JP2020072614A - Gas pressure monitoring device of gas insulation breaker - Google Patents

Abstract

To provide a gas pressure monitoring device for a gas breaker that can be easily attached and detached in an operating state, has a function of more accurately correcting pressure changes due to temperature changes, and has a function of estimating a time margin until gas pressure reaches a low level (hereinafter referred to as "alarm level") where arc discharge cannot be suppressed by gas pressure.SOLUTION: An angle of a pointer of a gas pressure meter is detected using a magnetic sensor. Gas pressure at 20°C is calculated from a measured value of a temperature sensor attached to a breaker body. Time margin from a change status of the gas pressure to reaching an alarm level is estimated by a mathematical method.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas pressure monitoring device for a gas insulation circuit breaker.

There are many circuit breakers installed at power plants and substations that shut off the power transmission line in the event of a failure. These circuit breakers are filled with an inert gas to suppress arc discharge at the time of breaking, and are called gas-insulated circuit breakers (or simply gas circuit breakers) because they blow the inert gas to extinguish the arc. ing.

In these circuit breakers, the inert gas is usually pressurized to about several atmospheres to ensure insulation performance. However, due to deterioration of the sealing material in the gap between the containers during many years of use, leakage gradually occurs and the amount decreases. Therefore, a pressure gauge for the enclosed gas is installed in each circuit breaker, and a staff member regularly checks the indicated value of the pressure gauge to determine whether or not the enclosed gas leaks.

However, the temperature of the main body of the circuit breaker changes significantly under direct sunlight outdoors, and when the temperature changes, the gas in the sealed circuit breaker container changes its pressure due to its expansion or contraction. It cannot be determined whether there was a leak. Therefore, the indicated value of the pressure gauge is corrected by the temperature to judge the presence or absence of leakage of the enclosed gas.

Therefore, it takes a lot of time and labor to perform the above inspection manually. At some large-scale substations that can be remotely controlled, the gas pressure is measured with a dedicated sensor, converted into a digital amount, and the data is transmitted to the control station, etc. where there is a staff member via a communication line. The data processing device, etc. corrects the temperature and records it, and displays a gas pressure drop alarm if necessary.

However, in many small substations, etc., an analog pointer type gas pressure meter is installed in the cubicle near the circuit breaker and often requires patrol inspection by an inspector.

In large-scale substations, the amount of electricity that passes is large, so even if it costs a lot to pay for automatic monitoring, paying is sufficient, but in small-scale substations, the amount of electricity that passes is small and there is the fact that monitoring devices cannot be expensive.

Also, leakage of insulating gas from the circuit breaker is a phenomenon that can be seen after deterioration has progressed considerably after installation, so it is wasteful to install and operate a device that automatically monitors gas pressure from the beginning of the circuit breaker installation. However, maintenance of the monitoring device is costly.

If so, it may be true that there would be no problem in manual inspection.In fact, in circuit breakers that have deteriorated over a considerable number of years after installation, there is a sudden increase in the amount of gas leakage during a weekly inspection. It is not possible to deal with such cases, and even if an increase in the amount of leak is found, it is clarified how much time is left before the gas pressure falls to a dangerous level where arc discharge cannot be suppressed only by the data at that time point. I can't.

  In the cited document 1, the pressure detecting unit for detecting the gas pressure and the temperature detecting unit for detecting the ambient outside temperature as the gas temperature inside the circuit breaker are provided in claim 1, and the calculation for converting the gas pressure into the gas pressure at a predetermined temperature is performed. It is described that the calculation result is corrected by linear approximation and the presence or absence of gas pressure abnormality is determined from the result.

  However, in most substations except the substations in urban areas, the circuit breakers are outdoors, and in the summer they can rise to about 60 to 70 degrees Celsius, as in a passenger car left in the hot sun. Since the temperature greatly deviates from the outside air temperature in the range of 30 ° C., it is not possible to obtain a temperature-corrected gas pressure by the method of the cited document 1.

