JP2506744Y2 - Electric line accident detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION {Industrial application field} The present invention relates to an improvement of an electric line accident detection device.

{Prior Art} A Mare-type annulus testing device is known as an accident detection device for electric lines. However, since this known Mare-type device is a bridge type, there is a problem that its measuring operation is troublesome. The inventor of the present application has devised an electric line accident detection device that uses the voltage drop method as an alternative to the Mahle-type ring line test method. "Exploration device" was filed on October 8, 1987. This voltage drop method has a feature that the measurement operation is extremely easy as compared with the Mare type environmental test method. The present invention is a further development of the electric line accident detection device by the voltage drop method. Before the present invention is described, the contents of the existing application will be described.

FIG. 2 is a block diagram of a main part of an accident detection device by the voltage drop method developed by the inventor of the present application and already applied as described above. In the figure, DS is the accident investigation device and L is the electric line under test.

In the device DS, Es is a voltage source that outputs a constant DC voltage, and Rs is a resistor. L1 and L2 are line terminals (hereinafter, simply referred to as terminals), E is a ground terminal, and the terminal L2 is connected to a common potential point COM of the circuit. The positive side of the voltage source Es is a resistor R
It is connected to the terminal L1 via s, and the negative electrode side is connected to the terminal L2. A / D is an analog / digital converter, DP is a display, and this display is connected to the ground terminal E via the A / D converter. Both ends of the electric line L to be tested are connected to terminals L1 and L2 in such an exploration device DS. Electric line L
Is a telephone line, T represents a telephone station portion installed at a position approximately half the length of the electric line L. In the electric line L, Rl is a resistance value of the electric line L to the telephone station T, g is a ground fault point, and Rx is the electric line L from the terminal L2 to the ground fault point g.
Represents the resistance value of.

In the apparatus having such a configuration, the electric line L is connected to the terminals L1 and L2 and the terminal E is grounded for the measurement.
When the above connection is normally performed, the ground fault point g becomes the terminal L2 point when Rx = 0. In this case, the input of the A / D converter is 0 volt, and the display DP shows 0%. When Rl = Rx, the display DP displays 100%. In this case, the ground fault point g
Is the T point. If a ground fault occurs at point g in the figure, the voltage Ex represented by the following equation (1) is generated at the ground terminal E.

Ex = {Rx / (Rs + 2Rl)} · Es (1) The voltage Ex expressed by the equation (1) is added to the A / D converter and converted into a digital signal, and then its value is displayed on the display DP. Is displayed. In this case, since the voltage Es is a constant value and the resistance value (2Rl) of the electric line L is also constant, Ex is proportional to Rx. Therefore, with reference to the potential of the line terminal L2 connected to the negative side of the DC voltage source Es, 100% when Rx = Rl, Rx = 0
Is set to 0%, the position of the ground fault point g can be obtained by the display DP by the ratio (%) of the voltage drop occurring in the electric line L up to the point g and the voltage drop occurring in the entire electric line L. it can.

FIG. 3 is a diagram for explaining the above operation, in which the horizontal axis represents the resistance value of the electric line L and the vertical axis represents the display value of the display DP (voltage drop Ex).
Has been taken. In the embodiment, when Ex = 0 to 1 V, the display on the display DP is 0 to 100%. The value of the DC voltage source Es is 2V. By detecting the voltage at the ground fault point g, the location of the ground fault point g is displayed as a ratio of the voltage Ex to the display unit.
It can be calculated by DP.

Since the accident detection device using the voltage drop method is a direct-reading type, it has the characteristics that the measurement operation is easier and cheaper than the Mare-type environmental test method which is a bridge type.

However, in the case of such a proposed voltage drop method,
When the electric line L is not connected to the terminals L1 and L2 and the installation terminal E is not grounded, that is, a random voltage appears at the ground terminal E even if it is not connected, and this voltage is held, for example, and the display DP When it is displayed with, the displayed value is likely to be regarded as a measured value.

{Problems to be solved by the present invention} The present invention has been made to solve such problems, and the purpose thereof is to confirm that the measurement circuit is normally connected to each terminal by the display. The purpose of the present invention is to provide an accident exploration device by means of a voltage drop method equipped with means.

