, a switch operated by the displacement of 0.8 to 2k is installed.
In order to operate at a pressure as low as 9/d (gauge pressure or less), the pressure-receiving area of the rupture disc must be increased, which poses problems when applied to this kind of cylinder type capacitor, and the rupture disc may rupture. However, it has the disadvantage that the insulating oil inside may scatter. Furthermore, the latter has drawbacks such as a larger structure for mounting the switch, an increased installation area, and variations in the characteristics of the flexible wall. In view of the above-mentioned matters, the present invention provides a protection device for a rod-shaped capacitor in which a container with a flexible wall containing a capacitor element is filled with insulating oil, and includes a conduit connectable to the inside of the container, and a conduit that is connected to the inside of the container. a pressure-receiving element that is in oil-tight communication with the pressure-receiving element; a movable plate that is in pressure contact with the pressure-receiving element and is displaced by expansion of the pressure-receiving element; and a movable plate that is connected to the movable plate via an adjustment tool that adjusts the operating pressure and that is An internal pressure detection device is attached to the cane-shaped capacitor, and includes a pressure balance spring that applies a reaction force to the element, and a deformable spring that is activated by a predetermined displacement of the movable plate and applies contact pressure to the contact point accordingly. However, the protection circuit is configured to be activated based on the operation of the contact.

The following description will be made based on FIGS. 1 to 3 showing one embodiment of the present invention. Reference numeral 1 indicates a flexible wall 3 housing a capacitor element 2.
A can-shaped capacitor is constructed by filling a container 4 with an insulating oil 5 made of mineral oil, synthetic oil, etc., and 6 is inside the container 4. An internal pressure detection device equipped with a contact 8 that operates based on the expansion of a pressure receiving element 7 (in the illustrated example, a bellows for internal pressure detection) made of, for example, a diaphragm or a bellows for detecting internal pressure, which communicates with the container 4.
What is the inside of the bellows 7 for detecting internal pressure? They are tightly coupled via a first connector 9, a second connector 10, a third connector 11, and a conduit 12.

A movable plate 13 is in pressure contact with the pressure receiving element 7, and is displaced by expansion of the pressure receiving element 7, and operates the contact 8 when the set pressure is reached.

Reference numeral 14 denotes a pressure balancing spring for detecting internal pressure and applying a reaction force to the bellows 7.

Reference numeral 15 includes a bolt 16 and a nut 17, which connects the movable plate 13 and the pressure balance spring 14, and adjusts the operating pressure of the contact 8. Reference numeral 18 applies contact pressure to the contact 8, and
This is a deformable spring that maintains the position of the contact point 8.

Reference numeral 19 denotes a push button switch C of a wire breaker (not shown) inserted between the rod-shaped capacitor 1 and the line (not shown).
20 is a tripping circuit having a pushbutton switch CS2, a tripping coil 52T, and a normally open contact, AXa, of an auxiliary relay (not shown) for the breaker, and the contact 8 is pushbutton switch C
It is connected in parallel with S2 to form a protection circuit 21.

In addition, 8'', ``...'' is the contact point of another cane-shaped capacitor (not shown) connected in parallel or series with this cane-shaped capacitor 1, A is the fulcrum of the movable plate 13, and 22 is the bushing. In the above-mentioned embodiment, the conduit 12 is closely connected to the container 4 using the connectors 9, 10, and 11, but instead of this, the conduit 12 is attached inside the container 4 by brazing, welding, etc. Therefore, it goes without saying that they may be tightly coupled, and the point is that the interior of the container 4 and the pressure receiving element 7 may be configured to communicate in an oil-tight manner via the conduit 12. To explain the invention in detail, when the can-shaped capacitor 1 is connected to a railway line and is operating normally, the pressure inside the container 4 is equal to the temperature and pressure inside the can-shaped condenser 1 shown in FIG. As is clear from the relationship diagram, the minimum bursting pressure of the container 4 is 2 to 5k9/Clt, and the minimum operating pressure of the contact 8 of the internal pressure detection device 6 is, for example, 0.7 to 1.8k.
Pressure range lower than 9/Ci, e.g. 0.2-0.7k9
/C It is a chisel.

Therefore, the contact 8 does not operate and operation continues in a normal state. However, if an abnormality occurs inside the can-shaped capacitor 1 and the internal pressure of the container 4 rises, the internal pressure of the container 4 will be
The pressure is transmitted to the internal pressure detection bellows 7 through the coupling 11 and the conduit 12.

