JPH0736039U - Abnormal overheat detector for gas insulated switchgear - Google Patents

Abstract

(57) [Abstract] [Purpose] Sensitive detection of abnormal overheat generated in the container of the gas insulated switchgear. [Composition] The gas pressure Px inside the container and the temperature Tx outside the container are given to a room temperature converted gas pressure calculating means 5 to obtain a room temperature converted gas pressure Pnx. The base pressure selecting means 6 compares the room temperature converted gas pressure Pnx at 5 am with the lowest value of the room temperature converted gas pressure at the same time before the previous day, and sets the lowest room temperature converted gas pressure as the base pressure Pb. Overheat determination level for winter by adding the base pressure Pb, the maximum decrease in the room-temperature-equivalent gas pressure due to the disturbance at 5 am, the increase in the gas pressure when the maximum load current is applied, and the maximum increase in the gas pressure due to the disturbance Find Prw,
The maximum change width ΔPnp of the year-round change in the room temperature converted gas pressure at 5 am is added to this Prw to obtain the summer overheat determination level Prs. The presence or absence of abnormal overheat is detected by comparing the room temperature converted gas pressure Pnx with the overheat determination level Prw or Prs.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an abnormal overheat detection device for detecting whether or not abnormal overheat has occurred in a container of a gas insulated switchgear.

[0002]

[Prior art]

 Gas pressure detection inside the gas insulated switchgear as a device to detect whether abnormal overheating has occurred due to an abnormal current flow (increased contact resistance, etc.) or defective contact at the electrical contact area. There is a method in which the presence or absence of abnormal overheating is detected by converting the value into a gas pressure at room temperature and comparing this room temperature converted gas pressure with a predetermined overheat determination level. In this case, the temperature used to calculate the room temperature converted gas pressure should originally be the temperature of the gas in the container, but it is necessary to avoid the insertion of foreign matter that may disturb the electric field as much as possible. Since it is difficult to insert a temperature sensor into the container, in practice, the ambient temperature of the container is detected and the detected value is used for gas pressure conversion.

This type of detection device includes a pressure sensor for detecting the pressure of the gas in the container of the gas insulated switchgear, a temperature sensor for detecting the temperature outside the container, a detection output of the pressure sensor and a detection output of the temperature sensor. Inputting and, the gas pressure detected by the pressure sensor is converted to the gas pressure at room temperature (usually 20 ° C) to calculate the room temperature converted gas pressure. It is constituted by an abnormal overheat judging means for judging that abnormal overheat has occurred in the container when the room temperature converted gas pressure exceeds the overheat judgment level as compared with the overheat judgment level.

FIG. 11 shows a schematic configuration of a device (hardware) used in this detection method. In FIG. 11, 1 is a pressure sensor for detecting the pressure in the container of the gas insulated switchgear, and 2 is the periphery of the container. A temperature sensor that detects the temperature. The outputs of these sensors are input to the computer 4 via the sensor input unit 3.

The computer reads the detected value of the pressure sensor and the detected value of the temperature sensor every predetermined time, for example, every 10 minutes, and performs an operation of converting the detected value of the pressure sensor into a pressure value at room temperature. To do. Assuming that the gas density coefficient of the gas in the container is L, the room temperature is 20 ° C., the gas pressure detection value at time n is Px, the temperature detection value is Tx, and the room temperature conversion gas pressure is Pnx, Pnx is It is calculated by the formula.

Pnx = Px + L (20−Tx) (1) By the process of performing the above calculation, the room temperature converted gas pressure calculating means is realized.

In the process of realizing the abnormal overheat determination means, the presence or absence of abnormal overheat is determined by comparing the above-mentioned normal temperature converted gas pressure Pnx with the overheat determination level. That is, the pressure increase in the container when abnormal overheating does not occur is only the increase in the gas pressure due to the increase in the outside temperature and the increase in the gas pressure due to the heat generated due to the energization in the steady state. The converted gas pressure does not exceed a certain range. On the other hand, if abnormal overheating is added to the cause of the increase in the gas pressure in the container, the room temperature equivalent gas pressure rises above the predetermined range. Therefore, it is possible to detect that abnormal heating has occurred when Pnx> Pr by comparing the appropriately set determination level Pr and the normal temperature converted gas pressure Pnx at each sampling time. In the conventional detection device, for example, sampling is performed every 10 minutes, and the room temperature converted gas pressure Pnx calculated from the sampling value is compared with the overheat judgment level Pr, and the room temperature converted gas pressure indicates the overheat judgment level twice consecutively. When the exceeding is detected, an overheat detection output such as an alarm is generated.

In the conventional abnormal overheat detection device, the overheat determination level Pr is basically the charging gas pressure Po in the container at 20 ° C., the pressure increase ΔPImax expected when the maximum load current is applied, and the disturbance ( The value is the sum of the maximum pressure increase ΔP (+) max, which is expected mainly due to the change in outside temperature. The pressure increase ΔPImax expected when the maximum load current is applied and the maximum pressure increase ΔP (+) max expected due to disturbance are obtained by actual measurement and are fixed values, but the charging gas pressure Po (load current The pressure in the container when there is no heat generation due to the ambient temperature and the ambient temperature is 20 ° C) changes every time the container is filled with air after maintenance and inspections and repairs. Therefore, in practice, the tolerance α is set and the overheat determination level Pr is set by the following equation (2).

Pr = Po + ΔPImax + ΔP (+) max + α (2) FIG. 12 shows a change in the gas temperature at room temperature converted with respect to the load current. In FIG. 12, a curve a indicates a pressure due to disturbance (change in temperature, etc.). It shows the change in gas pressure in the container with respect to the load current when there is no change, and its maximum value is ΔP Imax. The curved line B shows the pressure change when the pressure change ΔP (+) max due to the disturbance is applied. Conventionally, when the gas pressure in the container exceeds the overheat determination level Pr = Po + ΔPImax + ΔP (+) max + α, abnormal overheat is detected.

As described above, in the conventional abnormal overheat detection device, the overheat determination level Pr is set by the equation (2), but the change width of the charging gas pressure Po is larger than ΔPImax + ΔP (+) max. Since it is large, it is necessary to set the margin α in Equation (2) to be considerably large. Therefore, the overheat determination level Pr becomes considerably large, and it is inevitable that the detection sensitivity for abnormal overheat is lowered.

In addition, when trying to detect abnormal overheating of an existing gas-insulated switchgear, the pressure rise due to the load current cannot be made zero, so the pressure of the filled gas in the container may not be measured. However, in that case, the overheat determination level Pr could not be set accurately.

Therefore, the inventor of the present invention can set the overheat determination level appropriately without being affected by the change width of the charging gas pressure Po and the pressure increase due to the load current. An abnormal overheat detection device was proposed.