  Further, since the inside of the circuit breaker is a sealed space and a large current flows through it, it can be easily inferred that the temperature becomes higher. Therefore, it is not possible to approximate the average outside temperature obtained from the graph by linearly approximating the change in the temperature outside the circuit breaker by regression analysis, etc., and to regard the average outside temperature obtained from the graph as the temperature of the insulating gas inside the circuit breaker. It is impossible.

  In the cited document 2, it is stated in claim 1 that the pressure value of the insulating gas in the circuit breaker is normalized to the pressure value of 20 ° C. based on the outside air temperature, and in claim 8 and the specification [0009]. The calculation formula is written. Further, in claim 3, the rate of decrease of the pressure value is calculated, and when it is equal to or higher than a predetermined value, the period required for the gas pressure to reach the non-permissible value is calculated, and the insulating gas is calculated before the period expires. It is written to automatically recharge.

The calculation formula of the gas pressure correction by temperature described in the claim 8 and the specification [0009] of the cited document is as follows.
MPa = Pa + (t ° C.−20 ° C.) × 0.0025 MPa / ° C. (1)
However, MPa: value converted to gas pressure at 20 ° C.
Pa: Gas pressure detected by gas pressure detection means
t: outside temperature measured by outside temperature measuring means

  However, for example, if Pa is a value measured at 40 ° C., it expands more than at 20 ° C., and the value MPa converted into gas pressure at 20 ° C. should be a value lower than Pa. There is a contradiction that MPa is higher in the calculation formula.

In general, the following Boyle-Charles law is established among the pressure, temperature, and volume of gas in a closed container, so that pressures under different temperature conditions can be easily derived from this law.
P ・ V / T = n ・ R (constant) (2)
However, P: gas pressure [N / m ² ]
(The meter reading "gauge pressure" is the atmospheric pressure minus this.)
V: volume of gas [m ³ ],
n: number of moles of gas R: gas constant [Nm / mol · K],
T: Absolute temperature of gas [K]

  Also, if gas leakage is suspected, measures must be taken such as investigating the location of gas leakage and replacing or replenishing deteriorated sealing material, but if gas is automatically replenished, drastic measures will be taken. Implementation tends to be deferred and can lead to even greater gas leaks.

  Normally, the maximum reduction rate of gas pressure is about 1 [% / year]. Regarding the actual value of the circuit breaker, it is said that it has a maximum actual value of 0.1 [% / year] or less at the time of inspection during installation. Therefore, it is only after several decades to 10 years after the circuit breaker is installed that the decrease in gas pressure becomes visibly and clearly visible on the analog pointer type gas pressure meter.

  Therefore, it can be said that installing the gas pressure monitoring device at the time of installing the circuit breaker is less effective despite the large cost burden. That is, it can be said that the gas pressure monitoring device is effectively installed several years to ten years after the sealing material is deteriorated after the circuit breaker is installed.

Patent No. 5142783 Patent No. 5349520 Japanese Patent Application No. 54-113335

  The invention of the present application has been made in view of such points, and the object of the present application is to easily attach and detach the gas circuit breaker in the operating state, measure a temperature closer to the internal temperature of the circuit breaker than the outside air temperature, and change the pressure due to temperature change. To provide a gas pressure monitoring device for a gas circuit breaker, which has a function of more accurately correcting the gas pressure and a function of estimating a time margin until the gas pressure reaches a low level at which arc discharge cannot be suppressed. is there.

  The inventor of the present application reads the display value of the insulation gas pressure display meter of the circuit breaker currently in operation in the substation, corrects it according to the temperature, and then confirms that the above-mentioned arc discharge is not at a low level. In comparison with past data, if there is no gas leakage, or if leakage is confirmed, is there sufficient time to reach the above low level? I examined whether it would be possible to replace all of them with machines.

