JP3983916B2 - Gas insulated electrical equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas-insulated electric device having an electric device insulated with an insulating gas.
[0002]
[Prior art]
In recent years, circuit breakers, disconnectors, busbars, and bushings in substations are composed of a gas-insulated switchgear that is formed of a sealed metal container and insulated by SF ₆ gas enclosed in the container. However, recent research has revealed that SF ₆ is a gas with an extremely large global warming potential, and a reduction in the amount of SF ₆ used is required on a global scale. In addition, as a technique using an electrically insulating gas for an electric device, JP-A-60-13414, JP-A-60-20405, JP-A-60-20406, JP-A-2-204907 are listed. be able to.
[0003]
[Problems to be solved by the invention]
CF ₃ I is a gas that has a global warming potential smaller than CO ₂ , an ozone depletion potential of 0, nonflammable, and extremely low toxicity. However, since CF ₃ I has a higher saturation temperature than SF ₆ , liquefaction may occur at low temperatures when used in a gas insulated switchgear. When CF ₃ I is liquefied in the gas insulated switchgear, the dielectric strength is drastically reduced, and there is a risk of causing dielectric breakdown.
[0004]
It is an object of the present invention to prevent a decrease in dielectric strength without being liquefied during operation of a gas insulated switchgear when CF ₃ I is used as an electrically insulating gas having a global warming potential smaller than that of SF ₆ gas. Thus, an object of the present invention is to provide a gas-insulated electrical apparatus that can ensure excellent electrical insulation without causing dielectric breakdown, is nonflammable, has almost no toxicity, and has an ozone depletion coefficient of zero.
[0005]
[Means for Solving the Problems]
FIG. 2 shows an AC breakdown voltage as an example of the dielectric strength of CF ₃ I. In this figure, the horizontal axis indicates the gas pressure (MPa), and the AC breakdown voltage (based on SF ₆ 0.1 MPa) at that time is indicated on the vertical axis. As is apparent from the figure, the electrical insulation of CF ₃ I is equal to or higher than that of SF _{6 in the} gas state. In addition, chemical stability is easily decomposed by light, but it is not a problem in practical use because it is enclosed in a sealed container in a bus bar, a lightning arrester, or a bushing of a gas insulated switchgear.
[0006]
FIG. 3 shows a gas-insulated switchgear as an example. The operating line of the rated operating condition is 60 ° C. and the pressure is 0.568 MPa. The horizontal axis indicates the gas temperature t (° C.) and the vertical axis indicates the gas pressure P (MPa). Show. The relationship between the saturation pressure of CF ₃ I and the temperature is as shown in FIG. 3, and liquefies when the gas pressure of CF ₃ I exceeds the vapor pressure curve. When CF ₃ I is confined in a sealed space such as a bus bar, lightning arrester, or bushing of a gas insulated switchgear, the density (specific weight) remains constant even when the temperature changes in a gas state above the saturation temperature. CF ₃ I is not liquefied.
[0007]
However, CF ₃ I has a boiling point (saturation temperature at atmospheric pressure) of −22.5 ° C., and the saturation temperature is higher than that of SF _6. It is conceivable that the gas temperature in the device's bus bar, lightning arrester, and bushing sealed container is equal to the saturation temperature. In this case, when the gas temperature in the sealed container decreases, liquefaction begins to intersect with the vapor pressure curve shown in FIG. 3, deviates from a constant density state, changes to the temperature and pressure along the vapor pressure curve, and the pressure rapidly increases. descend. Since the density (specific weight) of the gas is proportional to the pressure if the temperature is the same, the density (specific weight) of the gas also rapidly decreases.
[0008]
There is a relation of V _BD .∝γ 0.9 between the AC breakdown voltage V _BD, which is an example of dielectric strength, and the gas density (specific weight) γ, so the AC breakdown voltage V _BD also decreases rapidly. To do. Therefore, if liquefaction occurs in CF ₃ I within the range of use of the gas insulated switchgear, the dielectric strength is drastically reduced and there is a risk of dielectric breakdown. This point needs to be considered.
