JPH02133033A - Protective device for static electrical equipment - Google Patents

Abstract

PURPOSE:To detect internal trouble without generating the null time under a protective state by controlling a protective device so that the protective device is operated when pressure is brought to a specified value or more and operated when pressure is brought to a predetermined value or less higher than the specified value on the basis of the result of the detection of the pressure of an air chamber while detecting an external factor. CONSTITUTION:An oil-filled transformer is not interrupted even when a make and break contact 25A is operated during a time when an earthquake relay 24 is worked. That is, the transformer is not interrupted even when internal trouble in which pressure is increased at the same time as an earthquake is generated is generated and the make and break contact 25A is operated, and a make and break contact 25B is worked and the oil-filled transformer is interrupted when pressure is further elevated. Since the oil filled transformer is intercepted, the progress of the internal trouble is stopped, thus preventing a rise up to the breaking of a tank of pressure in a tank 1, then protecting the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a protection device for detecting and protecting internal failures of stationary electric appliances such as oil-immersed transformers.

[Conventional technology]

Figures 6 and 7 show an example of a protection device for an oil-immersed transformer, which is an example of a conventional stationary electric appliance. Figure 6 is a cross-sectional view of a pressure relay, and Figure 7 is a characteristic diagram showing its operating characteristics. It is. 6th
In the figure, (1) is a nearly airtight tank that houses the transformer main body (not shown), and (2) is a pressure relay installed in communication with this tank (1), which is configured as follows. ing. (3) is communicated with tank (1) and tank (1)
An oil chamber filled with the same insulating oil (4) as shown in FIG. A fixing plate (
6) is welded and laterally formed. (5c) is a coil spring provided to adjust the expansion and contraction characteristics when the separate bellows (5a) expands and contracts in response to changes in the pressure in the oil chamber (3), and (7) is a coil spring installed in the air chamber (5) and outside air. An air chamber {9
This is a communication part to maintain the pressure of the outside air at the same pressure as the outside air. (
8) is an expandable chamber that is connected to the air chamber (5l), and includes an expandable bellows (8a) and a top (8b) that expand and contract according to changes in the pressure difference between the odor and the outside air. It has

The telescopic bellow (8a) is a cylindrical metal bellow whose diameter is smaller than that of the separate bellow (5a) in the air chamber and is hermetically welded to the fixed plate (6) in order to increase the sensitivity to changes in the differential pressure. It is configured. The telescopic bellows (8a) expands and contracts in response to changes in the pressure in the air chamber {9.

(9) is a micro switch that is an opening/closing contact placed near the top (8b) of the telescopic chamber (8), and is
8a) is activated by the top portion (8b) when it has expanded beyond a predetermined value. 0■ is a cover that covers the microswitch (9), the expansion chamber (8), and the communication portion (7), and is configured to communicate with the outside air.

Next, the operation will be explained. If a short circuit occurs inside the transformer (not shown) due to insulation breakdown, the insulating oil (d) in the tank (1) will be decomposed by the arc energy generated by the short circuit, and a large amount of decomposed gas will be released. occurs, and the internal pressure of the tank (1) rises rapidly. At the same time, the pressure in the oil chamber (3), which is connected to the tank (1) and filled with the common insulating oil (4), also increases, and the air chamber ((5)
receives this pressure and contracts in the axial direction of the separate bellows (5a), that is, in the vertical direction of the figure, so the pressure in the air chamber increases. The telescopic bellows (8a) is an air chamber ((5)
It expands as the pressure inside increases, and the top (8b) operates a microswitch (9) placed above it. The pressure relay (2J) that operates in this way is, for example, an air chamber (
5l, volume ratio of expansion chamber (8), separate bellows (5a
), the elastic bellows (8a), and the spring characteristics of the coil springs (5c), etc., as shown in the characteristic curve (11) in Figure 7. It is designed to operate in the region above the pressure on the characteristic curve (1l), which has an inverse time limit characteristic with respect to the differential pressure between the outside air and the air chamber, so that protection coordination can be achieved.
Since the tank (1) is almost airtight, slow pressure changes occur such as expansion and contraction due to temperature changes in the insulating oil (4) due to changes in the load of the oil-immersed transformer. The pressure relay (
Connect the air chamber (5) to the communication part (2) so that the air chamber (5) does not operate.
The air chamber 51 breathes by communicating with the outside air through a minute opening, and the pressure in the air chamber 51 is maintained at the same pressure as the outside air. In addition, if the pressure inside the tank (1) increases in a short period of time as described above, the air chamber (5)
is pushed and contracted by the pressure increase of the insulating oil (4), but since the amount of air escaping from the communication part (7) to the outside air is small, the contracted amount appears almost as is as a pressure increase in the air chamber (5). When an internal failure of the oil-immersed transformer is detected by the pressure relay (2), which operates as described above, and the pressure relay (2) operates, that is, when the microswitch (9) operates, the oil-immersed transformer is disconnected from the electrical circuit. It automatically shuts off (hereinafter simply referred to as shutoff) to prevent the failure from progressing. However, in addition to the above-mentioned internal failures, external factors such as earthquakes may cause the pressure inside the tank (1) to suddenly change, causing the pressure relay (2) to operate.