In the proposed abnormal overheat detection device, the output of the pressure sensor that detects the gas pressure inside the container of the gas insulated switchgear and the output of the temperature sensor that detects the temperature outside the container are used to detect gas caused by disturbance. Calculate the room temperature-converted gas pressure in the container at a specific time (for example, 5:00 am) set in a time zone where the pressure change is small and the load change is small, as the specific time room temperature-converted gas pressure Pnp, and convert it to the specific time room temperature. The gas pressure Pnp is compared with the lowest value of the specific time room temperature converted gas pressure Pnp calculated at the same time before the previous day, and the lower one of the compared specific time room temperature converted gas pressures is selected as the base pressure Pb. Then, the base pressure Pb has a maximum decrease ΔP (-) max in the room-temperature-equivalent gas pressure due to the disturbance at the above-mentioned specific time and an increase ΔPmax in the gas pressure when the maximum load current is applied and the maximum increase in the gas pressure due to the disturbance. When the overheat determination level Pr = Pb + ΔP (-) max + ΔP Imax + ΔP (+) max is calculated by adding the amount ΔP (+) max and the successively calculated room temperature converted gas pressure Pnx exceeds the overheat determination level Pr. Detects that abnormal overheating has occurred.

[0014]

[Problems to be solved by the device]

 In the above-mentioned proposed abnormal overheat detection device, the second term to the fourth term [ΔP (-) max + ΔPImax + ΔP (+) max] on the right side of the expression Pr = Pb + ΔP (-) max + ΔPImax + ΔP (+) max for determining the overheat determination level Is a fixed value, but Pb of the first term is changed to a low value every time the room-temperature-equivalent gas pressure in the container becomes low at a specific time. By doing this, the base pressure Pb becomes asymptotic to the gas pressure when the load current is minimum and the pressure drop due to disturbance is maximum [when a pressure drop of ΔP (-) max occurs]. Therefore, the term of Pb + ΔP (-) max on the right side of the equation for obtaining the overheat determination level Pr is asymptotic to the charged gas pressure in the container.

Therefore, if the overheat determination level is set by the above equation, the overheat determination level can be converged to a necessary minimum appropriate value, and the overheat determination level must be set with a large margin. The detection sensitivity can be increased as compared to the conventional abnormal overheat detection device which has not been provided.

As described above, in the gas-insulated switchgear, it is difficult to directly measure the temperature of the gas in the container. Therefore, when converting the gas pressure detected by the pressure sensor into the gas pressure at room temperature, Inevitably, the temperature outside the container detected by the temperature sensor is used. However, since the difference between the temperature outside the container and the gas temperature inside the container is not constant and greatly differs between the summer and winter, the temperature outside the container was used to calculate the gas temperature Pnp at the specific time normal temperature. In that case, the value will be significantly different between summer and winter, and it is clear that the proposed abnormal overheat detection device may cause false detection due to the overheat determination level becoming too low in the summer. became.

Generally, there is a linear relationship between the gas pressure P and the gas temperature T as shown by the straight line in FIG. 9, and there is a relationship of P = Lo · T + Mo. Here, Lo is a gas density coefficient, Mo is a constant, and the gas density coefficient Lo shows a constant value if the gas type is constant and there is no gas leakage. On the other hand, the relationship between the temperature T outside the container of the gas insulated switchgear and the gas pressure P inside the container is generally as shown by the straight line in FIG. 9, and this can be expressed by the equation: P = L · T + M . Here, L is an apparent gas density coefficient and M is a constant, but generally the apparent gas density coefficient L shows a value larger than the actual gas density coefficient Lo. In the proposed device, the gas pressure coefficient Pnp at a specific time was calculated using the previously known gas density coefficient Lo, but it was detected by the gas pressure and temperature sensor detected by the pressure sensor at a specific time. Since the ambient temperature is on the straight line in FIG. 9, for example, the detected value Px1 of the gas pressure at the ambient temperature T1 higher than the ambient temperature (20 ° C. in this example) is measured at the ambient temperature using the gas density coefficient Lo. When converted into pressure, the converted value becomes like Pnp1 shown in FIG. 9, and becomes larger than the correct room temperature converted gas pressure Pnp. Similarly, when the detected value Px2 of the gas pressure at an ambient temperature lower than room temperature is converted into the gas pressure at room temperature using the gas density coefficient Lo, the converted value becomes as shown in Pnp2 in FIG. 9, and the correct room temperature converted gas pressure is obtained. It is smaller than Pnp.

FIG. 10 shows a change (a year-round change) in the specific time room temperature converted gas pressure Pnp throughout the year. As is clear from the figure, the specific time room temperature converted gas pressure Pnp is higher than the normal temperature. The maximum value Pnpmax is shown in the summer when the temperature is high, and the minimum value Pnpmin is shown in the winter when the temperature is lower than room temperature.

In the proposed abnormal overheat detection device, when the specific time room temperature converted gas pressure Pnp reaches the minimum value Pnpmin in winter, the base pressure Pb is fixed to the minimum value thereafter. Therefore, in the next summer when the room temperature converted gas pressure at the specific time rises to the maximum value Pnpmax, the sequentially calculated room temperature converted gas pressure Pnx approaches the overheat determination level Pr by the maximum ΔPnp, and the overheat determination level is low. There is a possibility that it will become too much and cause false detection. In order to avoid this erroneous detection, it is possible to set the overheat determination level Pr higher by ΔPnp, but in such a case, the overheat determination level in winter will become too high and the detection sensitivity will decrease. I cannot avoid doing it.

An object of the present invention is to provide an abnormal overheat detection device for a gas insulated switchgear that can improve detection sensitivity throughout the year without causing erroneous detection in a specific period.

[0021]

[Means for Solving the Problems]

 As shown in FIG. 1, the abnormal overheat detecting device according to the invention as set forth in claim 1 includes a pressure sensor 1, a temperature sensor 2, a room temperature conversion gas pressure calculating means 5, a base pressure selecting means 6, and a winter season. For overheat determination level calculation means 8, summer overheat determination level calculation means 9, and abnormal overheat determination means 10.

The pressure sensor 1 detects the pressure of the gas inside the container of the gas insulated switchgear, and the temperature sensor 2 detects the temperature outside the container.

The room-temperature-converted gas pressure calculation means 5 inputs the detection output of the pressure sensor and the detection output of the temperature sensor and performs a calculation to convert the gas pressure Px detected by the pressure sensor into the gas pressure at room temperature. Then, the room temperature converted gas pressure Pnx is obtained.

