JPS595970A - Apparatus for diagnosis of interior of enclosed bus bar - Google Patents

Abstract

PURPOSE:To facilitate maintenance and inspection, by detecting the potential of a shield embedded in an insulation spacer as light by a pair of light emitting diodes connected in parallel in positive and negative opposite relationship to make it possible to easily carry out the positional confirmation of the partial discharge place of the insulation spacer. CONSTITUTION:When rated voltage is charged to a bus bar, a current sufficient to emit light from light emitting diodes 5, 6 is not flowed through a circuit constituted from a condenser 8, a resistor 7 and the light emitting diodes 5, 6. On the other hand, when abnormal voltage with positive polarity is generated relative to the bus bar, voltage is generated in a shield and light is emitted from the light emitting diode 5. When abnormal voltage with negative polarity is generated, light is emitted from the light emitting diode 6. Lights from the light emitting diodes 5, 6 are guided to O/E converters 20, 21 through light guides 18, 19 to be converted to electric signals. Respective electric signals are transmitted to a differential amplifier 22 and, by calculating the difference of the respective electric signals, both positive and negative wave forms are measured and an abnormal place can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION - TECHNICAL FIELD The present invention relates to an internal diagnosis of a sealed busbar, that is, a device for detecting internal abnormalities and abnormal locations.

[Background technology and its problems] Recently, due to the problem of land shortage in cities, substation 1 has changed from an air insulation method in which live parts are insulated by air.
Due to the use of an insulating gas such as SF6 gas filled in a pressure vessel set to ground potential, substations are being transformed into so-called scaled-down substations of the gas-insulated type, in which conductors of live parts are placed insulated from the pressure vessel. □However, in this scaled-down substation, since the conductor of the live part is covered by a pressure vessel, especially the sealed busbar 1 which covers the busbar with a metal sheath: It has not been easy to detect partial discharges that occur in the insulating spacer that insulates and supports the busbar from the ground. Detection of the corona pulse current flowing from the metal sheath to the ground is known as a method for detecting this partial discharge, but since it is detected from the entire metal sheath, it is difficult to confirm the location of the partial discharge, and furthermore, it is difficult to confirm the location of the partial discharge. The influence of noise was very large, and the sensitivity was extremely poor even in the case of Shunno.

[Purpose of the invention]

The present invention has been made in view of the drawbacks listed in -F, and it is possible to easily confirm the position of a partial discharge point in an insulating spacer without being affected by external noise, as well as detecting charges at the sealed cutting line 1 of a reduced-sized substation. It is an object of the present invention to provide an internal diagnostic device for a sealed bus bar that can be easily inspected and maintained in one step.

[Summary of the invention]

In order to achieve the above object, the present invention detects the potential of a shield embedded in an insulating spacer as light using a pair of light emitting diodes connected in positive and negative parallels, and converts this light into an electrical signal. It is characterized in that it detects abnormalities inside the sealed bus bar by comparing electrical signals.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the principle of the present invention. In Fig. 1, a bus bar 2, which is a filled conductor, is inside a metal sheath 1, which is filled with an insulating gas such as 1-8F6 gas and brought to the ground potential.
The bus bar 2 is insulated from the metal sheath 1 and supported by an insulating spacer 3. In other words, insulating spacer 3
The metal sheath 1 corresponding to the above is divided, flanges are formed on opposing parts of both metal sheaths, and the insulating spacer 3 is held between the seven flanges. They are connected to each other by bolts (not shown). An electric field mitigation shield 4 surrounding the bus bar 2 is buried within the insulating spacer 3 at a predetermined distance from the bus bar 2. It consists of a resistor 7 connected in series to two light emitting diodes 5 and 6 connected in parallel in opposite positive and negative directions, and a capacitor 8 connected in parallel to a circuit consisting of the light emitting diodes 5 and 6 and a resistor 71. Connect one end of the capacitor 8 of the circuit to be connected to the shield 41, and connect the capacitor 8 to the shield 41.
The other end is connected to a metal sheath 1 which is at ground potential. That is, it is grounded. The capacitor 9 represents the equivalent stray capacitance between the bus bar 2 and the shield 4, and the capacitor lO represents the equivalent stray capacitance between the metal sheath 1 and the shield 4. Next, in FIG. 2 1=, the same symbols as those in FIG. t41 represent the same parts. The electric field mitigation shield 4 buried within the insulating spacer 3 is connected to the resistor 7 and the capacitor 81 via conductors 11 and 12. A ring-shaped metal flange 13 is attached to the outer periphery of the insulating spacer 3, and mechanically and electrically connects the metal sheaths 1 to each other. Resistance 7. A box body 14 containing a capacitor 89, a light emitting diode 5.6, and a conductor 12 is attached to a ring-shaped flange 131, which is a concave portion 13aH. The conductor 12 is supported by an insulator 151;
6.17 and a light guide 18.19, an optical-to-electrical converter (E-converter) 20 converts light into an electrical signal.
．． It is connected to 21. The converters 20.21 are also coupled to a differential amplifier 22 which compares the respective electrical signals.