This is caused by tank (1) being shaken by an earthquake.
1) This is because the pressure inside fluctuates. Mechanical shocks caused by earthquakes, external short circuits in oil-immersed transformers, activation of oil pumps,
It may also operate due to external factors such as transient vibrations in pressure associated with stopping. Therefore, in order to avoid the problem of shutting off the oil-immersed transformer when the pressure relay ('2) operates due to an external factor such as the one described above, external factors such as detecting an earthquake using an earthquake relay (not shown) are necessary. A detection means is used so that it is not shut off when it is in operation.

Note that when the pressure relay (2) operates, a method is sometimes used that issues an alarm instead of shutting off the oil-immersed transformer, but in this case, a false alarm will be issued, so do not use this method. To prevent this, the same methods as above are used. [Problem to be solved by the invention] The conventional oil-immersed transformer protection device is configured as described above,
In order to avoid shutting down due to external factors such as earthquakes, the oil-immersed transformer is interlocked so that it will not shut off even if the pressure relay is activated when an external factor detection means such as an earthquake relay is activated. However, there was a problem in that if an internal failure occurred at the same time that the external factor detection means was operating, the system would not be protected because it is interlocked as described above. For example, in Fig. 7, if TI (seconds) is the time during which the earthquake relay is operating, that is, the time until the pressure fluctuation in the tank (1) due to the earthquake is brought under a predetermined value, then this TI [seconds] is The oil-immersed transformer will not be protected from internal failures that occur during this period, and the shaded area (12) in the diagram will be the unprotectable area. When the pressure in the tank (1) increases as shown by the straight line (l3) in Figure 7, if the operation of the pressure relay (2) is not interlocked by the seismic relay, the characteristic curve <<1l>> and the straight line ( 13) and the intersection (13a
), the pressure relay (2) operates and the oil-immersed transformer is shut off and protected, but since it is not shut off, the tank (
The pressure inside 1) continues to rise and reaches the intersection (+3b) with the tank breakdown pressure line, causing the tank to breakdown and the insulating oil to scatter. Of course, a separate pressure relief device is provided to prevent such a worst case scenario, but there are problems such as the unavoidable release of insulating oil and cracked gas from this pressure relief device.

This invention was made to solve the above-mentioned problems.During normal times when there are no external factors such as earthquakes, the system operates at a predetermined pressure value to detect internal failures, and when an external factor occurs, To provide a protection device for stationary electrical appliances that can detect internal failures without causing any blank time when the stationary electrical appliances are unprotected, and can reliably protect the stationary electrical appliances in any case.

In addition, it is equipped with a volumetrically efficient and compact pressure detection and control means that can detect internal failures even when external factors are occurring, without unnecessarily shutting down stationary appliances due to external factors such as earthquakes. The purpose is to obtain a protection device for stationary electrical appliances that can reliably protect them. Means for Solving Problem 4♂] In order to achieve the above object, in the protection device for stationary electrical appliances according to the present invention, the above pressure is determined based on the detection result of the pressure detection means for detecting the pressure in the air chamber. A control means is provided which performs a first operation when the temperature is above a first predetermined value and performs a second operation when the second predetermined value is higher than the first predetermined value. An external factor detecting means is provided which operates depending on the external factor causing the problem, and when the external factor detecting means is activated, an alarm is issued by the second operation described above, or the stationary electric appliance is cut off, and the above-mentioned condition is set during normal times when the external factor detecting means is not operating. The first action is to issue an alarm or shut off stationary electrical appliances.