The base pressure selection means 6 sets the room temperature conversion gas pressure calculated by the room temperature conversion gas pressure calculation means to a specific time at a specific time set in a time zone in which the change in gas pressure due to disturbance is small and the load fluctuation is small. The normal temperature converted gas pressure Pnp is compared with the lowest value of the specific time normal temperature converted gas pressure Pnp calculated at the same time before the previous day, and the lower one of the compared specific time normal temperature converted gas pressures is selected as the base pressure Pb.

The winter overheat determination level calculation means 8 includes the base pressure Pb selected by the base pressure selection means 6 and the maximum decrease ΔP (-) max in the room temperature converted gas pressure due to the disturbance at a specific time and the maximum load current energization. The increase amount ΔPmax of the gas pressure at the time and the maximum increase amount ΔP (+) max of the gas pressure due to the disturbance are added to calculate the winter overheat determination level Prw = Pb + ΔP (−) max + ΔPImax + ΔP (+) max.

The summer overheat determination level calculation means 9 calculates the difference ΔPnp = Pnp max −Pnpmin between the minimum value Pnpmin and the maximum value Pnpmax when observing the change in the specific time room temperature converted gas pressure Pnp over a year. As the specific time room temperature converted gas pressure difference, the summer time overheat judgment level Prs is calculated by adding the specific time room temperature converted pressure difference ΔPnp to the winter overheat judgment level P rw.

The abnormal overheat determination means 10 sets a certain period before and after the month and day when the specified time room temperature converted gas pressure Pnp shows the minimum value Pnpmin as a winter period, and the month and day when the specified time room temperature gas pressure Pnp shows the maximum value Pnp max. One year is divided into winter and summer in a certain period before and after the summer, and in the winter, the room temperature converted gas pressure Pnx is compared with the winter overheat judgment level Prw, and the room temperature converted gas pressure Pnx is compared with the winter overheat judgment level. When Prw is exceeded, it is judged that abnormal overheating has occurred in the container of the gas insulated switchgear, and in the summer, the room temperature converted gas pressure Pnx is compared with the summer overheat judgment level Prs and the room temperature converted gas pressure Pn is compared. When the temperature exceeds the summer overheat judgment level Prs, it is judged that abnormal overheat has occurred in the container of the gas insulated switchgear.

According to the invention described in claim 1, one year is divided into the winter and the summer as described above, but in the present invention, in each of the winter and the summer, at the installation location of the gas insulated switchgear. It is appropriately determined according to the actual change in the specific time room temperature converted gas pressure Pnp. In other words, the winter and summer periods are determined from the characteristics of the year-to-year change in the gas pressure Pnp converted to the normal temperature at certain times, and the days to days are defined as the winter season, and the days to days from the winter season. Whether it is summer depends on the climate of the place where the gas insulated switchgear is installed (change in temperature throughout the year). In determining each of the winter and summer periods, for example, the change in the specific time room temperature-equivalent gas pressure Pnp throughout the year is stored, and the change in the specific time room temperature-equivalent gas pressure Pnp for one year is grasped. A certain period before and after the day when the specified time normal temperature converted gas pressure Pnp shows the maximum value is defined as the summer period, and a constant period before and after that around the day when the specified time room temperature converted gas pressure Pnp shows the minimum value. The period should be winter. The length may not be equal in summer and winter.

The winter period and the summer period may be set to be the same every year, and the winter period and the summer period may be corrected based on the data accumulated every year or after a certain number of years have passed. May be.

Similarly, the value of the specific-time room-temperature-converted gas pressure difference ΔPnp may be updated every year based on an actual measurement value, or the same value may be used for a predetermined year and month.

As shown in FIG. 2, the abnormal overheat detecting device according to the invention as defined in claim 2 includes a pressure sensor 1 for detecting the gas pressure in the container of the gas insulated switchgear, and a temperature outside the container. A temperature sensor 2, a gas density coefficient calculation means 11, a room temperature converted gas pressure calculation means 5 ', a base pressure selection means 6, an overheat determination level calculation means 8', and an abnormal overheat determination means 10 '. It is composed of

The gas density coefficient calculating means 11 determines the gas pressure versus the ambient temperature from the ambient temperature and the gas pressure detected by the pressure sensor and the temperature sensor in a specific time zone in which the change in the gas pressure due to the disturbance is small and the load fluctuation is small. The temperature characteristic is obtained, and the apparent gas density coefficient L is obtained from the gas pressure vs. ambient temperature characteristic.

The normal temperature conversion gas pressure calculation means 5 ′ uses the detection output of the pressure sensor and the detection output of the temperature sensor as input, and uses the latest apparent gas density coefficient L to detect the gas pressure detected by the pressure sensor at room temperature. The gas pressure Pnx at room temperature is calculated by converting to the gas pressure at.

The base pressure selecting means 6 sets the normal temperature converted gas pressure calculated by the normal temperature converted gas pressure calculating means 5 ′ at a specific time set in a time zone in which the change in gas pressure due to disturbance is small and the load fluctuation is small. Compared to the lowest value of the specific time room temperature converted gas pressure Pnp calculated at the same time before the previous day as the specified time room temperature converted gas pressure Pnp, and select the lower one of the compared specific time room temperature converted gas pressures as the base pressure Pb. To do.

The overheat determination level calculating means 8 ′ is the base pressure Pb selected by the base pressure selecting means and the maximum decrease ΔP (−) max of the normal-temperature-converted gas pressure due to the disturbance at a specific time and the maximum load current at the time of energization. The overheating determination level Pr = Pb + ΔP (−) max + ΔP Imax + ΔP (+) max is calculated by adding the gas pressure increase ΔP Imax and the maximum gas pressure increase ΔP (+) max due to disturbance.

The abnormal overheat judging means 10 ′ compares the room temperature converted gas pressure Pnx with the overheat judgment level Pr to generate abnormal overheat in the container when the room temperature converted gas pressure Pnx exceeds the overheat judgment level Pr. It is determined that

The above-mentioned specific time zone is a time zone in which the change in gas pressure due to disturbance is small and the load fluctuation is small, similarly to the time zone in which the gas pressure for detecting the gas pressure for normal temperature calculation is set. In general, it is preferable to set the specific time zone to the time zone from midnight to 6:00 am. Further, in order to calculate the room temperature equivalent gas pressure Pnp at a specific time using the latest gas density coefficient L, it is preferable that the specific time zone be a time zone before the specific time.

