JPS6112661Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a current transformer without magnetic saturation characteristics, which is particularly used in a high-voltage line disconnection fault section automatic classification device, provides high reliability, and has an output linearly proportional to the short-circuit current. The present invention relates to a current transformer that provides voltage to ensure correct operation of the partitioning device.

Disconnection accidents caused by lightning, etc. on power transmission and distribution lines can be detected by applying disconnection relays, but since it takes time to investigate the area where the accident occurred, power outage accidents may continue for a long time. Become. To solve this problem, an automatic high-voltage line disconnection area automatic classification device is used that quickly and automatically localizes the accident area, making it possible to transmit power to healthy areas. This device includes a switch that divides a high-voltage distribution line into several sections and has a built-in current transformer for detecting short-circuit current in each section, and a
A disconnection detection mechanism that senses no voltage on the power transmission and distribution line and provides a control signal while maintaining one state, and a timed accident that locks the switch in the open state by operating a relay based on the control signal. Includes an investigative organization.

A conventional current transformer built into this switch causes magnetic saturation due to a short circuit current exceeding a certain value, making it difficult to obtain an accurate output that is linearly proportional to the short circuit current. Therefore, the reliability of the entire device is poor, and malfunctions may occur.

Therefore, the object of the present invention is to provide an output voltage that is free of magnetic saturation characteristics and is linearly proportional to the short-circuit current, thereby ensuring reliable operation of the automatic high-voltage line disconnection fault zone classification device. It is to provide a flushing device.

The current transformer according to the present invention includes a coil having a predetermined current transformation ratio, a leader wire connected to the coil, and a magnetic core around which the coil is wound. It has a configuration in which a non-magnetic material and an iron core are magnetically arranged in series to prevent saturation phenomenon, and for application to a three-phase electric circuit, the three current transformers are made of epoxy resin. It is integrally molded. The coil has an annular shape, and a through hole through which the switch wire passes is formed in the center of the coil.

The non-magnetic material may be a void, or may be an insulating material such as rubber or plastic.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1A, a three-phase current transformer according to the present invention is shown. The entire current transformer is made of epoxy resin 1
60, and is provided with three through holes 161 through which switch electric wires pass. Three lead wires 162 are drawn out from the epoxy resin molded body 160, and their conductors are connected to an annular coil 164. Annular coil 1
The magnetic core around which 64 is wound is composed of two iron cores 163 and a gap 166.
A non-magnetic spacer 165 is interposed between them.
Three coils 164 having the same configuration are arranged, and a magnetic shield 167 such as iron tape is provided between them to prevent interference due to mutual induction between the coils. However, if a mutual induction effect is not particularly recognized, it is possible to omit this, and even if it is provided,
The shape is not limited to the illustrated shape, and may be semicircular or circular and may be arranged so as to surround the entire coil 164.

Referring to FIG. 1B, there is shown another configuration of a three-phase current transformer (only the right half is shown) according to the present invention. As in FIG. 1A, the epoxy resin molded body 160 has a through hole 161 through which a switch electric wire passes, and a lead wire 162 is connected to an annular coil 164. The annular coil 164 is wound around a magnetic core consisting of three iron cores 163 and three rubber insulators 165.
A magnetic shield 167 is provided between them.

According to the configuration shown in FIG. 1A, there is a gap 166 that occupies about half of the magnetic core, and the iron core 163 is divided by spacers 165, so that the magnetic saturation phenomenon is substantially prevented. In addition, since the rubber insulator 165 of sufficient length is present in FIG. 1B, magnetic saturation can be substantially suppressed. Therefore, as shown in FIG. 2, the primary current flowing through the switch wire, that is,
It is possible to obtain an output linearly proportional to the short-circuit current, and one result confirms that magnetic saturation does not occur even at short-circuit currents up to 7 KA, as shown in the figure.