Meter readings for gas pressure of circuit breakers are mainly analog pointer-type meters, and the meter cover can be easily opened and closed, so the meter pointer can be about 1 mm wide and about a few millimeters long. Attach a permanent magnet piece magnetized in the long axis direction so that the long axis overlaps the pointer of the meter, and on the other hand, attach a magnetic sensor that can measure the direction of the magnetic field as a two-dimensional vector quantity to the meter cover, It was decided to measure the direction (angle) in the long axis direction of the permanent magnet piece.

The method for reading the indicated value of the meter as described above is described in detail in the cited [Patent Document 3]. Also, a sensor for reading the rotation angle is commercially available.

  On the other hand, for temperature measurement, it is necessary to measure the temperature closest to the gas temperature inside the circuit breaker, so a thermometer is attached inside and outside the metal case simulating the circuit breaker to measure the temperature closest to the internal temperature in direct sunlight. After investigating whether or not it was possible, it was found that the best position was on a metal surface and where the temperature sensor was not exposed to direct sunlight, so it was decided to attach a thermocouple temperature sensor to that position. If it is difficult to install the sensor in the main body of the circuit breaker in operation, install the sensor in a metal case that is near the circuit breaker and is painted and sealed in the same quality as the circuit breaker body is exposed to almost the same amount of sunlight. The temperature inside the metal case may be measured.

Regarding the measured gas pressure value, it is possible to obtain the pressure under a constant temperature condition even if the temperature changes, from the Boyle-Charles law of (2).

For example, when the pressure at 20 ° C. is P ₂₀ , the following relationship holds at temperatures t ° C. other than 20 ° C.
P ₂₀ · V / (20 + 273) = P · V / (t + 273) (3)
Since the volume of the circuit breaker does not change even if the temperature changes, the volume V of the insulating gas inside is also constant, so V can be omitted.
P ₂₀ = P · 293 / (t + 273) (4)
Can be expressed like.

However, the pressures P and P ₂₀ here are the pressures defined in physics, and the pressure (generally called a gauge pressure) displayed on the meter at the site is the above P and P ₂₀ minus the atmospheric pressure. There are some points to note.

By the way, when a hole is opened in the closed container of the insulating gas and the gas leaks, the outflow amount of the gas per unit time is proportional to the difference from the atmospheric pressure P _0. Therefore, the change amount of the gas pressure P is (5) Like the formula,
dP / dt = −α · (P−P ₀ ) (5)
(However, α is a positive constant indicating the rate of change of the gas pressure P, P ₀ is the atmospheric pressure)
Can be expressed.

When the gas pressure at time t ₁ is set to P ₁ as an initial value from the above differential equation, from (5),
P = (P ₁ −P ₀ ) · exp (−α · (t−t ₁ )) + P ₀ (6)
Can be obtained.
However, exp {x} represents the exponential function e ^x .

When the gas pressure at time t ₂ is P ₂ ,
P ₂ = (P ₁ −P ₀ ) · exp (−α · (t ₂ −t ₁ )) + P ₀ (7)
Therefore, in this case, α is α = −Ln {(P ₂ −P ₀ ) / (P ₁ −P ₀ )} / (t ₂ −t ₁ ) (8)
Is required as.
However, Ln {x} represents the natural logarithm of x.

Substituting (8) into (6),
_{P = (P 1 -P 0)} · {(P 2 -P 0) / (P 1 -P 0)} {(t-t1) / (t2-t1)} + P 0 (9)
Can be obtained.

If the minimum gas pressure at which the operation cannot be guaranteed because the arc cannot be interrupted when the gas pressure decreases more than this is P _ALM and the time at that time is t _ALM ,
(t _ALM −t ₁ ) = (t ₂ −t ₁ ) · Ln {(P _ALM −P ₀ ) / (P ₁ −P ₀ )}
_{/ Ln {(P 2 -P 0} ) / (P 1 -P 0)} (10)
Becomes

From the above formula (10), for example, in the case of a circuit breaker with a minimum operation guarantee gauge pressure of 0.4 [MPa], the gas pressure that initially had a gauge pressure of 0.6 [MPa] suddenly starts to drop for some reason. When the gauge pressure is reduced to 0.55 [MPa] per day, the number of days from when the gas pressure starts to fall to the minimum operation guarantee gauge pressure (hereinafter referred to as "alarm level pressure") is as follows. It is calculated as in 11).