[0038]

According to the first aspect of the invention, the base pressure selecting means sets the specific time room temperature converted gas pressure Pnp of the day and the minimum value of the specific time room temperature converted gas pressure Pnp at the same time before the previous day. By comparison, the lower one is the base pressure Pb. Therefore, Pb of the first term on the right side of the calculation formula Prw = Pb + ΔP (-) max + ΔPImax + ΔP (+) max that gives the overheat determination level in the winter is calculated every time when the room temperature converted gas pressure in the container becomes low. It will be changed to that lower value. Since the base pressure Pb is asymptotic to the gas pressure when the load current is minimum and the pressure drop due to disturbance is maximum [when a pressure drop of ΔP (-) max occurs], the overheat judgment is made. The term of Pb + ΔP (-) max on the right side of the equation for obtaining the level Prw gradually approaches the charged gas pressure in the container. When Pnp reaches the minimum value in winter, the overheat determination level Prw is fixed thereafter. In winter, by using this overheat determination level Prw, the detection sensitivity for abnormal overheat can be increased without causing erroneous detection. The overheat determination level Prw in this winter is similar to the overheat determination level used in the already proposed device, and it converges to the minimum required value in winter.

As described above, if the abnormal overheat is detected by using the winter overheat determination level Prw as it is in the summer, erroneous detection may occur. Therefore, in the present invention, the minimum value Pnpmin and the maximum value Pnpmax in the case of observing the change in the specified time room temperature converted gas pressure Pnp over a year are obtained, and the difference ΔPnp = Pnpmax −Pnpmin between the two is determined. It is calculated as a pressure difference, and the sum of the gas pressure difference ΔPnp at room temperature converted to the specific time is added to the winter overheat determination level Prw to be used as the abnormal overheat determination level Prs in summer. As a result, the overheat determination level Prs in the summer can be given a minimum necessary margin, and the detection error can be prevented from occurring in the summer without a decrease in the detection sensitivity.

As described above, in the device according to the first aspect, the overheat determination level is converged to the minimum necessary value in the winter when the room temperature converted gas pressure is calculated lower, and the room temperature converted gas pressure is increased. In the summer calculated as, the overheat determination level is given the minimum necessary margin by setting the level obtained by adding the temperature-converted gas pressure difference ΔPnp at the specific time to the winter overheat determination level. As a result, the detection sensitivity can be increased throughout the year without causing false detections.

According to the second aspect of the invention, the gas pressure is changed from the ambient temperature and the gas pressure respectively detected by the pressure sensor and the temperature sensor during a specific time period when the change in the gas pressure due to disturbance is small and the load fluctuation is small. When the pressure-ambient temperature characteristic is obtained, the apparent gas density coefficient L is obtained from the gas pressure-ambient temperature characteristic, and the room temperature-converted gas pressure is calculated using the latest apparent gas density coefficient L. Since the calculation error of the room temperature converted gas pressure due to the difference between the outside temperature and the gas temperature can be almost eliminated, the overheat judgment calculated by the calculation formula Pr = Pb + ΔP (-) max + ΔPImax + ΔP (+) max throughout the year. The level can be used to detect abnormal overheat with high sensitivity without causing erroneous detection.

[0042]

【Example】

FIG. 3 schematically shows a hardware configuration used in an embodiment of the present invention. In FIG. 3, reference numeral 20 indicates that necessary equipment such as a circuit breaker and a disconnector is housed in a container filled with SF ₆ gas. It is a gas insulated switchgear (GIS). Although not shown, the gas insulation switchgear 20 has a plurality of gas sections (containers), and the pressure sensors 1a, 1b, which detect the gas pressure for each of the plurality of gas sections. …, 1k is provided. A temperature sensor 2 for detecting the temperature around the container is arranged outside the gas insulated switchgear.

Reference numeral 3 denotes a sensor input section for receiving the outputs of the pressure sensor and the temperature sensor. The sensor input section includes amplifiers 21a, 21b, ..., 21k for amplifying the outputs of the pressure sensors 1a, 1b ,. 22k that passes only low-frequency components of the outputs of these amplifiers, and the output of the temperature sensor 2 including a temperature-sensitive resistance element, etc., is converted into a voltage signal proportional to temperature. Signal converter 23, an amplifier 24 that amplifies the output of the signal converter 23, and a low-pass filter 25 that passes only the low-frequency component of the output of the amplifier 24.

Outputs of the filters 22a, 22b, ... And 25 are input to a multiplexer (MPX) 26, and a signal selected by the multiplexer is passed through an A / D converter 27, a CPU 28, a memory 29, a bus line 30, It is input to the computer 4 including a terminating impedance 31 for terminating the terminal portion of the bus line.

By the computer and predetermined software, the room temperature converted gas pressure calculating means 5, the base pressure selecting means 6, the specific time room temperature converted gas pressure difference calculating means 7 and the winter overheat determination level calculating means 8 shown in FIG. , Summer overheat determination level calculation means 9 and abnormal overheat determination means 10, or the gas density coefficient calculation means 11, the room temperature replacement gas pressure calculation means 5 ', the base pressure selection means 6, the overheat determination level shown in FIG. The calculation means 8'and the abnormal overheat determination means 10 'are realized.

First, the case where the function realizing means of FIG. 1 is realized by the microcomputer 4 will be described. The normal temperature conversion gas pressure calculating means 5 receives the output Px of the pressure sensor and the output Tx of the temperature sensor as inputs, and The converted gas pressure Pnx is calculated. In this embodiment, the room temperature is set to 20 ° C., and the room-temperature-converted gas pressure Pnx is calculated by the equation (1). The base pressure selecting means 6 changes the room temperature converted gas pressure calculated by the room temperature converted gas pressure calculating means 5 at a specific time set in a time zone in which a change in gas pressure due to disturbance is small and a load fluctuation is small, to a specific time room temperature converted gas. The pressure Pnp is set, and this is compared with the lowest value of the specific time room temperature converted gas pressure Pnp calculated at the same time before the previous day, and the lower one is selected as the base pressure Pb. In this embodiment, the specific time (24-hour display) is 5 o'clock.

The specific time room temperature converted gas pressure difference calculating means 7 is provided with a storage means for storing the specific time room temperature converted gas pressure Pnp which is calculated every day, and changes in the specific time room temperature converted gas pressure Pnp throughout the year. The minimum value Pnpmin and the maximum value Pnpmax in the case of seeing are obtained, and the difference ΔPnp = Pnpmax-Pnpmin between them is calculated as the gas pressure difference at the normal time at the specific time.

The winter overheat determination level calculation means 8 includes the base pressure Pb selected by the base pressure selection means 6 and the maximum decrease ΔP (-) max in the room temperature converted gas pressure due to the disturbance at a specific time and the maximum load current energization. Using the increase amount ΔP Imax of the gas pressure at the time and the maximum increase ΔP (+) max of the gas pressure due to the disturbance, the overheat determination level Prw for the winter period is calculated by the formula of the summer period.

