JPH1031937A - Arc space deciding method for air circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a method for deciding the arc space of an air circuit breaker which allows simple measuring works and can set the arc space with a high precision. SOLUTION: A sonic wave generating device 8 is furnished at one end of the space surrounding an arc extinguishing chamber 4, and sound collecting devices 9 and 10 are provided a certain distance L apart in the sonic wave transmitting direction of the wave generating device 8, and pulsed sonic waves S are transmitted from the device 8 at time intervals Δt, and the wave transmission times Δt1 to Δt3 of the heated air 5 in the upper space of the arc extinguishing chamber 4 at the time of break are measured from the time difference between the sonic waves S0 and S1 which are received by the sound collecting device 9 and 10, followed by determination of the temp. T and voltage withstand value from the density ρ of the heated air 5 determined from the measured transmission times, and thereby it is possible to set the arc space having a spatial distance from the air circuit breaker concerned 1 having the specified temp. and voltage withstand value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting an arc space around an arc-extinguishing chamber of an air circuit breaker required for maintenance when the air circuit breaker is shut off.

[0002]

2. Description of the Related Art FIG. 6 is an external view of an air circuit breaker, and FIG. 7 shows a measuring method for determining an arc space of a conventional air circuit breaker. Aerial circuit breakers are commonly used for AC low-voltage and DC circuits, and open and close circuits in the atmosphere.However, they are highly reliable and easy to maintain and inspect. It is used as a main circuit breaker for required low-voltage power distribution equipment. As shown in FIG. 6, the closed switchboard including the air circuit breaker has a space H which is a so-called arc space having a space distance where nothing is placed within a certain range around the air circuit breaker 1.
(H ₁ , H ₂ , H ₃ ) is required. This arc space is heated to a high temperature by an arc or an arc generated between the contacts 3 when the current flowing through the main circuit terminals 2 and 2 of the air circuit breaker 1 is interrupted, and has a low density and low resistance. Since gas (air) having a low voltage characteristic (dielectric breakdown voltage characteristic) is discharged from the upper part of the arc-extinguishing chamber 4, the space near the arc-extinguishing chamber 4 may have a high temperature and a low withstand voltage. Therefore, it is provided.

As a method for determining the arc space, a method shown in FIG. 7 is conventionally used. In this method, the metallic probe 6 is exposed to the high temperature by the arc generated between the contacts 3 when the air circuit breaker 1 is cut off and discharged from the arc extinguishing chamber 4. Is installed as shown in the figure, ions and electrons of the heated air 5 and the contact 3 exposed to high temperature are captured by the probe 6, and the ions and electrons are captured by the ammeter 7a via the resistor 7. The distance from the arc-extinguishing chamber 4 where the leakage current becomes zero is measured by measuring the leakage current due to
(H ₁ , H ₂ , H ₃ ).

[0004]

By the way, the range of the region where the leakage current due to the ions or electrons of the heated air exposed to the arc can be measured is a state where the region is heated to at least several thousand degrees. In the above-described conventional probe electrode method for measuring a weak leakage current at a high temperature, a precise and expensive measuring device such as an oscilloscope is required for measuring the current, and further, a special measure against noise at the time of interruption is required. There is a problem that it is necessary to take various measures.

The conditions for setting the arc space of the air circuit breaker are as follows: the temperature is not affected by the high-temperature heated air discharged from the arc-extinguishing chamber, and the temperature is sufficiently low.
It must be a low-temperature space of の 100 ° C. However, in the conventional measuring method using the probe electrode for measuring the leak current, the leak current cannot be measured in the low-temperature atmosphere, so that the air current in the heated air heated to several thousand degrees when the air circuit breaker is shut off. Since the distance in the low-temperature space is estimated from the measurement of the leakage current in the above, there is a possibility that an error may occur in the estimated distance and the arc space may be set wider than necessary, or conversely, may be set narrower. There is a problem that it is difficult to determine an accurate arc space.