(t _ALM- t ₁ ) = 10 [days] × Ln {0.4 / 0.6} / Ln {0.55 / 0.6}
= 46.599 ・ ・ ・ [Sun] (11)

As for the number of days of (11), even if the gas pressure is replenished to the original gauge pressure of 0.6 [MPa] and the cause of the gas leak is not found and repaired, the gas pressure drops to the alarm level in the above days. It shows that you do. The value of this number of days is an important data for establishing a repair schedule.

The alarm can be issued from the device of the present application when the gas pressure becomes equal to or lower than a value set separately, and before the number of days when the pressure reaches the alarm level is set separately.

  By the way, the device of the present application is designed so that it can be retrofitted to the breaker in the 10th to 20th years when the sealing material of the breaker has deteriorated. Since it is easy to remove, when the sealing material has been repaired and gas leakage has almost disappeared, it is possible to remove it and use it for monitoring other circuit breakers.

Further, as a means for solving the problem of the present application, the method of reading the indicated value of the analog pointer type meter by using the magnet and the magnetic sensor has been described, but in addition to the above, the pointer of the meter is photographed by using the camera, and the image analysis is performed. You may use the method of reading the indicated value of the said meter with software etc.

  Further, the measurement result by the device of the present application may be displayed on the device of the present application, or may be displayed on a distant place by being placed on an information communication network such as a wired or wireless network. Further, the data of the sensor may be placed on the network as it is and sent to a distant place, and a portion other than the sensor of the device of the present application may be arranged at a distant place.

Based on the above points, the first invention of the present application implemented as a means for solving the problem of the present application is an existing rotation indicating a gas pressure of a gas circuit breaker or a gas insulated switchgear (hereinafter simply referred to as a gas circuit breaker). A gas pressure for a gas circuit breaker that attaches a permanent magnet piece to the needle of a pointer type analog meter, reads the rotation angle of the meter needle with a magnetic sensor attached to the transparent cover surface on the front of the meter, and converts it into gas pressure for monitoring. A monitoring device, which incorporates a microcomputer or an equivalent arithmetic function device, and in addition to the magnetic sensor, a temperature sensor attached to the gas circuit breaker body case at a position avoiding direct sunlight, the magnetic sensor, and Input unit to input the measured value of the temperature sensor, convert the measured value of the magnetic sensor to gas pressure, and change the gas pressure value to any temperature A calculation unit for calculating the gas pressure value, a recording unit for recording the read measurement value and the calculation result, and whether the read value or the calculation result is within a separately set normal range of the gas pressure. It has a determination unit for determination, an output unit for externally displaying or notifying the measured value, the calculation result, and the determination result, and a constant temperature (for example, 20 ° C.) set separately in addition to the gas pressure at the current temperature. If the gas pressure at the constant temperature is lower than the pressure set separately or is estimated to drop within the number of days set separately, A gas pressure monitoring device for the gas circuit breaker, which is characterized by transmitting an alarm,
A second invention is the gas pressure monitoring device for a gas circuit breaker according to the first invention, wherein the presence or absence of gas leakage is recorded from the record of the calculation result of the gas pressure at the constant temperature, and the constant value is calculated from the calculation result. A gas pressure monitoring device for a gas circuit breaker, which is characterized by estimating a future value of the gas pressure at a temperature of, and estimating a date and time when the gas pressure deviates from a normal range.
A third invention is a gas pressure monitoring device for a gas circuit breaker according to the first invention and the second invention, wherein a camera displays an indication value display screen of the rotary pointer type analog meter instead of the magnetic sensor. A gas pressure monitoring device for a gas circuit breaker characterized by recognizing the indicated value of the rotary pointer type analog meter by image analysis,
A fourth invention is a system including a plurality of devices having the function of the gas pressure monitoring device for a gas circuit breaker according to the first invention, the second invention and the third invention, and the measured value and the A gas pressure monitoring system for a gas circuit breaker, characterized in that the calculation result and the determination result are placed on a wired or wireless communication network line and delivered to a distant place,
A fifth invention is a system comprising a plurality of devices having the function of the gas pressure monitoring system for a gas circuit breaker of the above-mentioned fourth invention, wherein the computing unit for performing the computation and the determination and the determination unit are independent from each other. The gas pressure monitoring system for a gas circuit breaker, characterized in that the device is provided at a distance via the wired or wireless communication network line.