[0009]
Therefore, in order to achieve the above object, in the present invention, when operating using CF ₃ I as an insulating cooling medium, CF ₃ I is always kept in a gaseous state when the apparatus is in an operating state. It is characterized by.
[0010]
Specifically, the saturation pressure of CF ₃ I at the minimum temperature t _min ° C that guarantees the operation of the gas insulated switchgear using CF ₃ I as the insulating gas is P _min MPa, and the CF ₃ in the gas insulated switchgear When the relationship between the gas temperature t ° C. of I and the gas pressure PMP is P ≧ (P _min / (t _min +273.15)) · (t + 273.15), the gas temperature is the CF ₃ I in the gas insulated switchgear. It is expressed using specific weight (density) γ and gas constant R.
[0011]
P = γR (t + 273.15) and the temperature at the intersection of the vapor pressure curves of CF ₃ I are set to be equal to or higher.
[0012]
Further, the saturation pressure of CF ₃ I at the minimum temperature t _min ° C for guaranteeing the operation of the gas insulated switchgear using a mixture containing CF ₃ I as the insulating gas is P _min MPa, and the CF ₃ in the gas insulated switchgear is When the relationship between the gas temperature t ° C of I and the gas partial pressure P _CF3I MPa is P _CF3I ≧ (P _min / (t _min +273.15)) · (t + 273.15), the gas temperature is changed in the gas insulated switchgear. It is expressed using the specific weight (density) γ of CF ₃ I and the gas constant.
[0013]
P _CF3I = γR (t + 273.15) and the temperature at the intersection of the vapor pressure curves of CF ₃ I are characterized by being equal to or higher.
[0014]
When a mixture containing CF ₃ I is used as an insulating gas, the substance other than CF ₃ I is excellent in electrical insulation, nonflammable, non-toxic, and has a global warming potential and ozone depletion potential of 0. In addition, inexpensive N ₂ can be preferably used, but rare gases such as helium, neon, argon, and xenon, CO ₂ , and other general-purpose substances can be used. Moreover, it is excellent in electrical insulation when used in combination with SF ₆ , C ₂ F ₆ , C ₄ F _8, etc., but the use amount of these substances having a large global warming potential can be reduced.
[0015]
That is, in such a method of operating a gas insulated electrical device, the gas temperature of CF ₃ I in the gas insulated electrical device is equal to the gas pressure of CF ₃ I in the gas insulated electrical device even at the minimum operating temperature of the gas insulated electrical device. Alternatively, CF ₃ I is not liquefied because it is maintained at a temperature equal to or higher than the saturation temperature at the gas partial pressure. For this reason, the density (specific weight) of CF ₃ I at the gas temperature in the operating range is constant, and a decrease in the dielectric strength represented by the AC breakdown voltage is prevented, and excellent electrical insulation can be ensured.
[0016]
That is, by using CF ₃ I or a mixture containing CF ₃ I as an insulating gas, it has excellent electrical insulation, is non-flammable, has almost no toxicity, has a global warming potential smaller than CO ₂ , and has an ozone depletion potential. It can be used as zero gas-insulated electrical equipment.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows an example of a method for operating a gas insulated switchgear when CF ₃ I is used as the insulating gas of the gas insulated switchgear, and CF ₃ I at the minimum temperature t _min ° C that guarantees the operation of the switchgear. a saturation pressure of P _min MPa, relationship P ≧ the gas temperature t ° C. and the gas pressure PMPa of CF ₃ I in switchgear _{(P min / (t min +273.15} )) · (t + 273.15) ( This is the absolute temperature: T _min, if T (K), expressed as _{P ≧ (P min / T min} ) · T degrees Fahrenheit:. t _Fmin, if t _F (1 ° R), This is a case where P ≧ (P _min / (t _Fmin +459.67)) · (t _F +459.67)).
[0018]
In this case, CF ₃ I is liquefied when the temperature of the CF ₃ I in the switchgear is low, such as during startup, when the temperature is low. The structure of the gas insulated switchgear for preventing this is shown in FIG.