Referring to FIGS. 3 and 4, the three-phase current transformer described above is shown built into a switch. A three-phase current transformer 16 is installed in a bushing 11 fixed to the switch main body, and provides an output voltage linearly proportional to the short circuit current flowing in the electric line passing through the bushing 16 to the current transformer lead wire. It has a configuration that Here, 12 is a fixed insulator, 13
1 is an arc extinguishing chamber, 14 is a movable conductor, 15 is a rotating insulator, 1
7 indicates a hanger hook.

Referring to FIG. 5, there is shown a power distribution system in which a disconnection fault section automatic classification device to which the current transformer of the present invention is applied is arranged.

The distribution system branching out from the substation SS is divided into sections based on the magnitude of the short circuit current Is (as shown by the chain lines A, B, C, D, and E in the figure), and automatic disconnection fault section division devices are installed at points A, B, C, and D, respectively. The short circuit current detection level of the disconnection detection unit of each disconnection fault section division device is stepped, for example, the device at point A is
5KAIso2KA (Iso is the set value, same below), B and C points are 2KAIso1KA, D
The equipment at point B is set to 1KAIso0.3KA. Now, assuming that a line breakage accident occurs in the Hani section, a current will flow through the equipment at point B, 2KAIs1KA, and only the equipment at point B will detect the accident and store it. Then, after the time-delayed accident investigation unit detects no voltage and the breaker relay at substation SS cuts off the breaker, the switch at point B is locked in the open state, and the reclosing operation of substation SS is controlled to separate the equipment at point B and beyond.

Next, the automatic disconnection accident zone classification device will be explained. FIG. 6 shows a schematic explanatory diagram thereof. A three-phase power distribution system is divided into an area close to the main transformer and an area other than the main transformer. The area is a means for protecting the generator and is not directly related to the automatic fault zone classification device having a current transformer according to the present invention, so a description thereof will be omitted. In the figure, 1 is a switch, 2 is a time-limited accident investigation device with a disconnection detection mechanism, and 3 is a transformer. A signal from a current transformer for short-circuit current detection built in the switch 1 and a distribution line voltage signal are given to the time-limited fault investigation device 2 with a disconnection detection mechanism, and the signal from the current transformer for short-circuit current detection built in the switch 1 and the distribution line voltage signal are applied to the time-limited fault investigation device 2. It has a configuration that controls the operation of the controller. In order to simplify the explanation, Fig. 6 shows that the input given to the time-limited accident investigation device 2 with disconnection detection mechanism is obtained from a single-phase distribution line, but in reality it is obtained from a three-phase distribution line. Timed accident investigation device 2 with disconnection detection mechanism that detects each signal simultaneously from each line with the same configuration
is configured to be given to

The automatic sorting device comprising the switch 1, the time-limited accident investigation device 2 with a disconnection detection mechanism, and the transformer 3 will be explained in more detail in FIG.

The upper half of the device is a wire breakage detection mechanism, and the lower half inside the frame is a timed accident investigation device.