Prw = Pb + ΔP (−) max + ΔP Imax + ΔP (+) max (3) Further, the summer overheat determination level calculation means 9 determines the normal temperature conversion gas pressure difference ΔPnp (specific time) as the winter overheat determination level Prw. Calculate the summer overheat determination level Prs by adding the maximum variation of the year-to-year variation in the room temperature equivalent gas pressure. This overheat judgment level Prs is expressed by the following equation.

Prs = Prw + ΔPnp = Pb + ΔP (−) max + ΔPImax + ΔP (+) max + ΔPnp (4) In the present embodiment, the output of the pressure sensor and the output of the temperature sensor are sampled at regular intervals (for example, 10 minutes). Then, the room temperature converted gas pressure Pnx is calculated. Then, in the winter, the room temperature converted gas pressure Pnx is compared with the winter overheat determination level Prw, and when it is detected that the room temperature converted gas pressure exceeds the overheat determination value twice in succession, an abnormal overheat detection signal is output. generate. Further, in the summer, the room temperature converted gas pressure Pnx is compared with the summer overheat determination level Prs, and an abnormal overheat detection signal is generated when the room temperature converted gas pressure Pnx exceeds the overheat determination level Prs twice in succession. .

FIG. 4 is a flow chart showing an algorithm of software for realizing each function realizing means in the embodiment of the present invention. The operation of the embodiment of the present invention will be described below using this flowchart.

When the detection operation is started, first, an initial setting step S0 is performed. In this step, the number of continuous determinations N is set to 0, and the initial value of the base pressure Pb is set. The initial value of this base pressure should be set to a value corresponding to the minimum value of the room temperature converted gas pressure measured at 5 o'clock in the morning before the previous day. Next, the initial value of this base pressure Pb, the maximum decrease ΔP (-) max in the ambient temperature converted gas pressure due to the disturbance (mainly temperature change) at 5 am which was actually measured and stored in the memory, and the daytime Using the increase ΔPmax of the gas pressure when the maximum load current is applied in the zone and the maximum increase ΔP (+) max of the gas pressure due to the disturbance in the daytime, use the equation (3) to determine the initial overheat determination level Prw for winter. A value is calculated, and further, the initial value of the summer overheat determination level Prs is calculated by adding the predetermined time / room temperature converted gas pressure difference ΔPnp to this overheat determination level Prw.

After the above initial setting is completed, the process proceeds to step S1 and the sampling time is measured. In this embodiment, sampling is performed every 10 minutes. At the sampling time, in step S2, the output Px of the pressure sensors 1a to 1k and the output Tx of the temperature sensor 2 are sampled, and the sampling value of the output of the temperature sensor 2 and the sampling value of the output of the pressure sensors 1a to 1k are compared with each other. Are sequentially supplied to the CPU 28 through the multiplexer 26 and the A / D converter 27. When the sampling value Tx of the output of the temperature sensor and the sampling value Px of the output of the pressure sensor are given to the CPU, step S3 is carried out to calculate the room temperature equivalent gas pressure Pnx.

Next, in step S4, it is determined whether or not the sampling time of this time is 5:00 in the morning. If it is 5:00 in the morning, the process proceeds to step S5 and the calculation is performed this time (5:00 in the morning). The normal temperature converted gas pressure Pnx is set as the specific time normal temperature converted gas pressure Pnp, and Pnp is compared with the base pressure (the lowest value of the normal temperature gas pressure calculated at 5 o'clock before the previous day) Pb in step S6. As a result, when Pnp <Pb, the value of the base pressure Pb is replaced with the specific time room temperature conversion gas pressure Pnp calculated this time in step S7, and the value of the base pressure Pb is printed.

Further, as a result of comparing the specific time room temperature converted gas pressure Pnp with the stored base pressure Pb in step S6, when Pnp ≧ Pb, the value of the base pressure Pb is not updated in the next step. Go to S8 and step S9. In step S8, the winter overheat determination level Prw is calculated using the base pressure Pb and ΔP (-) max + ΔPImax + ΔP (+) max. In step S9, the specific time room temperature converted gas pressure difference ΔPnp is added to Prw. The summer overheat determination level Prs is calculated. Therefore, when the value of the base pressure Pb is updated at 5 o'clock in the morning, the values of Prw and Prs are updated.

After calculating the summer overheat determination level Prs, the process proceeds to step S10. Also, as a result of the time determination in step S4, if the current sampling time is not 5 am, the process proceeds to step S10.

In step S10, it is determined whether or not the present time is winter, and if it is winter, the process proceeds to step S11 in which the calculated room temperature converted gas pressure Pnx and the overheat determination level Prw for winter are set. Compare. If it is determined in step S10 that the present time is not winter, the normal temperature conversion gas pressure Pnx calculated this time is compared with the summer overheat determination level Prs in step S12.

When Pnx ≦ Prw is satisfied in step S11 and when Pnx ≦ Prs is satisfied in step S12, the determination count N is set to 0 in step S13 to prepare for the next sampling. When Pnx> Prw is satisfied in step S11, and when Pnx> Prs is satisfied in step S12, 1 is added to the value of the judgment count N in step S14, and then the judgment count N is equal to 2 in step S15. If it is determined that the number of determinations N is not equal to 2, the process proceeds to step S1 to prepare for the next sampling.

In the winter and summer, when it is determined that N = 2 (when Pnx> Prw or Pnx> Prs is detected twice in succession), it is determined that abnormal overheating has occurred. Generate an abnormal overheat detection signal. At this time, it is possible to specify the gas section in which the abnormal overheating has occurred by determining which of the gas sections the room-temperature-equivalent gas pressure Pnx satisfying the condition for generating the abnormality detection signal is.

When Pnx> Prw or Pnx> Prs is detected only once, the value of N is set to 0 when the next Pnx ≦ Prw or Pnx ≦ Prs is detected, so that the abnormal overheat detection signal is generated. do not do.

In this embodiment, the base pressure selecting means 6 of FIG. 1 is realized by steps S4 to S7 of FIG. 4, and the winter overheat determination level calculation step 8 and the summer overheat determination level calculation are performed by steps S8 and S9, respectively. Means 9 are realized. Further, the abnormal overheat determination means 10 is realized by steps S10 to S15.

FIG. 6 shows an example of changes in the normal temperature equivalent gas pressure Pnx and how the overheat determination level Prw is updated every day at 5 am. When the specific time room temperature converted gas pressure Pnp calculated at 5 am becomes lower than the minimum value of the specific time room temperature converted gas pressure before the previous day, the base pressure Pb is updated, and the base pressure is the minimum load current. Then, when the pressure drop due to the disturbance is the maximum, the gas pressure gradually approaches the gas pressure [when the pressure drop of ΔP (-) max occurs]. Therefore, the term of Pb + ΔP (-) max on the right side of the equation (3) becomes asymptotic to the charging gas pressure in the container, and the overheat determination level Prw converges to the minimum necessary optimum value.