[0019]
As shown in FIG. 6, the gas-insulated switchgear introduces a circuit breaker 1 that cuts off current, disconnectors 3 a to 3 c that electrically disconnect high voltage conductors 2 a to 2 c to which high voltage is applied, and a high voltage from a transmission line. The bushing 4 insulated with the gas to be operated, the lightning arrester 5 for suppressing the surge voltage, and the buses 6a to 6g connecting them. Each part is delimited by spacers 7a to 7l made of an insulator. The gas insulated switchgear is connected to the gas insulated transformer 12 by ducts 8a and 8b.
[0020]
Moreover, the circuit breaker 1, the disconnector 3, the bus-line 6, the lightning arrester 5, and the bushing 4 are connected by ducts 8c to 8L. Valves 13 a to 13 L are provided in a duct 8 that connects the circuit breaker 1, the disconnector 3, the bus 6, the lightning arrester 5, the bushing 4, and the gas insulating transformer 12. The circuit breaker 1, the disconnector 3, the bushing 4, the lightning arrester 5, the hermetic container of the bus 6 and the gas insulating transformer 12 are filled with CF ₃ I which is an insulating gas. A blower 11 is provided in the middle of the duct 8a.
[0021]
With such a configuration, CF ₃ I, which is an insulating gas filled in the gas insulated transformer 12, the circuit breaker 1, the disconnector 3, the bus 6, the lightning arrester 5, and the bushing 4, is blower. 11 can be used to circulate. For this reason, CF ₃ I heated above the saturation temperature by the transformer 12 always flows in the sealed containers of the circuit breaker 1, the disconnector 3, the bus 6, the lightning arrester 5, and the bushing 4.
[0022]
As shown in FIG. 4, assuming that the gas temperature of CF ₃ I as the rated load condition of the switchgear is t _f ° C, the gas pressure is P _f MPa, the specific weight (density) is γkg / m ³ , and the gas constant is R. , CF ₃ I in the gas state is P = (P _f / (t _f +273.15)) · (t + 273.15) = γR (t + 273.15) (this is absolute temperature: T _f , T (K) Then, P = (P _f / T _f ) · T = γRT If Fahrenheit temperature: t _F , _f , t _F (oR), then P = (P _f / (t _F , _f +459) .67)) · (t _F +459.67) = γR (t _F +459.67))), the gas temperature t ° C. and the gas pressure PMPa on the operation line are maintained.
[0023]
Since the gas temperature of CF ₃ I is maintained so as to be equal to or higher than the temperature at the intersection of this straight line and the CF ₃ I vapor pressure curve, even when the temperature is low and the switchgear is not warmed at the time of startup or the like, the CF _Since no liquefaction of ₃ I occurs, it is possible to prevent a decrease in dielectric strength.
[0024]
FIG. 5 shows an example of the operation method of the gas insulated switchgear when a mixture containing CF ₃ I is used as the insulating cooling medium of the gas insulated switchgear, and the minimum temperature t _min that guarantees the operation of the gas insulated switchgear. The saturation pressure of CF ₃ I at 0 ° C. is P _min MPa, and the relationship between the gas temperature t ° C. of CF ₃ I in the switchgear and the gas partial pressure P _CF3I MPa is P _CF3I ≧ (P _min / (t _min +273.15 )) · (T + 273.15) (This is expressed as P _CF3I ≧ (P _min / T _min ) · T if absolute temperature: T _min , T (K). Fahrenheit temperature: tF _min , tF if (oR), the case of P _CF3I ≧., denoted _{(P min / (tF min +459.67} )) · (tF + 459.67)).