  With the gas pressure monitoring device of the present invention, it is possible to automatically monitor the insulating gas pressure of the gas circuit breaker, which has been regularly inspected by humans. The device of the present application can be easily attached to and detached from an existing meter, and it is not necessary to stop the circuit breaker during installation work. Also, the amount of gas leakage increases due to deterioration of the sealing material such as the seams of the casing of the gas circuit breaker only after several years to ten and several years after the circuit breaker is installed.Therefore, there is almost no gas leakage in the permanent monitoring device. Maintenance of the monitoring device is necessary for up to about 10 years after installation, which is wasteful, but the device of this application is detachable and can be retrofitted to a circuit breaker whose gas pressure has dropped, so there is little waste and excellent cost performance. There is.

In the gas pressure monitoring device of the present invention, the temperature of the point closest to the gas temperature inside the circuit breaker is measured, and the data is collected by converting the temperature data into a gas pressure value at a certain temperature. The error due to the temperature change is extremely small compared to the case where the error is corrected based on the temperature.

In the gas pressure monitoring device of the present invention, when the amount of gas leak increases, the number of days until it reaches the alarm level pressure can be calculated, and therefore the repair work schedule can be established based on this.

Block Diagram Diagram of the positional relationship between the magnet attached to the pressure gauge and the magnetic sensor Illustration of mounting position of temperature sensor

  Hereinafter, modes for carrying out the present invention will be described in detail.

  FIG. 1 is a block diagram showing the entire device of the present application. In the device of the present application, the direction of the magnetic field generated by the minute magnet pieces attached to the pointer of the meter is read by the magnetic sensor 1 while the surface temperature of the circuit breaker main body is measured by the temperature sensor 2.

  The input section 3 reads the output values of the magnetic sensor and the temperature sensor. The magnetic sensor and the temperature sensor are commercially available in a digital output system using a USB port and a so-called WIFI output system using a wireless LAN. The input section 3 is a USB input interface of a microcomputer and a so-called WIFI input by a wireless LAN chip. Interface.

  The timing unit of 4 is realized by a microcomputer and software, but the periodic interrupt processing function of the microcomputer recognizes the passage of time and keeps the data recording time interval constant. The clock unit of No. 4 may use a GPS-dedicated clock-dedicated module other than the microcomputer to read the time data from the microcomputer.

  The calculation unit 5 is realized by a microcomputer and software, but converts the measurement value of the magnetic sensor 1 into a gas pressure value, and further uses the measurement value of the temperature sensor to determine a specific temperature (for example, from the gas pressure value). The gas pressure value at 20 ° C.) is calculated. Further, the change rate α of the gas pressure is obtained by the equation (5), and the number of days until the gas pressure falls below the minimum operation guaranteed gauge pressure is calculated by the equation (10).

  The recording unit 6 is also realized by a microcomputer, software, and a memory inside and outside the microcomputer. The read measurement value and the calculation result are transferred and recorded on the memory by the software of the microcomputer.