FIG. 7 shows the minimum value P5min of the room temperature converted gas pressure at 5 o'clock in the morning, the maximum value P5max of the room temperature converted gas pressure at 5 o'clock in the morning, the charging pressure Po of each gas segment, and the base pressure Pb. It shows the relationship with the overheat determination level Prw. That is, the room temperature gas pressure at 5:00 am is P5min obtained by subtracting the maximum pressure drop ΔP (-) max due to the disturbance expected at 5:00 am from the charging pressure Po, and the charging pressure Po is the maximum pressure due to the load current. It takes a value between P5max, which is the sum of the increase ΔP Imax and the maximum pressure increase ΔP (+) max due to disturbance. The base pressure Pb becomes a low value each time it is updated, and when the load current is zero, the base pressure Pb can drop to P5min. When the base pressure Pb becomes lower than the charging pressure Po, the overheat determination level becomes too low only by adding ΔP Imax and ΔP (+) max to the base pressure Pb. Therefore, in the present invention, the base pressure Pb becomes ΔP. After adding (-) max, ΔP Imax and ΔP (+) max are further added to obtain the overheat determination level Prw.

FIG. 8 shows year-over-year changes in the overheat determination level and the specific time room temperature converted gas pressure Pnp. Initially, the overheat determination levels Prs and Prw show relatively high values, but as the gas temperature Pnp converted to the normal temperature at a specific time decreases from summer to winter, the overheat determination level decreases, and at a certain point in winter. At tw, once the specific time room temperature converted gas pressure Pnp once reaches the minimum value Pnpmin, the winter overheat determination level Prw converges to the minimum value. After the winter overheat determination level Prw once converges to the minimum value, the winter overheat determination level Prw becomes constant, and the summer overheat determination level Prs becomes the magnitude of Prw plus ΔPnp.

As described above, in the abnormality detecting device of the present invention, the overheat determination level can be converged to the minimum necessary optimum value, and therefore the detection sensitivity of abnormal overheat can be significantly increased.

In the above-described embodiment, the calculation for updating the base pressure Ps is performed every day at 5 am in the morning. However, the time at which the calculation for updating the base pressure is performed is the gas pressure due to the disturbance. The time may be any time other than 5 am, as long as it is a specific time set in a time zone in which there is little change in load fluctuation.

In the above embodiment, one overheat determination level is set throughout the day. However, the day is divided into daytime and nighttime, and the daytime overheat determination level and the nighttime overheat determination level are set. And may be set. For example, from 6 o'clock to 20:50 the daytime zone, from 20:50 to 6 o'clock the next morning is the night zone, and different winter overheat determination levels and summer overheat for the daytime zone and the nighttime zone. The judgment level may be set.

In the above embodiment, the microcomputer realizes the function realizing means of FIG. 1 and sets the appropriate overheat determination level for each of the winter season and the summer season, so that the false detection occurs throughout the year. It was possible to detect abnormal overheat with high sensitivity without having to do so, but by implementing each function realizing means in Fig. 2 using a microcomputer, the overheat judgment level can be set to an appropriate level throughout the year. Then, abnormal overheat can be detected with high sensitivity without causing erroneous detection.

In the case of the configuration of FIG. 2, the gas density coefficient computing means 11 has a specific time zone in which the change in gas pressure due to disturbance is small and the load fluctuation is small (for example, the time zone from midnight to 6:00 am). The gas pressure-ambient temperature characteristic is obtained from the ambient temperature and the gas pressure respectively detected by the pressure sensor and the temperature sensor, and the apparent gas density coefficient L is obtained from the gas pressure-ambient temperature characteristic. It is preferable that the calculation of the gas density coefficient is performed every day at a fixed time. In order to be able to use the apparent gas density coefficient calculated immediately before when calculating the room temperature equivalent gas pressure at a specific time, the apparent gas density coefficient before the specific time (for example, 5 am) arrives. It is preferable to finish the calculation of the gas density coefficient of.

The room temperature converted gas pressure calculation means 5 ′ uses the detection output of the pressure sensor and the detection output of the temperature sensor as input, and uses the latest apparent gas density coefficient L to calculate the gas pressure detected by the pressure sensor at room temperature. The gas pressure Pnx at room temperature is calculated by converting to the gas pressure at.

As in the case of the configuration shown in FIG. 1, the base pressure selecting means 6 sets the room temperature converted gas pressure calculated by the room temperature converted gas pressure calculating means 5 ′ at 5 am as the specific time room temperature converted gas pressure Pnp. It is compared with the lowest value of the specific time room temperature converted gas pressure Pnp calculated at the same time before the previous day, and the lower one of the compared specific time room temperature converted gas pressures is selected as the base pressure Pb.

The overheat determination level calculation means 8 ′ is the base pressure Pb selected by the base pressure selection means and the maximum decrease ΔP (−) max in the room temperature-converted gas pressure due to the disturbance at a specific time and the maximum load current when energized. The overheating determination level Pr = Pb + ΔP (−) max + ΔP Imax + ΔP (+) max is calculated by adding the gas pressure increase ΔP Imax and the maximum gas pressure increase ΔP (+) max due to disturbance.

The abnormal overheat judging means 10 ′ compares the room temperature converted gas pressure Pnx with the overheat judgment level Pr, and when the room temperature converted gas pressure Pnx exceeds the overheat judgment level Pr, abnormal overheating occurs in the container. It is determined that

In this way, when the apparent gas density coefficient is updated at any time, and the room temperature converted gas pressure is calculated using the latest apparent gas density coefficient, the difference between the temperature outside the container and the gas temperature is calculated. It is possible to almost eliminate the calculation error of the gas pressure converted to the normal temperature due to the above. Therefore, using the overheat judgment level calculated by the calculation formula Pr = Pb + ΔP (-) max + ΔP Imax + ΔP (+) max throughout the year, it is possible to detect abnormal overheat with high sensitivity without causing erroneous detection. be able to.

FIG. 5 shows a flowchart showing a software algorithm when each function realizing means of FIG. 2 is realized by a microcomputer. When following this flowchart, first, step S0 of initial setting is performed. In this step, the number of continuous determinations N is set to 0, and the initial values of the base pressure Pb and the gas density coefficient L are set. Similar to the above-mentioned example, the initial value of the base pressure Pb is set to a value corresponding to the minimum value of the room temperature converted gas pressure measured at 5 o'clock in the morning before the previous day. Next, the initial value of the base pressure Pb and the maximum decrease ΔP (-) max in the room temperature converted gas pressure due to the disturbance (mainly the change in temperature) at 5 am, which was actually measured and stored in memory in advance, and the daytime zone Using the maximum increase ΔPmax in gas pressure during energization of the maximum load current and the maximum increase ΔP (+) max in gas pressure due to disturbance during the daytime, use Equation (3) to determine the winter overheat determination level Prw. An initial value is calculated, and further, a predetermined time normal temperature converted gas pressure difference ΔPnp is added to the overheat determination level Prw to calculate an initial value of the summer overheat determination level Prs.