A switch 1 installed on a distribution line is composed of a three-phase current transformer BCT according to the present invention (consisting of current transformers BCT ₁ , BCT ₂ and BCT ₃ for each phase) and a switching contact CC. The current detected in the three-phase current transformer BCT is
The zero-phase current rectifier circuit RE ₁ and each phase current rectifier circuit RE ₂ , RE ₃ and _{RE 4 are} provided through auxiliary current transformers Tr 1 , Tr ₂ and Tr ₃ . Output e ₁₀ of rectifier circuit RE ₁
is simultaneously given to the level detection circuits DE ₁ and DE ₂ via the setting circuit SE ₁ , and the output e ₂₆ of the level detection circuit DE ₁ is sent to the OR circuit together with the output e ₂₇ of the AND circuit AND ₄ .
OR is given in ₂ . On the other hand, the level detection circuit
The output e ₂₅ of DE ₂ is the output of OR circuit OR ₁ , which will be described later.
It is given to the AND circuit AND ₄ along with e ₂₃ . OR
In circuit OR ₁ , the current of each phase is rectified (rectifier circuit
RE ₂ , RE ₃ and RE ₄ ), then the setting circuit SE ₂ ,
Level detection circuit DE ₃ , DE ₄ via SE ₃ and SE ₄
and DE ₅ , and the outputs e ₂₀ , e ₂₁ and e ₂₂ obtained from the logical operation of the obtained outputs e ₁₄ , e ₁₅ and e ₁₆ are given. The above output e ₁₄ , e ₁₅ and
The logical operation of e ₁₆ is 3 inverters and 3 ANDs.
This is performed using a logic circuit consisting of circuits AND ₁ , AND ₂ and AND ₃ . That is, the output e ₁₄ and the inverted outputs e ₁₅ and e ₁₆ are input to the AND circuit AND ₁ .
Furthermore, the AND circuit AND ₂ has a configuration in which an output e ₁₅ and inverted outputs e ₁₄ and e ₁₆ are provided, and the AND circuit AND ₃ is provided with an output e ₁₆ and inverted outputs e ₁₄ and e ₁₅ , respectively. ing. OR circuit
The output e ₂₈ of OR ₂ is a monostable multivibrator SS
The output e ₂₉ is applied to the AND circuit AND ₇ together with the output e ₃₁ of the undervoltage detection circuit of the power supply of the automatic disconnection fault zone classification device, which will be described later. The keep relays K ₂ and K ₃ and the mechanical display means IND are driven by the output e ₃₂ of the AND circuit AND ₇ . And keep relay K ₃
The a-contact opens and closes the circuit of the indicator lamp _L2 .

On the other hand, the output e ₁ or
e ₁ ′ has a configuration in which the switch SW ₁ is supplied to each of the time-limited accident investigation devices within the frame. In the circuit constituting this investigation device, the output e ₁ (or e ₁ ′) becomes the input to the AND circuit AND ₆ through a parallel circuit of the b contact of keep relay K ₂ and the b contact of keep relay K ₁ , which will be described later. , its output e ₄ is timer
becomes the drive signal and the output e of timer X ₅ is an OR circuit
This becomes the input for OR ₃ . The output _e6 of the OR circuit _OR3 becomes a drive signal for the relay _R1 and is fed back to the OR circuit _OR3 via a timer Z. Further, the output _e5 of the timer X serves as a drive signal for the keep relay _K1 , and also serves as a drive signal for the timer Y via the a contact point of the keep relay _K1 . The output _e8 of the timer Y serves as a reset signal for the keep relays _K1 , _K2 , _K3 and the mechanical display means IND. Note that the reset line is configured so that it can also be operated manually using switch _SW2 . Output e ₁ obtained via switch SW ₁ (or
e ₁ ′) is also provided to a no-voltage detection circuit DE _{6 and a constant voltage circuit ST via a rectifier circuit RE 5 and} a smoothing circuit RE ₆ . The output e ₃₀ of the no-voltage detection circuit DE ₆ drives the timer TA, and its output e ₃₁ serves as the input of the AND circuit AND ₇ described above. Each circuit of this device is driven by the output of the constant voltage circuit ST. Last but not least, to explain the configuration, power is supplied to the excitation coil of contact CC of the switch through the output e ₁ (or e ₁ ') selected by switch SW ₁ via the a contact of relay R ₁ . It is structured so that it is given by

Next, the operation of the apparatus having the configuration described above will be explained with reference to FIGS. 8 to 11. FIGS. 8 to 10 are time charts, the time axes of which are drawn with time t ₀ as a reference, and the same reference numerals indicate the same times.