In the configuration 1 described above, when the bus 2 (in steady state I) is charged with a voltage of rated voltage 1E or -B,
Light emitting diodes 5, 61 = capacitor 8゜9,...
．． 10, and the specified current flows through the resistor 7.1: However, under normal rated voltage and pressure, the light emitting diode 5.6 does not emit light, and when an abnormality occurs inside the sealed bus bar, the light emitting diode 5. , 6 to emit light to detect the abnormal location, the capacitance of the capacitor 8 and the value of the resistor 7 must satisfy the following conditions. Note that capacitor 9 represents the equivalent stray capacitance between bus bar 2 and shield 4, and capacitor 10 represents the equivalent stray capacitance between metal sheath 1 and shield 4.
It is a specific value, and the equivalent stray capacitance CII of a general 1-capacitor 9 is 3 [pF] to 10 [pF], and the capacitance CII is 3 [pF] to 10 [pF].
The equivalent stray capacitance C,. is 100[1)F') ~ 500
[pF').

The first condition is that the frequency response characteristic of the internal diagnosis device for a sealed bus bar according to the present invention (2) must be flat for all frequencies that cover the abnormal voltage generated from the bus bar 21''.

As a second condition, it is necessary to maintain a proportional relationship between the voltage generated between the shield 4 and the metal sheath 1 and the light emission intensity of the light emitting diode 5.6.

As a third condition, when an abnormal voltage occurs on the bus bar 2, a current sufficient to cause the light emitting diodes 5 and 6 to emit light must flow through the light emitting diodes 5 and 6.

As a fourth condition, since the shield 4 also plays the role of mitigating the electric field at the end of the insulating spacer 3, the potential of the shield 4 must not become abnormally high at L due to the abnormal voltage generated on the bus bar 2. These four conditions are expressed as formula 1 and calculated as follows.

First, regarding the first condition, since the abnormal voltage generated on the bus 2 is at a high frequency of several IQKJ (z or more), the frequency response characteristic of the internal diagnostic device according to the present invention is flat at frequencies of 10KHz or more. This can be expressed mathematically as follows:

(C6+C1o)Ichi〉τ0・・・・・・・・・・・・
・(1) C here! l l C10 is the capacitance of capacitors 8 and 10, respectively, 几 is the resistance value of resistor 7, and τ. is l0
KHz t is the time constant of the corresponding abnormal voltage.

Next, regarding the second condition, the light emitting diode is generally 2
It has a forward voltage drop of about v.

Therefore, the terminal voltage of the capacitor 8 is the same as that of the light emitting diode 5.
6, the forward voltage drop should be negligible. ■ The forward current flowing through the light emitting diodes 5 and 6. , the forward voltage drop is V. In the case of binding, the second condition is expressed by the following equation.

R, I, )) Vo ・・・・・・・・・・・・(
2) Next, the third condition (secondly, if the surge voltage generated by the bus 21 is v1 and the capacitance of the capacitor 9 is C), the third condition is expressed by the following equation.

Finally, regarding the fourth condition, if the partial pressure of the shield 4 due to the capacitors 8 and 9° 10 is less than a certain value C2, -L
stomach. Then, the fourth condition is expressed by the following equation.

However, -n is a certain voltage ratio, and represents (shield 41: maximum allowable voltage)/(bus bar 21: maximum generated voltage). Here, the capacitance of C6 and the resistance value of R1 are specifically determined. C, is 3 [pF] ~ lO [pF], C1o
is 100[pF) to 500[[)F), the maximum voltage generated at the bus bar 21'' is 1500KV, and the forward voltage drop v0 of a typical light emitting diode is 2[V].
, the maximum forward current Imax is 200 [rnA]%, and the minute forward current lm1n is 5Q [mA]. The maximum voltage allowed for shield 4 is 3 [KV] as a result of the experiment.
Therefore, the capacitance C8 of capacitor 8 that satisfies the above four conditions is
and the resistance value R1 of the resistor 7 are determined as follows.

In formula (4), “” is 1500 and co=3
If we substitute [pF) and C0°=too[pF'), we get c,
> too [pF), and c, C10[pF'
), c,. Substituting C500[pF') gives C,>45
00 [pF). Therefore, by selecting a value of 1000 [pF] or more as C8 according to the values of C and C3°, the condition expressed by equation (4) is satisfied.

In equation (2), R, I0+v0 mean the terminal voltage of capacitor 8, so equation (2) can be rewritten as follows.

The error due to the influence of Raba vo is 5 inches, which is within the tolerance range of ±3 inches for high voltage measurement determined by the standard. Also, for disconnector surges, the ratio of maximum surge to minimum surge is 2.
It is about o. Therefore, 11°. Just make 10v 400 times vo, (5
) formula becomes as follows.

f61 Formula +: Substituting Oi1'', C0=3[pF], C5°C100[pF], V=1500[KV], Ca<5525[pF], and C9-10[pF].
F), C,. C500 [pF], V=1500 [KV]
Substituting , we get C,< 18250[1)F). Therefore, by selecting C3 to an appropriate value of 20,000 [pF] or less, the condition expressed by equation (2) is satisfied.

