JPH0217892B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for externally diagnosing failures in gas-insulated switchgear, particularly loosening of parts that occur when used for a long period of time.

Analysis of the causes of failures in gas-insulated switchgear equipment shows that so-called mechanical failures, such as inoperability, malfunction, air leakage, oil leakage, damage, and loosening or falling off of installed parts, account for more than 90% of all failures. It has been known. Among these, air leaks and oil leaks can be dealt with by using pressure relays, etc. to issue alarms before the opening/closing function is lost, and in the case of inoperability or malfunction, the chopper or disconnector can be used several minutes before normal operation. A method has been proposed in which failures are detected by driving the motor at a slow speed of approximately 1 and analyzing this speed.

By the way, light loosening that occurs in mounting parts,
If this develops and falls off, there is currently no way to prevent an accident such as a sudden flashover and a power outage to the grid. Therefore, it was extremely difficult to take countermeasures and treatments. The reason for this is that in most cases, the switch is in a stationary state under normal conditions and therefore does not generate any vibration or noise during its own operation, so there is no signal to be detected from the outside.

In order to make the explanation more specific, the explanation will be given by taking as an example a gas insulated switchgear, which particularly requires reliability in terms of its mission, among gas-insulated switchgear. FIG. 1 is a block diagram of a tank-type gas shield and disconnector. Reference numeral 1 denotes a gas tank in which an insulating gas such as SF ₆ gas is sealed. 2 is the edge section, which will be explained later in FIG. 2. 3 is a bushing, and 4 is an insulated operating rod which serves to transmit the operating force from the driving section 5 to the shear cutting section 2. Although not shown in the figure, there is a tank wall parallel to the plane of the paper between the operating rod 4 and the drive section 5, and therefore the drive section 5 is on the air side.

FIG. 2 shows an outline of the sheath section 2,
Consisting of a fixed piston 6, a movable cylinder 7, a fixed electrode 8, etc., when the cylinder breaks down, the movable cylinder moves to the left in the figure by the operating driving force via the transmission mechanism 16, thereby causing the insulating gas in the compression chamber 17 to The structure is such that the high pressure is rapidly compressed and is blown onto the fixed electrode 8 via a valve (not shown) to extinguish the arc. In the figure, 12 and 14 are shields fixed with mounting screws 13 and 15 in order to alleviate the electric field of the electrode with respect to the ground, and 9 is a capacitor that mechanically holds the electromagnetic space and equalizes the shared voltage, and 10
is a support, and 11 is a terminal for external extraction.

Conventionally, the JEC-181 method has been commonly used to confirm the mechanical reliability of a breaker.
(1975), but it is customary to conduct a 10,000-times continuous opening/closing test as a reference test. During these tests, the opening time, stroke of the movable part, closing time, and operating voltage are measured at the same time.Furthermore, with regard to operating voltage or pressure, tests are performed not only at the rated value but also at the maximum and minimum values. I am also scheduled to do so. Combinations of these values are also specified in JEC-181. Manufacturers conduct factory tests using a combination of these tests before shipping to confirm product reliability.

However, opening/closing devices such as shield disconnectors need to operate in an extremely short period of time due to their functions, and therefore require a great deal of operating force. For this reason, internal parts are firmly attached, and fasteners such as screws are sufficiently prevented from rotating, but items with relatively low structural rigidity, such as shields, are subject to excitation forces during operation. It may vibrate, gradually reduce its mounting strength, and in the worst case, it may fall off. In such a state, it becomes a conductive part between the high voltage part and the ground potential, causing a grounding accident. Conventionally, there was no way to detect such looseness in component attachment.

With the increase in electricity demand in recent years. All switchgear equipment, including circuit breakers, are expected to have higher voltages and larger capacities, and the impact that their failures will have on society will be enormous and serious. Therefore, it is desirable to improve the reliability of equipment by predicting mechanical failures, which account for the majority of failures, in advance and taking countermeasures for the equipment and disconnectors that make up the power system. . Gas insulated equipment utilizes the high insulation properties of _SF6 gas to dramatically improve the integration density of substations, but many important parts are housed inside pressure vessels and, as mentioned above, are self-contained during normal operation. It does not have a signal source that informs the outside of its operating status. Since it is a passive device, it has been even more difficult to deal with it and treat it.

The present invention was conceived in view of these points,
The object of the present invention is to provide an external diagnosis method for abnormalities in gas-insulated switchgear equipment, which diagnoses mechanical failures such as loosening of parts that occur or are progressing inside gas-insulated switchgear equipment from the outside.

In order to achieve this objective, in the present invention, since gas insulated equipment is a so-called passive equipment that does not generate signals during normal operation, it is possible to perform sensitive abnormality diagnosis by stimulating it externally and investigating its response. This makes it possible to Embodiments of the present invention will be described below with reference to the drawings. In the following figures, the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted.