[0025]
For CF ₃ mixture of I with other substances, CF ₃ liquefaction I may be evaluated at a partial pressure of CF ₃ I, CF ₃ I gas temperature t _f ° C. rated load condition of the switchgear, gas partial pressure Is P _f , _{CF 3 I} MPa, the specific weight (density) is γkg / m ³ , and the gas constant is R, P _CF3I = (P _f , _{CF 3I} / (t _f +273.15)) · (t + 273.15) = ΓR (t + 273.15) (This is expressed as P _CF3I = (P _f , _CF 3I / T _f ) · T = γRT, where absolute temperature is T _f , T (K). Fahrenheit temperature: t _F , _F , t _F (oR), P _CF3I = (P _f , _CF 3I / (t _F , _f +459.67)) · (t _F +459.67) = γR (t _F +45.9.67) )
If the gas temperature is raised so that it is equal to or higher than the intersection of the vapor pressure curves of CF ₃ I and CF ₃ I, and the gas temperature of the mixture containing CF ₃ I is kept above the saturation temperature, the switchgear Since the mixture containing CF ₃ I is not liquefied even when the temperature is low, it is possible to prevent a decrease in dielectric strength.
[0026]
In the gas insulated switchgear, the circuit breaker 1 is a device that interrupts an electric circuit through which a large current flows in the event of an accident, but an arc is generated in the sealed container of the circuit breaker 1 at this time. If CF ₃ I, which is an insulating gas in the sealed container, is decomposed by arc light or high temperature, there is a possibility that sufficient dielectric strength and interruption performance cannot be ensured. In this case, as in the embodiment of FIG. 7, the circuit breaker 1 is filled with SF ₆ or the like that is not easily disassembled when an arc is generated and has excellent dielectric strength and interruption performance, and the other disconnectors 3 and bus 6 are sealed. CF ₃ I, which is an insulating gas, may be sealed in the container.
[0027]
In addition, only a small current flows in the disconnector 3 that disconnects the electric circuit for periodic inspections, etc., but when the dielectric strength and interrupting performance of CF ₃ I in the sealed container of the disconnector 3 are reduced due to the occurrence of an arc, As shown in Fig. 1, only CF ₃ I is used as an insulating gas in the sealed container of the bus bar 6, the lightning arrester 5 and the bushing 4 other than the switch that mechanically turns on and off the electric circuit such as the circuit breaker 1 and the disconnect circuit 3 SF ₆ may be used for the device 1 and the disconnector 3.
[0028]
In the case of an oil-filled transformer, the oil warmed in the tank is passed through the duct 8 or the duct 8 is brought into contact with the oil-warmed tank, and the duct 8 is sealed in each of the bus 6, the lightning arrester 5, the bushing 4, etc. If the air blower 11 is installed in the middle of the duct 8 connected to the container, CF ₃ I or CF ₃ I in each hermetic container such as the bus 6, the lightning arrester 5, and the bushing 4 connected by the duct 8. By circulating the mixture containing the oil by the blower 11, the heat of the oil warmed in the tank of the oil-filled transformer can be utilized to warm the CF ₃ I.
[0029]
FIG. 8 shows another embodiment of the present invention. In the figure, a tap lead wire 16, a neutral lead wire 17, and a secondary lead wire 18 that connect the gas insulating transformers 12 a to 12 c and the tap changer 15 are routed in the lead duct 14. The connection between the gas insulating transformer 12 and the lead duct 14 is airtightly partitioned by spacers 7a to 7f made of an insulating material. The gas insulation transformer 12 and the lead duct 14 are communicated with each other by ducts 8a to 8L, and valves 13a to 13f and blowers 11a to 11f are installed on the way. Mixture containing CF ₃ I, or CF ₃ I is enclosed in lead duct 14.
[0030]
With such a configuration, CF ₃ I which is an insulating cooling medium used in the gas-insulated transformer 12 or a mixture containing CF ₃ I is circulated in the lead duct 14 through the duct 8 by the blower 11. be able to. Since the CF ₃ I in the lead duct 14 or the mixture containing CF ₃ I is supplied with a gas having a saturation temperature or higher in the gas-insulated transformer 12, the gas temperature must be maintained at or higher than the saturation temperature. Is possible.
[0031]
If the gas temperature of the CF ₃ I or the mixture containing CF ₃ I in the lead duct is maintained at a saturation temperature or higher by performing such an operation method, the temperature of the lead duct is low, such as at startup. In addition, since CF ₃ I or a mixture containing CF ₃ I is not liquefied, a decrease in dielectric strength can be prevented.