Further, a telescoping chamber is provided in communication with the air chamber and has a telescoping section that expands and contracts according to the pressure of the air chamber, and a first opening/closing contact that is operated by the telescoping section when the pressure is equal to or higher than the first predetermined value. and a second switching contact that is activated when the pressure exceeds the second predetermined value. It is designed to emit electricity or cut off stationary electrical appliances.

[For production]

In this invention, an external factor detection means that operates due to an external factor such as an earthquake, and a pressure detection means that detects a relatively sudden change in the pressure inside the tank due to an internal failure or an external factor are used to detect the pressure in the air chamber. External factor detection means is combined with a control means that performs a first action when the pressure is above a first predetermined value and a second action when the pressure is above a second predetermined value higher than the first predetermined value. When it is not operating, the above-mentioned first action is used, and when it is operating, the above-mentioned second action is used to issue an alarm or shut off stationary electrical appliances to protect them, and prevent unnecessary alarms and shutoffs when external factors occur. This also prevents unprotected blank time from occurring at this time.

In addition, by providing a first switching contact and a second switching contact that are operated by an expandable part that expands and contracts according to changes in the pressure of the air chamber, the alarm or the interruption of stationary electric appliances can be performed by the operation of each switching contact. To prevent the occurrence of blank time that becomes unprotected when an external factor occurs. In addition, the pressure detection and control means are integrated into a small and compact device.

[Embodiments of the invention]

FIGS. 1 and 2 show an embodiment of the present invention, with FIG. 1 being a configuration diagram of the protection device, and FIG. 2 being a characteristic diagram showing its operating characteristics. In these figures, (1) to (l3) are the same as those of the above-mentioned conventional device, so explanations thereof will be omitted. (23
) is a pressure sensor, which is an example of a pressure detection means for detecting the pressure in the air chamber (51), and (24) is an external factor that is activated by an external factor that causes a pressure change in the tank, such as an earthquake. The detection means, in this example, is an earthquake relay that closes the contact (24A) when activated.The detection means (25) detects when the pressure in the air chamber (5) exceeds a first predetermined value based on the detection result of the pressure sensor (23). When the value is higher than the second predetermined value, which is higher than the first predetermined value, the second operation is performed, in this example, the second predetermined value is reached. It is a control means for closing the opening/closing contact (251+) of the air chamber (51), and as shown in FIG. The first switching contact (25A) is closed at a pressure equal to or higher than that of the curve (11), and this first characteristic curve (l1
), the second opening/closing contact (25B
) is designed to perform the closing operation. In addition, if the pressure fluctuation in the tank (1) caused by an external factor such as an earthquake is due to a moderate earthquake, the pressure will exceed the pressure of the second characteristic curve (14) and the second switching contact (25 [3 ) is determined so that the second characteristic curve (l4) is not closed. Note that the characteristics of characteristic curves (I1) and (+4) are realized in this example by a combination of analog operational amplifiers and other electronic circuits. Furthermore, the contacts of the earthquake relay (24A) and the first and second opening/closing contacts of the control means (25A)
A). The operations of (25B) are combined as shown in the logic circuit shown by the dotted line in Figure 1, and the contacts (24B) of the earthquake relay are combined.
If A) is not closed and the first switching contact (25A) is closed, it is due to an internal failure, so the oil-immersed transformer is shut off, and if the earthquake relay contact (24A) is closed, the first switching contact (25A) is closed. Even if the switching contact (25A) is closed, the oil-immersed transformer is not shut off because it may have been activated due to an external factor.
If the second switching contact <258) further closes in this state, it is determined that an internal failure has occurred and the oil-immersed transformer is shut off.

Next, the operation when an internal failure occurs simultaneously when an earthquake occurs and the earthquake relay (24) is operating will be described with reference to FIG. If the time during which the earthquake relay (24) is operating is TI [seconds], during this time the oil-immersed transformer will not be shut off even if the first switching contact (25A) is operated as described above. That is, at the same time as the earthquake occurs, an internal failure occurs that causes the pressure to rise as shown by the straight line (13) in the figure, and the pressure reaches the intersection (13a) with the first characteristic curve (11), causing the first switching contact to close. Even if (25Δ) is operated, the cutoff is not performed, and the pressure increases further and when it reaches the intersection point (14a> with the second characteristic curve (14)), the second opening/closing contact (25I31
operates and shuts off the oil-immersed transformer. By shutting off the oil-immersed transformer, the progress of the internal failure will be stopped, so the tank (
1) The internal pressure is protected from rising to the tank burst pressure. -h if the earthquake relay (24) is not working
The first switching contact (25A) operates and is protected according to the first characteristic curve (11) similar to the conventional example described above.

