JPH05333080A - Detection method for overheat of gas insulation electric appliance - Google Patents

Abstract

PURPOSE:To improve the sensitivity of judgment of overheat by performing the detection of overheat in gas insulation electric appliances during a specific term in a particular time zone. CONSTITUTION:In detecting abnormal overheat in gas insulation switchgears, it is necessary to lower the effects of gas pressure change due to temperature rise in day time and sun shine on these gas insulation switchgears in normal state. The gap between the maximum and minimum of the gas pressure becomes smallest during 11pm to 5am. By judging abnormal overheat in a specific term in this time zone, abnormal overheat judgment with good sensitivity is possible. That means, by using a judgment level 7 on the basis of the maximum of risen saturation value in the time zone from 11pm to 5am and a judgment level 9 on the basis of the maximum of pressure rising rate, the judgment of abnormal overheat is done in a term in this time zone. As the judgment levels 7 and 9 are set at values close to the risen saturation value of the gas insulation switchgear in normal state and the pressure rising rate, the detection sensitivity becomes high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting overheat of gas-insulated switchgear, gas-insulated transformer, gas-insulated capacitor and other gas-insulated electrical equipment.

[0002]

2. Description of the Related Art FIG. 4 shows a gas-insulated switchgear as an example of gas-insulated electrical equipment. In the gas-insulated switchgear of FIG. 4, main circuit parts such as a circuit breaker 41, a cable head 42, and a bus bar 43 are housed in gas compartments divided for each device unit,
SF6 gas serving as an insulating medium for the main circuit is filled and sealed in each gas compartment.

In such a gas insulated switchgear,
A method is adopted in which abnormal overheating caused by a contact failure of the main circuit conductive contact portion is detected and determined by monitoring the gas pressure of each gas section. In the determination, when the calculated pressure of the gas pressure at each time exceeds the determination level set in advance by the overheating characteristic of each gas section, it is determined that abnormal overheating has occurred in the gas section.

[0004]

When detecting the above-mentioned abnormal overheat, the judgment is made by using the gas pressure at each time. Therefore, the judgment level of the abnormal overheat is set by the gas insulation due to the influence of the daytime temperature and the solar radiation. This must be done in consideration of the rise in gas pressure due to the rise in switchgear container temperature. Therefore, in order to prevent erroneous detection, the determination level must be set higher, and the sensitivity of overheat determination is relatively poor.

An object of the present invention is to improve the sensitivity of overheat determination in a method of detecting and determining abnormal overheat inside a gas-insulated electric device by monitoring gas pressure.

[0006]

In order to achieve the above-mentioned object, the present invention provides a method for detecting overheating of a gas-insulated electrical device, which detects abnormal overheating by monitoring the gas pressure of the gas-insulated electrical device. It is supposed to be performed during a predetermined period from 11:00 pm to 5:00 am.

[0007]

According to the above-mentioned means, the fluctuation of the gas pressure in the gas-insulated electric equipment is small between 11:00 pm and 5:00 am, so that the abnormal overheat judgment level can be set low and the judgment with high sensitivity becomes possible. ..

[0008]

EXAMPLE An example in which the present invention is applied to a gas-insulated switchgear will be described with reference to FIGS. 1 to 3 are diagrams for explaining the method for determining abnormal overheating according to the present embodiment, and FIG.
Shows an example of a gas-insulated switchgear.

The gas-insulated switchgear of FIG. 4 includes a circuit breaker 41,
The main circuit portion such as the cable head 42 and the bus bar 43 is housed in a gas compartment divided for each device unit, and each gas compartment is filled and sealed with SF6 gas serving as an insulating medium for the main circuit.

FIG. 1 shows the maximum value 1, the average value 2 and the minimum value 3 of the result of the actual measurement of the change in the gas pressure (increase saturation value) in the normal state of the gas insulated switchgear installed outdoors every month for one hour. Shown in 1. In addition, FIG. 2 shows the maximum value 4, the average value 5, and the minimum value 6 of the result of measuring the gas pressure change (pressure increase rate) from 60 minutes before every hour for one month. 1 and 2
As is clear from the results, during the daytime, due to the effects of temperature and solar radiation,
High saturation value and high pressure increase rate. In addition, its value and change are small at night.