After the above initial setting is completed, the process proceeds to step S1 and the sampling time (10 minutes in this example) is measured. At the sampling time, in step S2, the output Px of the pressure sensors 1a to 1k and the output Tx of the temperature sensor 2 are sampled, and the sampling value of the output of the temperature sensor 2 and the sampling value of the output of the pressure sensors 1a to 1k are sampled. The data is supplied to the CPU 28 through the sequential multiplexer 26 and the A / D converter 27. The gas pressure sampling value Px and the ambient temperature sampling value Tx are stored in a memory.

Next, in step S3, it is determined whether or not the current time zone is the specific time zone from midnight to 5:00 am. If it is determined that the current time zone is the specific time zone, step S4 If it is determined that the time is not within the specific time zone, the process proceeds to step S5. In step S4, the gas pressure Px1 and the temperature Tx2 outside the container sampled at an arbitrary time t1 in a specific time period, and the gas pressure Px2 and the temperature Tx2 outside the container sampled at an arbitrary time t2 after time t1. Using and, the gas density coefficient L [= (Px1-Px2) / (Tx1-Tx2)] is calculated, and the process proceeds to the next step S5.

In step S5, it is determined whether or not the current time is 5:00 am, and if it is 5:00 am, the process proceeds to step S6. In step S6, the latest gas density coefficient L to be used when calculating the room temperature converted gas pressure is determined by taking the average value of the gas density coefficient L calculated a plurality of times during a specific time period from midnight to 5:00 am. To do. After determining the gas density coefficient L, the process proceeds to step S7, the room temperature converted gas pressure Pnx is calculated using the latest sampling values Px and Tx and the gas density coefficient L, and this room temperature converted gas pressure Pnx is calculated in step S8. Is the gas pressure Pnp at the specific time and converted to the normal temperature. Next, in step S9, Pnp is compared with the base pressure (the lowest value of the normal temperature gas pressure calculated at 5 o'clock before the previous day) Pb. As a result, when Pnp <Pb, the value of the base pressure Pb is replaced by the gas pressure Pnp calculated at this time calculated as the normal temperature at step S10, and a new value of the base pressure Pb is printed. When it is determined in step S9 that Pnp ≧ Pb is satisfied as a result of comparison between the stored gas pressure Pnp and the ambient temperature conversion gas pressure Pnp at the specific time, the following value is updated without updating the value of the base pressure Pb. In step S11, the overheat determination level Pr is calculated using the base pressure Pb and ΔP (−) max + ΔPImax + ΔP (+) max. After calculating the overheat determination level Pr, the process proceeds to step S13.

If it is determined in step S5 that it is not 5:00 am, the process proceeds to step S12, in which the room temperature converted gas pressure Pnx is calculated using the latest sampling values Px and Tx and the gas density coefficient L, and the next Go to step S13.

In step S13, the normal temperature conversion gas pressure Pnx is compared with the overheat determination value Pr. As a result, when Pnx≤Pr is satisfied, the number of determinations N is set to 0 in step S14 to prepare for the next sampling. If Pnx> Pr is satisfied in step S13, 1 is added to the value of the judgment number N in step S15, and then it is judged in step S16 whether the judgment number N is equal to 2 or not. If the number of times N is not equal to 2, the process proceeds to step S1 to prepare for the next sampling.

When it is determined that N = 2 in step S16 (when Pnx> Pr is detected twice in succession), it is determined that abnormal overheating has occurred, and the abnormal overheat detection signal is output. generate. When Pnx> Pr is detected only once, the value of N is set to 0 the next time Pnx≤Pr is detected, so the abnormal overheat detection signal does not occur.

In the case of the flowchart shown in FIG. 5, the gas density coefficient computing means 11 of FIG. 2 is realized by the process of steps S3 to S6. Further, the base pressure selecting means 6 is realized by the process of steps S7 to S10, and the overheat determination level calculating means 8'of FIG. 2 is realized by step S11. Further, the steps S7 and S12 realize the room temperature conversion gas pressure calculating means 5'of FIG. 2, and the steps S13 to S16 realize the abnormal overheat determining means 10 'of FIG.

In the flow chart shown in FIG. 5, the gas density coefficient L is calculated a plurality of times in a specific time zone, and the average value is taken to determine the latest gas density coefficient. Since the gas pressure and the temperature have a linear relationship, the gas density coefficient is calculated only once using the values of the gas pressure Px and the outside temperature Tx sampled at the start time and the end time of the specific time zone. You may do it.

[0084]

[Effect of device]

 As described above, according to the invention as set forth in claim 1, in the winter when the room temperature converted gas pressure is calculated to be low, the overheat determination level is converged to the minimum required value, and the room temperature converted gas pressure is increased. In the calculated summer, the minimum level of margin is required for the overheat determination level by setting the level obtained by adding the temperature-specific gas conversion gas pressure difference ΔPnp to the overheat determination level in winter as the overheat determination level. However, there is an advantage that the detection sensitivity can be improved throughout the year without causing false detection.

Further, according to the second aspect of the invention, the gas pressure is changed from the ambient temperature and the gas pressure respectively detected by the pressure sensor and the temperature sensor in a specific time zone in which the change in the gas pressure due to disturbance is small and the load fluctuation is small. Since the pressure-ambient temperature characteristic is obtained, the apparent gas density coefficient L is obtained from the gas pressure-ambient temperature characteristic, and the room-temperature-converted gas pressure is calculated using the latest apparent gas density coefficient L. It is possible to almost eliminate the calculation error of the room temperature converted gas pressure due to the difference between the temperature outside the container and the gas temperature, and set the overheat judgment level to an appropriate value throughout the year to prevent abnormal overheat without causing erroneous detection. Can be detected with high sensitivity.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of the device according to claim 1.

FIG. 2 is a block diagram showing a configuration example of the device according to claim 2.

FIG. 3 is a block diagram showing a configuration of hardware used in an embodiment of the present invention.

FIG. 4 is a flowchart showing an algorithm of software for realizing the function realizing means of FIG.

5 is a flowchart showing an algorithm of software for realizing the function realizing means of FIG.