In addition to the earthquakes mentioned above, external factors that cause pressure fluctuations in the tank (1) include starting and stopping of the oil circulation pump, and mechanical vibrations caused by external short circuits. It is sufficient to provide a means and input it as an OR condition with the operation of the earthquake relay (24).

Further, in the above embodiment, the earthquake relay (24) and the control means (
25) operation at each contact (24A), (25A), (
25B), but it goes without saying that all of these, including logic circuits, may be implemented by electronic circuits. Moreover, it is also possible to add a separate function so as to issue an alarm when the first switching contact (25A) operates while the earthquake relay (24) is operating.

Further, in the embodiment shown in FIG. 1, the oil-immersed transformer is shown to be shut off, but it is also possible to issue an alarm without shutting it off.

In addition, as another modification, it is also possible to issue an alarm by operating the first switching contact (25A) and to shut off by operating the second switching contact (25B).

FIG. 3 shows a composite pressure relay suitable as a pressure detection and control means in the above embodiment, and in the figure (32
) is a composite type pressure relay, and is configured as follows. (33) communicates with the air chamber ((5) and connects the fixing plate (6)
The metal lower bellows (33a
) and a rigid top (33b). (34) is an upper telescoping chamber provided at the top (33b) in communication with the lower telescoping chamber (33); It has a metal upper bellows (34a) which is an expandable part with a diameter smaller than that of 33a) and a rigid top part (34b). (35A) is a first opening/closing contact provided to be operated by the top (34b) when the pressure in the air chamber (5) is above a first predetermined value. (35B) is a second opening/closing contact arranged to be operated by the top (33b) when the pressure of the air chamber (odor) is higher than a second predetermined value.This composite pressure relay (32) , air chamber {(5
) increases, both the lower bellows (33a) and the upper bellows (34a) expand, but the top of the upper bellows (34a) expands.
4b) movement is the lower and upper bellows (33a), (34
Since the extension in a) is added and becomes larger, the first opening/closing contact (35Δ) is operated first, and then the second opening/closing contact (35B) is operated by the top of the lower bellows (33b). The operating characteristics of the air chamber (first and second switching contacts (35A) < 35B for a pressure of 5 liters) are shown in the characteristic curve It in FIG.
(Japanese), <14).

Now, the composite pressure relay (32) configured in this way
can be used as the pressure detection and control means shown in FIG. 1 and in combination with an earthquake relay (24) to provide protection similar to the embodiment of FIG. In addition, earthquake relay (2
Regardless of whether external factor detection means such as 3511) can generate another alarm or shut off the oil pressure regulator.

Figure 4 shows yet another composite pressure relay. (42) is a composite pressure relay. (44)
(46) are first and second expansion and contraction chambers that are connected to the air chamber (5l) and are provided on the fixed plate (6}, respectively, and are made of metal, such as a first bellows (44a) and a second bellows (46a), respectively. and the top (
44l]) and (46h). The first bellows (44a) is longer than the second bellows (46a), and the first and second opening/closing contacts (45Δ>, (
45B) are arranged, each with the characteristic curve (I
l1, (14).

Figure 5 shows yet another composite pressure relay.
In the figure, (52) is a composite pressure relay, which is constructed as follows. <57) is a telescopic chamber which communicates with the air chamber (5) and has an intermediate bellows (57a) and a top (57b) provided on the fixed plate (6), (55A), (
5511) are the first and second switching contacts operated by the top (57b), and the first switching contact < 55A)
The top (57b) is located at the position (58) indicated by the dashed line in the figure.
a), the second opening/closing contact (551
111 is at the position T where the top (57b) is indicated by the two-dot chain line in the figure.
! (58b). These composite pressure relays (42) and (52) can be used in the same manner as the composite pressure relay (32) shown in FIG. In each of the above embodiments, metal bellows are used for the expansion chamber, but the bellows are not limited to this and may be made of synthetic rubber, depending on the operating pressure range. It may also be a bellows or the like that does not have elasticity.