3 and 4 are diagrams showing one embodiment of the present invention, and FIG. 3 is a system diagram for applying electrical stimulation from the outside to a gas insulator or disconnector, which is a device to be diagnosed. The figure shows a measurement circuit that detects and processes vibrations of internal parts when electricity is applied to the charging part of the gas cylinder and disconnector using the circuit shown in Figure 3. That is, in FIG. 3, 24 is a variable frequency oscillator, and the output 36 of this oscillator 24 is connected to an amplifier 23, a low voltage conductor 22, and a high voltage generator 2 as shown in the figure.
1. Electricity is applied via the high-voltage conductor 20 to the bushing 3 of the gas shield and disconnector, which is the device to be diagnosed. The system disconnectors 18 and 19 are opened during measurement. Next, in FIG. 4, reference numerals 25 to 28 are vibration acceleration detection elements, for example, piezoelectric element type, which are attached to main parts such as the gas tank 1 or the shaft of the drive system, and the detection output of each vibration acceleration detection element is transmitted to a vibration amplifier. 33, the signal is introduced into a recorder 25, such as an x-y recorder, through a transducer 34 for increasing the S/N ratio of detection. The recorder 25 includes the variable frequency oscillator 24 shown in FIG.
The output 36 of is given.

Next, the operation of the present invention will be explained. FIG. 5 shows an example of the diagnosis results according to the present invention, where the horizontal axis is the excitation frequency of the gas shield disconnector, and the vertical axis is the vibration acceleration detection element 25.
28 are the outputs, 37 is the characteristic when the parts are normally installed, and 38 is the characteristic when there is an abnormality in the installation such as loosening of one of the internal parts.

According to electromagnetism, the force (F) that acts between two objects in an electric field e is given by F=1/2εe ² (1). ε is the dielectric constant.

Here, if e=Esinωt [v/m] ......(2), then from equations (1) and (2), F=1/2E ² sin ² ωt=1/4εE ² (1−cos2ωt) [N/ m ² ] ......(3) Therefore, if we take the maximum value, we get equation (4).

Fmax=1/4εE ² [N/m ² ] ………(4) When we specifically calculate the force that acts between objects in SF ₆ gas, the potential gradient E of the gas shield and disconnector is
It is about 30KV/cm. Fmax at this time is calculated as Fmax≒40 [N/m ² ]≒4 [Kg/m ² ].
Although the excitation force is extremely small, if there is resonance or chatter inside, the vibration will be greatly amplified.
In addition, the detection ability of the vibration acceleration detection elements 25 to 28 is
10 ^-3 [g] can be sufficiently sensed, so it is easily possible to obtain measurement results such as those shown in Figure 5.

Therefore, if you compare it with the normal frequency response 37 recorded in advance and detect the change, if the internal mounting part is loose, the vibration value will increase significantly as shown in 38 in Figure 5. , generation of new resonance components and shift of frequency to lower frequencies, etc. are observed.
In addition, when a chatter signal is detected, the part that is generating the signal can be determined by determining the correlation between the signals between multiple vibration acceleration detection elements that maintain a remarkable resonance state as described above. It is also possible to locate That is, according to the present invention, it is possible to diagnose from the outside whether or not the internal parts of a gas insulated device are loose.

FIG. 6 is a diagram showing another embodiment. In this example, an electromagnetic vibrator 39 that acts directly on the internal equipment as an external stimulus to the gas-insulated switch is attached to, for example, the drive shaft, and its excitation force P is detected by the force transducer 40. In addition, if the output of the vibration acceleration converter 41 attached to the drive unit is integrated and the mechanical impedance P/V is calculated and expressed from the excitation force P as the vibration velocity V, accurate transmission and response characteristics can be obtained. As shown in FIG. 7, since the response characteristics are different between normal (waveform 42) and abnormal (waveform 43), abnormalities such as loosening of internal parts can be diagnosed externally by comparing them.

As described above, in the present invention, vibration stimulation is applied directly to the internal parts of power switching equipment such as gas vents and disconnectors by electrical or mechanical means from the outside, and the response of the internal parts is compared with that under normal conditions. As a result, it is possible to provide an external diagnosis method for abnormalities in switching equipment that can accurately detect loosening of internal parts from the outside without disassembling the equipment.

[Brief explanation of drawings]

Figure 1 is a structural diagram of the gas shield and breaker showing the main parts cut away, Figure 2 is a sectional view showing the arc extinguishing chamber of the gas shield and breaker shown in Figure 1, and Figures 3 and 4 are the main parts. FIG. 1 is a diagram showing an embodiment in which the invention is applied to a gas shield and disconnector,
Figure 3 is a test circuit system diagram, Figure 4 is a measurement circuit that detects vibrations of internal parts when power is applied to the charging part by the circuit in Figure 3, and Figure 5 is a comparison of the measurement results with normal cases. FIG. 6 is a structural diagram of a gas shield and disconnector for explaining another embodiment, and FIG. 7 is a curve diagram showing a comparison of measurement results by the method shown in FIG. 6 with a normal case. 1...Gas tank, 2...Shell section, 4...Operation rod, 24...Variable frequency oscillator, 25-28
... Vibration acceleration detection element, 35 ... X-Y recorder, 39 ... Electromagnetic exciter.

Claims (1)

[Claims] 1. In a switching device, vibration is applied directly to the internal components of the switching device from the outside, the response of the internal components to this vibration is detected as a frequency or mechanical impedance, and this detection result is compared to a pre-recorded normal An external diagnosis method for abnormalities in switchgear equipment that detects abnormalities such as loose fittings of internal parts by comparing with the actual condition. 2. The method for externally diagnosing an abnormality in a switching device according to claim 1, wherein the vibration directly applied to the internal parts of the switching device is an electromagnetic force caused by applying a high voltage with a variable frequency. 3. The method for externally diagnosing an abnormality in a switching device according to claim 1, wherein the vibration directly applied to the internal parts of the switching device is caused by an electromagnetic vibrator attached to a drive mechanism.