[0032]
FIG. 9 shows another embodiment according to the present invention. In this figure, the gas-insulated switchgear is a circuit breaker 1 that cuts off current, disconnectors 3a to 3c that electrically disconnect high voltage conductors 2a to 2c to which high voltage is applied, and gas that introduces high voltage from a transmission line. It comprises an insulated bushing 4, a lightning arrester 5 for suppressing a surge voltage, and buses 6a to 6f connecting them. Each part is airtightly partitioned by spacers 7a to 7L made of an insulating material. Furthermore, electric heaters 9a to 9i are attached as heating means when the gas temperature is low in the sealed container of the bus bar 6, the lightning arrester 5, and the bushing 4.
[0033]
With such a configuration, bus 6, arrester 5, CF ₃ I in the sealed container of the bushing 4, or until the mixture comprising CF ₃ I is equal to or higher than the saturation temperature, and driving an electric heater 9a~i gas It becomes possible to operate the switchgear main body when the temperature becomes equal to or higher than the saturation temperature.
[0034]
By performing the operation method described above, is heated by CF ₃ I, or mixtures heating means comprising CF ₃ I, Keeping the gas temperature above the saturation temperature, the switchgear as such startup Even when the temperature is low, CF ₃ I or a mixture containing CF ₃ I is not liquefied, so that a decrease in dielectric strength can be prevented.
[0035]
The heating means does not necessarily need to be an electric heater, and a high-temperature fluid such as water vapor may flow through a pipe provided in contact with the bus bar 6, the lightning arrester 5, and the bushing 4 of the gas-insulated switchgear. flowing a warmed by the tank of the transformer oil pipe, utilizing the heat of the pipe, CF ₃ I, or may be warmed mixture containing CF ₃ I in the closed vessel.
[0036]
FIG. 10 shows an embodiment according to the present invention. The pipeline air transmission line shown in the figure is provided with a high voltage conductor 2 to which a high voltage is applied in a sheath 10 and a spacer 7 for forming a gas compartment, and the gas compartments are connected by a duct 8. . The gas section at the end is connected to a gas insulating transformer 12 by a duct 8, and a blower 11 is provided in the middle of the duct 8. The sheath 10 inside Yes encapsulated mixtures comprising CF ₃ I, or CF ₃ I as the insulating gas, and are configured to circulate the insulating gas by the blower 11.
[0037]
With such a configuration, CF ₃ I or a mixture containing CF ₃ I can be sent from the gas insulating transformer 12 through the duct 8 into the sheath 10 by the blower 11. Since CF ₃ I or a mixture containing CF ₃ I that has reached the saturation temperature in the transformer 12 flows in the sheath 10, the gas temperature can be maintained at or above the saturation temperature.
[0038]
As driving methods shown in the above embodiment, CF ₃ I in in the transmission line Kanroki or Keeping the temperature of the gas mixture containing CF ₃ I above the saturation temperature, the tube as such startup Even when the temperature of the road-side power transmission line is low, CF ₃ I or a mixture containing CF ₃ I is not liquefied, so that CF ₃ I, which is an insulating gas in the sheath, does not liquefy and the dielectric strength does not decrease. .
[0039]
Connect the electric heater 9a in Figure 9 to the control unit 100, the detection result detected by the temperature detector 100X the temperature of the sealed container, by controlling the value of the current flowing to the electric heater 9a in the control unit 100, CF ₃ I Is controlled to a temperature at which liquefaction does not decrease and the dielectric strength decreases.
[0040]
In FIG. 10, the current value corresponding to the temperature at which CF ₃ I of the control unit 100 is liquefied and the dielectric strength does not decrease is stored in the control unit 100 as a reference current value, and the current value flowing through the motor 100 y that rotates the blower 11 Is always controlled by the control unit 100 so as to become the reference current value, and the air flow rate from the blower 11 is controlled, the temperature detector 100X is not necessarily required.