An example of a method for determining abnormal overheating will be described with reference to FIG. In the determination of abnormal overheating, the rising saturation value P ₀ at the time 0 when the determination of the graph of FIG. 3a is made, the rising saturation value P _{-10 10} minutes before, the rising saturation value P _-60 , 7 minutes before 60 minutes.
The rising saturation value P ₋₇₀ obtained 0 minutes ago is obtained, and the next pressure calculation is performed from these. ΔP ₀ = P ₀ −P ₋₆₀ ΔP ₋₁₀ = P ₋₁₀ −P ₋₇₀ ΔP ₀ obtained here is 60 at the time of making a determination.
The rate of pressure increase compared to minutes before, and ΔP- ₁₀ is the rate of pressure increase compared to 60 minutes before 10 minutes before the determination. A typical example of a graph showing the change in the pressure increase rate is the change shown in FIG.

The value obtained from the above is input to the decision calculation circuit of FIG. 3b. ΔP ₀ and ΔP _-10 are respectively compared with the determination level ΔP of the pressure increase rate and input to the first AND circuit 31. P ₀ and P _-10 are respectively compared with the gas pressure determination level P and input to the second AND circuit 32.

The first AND circuit 31 outputs an output when both the pressure increase rates ΔP ₀ and ΔP _-10 at the time when the determination is made and 10 minutes before have exceeded the determination level ΔP. Second AND circuit 32
Is the rising saturation value P ₀ , P _{-10 at the} time when the determination is made and 10 minutes before.
Output when both exceed the judgment level P. When there is an output from either AND circuit 31 or 32, the OR
The circuit 33 outputs a signal notifying the occurrence of abnormal overheating.

In the method for detecting abnormal overheating of the gas insulated switchgear as described above, the influence of the gas pressure change due to the rise of the daytime temperature and the solar radiation in the normal state of these gas insulated switchgear is reduced. There is a need. Therefore, in this example, from the examination results of FIG. 1 and FIG.
By using the fact that the range of the maximum value and the minimum value of the gas pressure is the smallest from 1 o'clock to 5 am in the day, by judging the abnormal overheat during the predetermined period of this time zone, This makes it possible to detect abnormal overheat with high sensitivity.

That is, in this example, 11:00 pm to 5 am
During the time period from 11:00 pm to 5:00 am using judgment level 7 based on the maximum value of the saturation value of the hour and judgment level 9 based on the maximum value of the pressure increase rate. The above-mentioned abnormal overheat is determined.

Conventionally, the judgment levels 8 and 10 based on the maximum value during 24 hours must be used in order to make a judgment at the same level for 24 hours at all times and prevent erroneous detection. For this reason, the determination levels 8 and 10 are high and the detection sensitivity is low.

On the other hand, in this example, the judgment levels 7 and 9 set low are used for judgment during any one of the predetermined time periods from 11:00 pm to 5:00 am. As a result, the judgment levels 7 and 9 are set to values close to the rising saturation value and the pressure rising rate in the normal state of the gas insulated switchgear. Therefore, the detection sensitivity in this example is high.

[0018]

According to the present invention, in detecting abnormal overheat of gas-insulated electrical equipment, abnormalities are detected during a predetermined period of time from 11:00 pm to 5:00 am, when the rising saturation value and pressure rise rate are low and stable. The detection level can be set low by detecting overheating. Therefore, the detection sensitivity of the abnormal overheat detection method becomes high.

[Brief description of drawings]

FIG. 1 is a graph showing changes in an increasing saturation value of gas pressure according to the present invention and the related art.

FIG. 2 is a graph showing changes in the pressure increase rate of the gas pressure of the present invention and the conventional gas pressure.

FIG. 3 is a graph and a circuit diagram for explaining an example of determining abnormal overheating according to the present invention.

FIG. 4 is a side view showing a gas insulated switchgear according to the present invention and a conventional example.

[Explanation of symbols]

1, 2, 3 ... Change in rising saturation value, 4, 5, 6 ... Change in pressure rising rate, 7, 8 ... Judgment level of rising saturation value, 9, 10
... determination level of pressure rise rate, 31, 32 ... AND circuit,
33 ... OR circuit, 41 ... Circuit breaker, 42 ... Cable head, 43 ... Busbar.

Claims (1)

[Claims] 1. An overheat detection method for detecting abnormal overheat by monitoring gas pressure of a gas-insulated electric device in which an electric device is housed in a container together with an insulating gas. The overheat detection is performed from 11:00 pm to 5:00 am. The method for detecting overheat of gas-insulated electrical equipment, characterized in that it is carried out during a predetermined period.