{Means for Solving the Problems} In order to achieve the above-mentioned object, the present invention provides that an electric line is normally connected to the line terminal between the line terminal to which the positive side of the DC voltage source is connected and the ground terminal. It is characterized by connecting a resistor to check that the grounding terminal is grounded. Examples will be described below.

〔Example〕

FIG. 1 is a connection diagram of an embodiment of the device according to the present invention. In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals as those in FIG. 1 and their re-explanation is omitted. In FIG. 1, FL is a filter and Rb is a resistor for checking that the measuring circuit is properly connected. Filter
The input end of FL is connected to the ground terminal E, and the output end is connected to the display DP via the A / D converter. One end of the resistor Rb is connected to the positive side of the voltage source Es and the other end is connected to the ground terminal E.

In the device of the present invention having the structure in which the checking resistor Rb is connected as described above, when each terminal is normally connected, the ground fault point g is calculated by the equation (1) described in FIG.
However, if the input impedance of the filter FL is high enough (for example, 10 MΩ) when it is not properly connected (1) Ground terminal E is open, that is, when terminal E is not grounded, this terminal E Voltage VE is almost DC voltage source
It becomes Es, and after this voltage is converted into a digital signal by the A / D converter, its value is displayed on the display DP.

(2) Voltage of ground terminal E when terminal L1 is open
VE becomes 0V, and the display DP displays 0.

(3) When the terminal L2 is open, the potential generated at the ground fault point g is in the adding direction to the voltage Es in the calculation, and the display DP has 100
% Or more, that is, overdisplay.

(4) As shown in FIG. 3, in the device according to the present invention, the telephone station T is set to (1/2) the length of the electric line L and the terminal L2
Between the telephone station T and the telephone station T is 100%, and the ground fault point g is displayed at 0 to 100%.
If it is between L1, the display is a value of 100% or more,
That is, it simply displays an over display.

As described above, the device of the present invention searches for the ground fault point g between the terminal L2 and the telephone station T, and between the terminal L1 and the telephone station T, that is, 10
The range between 0 and 200% is out of the measurement range.

In order to reduce the error of the ground fault point g, the electric line L
If the total resistance of Rb is Rl and the resistance of resistor Rb is Rb, then Rb>
The condition of> R1 is necessary, and actually Rb = 1000Rl.

{Effect of the present invention} As described above, in the present invention, in the electric line accident detection device by the voltage drop method, by providing a means for displaying 0 or over depending on whether the electric line is connected, the electric line connection You can check the situation.

Thus, according to the present invention, it is possible to obtain a fault detection device for an electric line with a simple structure, which is easy to perform a measurement operation and can check the presence / absence of connection to the terminal of the electric line with a display.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an embodiment of an electric line accident exploration device according to the present invention, FIG. 2 is a connection diagram of a device for explaining the present invention, and FIG. 3 is a device shown in FIGS. 6 is a diagram for explaining the operation of FIG. L1, L2: Line terminal, E: Ground terminal, Es: DC voltage source, FL: Filter, A / D: Analog / digital converter, DP: Display.

Claims (1)

(57) [Scope of utility model registration request] 1. A pair of line terminals L1 and L2 connected to the near ends of an electric line L under test in which the far ends of two parallel wires are short-circuited, the positive side of which is connected to the line terminal L1 and the negative side is the line terminal L2. A direct current voltage source Es connected to the ground terminal E, and a display portion DP connected to the ground terminal E via an analog / digital converter A / D, and the negative electrode side of the direct current voltage source Es is connected. With reference to the potential COM of the line terminal L2, the voltage drop to the ground fault point g that occurs during the length of about 1/2 of the electric line L is displayed on the display unit DP via the analog / digital converter A / D. By displaying it, the device is such that the ground fault point g of the electric line L is obtained, and both ends of the electric line L are connected to the line terminals L1 and L2 between the positive electrode side of the DC voltage source Es and the ground terminal E. To check that it is properly connected to and that the ground terminal E is grounded. Accident locator electrical line, characterized in that connecting the anti-vessel Rb.