An object of the present invention is to provide a measuring method which solves the above-mentioned problems, is simple in measurement, and can accurately determine the arc space of the air circuit breaker.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a sound wave generator provided at one end of a space around an arc extinguishing chamber of an air circuit breaker; A plurality of sound collectors arranged at a certain distance across the space in the traveling direction of the transmitted sound wave, and a sound wave transmitted through a gas heated by an arc generated when the air circuit breaker is shut off; The transmission time of the gas is measured from the time difference between the time points at which the sound waves transmitted from the sound wave generator are received by each of the plurality of sound collectors, and the density of the gas is determined from the density of the gas obtained from the transmission time. The temperature and withstand voltage characteristics are obtained, and an arc space, which is a space distance from the air circuit breaker, is set.

That is, in FIG. 1 in an embodiment described later, in a space above the arc-extinguishing chamber 4, a predetermined distance L is interposed between the sound wave (heating air 5) of the sound wave transmitted from the sound wave generator 8. the transmission time by a Delta] t _s for transmitting between the sound collecting device 9, 10 installed Te, the sound velocity V _s of the gas is expressed by the following equation.

[0009]

V _s = L / Δt _s

Here, assuming that the specific heat ratio of the gas is κ, the gas density ρ is calculated from V _s and the gas pressure P (normally, the pressure P is the atmospheric pressure).

[0011]

V _s = (κ · P / ρ) ^1/2 ρ = κ · P / V _s ² Therefore, when the temperature T of the heated gas is estimated from the density ρ, the following equation is obtained from the following equation of state (R is a gas constant) of the gas.

[0012]

P = ρ · RT T = P / (ρ · R) = V _s ² / (R · κ)

Here, the withstand voltage characteristic (dielectric breakdown voltage) Vb of the gas is almost proportional to the density ρ, and if the density and the withstand voltage characteristic at normal temperature are ρ ₀ and Vb _0, it can be obtained by the following equation. it can.

[0014]

[Number 4] _{Vb = Vb 0 · ρ / ρ} 0

Therefore, based on the above-described principle, the temperature of the heated air in the space around the arc-extinguishing chamber and the withstand voltage characteristic when the air circuit breaker is shut off can be estimated from the above equations (3) and (4). If the temperature and withstand voltage characteristics for setting the arc space are set, the space distance around the upper part of the arc-extinguishing chamber that meets this condition can be accurately obtained.

If the sound wave generator transmits intermittent pulsed sound, the transmission distance of the gas at each pulse interval is determined to determine the temperature of the gas heated by the arc and the resistance to the gas. It is also possible to determine the time change of the voltage.

The intermittent pulse-like sound wave is transmitted to a sound source, a sound insulating plate disposed between the sound source and a sound collecting device adjacent thereto, and a sound insulating plate. If the sound insulating plate is provided with a slit in the circumferential direction, the interval between sound waves transmitted through the slit is controlled by the number of rotations of the sound insulating plate, so that the shutting process is performed. It is also possible to estimate the characteristics of temperature and withstand voltage in the instantaneous time change of the heated gas.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIGS. 1 and 2 show a method for determining an arc space of an air circuit breaker according to a first embodiment of the present invention. FIG. FIG. 2 is an explanatory diagram for measuring a transmission time of a sound wave. FIG. 1 shows the space discharged from the arc extinguishing chamber 4 for determining the arc space distance H ₁ (see FIG. 6) in the upper space of the arc extinguishing chamber 4 of the contacts 3 of the air circuit breaker 1. This figure shows a method for measuring the transmission time of the sound wave of the heated air 5 in which the sound wave generator 8 is placed at one end of the upper space of the arc-extinguishing chamber 4 and the sound wave transmission direction of the sound wave generator 8 Arrange to penetrate the air 5,
In addition, sound collectors 9 and 10 are provided at a predetermined distance L across the heated air 5 in the direction of transmission of the sound waves.

The sound wave transmitted from the sound wave generator 8 is shown in FIG.
The pulse-like intermittent sound wave shown in FIG. Then, with the pulsed sound waves S transmitted from the sound wave generator 8 at time intervals of Δt, the operation mechanism 11 of the air circuit breaker is operated to shut off the air circuit breaker 1. The sound wave S ₀ received by the sound collecting device 9 installed close to the sound wave generating device 8
Reception interval Δt ₀ (t ₂ −t _1, t ₃ −t ₂ , t ₄ −t
_3,...) Is almost the wave generator same time and time interval Δt which sound waves S is transmitted from the 8.