FIG. 6 is a diagram showing how the overheat determination level is updated in the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a relationship among a gas pressure converted into normal temperature, a base pressure Ps, and an overheat determination level Pr detected at a specific time in the present invention.

FIG. 8 is a graph showing changes in the level of overheat judgment in the device according to claim 2 with respect to time, and changes with time in the room temperature equivalent value of the gas pressure of the gas insulated switchgear at 5 am (specific time room temperature converted gas pressure). It is a diagram showing the relationship with.

FIG. 9 is a diagram showing a relationship between gas pressure and gas temperature and a relationship between gas pressure and temperature outside the container.

FIG. 10 is a diagram showing a relationship with a change with time of a gas pressure at a specific time and converted into a room temperature in the gas insulated switchgear.

FIG. 11 is a configuration diagram schematically showing a general configuration of an abnormal overheat detection device.

FIG. 12 is a diagram illustrating how to set an overheat determination level in a conventional abnormal overheat detection device.

[Explanation of symbols]

1, 1a to 1k Pressure sensor 2 Temperature sensor 3 Sensor input unit 4 Computer 5, 5'Normal temperature conversion gas pressure calculation means 6 Base pressure selection means 8 Overheat determination level calculation means for winter season 9 Overheat determination level calculation means for summer season 10, 10 ′ Abnormal overheat judgment means 11 Gas density coefficient calculation means Px Detected value of gas pressure Tx Detected value of temperature outside the container Pnx Converted room temperature gas pressure Pnp Pnp Pnp Daily specific time (for example, 5 am) At room temperature converted gas pressure (specific time room temperature converted gas pressure) Pb base pressure Pnpmin Minimum value of year-round change of room temperature converted gas pressure at specific time Pnpmax Maximum value of year-round change of room temperature converted gas pressure at specific time ΔPnp Room temperature converted gas pressure at specific time Difference ΔP (-) max Maximum drop in gas pressure converted to room temperature due to disturbance at a specific time ΔP (+) max Maximum increase in gas pressure due to disturbance Ascent ΔPImax Gas pressure increase when maximum load current is applied Pr Overheat judgment level Prw Winter overheat judgment level Prs Summer overheat judgment level

Claims (2)

[Scope of utility model registration request] 1. A pressure sensor for detecting a pressure of gas in a container of a gas insulated switchgear, a temperature sensor for detecting a temperature outside the container, a detection output of the pressure sensor and a detection output of the temperature sensor. As an input, the gas pressure detected by the pressure sensor is converted to a gas pressure at room temperature to calculate the room temperature converted gas pressure Pnx.
The room temperature converted gas pressure calculating means for calculating the room temperature converted gas pressure and the room temperature converted gas pressure calculated by the room temperature converted gas pressure calculating means at a specific time set at a time when the change in gas pressure due to disturbance is small and the load fluctuation is small. The converted gas pressure Pnp is compared with the lowest value of the specific time room temperature converted gas pressure Pnp calculated at the same time before the previous day, and the lower one of the compared specific time room temperature converted gas pressures is the base pressure Pb.
And a base pressure P selected by the base pressure selecting means.
b, the maximum decrease ΔP (-) max in the room-temperature-equivalent gas pressure due to the disturbance at the specific time, the increase ΔPmax in the gas pressure when the maximum load current is applied, and the maximum increase ΔP (+) max in the gas pressure due to the disturbance Is added for winter overheat determination level Prw =
Pb + ΔP (-) max + ΔP Imax + ΔP (+) max for calculating the winter overheat determination level calculating means, and the minimum value Pnpmin and the maximum value Pnpmax when the change in the specific time room temperature converted gas pressure Pnp over a year is observed. The difference ΔPnp = Pnpmax-Pnpmin is used as the specific time room temperature converted gas pressure difference, and the summer time overheat judgment level Prs is calculated by adding the winter time overheat judgment level Prw to the specific time room temperature converted pressure difference ΔPnp. And a certain period before and after the month and day when the specific time ordinary temperature-converted gas pressure Pnp shows the minimum value Pnpmin as a winter period, and a certain period before and after the month and day when the specific time ordinary temperature gas pressure Pnp shows the maximum value Pnpmax in the summer period. 1 year is divided into winter and summer, and in the winter, the room temperature converted gas pressure Pnx is compared with the winter overheat judgment level Prw to determine the room temperature converted gas pressure Pnx as the winter overheat judgment level Prw. When it exceeds, it is judged that abnormal overheating has occurred in the container, and in the summer, the room temperature converted gas pressure Pnx is compared with the summer overheat judgment level Prs so that the room temperature converted gas pressure Pn is in the summer overheat judgment level. An abnormal overheat detecting device for a gas insulated switchgear, comprising: abnormal overheat determining means for determining that abnormal overheat is occurring in the container when Prs is exceeded. 2. A pressure sensor for detecting a gas pressure inside a container of a gas insulated switchgear, a temperature sensor for detecting a temperature outside the container, and a specific change with a small change in gas pressure due to disturbance and a small load fluctuation. A gas density coefficient calculating means for obtaining a gas pressure-ambient temperature characteristic from the ambient temperature and the gas pressure respectively detected by the pressure sensor and the temperature sensor in a time zone, and obtaining an apparent gas density coefficient L from the gas pressure-ambient temperature characteristic. And the detection output of the pressure sensor and the detection output of the temperature sensor as input, and using the latest apparent gas density coefficient L to convert the gas pressure detected by the pressure sensor to the gas pressure at room temperature to convert the gas pressure to room temperature. Room temperature conversion gas pressure calculation means for obtaining the pressure Pnx, and the room temperature conversion at a specific time set in a time zone where there is little change in gas pressure due to disturbance and little load fluctuation. The normal temperature converted gas pressure calculated by the gas pressure calculating means is compared as the specific time normal temperature converted gas pressure Pnp with the lowest value of the specific time normal temperature converted gas pressure Pnp calculated at the same time before the previous day, and the compared specific time normal temperature converted gas Lower pressure is base pressure Pb
And a base pressure P selected by the base pressure selecting means.
b, the maximum decrease ΔP (-) max in the room-temperature-equivalent gas pressure due to the disturbance at the specific time, the increase ΔPmax in the gas pressure when the maximum load current is applied, and the maximum increase ΔP (+) max in the gas pressure due to the disturbance Is added to determine the overheat determination level Pr = Pb +
Overheat determination level calculation means for calculating ΔP (−) max + ΔPImax + ΔP (+) max, and when the room temperature converted gas pressure Pnx exceeds the overheat judgment level Pr by comparing the room temperature converted gas pressure Pnx with the overheat judgment level Pr. An abnormal overheat detecting device for a gas insulated switchgear, comprising: abnormal overheat determining means for determining that abnormal overheat is occurring in the container.