At the current time t ₀ (hereinafter, time will be simply indicated by a symbol), the switching contact CC is in the open state, the keep relays K ₁ , K ₂ , and K ₃ are in the non-set state, and the three-phase power line is in the inactive state. Assume that it is in a line state, and t ₁
It is assumed that the three-phase electric wire is in a live state and the distribution line is in a normal state. By voltage e ₁ applied through switch SW ₁ , AND circuit AND ₆
The following logic circuit performs the sequence operation shown by the arrow in FIG. 8 from _t1 to _t3 , and the accident investigation device enters the operating state. During this time, the switching contact CC is closed (t ₂
), switch 1 and subsequent switches are also live. On the other hand, for the circuits after rectifier circuits RE ₁ to _{RE 4} that are input via the three-phase current transformer BCT, the distribution lines are in a normal state, so the monostable multivibrator
There is no trigger on SS, so the output _e29 is "0" and the keep relays _K2 , _K3 and mechanical display means IND also maintain their initial states. Then, at t ₄ , a three-phase short circuit accident occurred (see e ₁₄ , e ₁₅ , e ₁₆ in Figure 9), and at t ₅ , the substation circuit breaker tripped (see Figure 8).
e ₁ ), due to these situational changes, relay R ₁ is de-energized in the circuit after switch SW ₁ , and therefore switching contact CC becomes open, and at the same time no-voltage detection occurs. A no-voltage detection signal e ₃₀ is obtained in the circuit DE ₆ to drive the timer TA, and at t ₆ the signal e ₃₁ becomes “1” (see e ₃₁ in FIG. 11).
On the other hand, at _t4 , the short-circuit fault current level is detected by the short-circuit fault current level detection circuits DE ₁ to DE ₅ (see Figure 9), and the OR circuit
The output e ₂₈ of OR ₂ assumes the "1" state. and,
Using the "1" state output _e28 as a trigger, the monostable multivibrator SS shifts to a metastable state (see _e29 in FIG. 9). Therefore, the output e ₃₂ of the AND circuit AND ₇ which receives the signals e ₃₁ and e ₂₉ as input is in the "1" state (see e ₃₂ in Figure 10), and the keep relay is activated.
Set K ₂ , K ₃ and mechanical display means IND ₁ (see K ₂ , K ₃ in FIG. 10). This allows us to know that a short-circuit fault current flowed in the three-phase distribution line at _t6 . At t ₇ , power is retransmitted from the substation. Since power has been retransmitted and keep relays K ₂ and K ₃ have not yet been reset, the output e ₄ of the AND circuit AND ₆ is in the "0" state, so the timer X is not driven and the relays R ₁ is in a de-energized state, the switching contact CC is not closed, and the lamp L ₂
It just lights up. In other words, the circuit of the accident investigation device has stopped (locked) the closing of the switching contact CC of the switch 1.

The following can be said from the above operation. Now, the first
As shown in Figure 1 A, the automatic disconnection accident zone classification device installed at points A _and B will be
Due to the operation at t ₇ (before t ₈ ), two different display formats as shown in Figure 11 (b) can be seen on the display means of the automatic disconnection accident zone classification device at points A and B. The short-circuit fault point can be determined from the shape. Therefore, if the current fault point is the X mark in A, after the short-circuit fault point is repaired, at t ₈ , the manual reset switch SW ₂ turns on the keep relays K ₁ , K ₂ , K. At the same time as setting ₃ is released, the display of the mechanical display means IND can also be switched to a non-accident display. This operation closes the switching contact CC.

Next, the generation of two-phase short-circuit current will be explained. A two-phase short circuit occurred at t ₁₂ , and signals e ₂₄ and
Suppose that e ₁₄ has a "1" state (e ₂₄ and e ₁₄ in Figure 9)
reference). Only the output e ₂₀ of the AND circuit AND ₁ becomes "1" and becomes the input to the AND circuit AND ₄ via the OR circuit OR ₁ . On the other hand, output e ₂₄ is a level detection circuit
When connected to DE ₂ , its output e ₂₅ becomes "1" and becomes the input of AND circuit AND ₄ . Therefore, the output e ₂₇ becomes "1" state, and the OR circuit
Trigger the monostable multivibrator SS via OR ₂ .