On the other hand, as shown in FIG. 2, the reception sound pulse S ₁ at the sound collection device 10 arranged at a distance L from the sound collection device 9 corresponds to the reception time t received by the sound collection device 9 described above. T ₁₀ , which is delayed from ₁ , t ₂ and t ₃ , respectively.
Since the signals are received at t ₂₀ and t ₃₀ , the transmission time Δt ₁ = t ₁ of the sound waves from the sound collector 9 to the sound collector 10 provided at a distance L by the pulse time measuring device 12 from these reception times.
₁₀ −t ₁ , Δt ₂ = t ₂₀ −t ₂ and Δt ₃ = t ₃₀ −t ₃
Respectively. Then, the sound speed V _S1 in the heated air 5 of each sound wave transmitted from the sound wave generator 8 from the above transmission time.
, V _S2 , and V _S3 are obtained from the above Equation 1 as shown below.

[0021]

V _S1 = L / Δt ₁ V _S2 = L / Δt ₂ V _S3 = L / Δt ₃

From the sound wave generator 8 described above, the time interval Δt
The sound speeds (V _S1 , V _S2 , V _S1 , V _{S2) of} the sound waves of the heated air 5 in the upper space of the arc-extinguishing chamber 4 in the three sound waves transmitted in succession at
From the data of V _S3 ), the density is obtained from the above equation 2, and
Based on this density, the temperature and the withstand voltage value of the heated air 5 at each time of the shut-off process can be estimated from Expressions 3 and 4. In the above description, three continuous pulsed sound waves S from the sound wave generator 8 at three time intervals Δt are described. Is performed, and the characteristics of the heated air 5 at each time interval are estimated, and the state where the temperature rise is highest and the withstand voltage characteristics are low before the air circuit breaker is completely shut off is used as a reference. These values must be sufficient to maintain a temperature that does not cause thermal degradation or deterioration of conductors and insulating materials around the air circuit breaker, and a withstand voltage value that can maintain an insulation distance that does not induce phase-to-phase short-circuits or ground faults. extinguishing chamber 4 in order to set the distance H ₁
The measurement is repeated while changing the distance in the upper space of the. Further, the arc space distances H ₂ , H ₂ of the space on the side surface of the arc extinguishing chamber 4.
₃ (see FIG. 4) is set in the same manner as above to determine the arc space of the air circuit breaker.

According to this embodiment, as described above, since the setting is made based on the characteristics of the heated air 5 in the shutoff process, a more accurate arc space can be determined. Further, a plurality of sets of sound collectors 9 and 10 are installed at a distance from the arc extinguishing chamber 4 at a distance, or a plurality of apparatuses including the sound wave generator and the sound collector according to this embodiment are installed. Thereby, the characteristic distribution of the heated gas in the space around the arc extinguishing chamber 4 can also be grasped.

Embodiment 2 FIGS. 3 to 5 show a method for determining an arc space of an air circuit breaker according to a second embodiment of the present invention.
4 is a measurement configuration diagram for measuring a sound wave transmission time, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, and FIG. 5 is an explanatory diagram for measuring a sound wave transmission time. The difference between the embodiment of the present invention and the first embodiment is that a stationary sound wave is used as a sound source of a sound wave generator, and the stationary sound wave passes through a slit of a rotating plate provided in a traveling direction of the sound wave. Thus, a pulsed sound wave is transmitted to the heated gas of the air circuit breaker.

That is, as shown in FIG.
As shown in FIG. 5, a stationary sound wave having a constant sound pressure is transmitted, and a width L in the circumferential direction shown in FIG. _A disk-shaped sound insulating plate 14 in which a plurality of slits 13 are formed at predetermined intervals is provided, and a center portion of the sound insulating plate 14 is fixed to a rotating shaft of a motor 15 to intermittently generate pulse-like sound waves. A transmitting sound wave generator is configured. When the sound insulating plate 14 is rotated by the driving of the motor 15, only the sound waves that have passed through the slits 13 of the sound insulating plate 14 are transmitted to the sound collectors 9 and 10, so that the slits 13 of the sound insulating plate 14 are used. by changing the rotational speed of the width L ₁ and the motor 15, pulse-like sound wave pulse width W
Alternatively, the transmission interval time Δt of the sound wave (see FIG. 2) can be set to an arbitrary value.