In each of the above embodiments, the air chamber receives oil pressure in an oil-filled transformer, but the air chamber may receive gas pressure in the oil-filled transformer, and the cooling may be performed using gas, etc. It may also be cooled by other refrigerants. The same effect can also be achieved with static electric beam actors, electrostatic capacitors, and other objects. [Effects of the Invention] As described above, according to the present invention, the first operation is performed when the pressure in the air chamber is equal to or higher than the first predetermined value, and the second predetermined value higher than the first predetermined value is performed. We provided a control means that performs the second operation in the above cases and an external factor detection means that operates due to external factors such as earthquakes, and combined these operations to issue an alarm or shut off the static electricity, so that in case of an earthquake, etc. No unnecessary alarms or shutoffs caused by pressure fluctuations caused by external factors, and even if pressure fluctuations are occurring due to external factors, internal failures that occur during that time can be detected and protected by alarms and shutoffs. By doing so, it is possible to obtain a protection device for stationary electric appliances that does not require blank time during protection.

In addition, the pressure detection means and control means are combined into a compact unit with good volumetric efficiency by using a composite pressure relay, and this can also be used as a protection device to perform unnecessary alarms and shutoffs in the same way as above. Therefore, it is possible to obtain a protection device for stationary electric appliances that does not require any blank time during protection.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the present invention. Figure 1 is a configuration diagram of the protective device, Figure 2 is a characteristic diagram showing its operating characteristics, and Figures 3 to 5 are diagrams of this device. 6 and 7 are cross-sectional views showing embodiments of each composite pressure relay according to the invention, and FIG. 7 shows a conventional protection device for an oil-immersed transformer. The figure is a characteristic diagram. In the figure, (1) is the tank, (the phrase is the air chamber, (to) is the communication part, (23) is the pressure sensor, (24) is the earthquake relay, (25) is the control means, (33) is the lower expansion chamber, (33a
) is the lower bellow, (34) is the upper telescopic chamber, and (34a) is the upper bellow (44) is the first telescopic chamber. (44a> is the first bellows, (46) is the second contraction chamber, (46a) is the second bellows, (57) is the expansion chamber, (57a) is the expansion bellow, (25
A). (35A>, (45A), (55th layer is the first switching contact, (25B). (35B). (45B) (
55B> is a second switching contact. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 1 Agent Patent Attorney Oiwa Masuo 5 Vacant room 7 Violation ξp 23 Melon 25 Plane] {Sokuteba 2SA. 25B 1st heaven 2nd n part rA 4#e Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Scope of Claims] 1. An air chamber that contracts and expands in response to pressure in a nearly airtight tank housing an electrical equipment main body, and an air chamber that is provided in this air chamber and communicates the air chamber with outside air through a minute opening. communication part,
A pressure detection means for detecting the pressure in the air chamber, an external factor detection means operated by an external factor that causes a pressure change in the tank such as an earthquake, and a first predetermined value based on the detection result of the pressure detection means. A control means is provided which performs a first operation when the above-mentioned condition is exceeded, and performs a second operation when the value is equal to or higher than a second predetermined value higher than the first predetermined value, and when the external factor detection means is inoperative, the first operation is performed. A protection device for a stationary electric appliance, characterized in that when the external factor detection means is activated, the second operation causes an alarm to be issued or the electric appliance body to be disconnected from the electrical circuit. 2. An air chamber that contracts and expands in response to pressure within a nearly airtight tank housing the electrical equipment main body; a communication section provided in this air chamber that communicates the air chamber with outside air through a minute opening;
at least one telescoping chamber that is provided in communication with the air chamber and has a telescoping section that expands and contracts in response to changes in the pressure of the air chamber, and is operated by the telescoping section when the pressure is equal to or higher than a first predetermined value. It is equipped with a first switching contact and a second switching contact that is activated when the voltage is equal to or higher than a second predetermined value higher than the first predetermined value, and an alarm is issued by the operation of the first switching contact, and the A protection device for a stationary electric appliance, characterized in that an alarm is issued or the electric appliance main body is cut off from an electric circuit by the operation of the second switching contact.