Hereinafter, the operation can be understood in the same way as the occurrence of the three-phase short circuit accident.

In the above embodiment, by setting the level of each level detection circuit as follows, the range that can be protected can be determined as shown in FIG.

Level detection circuit DE ₁ ... Setting value × √3 Level detection circuit DE ₂ ... Setting value × 3/2 Level detection circuit DE ₃ , DE ₄ , DE ₅ ... Setting value × 3/2 × 0.8 From the above explanation, The current transformer according to the present invention and the configuration of an automatic disconnection fault area classification device using the current transformer have been clarified. According to the current transformer of the present invention, the magnetic core forming the magnetic path is provided with a gap portion having a predetermined length or a non-magnetic material portion such as an insulator, and furthermore, the iron core is provided with a spacer. Because the expected short-circuit current is divided by , magnetic saturation does not occur and therefore an output linearly proportional thereto can be provided.

Therefore, the disconnection detection mechanism that receives the output as input does not malfunction due to magnetic saturation, and stable operation can be realized.

[Brief explanation of the drawing]

FIGS. 1A and 1B are partially cutaway explanatory views showing two embodiments of the present invention, respectively. FIG. 2 is an explanatory diagram of the operating characteristics of the current transformer of the present invention. FIG. 3 is an explanatory diagram of the inside of a switch incorporating the current transformer of the present invention.
FIG. 4 is an electrical diagram of the switch shown in FIG. 3.
FIG. 5 is an explanatory diagram showing the equipment of the automatic high-voltage disconnection accident zone classification device. FIG. 6 is a schematic diagram of the automatic classification device for high-voltage line breakage accident areas. FIG. 7 is an explanatory diagram showing the configuration of a high-voltage line breakage accident section automatic classification device. FIGS. 8 to 12 are explanatory diagrams showing the operation of the high-voltage line disconnection accident section automatic classification device. Explanation of symbols, 1... Switch, 11... Bushing, 12... Fixed insulator, 13... Arc extinguishing chamber, 14...
...Movable conductor, 15...Rotating insulator, 16...Three-phase current transformer, 17...Hanger hook, 160...Mold body, 161...Through hole, 162...Leader wire, 163...Iron core, 164 ...Coil, 165
... Spacer non-magnetic material, 166 ... Gap portion, 16
7...Magnetic shield, 2...Timed accident investigation device with disconnection detection mechanism, 3...Transformer, BCT...Three-phase current transformer, CC...Switching contact, Tr ₁ , Tr ₂ , Tr ₃ ... Auxiliary current transformer, RE ₁ , RE ₂ , RE ₃ , RE ₄ , RE ₅ ... Rectifier circuit, RE ₆ ... Smoothing circuit, SE ₁ , SE ₂ , SE ₃ ,
SE ₄ ... Setting circuit, DE ₁ , DE ₂ , DE ₃ , DE ₄ , DE ₅
...Level detection circuit, DE ₆ ...No voltage detection circuit,
AND ₁ , AND ₂ , AND ₃ , AND ₄ , AND ₅ , AND ₆ ,
AND ₇ ...AND circuit, OR ₁ , OR ₂ , OR ₃ ...OR circuit, SS...monostable multivibrator, K ₁ ,
K ₂ , K ₃ ...Keep relay, R ₁ ...Relay, L ₁ ...
...Mechanical display means, X, Y, Z, TA...timer, _L2 ...display lamp, ST...constant voltage circuit.

Claims (1)

[Claims for Utility Model Registration] A current transformer comprising a coil having a predetermined current transformation ratio, a leader wire connected to the coil, and a magnetic core around which the coil is wound, The core is an iron core having a predetermined magnetic saturation characteristic, and is placed in series with the iron core to lower the level of magnetic flux in response to magnetic force by increasing magnetic resistance, thereby reducing the magnetic saturation phenomenon in the operating region. A current transformer characterized by being provided with a non-magnetic material that prevents.