By increasing the rotation speed of the sound insulating plate 14 having the slit 13 using the above-described sound wave generator,
A very short time with a spacing waves of the heated air 5 in transmission time _{(Δt 1, Δt 2, Δt} 3 ···), i.e. can the instantaneous value measurement at arc interruption process, also detailed is also the time change Therefore, the temperature and withstand voltage characteristics of the heated air in the space near the arc-extinguishing chamber 4 can be examined in detail using the analysis method described above, and a more accurate arc space can be set. Become.

[0027]

As described above, according to the present invention, the sound wave generator disposed at one end of the space around the arc-extinguishing chamber of the air circuit breaker, and the traveling direction of the sound wave transmitted from the sound wave generator are provided. A plurality of sound collectors arranged at a fixed distance from each other with the space interposed therebetween, and the transmission time of the sound wave propagating in the gas heated by the arc generated when the air circuit breaker is cut off is set as the sound wave. By measuring the time difference between the points at which the sound waves transmitted from the generator are received by each of the plurality of sound collectors, and determining the gas temperature and withstand voltage characteristics from the density of the gas determined from the transmission time, The space distance around the arc-extinguishing chamber that matches the temperature and withstand voltage characteristic conditions of the surrounding space necessary for setting the arc space can be accurately obtained.

In the determination of the arc space by the above-described sound wave generator, the sound wave is transmitted from the sound wave generator in the form of a pulse, and the transmission time in the air at each pulse interval is determined. It is also possible to determine the time change of the temperature and the withstand voltage of the gas. In this case, a sound wave generator that transmits sound waves intermittently, a sound wave generator, a sound insulating plate disposed between the sound wave source and an adjacent sound collector, and a drive for rotating the sound insulating plate. The sound insulating plate is provided with a slit in the circumferential direction, and by controlling the rotation speed of the sound insulating plate, the interval time of sound waves transmitted through the slit can be arbitrarily changed. Therefore, the instantaneous temperature and withstand voltage characteristics of the space when the air circuit breaker is shut off can also be grasped.

Furthermore, the present invention is not limited to measurements intended for heated air of the air circuit breaker described in the embodiments above, the insulating gas such as SF ₆ used in the switching device The present invention can be applied to estimation of various characteristics such as density, heating temperature and withstand voltage characteristics at the time of interruption, and can contribute to obtaining an optimal insulation design of a circuit breaker and a switchgear.

[Brief description of the drawings]

FIG. 1 is a measurement configuration diagram of a transmission time of a sound wave for determining an arc space of an air circuit breaker according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for a method of measuring a transmission time of a sound wave.

FIG. 3 is a diagram illustrating a measurement configuration of a transmission time of a sound wave for determining an arc space of an air circuit breaker according to a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is an explanatory diagram for a method of measuring a transmission time of a sound wave.

FIG. 6 is an external view of an air circuit breaker.

FIG. 7 is a measurement method for determining an arc space of a conventional air circuit breaker.

[Description of Signs] 1 Air circuit breaker 4 Arc extinguishing chamber 5 Heated air 8 Sound wave generator 8a Sound wave generator 9 Sound collector 10 Sound collector 13 Slit 14 Sound insulation plate 15 Motor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadahiro Sakuta 2-3-7 Muraihigashi, Matsuto City, Ishikawa Prefecture

Claims (3)

[Claims] 1. A sound wave generator disposed at one end of a space surrounding an arc extinguishing chamber of an air circuit breaker, and a predetermined distance between the sound wave generator and the space in the traveling direction of a sound wave transmitted from the sound wave generator. Provided with a plurality of sound collecting devices arranged with, the transmission time of the sound wave transmitted through the gas heated by the arc generated when the air circuit breaker is interrupted, the plurality of sound waves transmitted from the sound wave generator Measured from the time difference between the points of time received by each of the sound collectors, to determine the temperature and withstand voltage characteristics of the gas from the density of the gas determined from the transmission time, the spatial distance from the air circuit breaker An arc space determination method for an air circuit breaker, wherein an arc space is set. 2. The method according to claim 1, wherein the sound wave generator transmits sound intermittently. 3. The method according to claim 2, wherein the intermittently transmitting sound wave generator includes a sound wave source and a sound insulating plate disposed between the sound collector and the sound collector adjacent to the sound source. And a drive unit for rotating the sound insulating plate, wherein the sound insulating plate is provided with a slit in a circumferential direction.