This internal pressure detection bellows 7 is displaced by the pressure, and in the illustrated example expands to the right, acting to move the movable plate 13 to the right and acting on the pressure balance spring 14 in the tension direction. The contact point 8 maintains an open state within a range where the restoring force of the balance spring 14 is greater. However, when the internal pressure of the container 4 further rises and exceeds the operating setting pressure, the displacement of the movable plate 13 increases, and the deformation spring 18 acts to instantly operate the contact 8, causing the protection circuit 21
The contact 8 of is closed. Therefore, the trip circuit 20 of the shield breaker is closed at the same time as the contact 8 is closed, and the trip coil 52T is energized, opening the shield breaker, disconnecting the rod-shaped capacitor 1 from the line, and stopping the operation. It happens. As a result, the pressure increase in the container 4 is eliminated because the power supply is stopped, and accidents such as destruction of the container 4 are prevented. Note that the return setting pressure of contact 8 may be set lower than the operation setting pressure, and the return setting pressure of contact 8
After the circuit is closed, the contact 8 may be configured not to open (return) automatically based on a decrease in the internal pressure of the container 4 mechanically or electrically.

According to the present invention, as described above, compared to conventional devices of this type, the structure is simpler and smaller, and there is no scattering of insulating oil. Further accidents can be prevented.

In addition, the operating set pressure of the internal pressure detection device is determined by the relationship between the internal pressure of the container applied to the pressure receiving element and a pressure balance spring that provides a reaction force to this, and the internal pressure of the container applied to the pressure receiving element is determined by the movable plate. The pressure is reliably transmitted to the pressure balancing spring, and the restoring force of the pressure balancing spring can be adjusted by changing the screwing position of the bolt and nut of the adjustment tool.

Therefore, the adjustment of the operation setting pressure can be performed extremely easily without any skill required, and
The deformable spring applies contact pressure to the contacts, thereby ensuring contact between the contacts. Moreover, these are integrally formed, and by applying pressure inside the pressure receiving element through a conduit before attaching it to the container, the internal pressure detection device can easily operate at the set pressure without actually applying pressure to the container. Adjustments and confirmations can be made. Furthermore, the pressure receiving element can be constructed with a small size, and variations in operating pressure settings can be reduced, so that an extremely reliable protection device can be achieved. Note that if the internal pressure detection device 6 is provided on the top surface 23 of the container 4 or the wall surface 24 on the less flexible side (narrow width side) as shown in FIG. It is smaller, allowing effective use of the installation area.

Further, as shown in FIG. 6, the protection circuit 21 connects an alarm lamp L or a buzzer B, or both, in series with the contact 8, and operates the lamp L or the buzzer B based on the operation of the contact 8 to generate an acoustic alarm. Of course, it may be configured so that the signal is emitted.

[Brief explanation of the drawing]

1 to 4 are diagrams showing one embodiment of the present invention, and FIG. 1 is a partially sectional front view showing the schematic structure of a rod-shaped capacitor;
Figure 2 is a wiring diagram showing the protection circuit, Figure 3 is an enlarged sectional view of the main part, and Figure 4 is a characteristic diagram showing the relationship between temperature and pressure inside the rod-shaped capacitor. . Figure 5 is a perspective view showing an example of installation of a rod-shaped capacitor;
The figure is a wiring diagram showing another embodiment of the protection circuit. 1...
...Can-shaped capacitor, 2 ... Capacitor element, 3 ... Flexible wall, 4 ... Container, 6.
...Internal pressure detection device, 7...Pressure receiving element,
8... Contact, 21... Protection circuit.

Claims (1)

[Claims] 1. A protection device for a can-shaped capacitor in which a container with a flexible wall containing a capacitor element is filled with insulating oil, which is connected in an oil-tight manner to a conduit connectable to the inside of the container through the conduit. A pressure receiving element, a movable plate that is in pressure contact with the pressure receiving element and is displaced by expansion of the pressure receiving element, and a pressure balance that is connected to the movable plate via an adjustment tool that adjusts the operating pressure and provides a reaction force to the pressure receiving element. An internal pressure detection device is attached to the rod-shaped capacitor and includes a spring and a deformable spring that operates according to a predetermined displacement of the movable plate and applies contact pressure to the contacts based on the operation of the contacts. A protection device for a can-shaped capacitor, characterized in that it is configured to operate a protection circuit.