In equation (3), the following relationship is obtained from equation (4) and equation (61).

[Krfl > R, 6>4 [+<Ω] is obtained. Therefore, it is necessary to select an appropriate value for 1III within the range from [application] to 5Q [KV], and the condition expressed by equation (3) is satisfied.

By the way, when (Ca+C+o) "r""τ. (3
) is expressed by the following equation.

50 [mA) (-"-< 200 [rnA) -
1-f8) τ0 (8) Formula 1:, 3 [pF] ≦co ≦10 [pF]
,"=1500[KV], the value of τ is 22.5 x 10-"<τ. <300 x 1(r'
This value satisfies equation (1). That is, it can be seen that by selecting Cs+''a that satisfies equations (2) to (4), equation (1) is automatically satisfied.

As explained above, the capacitance value C6 of the capacitor 8 and the resistance value ratio 6 of the resistor 6 that satisfy the first to fourth conditions are expressed by the following equation.

too[pF)≦C8≦20000 [pF')...
・・・・・・・・・(9) 4[KΩ]≦Rf≦60[Kfl
)・・・・・・・・・・・・・・・00Next, the operation of the internal diagnosis device for a sealed busbar according to the present invention having the above-mentioned configuration (
I will talk about two things.

fFh line 2 + = constant 4 + 2M + 4 pressure example, t halo 6 [KV
) ~soo[KV), the circuit consisting of a capacitor 8, a resistor 7 and a light-emitting diode 5.6 having values in the range mentioned above has a light-emitting diode 5.
, 6 does not flow enough to cause them to emit light. However, when an abnormal voltage of positive polarity occurs on the bus bar 2, a voltage is generated on the shield 4, causing the light emitting diode 5 to emit light.

(If an abnormal voltage of negative polarity occurs, the light emitting diode 6 emits light.) The light from the light emitting diode 5.6 passes through the light guide 18.19 to the O/FJ converter 20.2.
1+ = guided and converted into an electrical signal.

The respective electric signals are transmitted to the differential amplifier 22, and by determining the difference between the respective electric signals, both positive and negative waveforms can be measured, and an abnormal location can be detected.

Here C,=2ooo[pF') PL7=50[Kj
1], the frequency response characteristics of the current flowing through the light emitting diode 5.61 are shown in FIG. It can be seen that the frequency response characteristics are flat in the high frequency region. Further, it can be seen that almost no current flows through the light emitting diodes 5 and 6 in a low frequency region such as a commercial frequency.

〔Effect of the invention〕

As described above, if the present invention is applied, the surge voltage appearing on the bus bar can cause the light emitting diode to emit light directly, and as can be seen from the circuit diagram, a separate power supply is not required.The circuit is still simple. It is highly reliable and requires a small installation space.However, high frequency waves flow through the light-emitting diode only when there is an abnormality inside the sealed busbar, and the light-emitting diode does not emit light under normal conditions, so the life of the light-emitting diode is extremely long. In addition, since a light guide is used as a signal transmission means, it is not affected by fluctuations in metal sheath potential due to surge voltage or electrical induction from other control lines, reducing noise and improving reliability. can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the principle of the present invention, FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIG. 3 is a club diagram showing the characteristic frequency response characteristics of the internal diagnostic device according to the present invention. be. 1... Metal sheath 2... Bus bar 3... Insulating spacer 4... Shield 5.6... Light emitting diode 18, 19... Light guide 20.21...
Optical-electrical converter 22...Differential amplifier (7317) Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Figure 3 Ohni i4 gain 1-/AH7! /4H2/θ4'+'z
/θθ4n, /~〃n廚し skin 1 (Procedural amendment (spontaneous) 415/1. Correct 48 Commissioner of the Japan Patent Office 1, Indication of the case, Japanese Patent Application No. 112559/1982, 2, Name of the invention: Internal diagnosis of sealed bus bar Apparatus 3, relationship with the case of the person making the amendment Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 4, Agent 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tsukubai 100 Tokyo Shibaura Electric Co., Ltd. Kaman (φ 1 in the office) , Column 6 of "Detailed Description of the Invention" of the specification, Contents of amendment (1) The above stated on page 10, line 3 of the specification of the application

Claims (1)

[Claims] fl) A circuit comprising a capacitor connected in parallel to a circuit comprising a pair of light emitting diodes connected in parallel in opposite positive and negative directions and a resistor connected in series to the diodes, this circuit 1: One end of the capacitor is connected to a shield embedded in an insulating spacer that supports a live part, and the other end is connected to ground potential, and each signal from a pair of light guides that guide light from the light emitting diode is connected to the shield. An internal diagnosis device for a sealed bus bar, which is comprised of a device that converts into electrical signals using a converter, compares and outputs the respective electrical signals from the converters. (2) The resistance value of the resistor is IOKΩ or more and 100Ω or less,
and the capacitance value of the capacitor is 1000pF or more200
The internal diagnostic device for a sealed bus bar according to claim 1, characterized in that the voltage is 0 pF or less.