JPH06109778A - Charge indicator - Google Patents

Abstract

PURPOSE:To provide a charge indicator without any need to stop operation for a mounting and demounting work, when the indicator is provided and used at a grounding side such as the rack of an LS for specially high voltage and the lower side of bushing for an OCB and a transformer, while allowing the easy observation of display contents, and showing information properly coping with the live and dead lines of a high voltage section, when the indicator is mounted at a grounding side. CONSTITUTION:A conventional charge indicator circuit comprising a collecting board 2, an AC-DC conversion circuit 3, a liquid crystal display drive circuit 4 and a liquid crystal element 5, is additionally provided with a voltage discrimination circuit 6 allowing a threshold value to be preset, and a switching circuit 7, respectively operating to actuate a liquid crystal display, only when circuit voltage rises to and above the preset threshold value, thereby constituting a charge indicator 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a charging indicator which is used by being attached to the ground side of a high-voltage device having an extra high voltage or higher and which detects and displays whether or not the target high-voltage device is in a charged state. Is.

[0002]

2. Description of the Related Art A charging indicator is a safety device for displaying on a liquid crystal element that a voltage is being applied to a charging portion of a power receiving and transforming facility, and for preventing accidents due to illusions and misidentifications. The most common conventional charging indicator is used by directly attaching it to the vicinity of the high-voltage charging section, and is integrally formed with the case in the circuit configuration shown in FIG. In FIG. 4, 1 is a high-voltage charging unit such as a conductor or a power receiving and transforming facility, and 9 is a ground. The expression "earth 9" includes the influence of the equipment components of the ground potential such as the LS mount, OCB tank, other phases, and other lines. The circuit of the charging indicator 10 is
A current collector plate 2 made of two conductive materials P1 and P2, an AC / DC conversion circuit 3, a liquid crystal drive circuit 4, and a liquid crystal element 5.

In the current collector plate 2, P1 generally serves also as a fitting for a charging indicator and forms a capacitance C1 with the high voltage charging unit 1. Further, P2 is provided around the liquid crystal element 5 and forms a stray capacitance C0 with the ground 9. The two current collector plates 2 detect the AC electric field around the high-voltage charging unit 1 and supply the energy of the AC electric field to the AC conversion circuit 3 as an AC current IA. Hereinafter, IA is referred to as a current collector current. The size of IA substantially depends on the size of the stray capacitance C0, in other words, the size of the current collector P2.

The AC conversion circuit 3 converts the current collector current IA into a DC circuit current ID and supplies it to the liquid crystal drive circuit 4.
At this time, the peak value of the AC voltage VA applied to the AC / DC conversion circuit 3 is the current collector plate current IA, the AC / DC conversion circuit 3, the liquid crystal drive circuit 4,
It is determined in proportion to the product of the total impedance of the liquid crystal element 5. The magnitude of the DC circuit voltage VD applied to the liquid crystal drive circuit 4 and the liquid crystal element 5 is generally slightly smaller than the peak value of the AC voltage VA.

In the liquid crystal drive circuit 4, the voltage value is the circuit voltage VD.
A rectangular wave liquid crystal drive voltage having the same frequency as that of the above is generated and applied to the liquid crystal element 5. If the magnitude of the circuit voltage VD exceeds the display threshold value of the liquid crystal element 5, the liquid crystal element 5 provides a clear display. Charging indicator 10 that is used by being mounted near the conventional direct high voltage charging unit 1
Was adjusted so that the DC circuit voltage VD would exceed the indicated threshold value with a margin when the voltage of the high voltage charging section 1 reaches a predetermined rated ground voltage V0.

The charging indicator 10 of the type which is directly attached to the high-voltage charging section for use needs to be attached and detached while the work of the power receiving and transforming facility is stopped. Since special high voltage power receiving and transforming equipment is generally installed over several meters above the ground, it is difficult to see the contents displayed on the indicator. There was a drawback. If there is a charging indicator that can be used by being attached to the ground side portion of the high-voltage equipment as indicated by the ● mark in FIG. 5, such a defect can be solved. However, whether or not a charging indicator of this type is possible has not been deeply studied.

The high-voltage charging unit 1 of the special high-voltage equipment
When the voltage V0 applied to the liquid crystal display device is large and the generated AC electric field is large, the liquid crystal element 5 is not affected by the electric field near the ground side of the device.
It is possible to generate a circuit voltage VD of a magnitude that provides a sufficiently clear display. FIG. 6 is a diagram for explaining the configuration and operation when the charging indicator 10 is attached to the part of FIG. 5 and used. In the figure, the same parts as those in FIG. 4 are designated by the same reference numerals. In FIG. 6, unlike the case of FIG. 4, C1 is a stray capacitance between the current collector P1 and the high voltage charging unit 1,
The magnitude of the current collector plate current IA depends on the magnitude of C1, in other words, the size of the current collector P1. The current collector P2 is
One end is directly grounded so that labor can be saved.