[0041]
【The invention's effect】
According to the present invention, CF ₃ I or a mixture containing CF ₃ I is used as an insulating gas in a gas-insulated electrical apparatus. CF ₃ I is not liquefied, and a decrease in dielectric strength can be prevented. The coefficient is smaller than CO ₂ , excellent electrical insulation, non-flammability, almost no toxicity, and can reduce the ozone destruction and improve the natural environment.
[0042]
In addition, since a heating means is provided in a part of the sealed container so that the CF ₃ I is not liquefied, a decrease in the dielectric strength of the CF ₃ I can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a gas insulated switchgear according to an embodiment of the present invention.
FIG. 2 is a characteristic diagram showing measurement results of AC breakdown voltage of CF ₃ I and SF ₆ .
FIG. 3 is a characteristic diagram showing an operating range in a gas insulated switchgear using CF ₃ I as an insulating cooling medium.
FIG. 4 is a characteristic diagram showing an operating range in an embodiment of a gas insulated switchgear using CF ₃ I as an insulating cooling medium.
5 is a characteristic diagram showing the operating range in the embodiment of the CF ₃ I, or a gas insulated switchgear according to the mixture insulating cooling medium containing CF ₃ I.
FIG. 6 is a sectional view of a gas insulated switchgear showing another embodiment of the present invention.
FIG. 7 is a cross-sectional view of a gas insulated switchgear showing another embodiment of the present invention.
FIG. 8 is a cross-sectional view of a lead duct connected to a gas insulated transformer showing an embodiment of the present invention.
FIG. 9 is a cross-sectional view of a gas insulated switchgear provided with heating means according to an embodiment of the present invention.
FIG. 10 is a cross-sectional view of a pipeline air transmission line showing an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Circuit breaker, 2 ... High voltage conductor, 3 ... Disconnector, 4 ... Bushing, 5 ... Lightning arrester, 6 ... Busbar, 7 ... Spacer, 8 ... Duct, 9 ... Electric heater, 10 ... Sheath, 11 ... Blower, 12 ... Gas insulation transformer, 13 ... valve, 14 ... lead duct, 15 ... tap changer, 16 ... tap lead, 17 ... neutral lead, 18 ... secondary lead.

Claims (5)

In a gas insulated electrical device in which an electrical conductor or an electrical device connected to the electrical conductor is housed in a sealed container and an electrically insulating gas is sealed in the sealed container, CF ₃ I is used as the electrically insulating gas, and CF ₃ A gas-insulated electrical apparatus comprising a sealed container provided with a heating means for warming CF ₃ I to a temperature at which I does not liquefy. The sealed container is a sealed container divided for each electrical conductor or electrical device, and SF ₆ gas is enclosed in a sealed container that stores a device that generates an arc when current is interrupted, and other devices are stored. The gas-insulated electrical device according to claim 1, wherein CF ₃ I is sealed in the sealed container.   The gas insulated electric apparatus according to claim 1 or 2, wherein the heating means is an electric heater provided in the sealed container. Accommodating electrical equipment connected to the electrical conductors or electrical conductor in a closed container, in a gas insulated electric apparatus enclosing an electrically insulating gas in a sealed container, the sealed container, closed container and other housing the transformers And a sealed container containing the transformer and a sealed container containing the other electrical equipment, each containing CF ₃ I as the electrically insulating gas , and the transformer the heating means between the sealed container and the sealed container of the other electrical equipment is provided for, the heating means, a duct for circulating the CF 3 _I in a sealed container of the other electrical device from the sealed container of the transformer When the gas, characterized in that circulating constituted by a blower provided in the duct, the CF 3 _I warmed in a closed vessel of the transformer in a sealed container of the electrical device other than the transformer Edge electrical equipment. The temperature measuring means for detecting the temperature in the sealed container is provided, and a controller for controlling the heating means to a temperature at which the CF ₃ I is not liquefied by a detection value of the temperature measuring means is provided. 1, 2, 3 or 4 gas-insulated electrical equipment.

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