  The determination unit 7 is also realized by a microcomputer and software, but whether or not the gas pressure value at the specific temperature (for example, 20 ° C.) calculated by the calculation unit 5 is within the normal range changes the gas pressure. Check whether the rate α does not exceed the allowable value set separately, or if it exceeds, whether the number of days until the gas pressure falls below the minimum operation guaranteed gauge pressure can be calculated.

  The output unit 8 is realized by a LAN interface or a WIFI communication module, but outputs the calculation result data in the operation unit 5 and the determination result in the determination unit 7 to the wired LAN network or the wireless LAN network. Further, it is displayed on a liquid crystal display provided on the device.

  The above is the basic embodiment of the device of the present application, but recently, in substations, information communication infrastructures such as optical fibers have been prepared, and since they can be used relatively easily, a magnetic sensor and a temperature sensor. It is also possible to transmit the digital output value of 1 to a data server such as a control station by using an information communication infrastructure such as an optical fiber, perform arithmetic processing in the server, and display the result on a client personal computer on the network.

[FIG. 2] is a view showing a permanent magnet piece attached to the pointer of the pressure gauge meter and a magnetic sensor attached to the cover glass. A permanent magnet piece having a width of about 1 mm and a length of several mm and magnetized in the long axis direction is used. As the magnetic sensor, a commercially available product of the type that individually measures biaxial magnetic field components of the X axis and the Y axis in a plane and outputs the result as digital data is used.
The arctangent value is calculated in the microcomputer in order to calculate the angle of the pointer from the values of the X-axis and Y-axis direction components. Since an inexpensive microcomputer does not have a trigonometric function calculation function, a function data table for every 1 ° from 0 to 45 ° is prepared, and the portion of 1 ° or less is obtained by the linear interpolation method. In addition, the arc tangent value is obtained in the section from 45 ° to 90 ° and is subtracted from 90 ° to obtain the arc tangent value.

  Although it is an embodiment different from the above, the pressure gauge meter is photographed by a camera, the image data thereof is transmitted to the data server, and an instruction of the meter is given by using an image analysis software or the like on a client personal computer on the network. You can read the value.

  [FIG. 3] is a diagram showing an example of the mounting position of the temperature sensor. The temperature of the case of the main body of the circuit breaker, which is filled with gas, should be measured so that the temperature sensor is not directly heated by direct sunlight.

1. Magnetic sensor
2. Temperature sensor
3. Input section
4.Timekeeping section
5. Arithmetic section
6. Recording section
7. Judgment part
8. Output section
9. Permanent magnet pieces
10. Rotating pointer type analog meter
11. Magnetic sensor
12. Sensor leads
13. Permanent magnet piece
14. Bushing
15. Cubicles
16. Insulation gas pressure gauge meter
17. Circuit breaker body
18. Temperature sensor

Based on the above points, as a means of the present problem-solving, permanently needle existing rotary pointer type analog meter for indicating a gas pressure of the gas circuit breaker or a gas insulated switchgear (hereinafter simply referred to as gas circuit breaker) attaching a magnet piece, the rotation angle of the needle of the meter reading by the magnetic sensor affixed to the transparent cover surface of the front above the meter monitors in terms of gas pressure in the gas circuit breaker gas pressure monitoring equipment, microcomputer or In addition to the magnetic sensor, a temperature sensor installed in the gas circuit breaker body case in a position that avoids direct sunlight, and an input for inputting the measured values of the magnetic sensor and the temperature sensor in addition to the magnetic sensor. Part, the measured value of the magnetic sensor is converted into gas pressure, and the gas pressure value at an arbitrary temperature is calculated from the gas pressure value. Section, a recording section for recording the read measurement value or the calculation result, a determination section for determining whether or not the read value or the calculation result is within a separately set normal range of gas pressure, the measurement value And an output unit for externally displaying or notifying the calculation result and the determination result, and calculates and records the gas pressure at a predetermined temperature (for example, 20 ° C.) other than the gas pressure at the current temperature. and, display or notify, also when it is estimated to decrease within days set or separately gas pressure in the constant temperature is lower than the pressure set separately, characterized in that an alarm originating ,
The presence or absence of gas leakage from the record of the calculation result of the gas pressure at the constant temperature, and the future value of the gas pressure at the constant temperature is estimated from the calculation result, and the date and time when the gas pressure deviates from the normal range. A gas pressure monitoring device for a gas circuit breaker, which is characterized by estimating
A system comprising a plurality of devices having a function of a gas pressure monitoring device for a gas circuit breaker according to the present invention , wherein the measured value, the calculation result, and the determination result are placed on a wired or wireless communication network line and delivered to a distant place. A gas pressure monitoring system for a gas circuit breaker characterized in that the second invention of the present application,
A system comprising a plurality of devices having the function of a gas pressure monitoring system for a gas circuit breaker according to the second aspect of the present invention, wherein the calculation unit for performing the calculation and the determination and the determination unit as separate devices independent from each other are wired. Alternatively, the third invention of the present application is a gas pressure monitoring system for a gas circuit breaker, which is characterized in that the gas pressure monitoring system is provided at a distance via a wireless communication network line.