Generally speaking, in order for the method in which the charging indicator is attached and used on the ground side to be a practically effective method, the indication is that the high-voltage charging section immediately above it is in the live line state and dead line. It must correspond exactly to the condition. For that purpose, the following two conditions must be met. The first condition is that the electric field at the grounding side mounting portion of the charging indicator is generated when the high voltage charging section directly above the indicator is in a live line state and when the high voltage charging section immediately above is dead line state. This means that there must be a clear difference in the size between the case where it occurs due to the open / closed state of switches such as CB and CB and the state of power application of other lines. The second condition is that the display characteristics of the charging indicator must be such that the electric field magnitude in the live line state is surely displayed, and the electric field magnitude in the dead line state is never displayed. .

Regarding the first point above, a plurality of 60 k
At the V substation, using the electric field meter and the charging indicator for the test, the electric field and the current of the collector plate of the equipment such as the transformer, GPT, and arrester including the parts shown in Fig. 5 are measured. The measurement was investigated. The result is shown in FIG. 7 as the relationship between the electric field and the current collector plate current. In the figure, ◯ indicates data when the high-voltage charging unit is in a live state, and ● indicates data when the high-voltage charging unit is in a dead line state. From this figure, it can be seen that the current collector plate current of the charging indicator is almost proportional to the electric field, although there are variations, and the electric field at the grounded portion is 5 kV / m at the minimum when hot and 1.2 kV / m at the maximum when dead. In addition, the current collector current is 2.2 μA at the minimum when the line is live, and 1.1 μA or less at the maximum when the line is dead, indicating that there is a clear difference between the two.

Therefore, if there is a charge indicator having a characteristic that can clearly show the difference between the electric field and the current collector current as the difference in the display of the liquid crystal element, the above second condition is satisfied. The method of attaching the charging indicator to the ground side can be put into practical use. However, in order to put the charging indicator to the ground side into practical use by using the conventional charging indicator 10, the relationship between the display characteristics of the liquid crystal element and the characteristics of the current collector current and circuit voltage of the charging indicator 10 is to be realized. Turned out to be impossible. The reason will be described below.

First, general display characteristics of the liquid crystal element will be described. Although the TN-type liquid crystal element, which is the easiest to use, has a display threshold value, it does not suddenly start to display sharply at that threshold value, but rather than the nominal drive voltage for sharp display. The display starts from a low voltage. For example, in the case of a TN type liquid crystal element that clearly displays a 2.8 V rectangular wave when viewed from the front, even if the rectangular wave voltage is about 2 V, it looks thin from the front. In this case, it is very clear when viewed from an oblique direction. If you select the most suitable direction and see it, you can see a thin display even with a voltage of 1.5V. That is, the liquid crystal element has a considerable voltage range from the beginning of display to a clear display, and has directional characteristics relating to the visibility of display.

Next, the relation between the current collector plate current of the charging indicator and the circuit voltage will be described. FIG. 8 shows the relationship between the current collector plate current and the circuit voltage of the charge indicator 10 for the liquid crystal elements of two sizes. The circuit voltage becomes low when the load liquid crystal element is large even if the current collector current is the same. However, regardless of the size of the liquid crystal element, when the current value of the current collector plate is small, the circuit voltage rapidly increases as the current of the current collector plate increases, but thereafter the increasing tendency becomes smaller. The non-linear relationship between the circuit voltage and the current collector current is due to the characteristics of the CMOS-IC used as a circuit element, and is not a special characteristic of the charge indicator 10.

In FIG. 8, in the case of the charge indicator 10 using a liquid crystal element of 10 nF, the circuit voltage is 2.8 with a minimum current collector current of 2.2 μA corresponding to the live state of the charging section.
A clear liquid crystal display can be seen beyond V. However, in this case, the circuit voltage becomes 2 V or more even at 1.1 μA corresponding to the dead line state, and the liquid crystal display looks thin when viewed from the front, and is clearly visible when obliquely viewed from below. On the contrary, in the case of the charge indicator 10 using the liquid crystal element of 20 nF, the circuit voltage is 1.5 when the current collecting plate current is 1.1 μA.
At V or less, the liquid crystal display is absolutely invisible, but no clear display is shown even with a current collector current of 2.2 μA corresponding to the hot line state. In this way, when the conventional charging indicator 10 is attached to the ground side and used, it is inevitable that the high-voltage device does not clearly show whether it is in the live line state or the dead line state.

When the conventional charging indicator 10 is used immediately after being attached to the high-voltage charging unit 1, the other charging line, DS, L
Since the difference between the magnitude of the induced electric field received from the other side of the switches such as S and CB and the magnitude of the electric field directly generated by the high voltage charging unit to which the charging indicator 10 is attached is very large,
It was possible to make adjustments so that the liquid crystal element would not display an ambiguous display.

[0015]

However, when the conventional charging indicator 10 is attached to the ground side and used, the difference between the electric field that should be displayed and the electric field that should not be displayed is about 4 to 5 times, 2 when comparing the current of the current collector
There is only about twice the opening. As a result, the above-mentioned ambiguous display state is caused. Therefore, how to avoid the ambiguous display of the liquid crystal element has been a major issue in order to put the ground-side-attached charging indicator into practical use.

[0016]

In order to eliminate the above-mentioned defects, the present invention provides a conventional charge indicator circuit composed of a current collector, an AC / DC converter circuit, a liquid crystal drive circuit, and a liquid crystal element with a constant threshold voltage. A charge indicator is configured by adding a threshold voltage setting voltage judgment circuit and a switch circuit that operate to display a liquid crystal only when the voltage exceeds the value voltage. is there.

[0017]

In the charge indicator having the structure of the present invention, the minimum circuit voltage that reaches the voltage discrimination circuit in the hot line state to be displayed,
The threshold can be set to a voltage midway between the maximum voltage reached in the deadline state that should not be displayed. The voltage discriminating circuit turns on the switch circuit to display the liquid crystal only when the voltage becomes equal to or higher than the threshold value, so that an ambiguous display state can be avoided. In this case, the threshold value is set to 2.5 V or higher, preferably 2.8 V or higher in order to obtain a clear display. The configuration and operation of the present invention will be described in more detail in the following examples.

[0018]

1 is a diagram showing an example of the circuit configuration of a charging indicator 11 of the present invention mounted on the ground side. In the figure, 2 is P
A current collector plate consisting of two sheets of 1 and P2, 3 is an AC / DC converter circuit, 4 is a liquid crystal drive circuit, 5 is a liquid crystal element, 6 is a voltage discrimination circuit, and 7 is a switch circuit. Of the operation of each part of the circuit, the points that are particularly different from those described in FIG. 4 will be described. Two
Among the current collector plates 2, P1 forms a stray capacitance C1 between itself and the high voltage charging unit 1, and the current collector current IA is C1 in other words, P1 in other words. Depends on. Since P2 is directly connected to the ground 9, it can be omitted. These relationships are the same as in the case of FIG.
An arbitrary threshold voltage can be set in the voltage determination circuit 5. For example, if the threshold is set to 2.8V,
When the circuit voltage is 2.8 V or less, the output of the voltage determination circuit 6 is at L level, the switch circuit 7 remains open, and the drive voltage is not applied to the liquid crystal element 5. When the circuit voltage exceeds 2.8 V, the output of the voltage determination circuit 6 becomes H level, the switch circuit 7 is closed, and a clear liquid crystal display is performed.

FIG. 2 is a diagram for explaining the display area of the charging indicator 11 shown in FIG. In the figure, the horizontal axis represents the current collector current IA and the vertical axis represents the circuit voltage VD. Curves and are the characteristics of the three charging indicators 11 for the test, and the size of the current collector P2 is the same as that in the case of FIG. The horizontal line C drawn to 2.8V is a line showing the threshold voltage set in the voltage determination circuit 6. 1.1μ
The vertical line A drawn on A is the line showing the maximum current collector current that the charging indicator 11 shows when the charging part is in the dead line state. In the current region below this, the charging indicator 11 should never be displayed. I won't. The vertical line B drawn to 2.2 μA is a line showing the minimum value of the current collector current flowing through the charging indicator 11 when the charging section is in a live state, and the charging indicator 11 is always clear in the current region above this. Should be displayed.

In FIG. 2, the charging indicator 11 having a curved characteristic intersects with the straight line C at a point (a). The charge indicator 11 of the present invention has a configuration in which the liquid crystal element 5 does not display at a circuit voltage below the straight line C. In this case, the point (a) is the straight line A
Since it is between the line B and the straight line B, the charging indicator 11 satisfies the condition that the current collector current of A or less is never displayed and the current indicator current of B or more is always displayed clearly. . When the liquid crystal element 5 is small, the characteristic of the charge indicator 11 becomes a curve. In this case, even if the magnitude of the current collector current is less than or equal to the vertical line A, it is displayed, which is not preferable. Therefore, an appropriate display operation can be performed by adjusting the sensitivity to bring it closer to the characteristic of the curve or adjusting the threshold value to the dotted line C ′. In the case of the charge indicator 11 having the display characteristic shown by the curve, it may not be displayed even if the current value of the current collector current is equal to or more than the vertical line B, which is not appropriate. In this case, if the threshold value is lowered, the sharpness of the display is lost, so that the liquid crystal element 5 can be downsized or the current collecting plate P1 can be enlarged to perform an appropriate display operation.