Claims (5)

Attach a permanent magnet piece to the needle of an existing rotary pointer type analog meter that indicates the gas pressure of a gas circuit breaker or gas insulated switchgear (hereinafter simply referred to as gas circuit breaker), and change the rotation angle of the meter needle to the front of the meter. A gas pressure monitoring device for a gas circuit breaker, which is read by a magnetic sensor attached to a transparent cover surface of, and is converted into a gas pressure for monitoring, and which has a microcomputer or an equivalent arithmetic function device built therein. In addition to the temperature sensor attached to the gas circuit breaker main body case in a position to avoid direct sunlight, the input unit for inputting the measured values of the magnetic sensor and the temperature sensor, the measured value of the magnetic sensor is converted into gas pressure, A calculation unit that calculates a gas pressure value at an arbitrary temperature from the gas pressure value, records the read measurement value and the calculation result. Recording unit, determination unit that determines whether the read value or the calculation result is within a separately set normal range of gas pressure, the measured value, the calculation result, and the determination result are externally displayed or notified. In addition to the gas pressure at the current temperature, a gas pressure at a predetermined temperature (for example, 20 ° C.) that is separately set is calculated and recorded, displayed, or notified, and at the above-mentioned constant temperature. The gas pressure monitoring device for a gas circuit breaker, wherein when the gas pressure is lower than a pressure set separately or is estimated to drop within a number of days set separately, an alarm is issued. The gas pressure monitoring device for a gas circuit breaker according to claim 1, wherein the presence or absence of gas leakage is recorded from a record of the calculation result of the gas pressure at the constant temperature, and the future of the gas pressure at the constant temperature is determined from the calculation result. A gas pressure monitoring device for a gas circuit breaker, which estimates a value and estimates a date and time when the gas pressure deviates from the normal range. The gas pressure monitoring device for a gas circuit breaker according to claim 1 or 2, wherein the camera displays an indication value display screen of the rotating pointer type analog meter instead of the magnetic sensor, and the rotating pointer type analog meter is analyzed by image analysis. A gas pressure monitoring device for a gas circuit breaker characterized by recognizing the indicated value of. A system comprising a plurality of devices having the function of the gas pressure monitoring device for a gas circuit breaker according to claim 1, claim 2 or claim 3, wherein the measured value, the calculation result and the determination result are wired or wireless. A gas pressure monitoring system for gas circuit breakers, characterized by being delivered to a distant place on a communication network line. A system comprising a plurality of devices having the function of the gas pressure monitoring device for a gas circuit breaker according to claim 4, wherein the wired unit is a separate device having the calculation unit and the determination unit for performing the calculation and the determination. Alternatively, a gas pressure monitoring system for a gas circuit breaker, which is provided at a distance via a wireless communication network line.