As described above, when the charging indicator 11 of the present invention is used by being attached to the ground side, it does not give an ambiguous display and operates correctly in correspondence with the live line / dead line of the high-voltage charging section. did. The above description is based on the effectiveness of the charging indicator 11 of the present invention based on the experimental data obtained at 60 kV.
The charging indicator 11 of the present invention can be applied to a voltage system other than 60 kV by adjusting the size of the current collector plate and the threshold voltage according to the magnitude of the electric field.

FIG. 3 is a view showing another embodiment of the charging indicator 11 of the present invention mounted on the ground side. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals. The feature of this embodiment is that voltages H and L opposite to each other are taken out from two output terminals e1 and e2 from the voltage discriminating circuit 6, and two switch circuits 7 shown by SW1 and SW2 are alternately turned on and off. That is. The dummy circuit 8 is a circuit having substantially the same impedance as the liquid crystal element 5. When the circuit voltage VD is smaller than the threshold voltage set in the voltage discriminating circuit 6, the output end e1 is L, the output end e2 is H, the switch SW1 is OFF, and the switch SW2 is ON.
Becomes Therefore, the output of the liquid crystal drive circuit 4 flows through the dummy circuit 8 and the liquid crystal element 5 does not display. When the circuit voltage VD exceeds the threshold voltage, the voltages at the output terminal e1 and the output terminal e2 are reversed, and the open / closed states of the switches SW1 and SW2 are also reversed to display the liquid crystal element 5. The advantage of providing the dummy circuit 8 is that the fluctuation of the load due to the switching of the switch circuit 7 is small, the fluctuation of the circuit voltage VD is also small, and the operation of the voltage discriminating circuit 6 is stable.

[0023]

EFFECT OF THE INVENTION The charging indicator of the present invention comprises an LS mount, an O
When used by being attached to a ground side part such as a CB or the bottom of a bushing of a transformer, a clear liquid crystal display can be performed by appropriately corresponding to the live line and dead line of each high-voltage charging part. As a result, it is not only necessary to stop the work to install and remove the indicator, but because the displayed contents can be seen up close, it is easy to check the live and dead lines, which greatly contributes to the safety of high-voltage work. Is.

The conventional charging indicator displays the presence / absence of the voltage of the charging part to which it is attached. Since the charging indicator of the present invention can be attached and used at the position indicated by the ● mark in FIG. 5, it can be provided with the meaning of a danger zone indication that must not be approached above this. In that respect, it is a major evolution in the function of the charging indicator, and it significantly increases the importance of the charging indicator as a safety measure for high-voltage work.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a circuit configuration of a charging indicator of the present invention attached to a ground side.

FIG. 2 is a diagram for explaining a display area of the charging indicator of the present invention.

FIG. 3 is a diagram showing another embodiment of the charging indicator of the present invention attached to the ground side.

FIG. 4 is a diagram for explaining the circuit configuration and operation of a conventional charging indicator.

FIG. 5 is a view showing a ground side attachment portion of the charging indicator.

FIG. 6 is a diagram for explaining the operation of a conventional charging indicator attached to the ground side.

FIG. 7 is a diagram showing a relationship between a current collecting plate current and an electric field of the charging indicator.

FIG. 8 is a diagram showing a relationship between a current collecting plate current and a circuit voltage of the charging indicator.

[Explanation of Codes] 2 Current Collector Plate 3 AC / DC Converter Circuit 4 Liquid Crystal Driving Circuit 5 Liquid Crystal Element 6 Voltage Discrimination Circuit 7 Switch Circuit 11 Charge Indicator of the Present Invention

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Isao Hori, 3-chome, Yoshino-cho, Nishibiwajima-cho, Nishikasugai-gun, Aichi Prefecture, Takachi Manufacturing Co., Ltd. Technical Development Center (72) Inventor Masanori Yamamoto Nishibashijima, Nishikasugai-gun, Aichi Prefecture 3-chome, Yoshino-cho, Takadake Manufacturing Co., Ltd. Technical Development Center

Claims (1)

[Claims] 1. Two sheets or one for detecting the presence or absence of a charge state
A sheet of current collector, an AC / DC converter that converts the AC output current of the current collector into DC, a liquid crystal drive circuit that outputs the DC voltage output from the AC / DC converter as a voltage waveform that drives the liquid crystal element, and this liquid crystal It is composed of a switch circuit provided between the drive circuit and the liquid crystal element, a liquid crystal element for displaying the presence / absence of a charged state, and a voltage discriminating circuit with a threshold value that can be set. The charging indicator is characterized in that the switch circuit is turned on by an output signal from the voltage discriminating circuit when the voltage becomes other than the threshold voltage set in the voltage discriminating circuit.