JPH0611505Y2 - Electric line accident detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a device for searching for an accident point in a telephone power line.

[Conventional technology]

The Murray Ring Test Method is known as this type of exploration method. The device according to this test method consists of a Wheatstone bridge, and the side of the bridge is manually adjusted so that the reading of the galvanometer is "0". This is to find the ground fault point in the utility line.

The Murray type loop line test method as described above has been conventionally used as an accident detection method for telephone electric lines, but since it is a manual bridge method, the measurement operation is a manual operation and is troublesome.

As shown in (a) to (c) of Fig. 4, whether the "0" point is at the center of the scale A or if the scale A and the pointer B overlap each other. Can I have it? There is a problem such as.

With respect to the above points, the applicant of the present application filed a utility model registration application under the same date as the present invention under the name of the device, “accident search device for electric line”. The present invention is an improvement over the conventional Murray type test apparatus including the point of, but the apparatus applied for on the same date as the first point will be described below.

FIG. 2 is a block diagram of the exploration device filed on the same date as the present invention. In the figure, DS is the probing device, L is the electric line under test, and T is the central office. g represents an accident point (ground fault point or insulation inferior point) that occurred in this electric line.

In the device DS, CG is a comparison integrator, A / D is an analog / digital converter (hereinafter, referred to as A / D converter, P
Is a digital display, and + T and -T are terminals. Both ends of the electric line L are connected to terminals and + T and -T. G indicates a grounding point. The input side of the A / D converter is connected to the ground point G at the time of accident search.

In the comparative integrator CG, Es is a reference voltage source, Sw is a switch, R1 to R3 are resistors, and IG is an integrator including an operational amplifier OP and a capacitor C. The negative side of the reference voltage source Es is connected to the common COM, and the positive side is connected to the integrator IG via the switch Sw and the resistor R1. The addition point of the operational amplifier OP is connected to the terminal + T via the resistor R2, and the output end is connected to the terminal + T via the resistor R3.

In the device having such a configuration, both ends of the electric line L are connected to the terminals + T and -T, and then the input side of the A / D converter is connected to the ground point G. By turning on the switch Sw, the reference voltage Es is applied to the integrator IG and integrated. As a result, the output of the integrator IG gradually rises and then becomes a constant voltage Eι by the action of the resistor R2, and this constant voltage is applied between the terminals + T and -T. Here, it is assumed that an accident (for example, point g) has occurred somewhere on the electric line L. Rg represents a leak resistance generated between the accident point g and the ground point G. Here, assuming that the total resistance of the electric line L is 2Rι and the resistance of the electric line L from the terminal -T to the fault point g is Rx, the voltage Ex generated between the ground point G and the terminal -T is lower. It is expressed by equation (1).

Ex = (Rx / 2Rι) · Eι ... (1) The voltage Ex represented by the equation (1) is applied to the A / D converter and converted into a digital signal, and then the value is displayed on the display P. . In this case, since the voltage Eι is a constant value and the resistance value (2Rι) of the electric line L is also constant, Ex
Is proportional to Rx. Therefore, based on the terminal -T,
When Rx = Rι is set to 100% and Rx = 0 is set to 0%, the ratio of the voltage drop occurring in the electric line L up to the point g at the fault point g and the voltage drop occurring in the entire electric line L. (%).

FIG. 3 is a diagram for explaining the above operation, in which the horizontal axis represents the resistance value (Ω) of the electric line L and the vertical axis represents the voltage drop Ex occurring in the electric line L. In the embodiment, the display of the display P is 0 to 100% when Ex = 0 to 1V. When the switch Sw is turned on, the voltage Eι gradually increases and reaches a constant voltage of 2V. At this time, by detecting the voltage at the ground point G, the location of the accident point g can be obtained from the display P as the ratio of the entire voltage Ex.

In the device shown in FIG. 2, the device using the Wheatstone bridge in the related art can be automatically searched for an accident by using the voltage drop method, and the measurement operation can be extremely facilitated. That is, the above points are improved.

[Problems to be solved by the invention]

In such an electric line fault investigation apparatus of FIG. 2, it is necessary to check whether or not the circuit is balanced, like the bridge balance, after the power is turned on. That is, the present invention solves the above-mentioned problems and the above-mentioned problems, so that a voltage drop type electric line fault detection device can be used to easily determine whether or not the circuit is balanced. .

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides a balance state detection circuit including a light emitting element that emits light when the difference between the reference voltage and the line applied voltage is within a certain range. Hereinafter, examples will be described in detail.

〔Example〕

FIG. 1 is a block diagram of an embodiment of an electric line accident detection 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, SA is a difference voltage detection circuit, which receives the output voltage of the reference voltage source Es and the output voltage Eι of the comparison integrator CG applied to the terminal + T, and outputs the difference voltage ΔE of both inputs. ZA1 is a zecolonator to which the output of the differential voltage detection circuit DA is added. FL is a filter, A
M is an amplifier, which are connected in series between the terminal G and the A / D converter. DA is a differentiating circuit, which differentiates the voltage of the terminal G passing through the filter FL and the amplifier AM. ZA2 is a zero comparator, to which the output of the differentiating circuit DA is added. NG is a NAND gate, and LED is a light emitting diode. The outputs of the zero comparators ZA1 and ZA2 are added to the input terminal of the NAND gate NG, and NG
The output end of is connected to the voltage source + Vcc through the light emitting diode LED and the resistor R4. The operation of the device of the present invention having such a configuration will be described as follows. The part of the exploration device DS is exactly the same as that shown in FIG. 2, and therefore its explanation is omitted.

The reference voltage Es obtained via the switch Sw is applied to one input end of the difference voltage detection circuit SA, and the output voltage Eι of the comparison integrator CG is applied to the other input end. After the switch Sw is turned on, the output voltage Eι of the comparison integrator CG gradually rises and then becomes a constant value, and this voltage is applied between the terminals + T and -T. The difference voltage detection circuit SA detects the difference ΔE between Es and Eι, and when ΔE becomes “0” (or a certain range), the zero comparator ZA1 detects this. At this time, the output of ZA1 becomes "1" level. That is, if the applied voltage Eι of the electric line L is too low, or if a battery is used as the power source of the reference voltage Es, or if the battery is exhausted, Es and Eι do not match, so the zero comparator ZA1 Output remains at "0" level.

On the other hand, the detection voltage Ex generated between the terminals G and -T is differentiated by the differentiating circuit DA, and when the output becomes "0" (or a constant change range), this is detected by the zero comparator ZA2. At this time, the output of ZA2 becomes "1" level. That is, when there is noise or when Ex is not in a balanced state, the output of the zero comparator ZA2 remains at "0" level. The outputs of the zero comparators ZA1 and ZA2 are applied to the NAND gate NG. The output of the NAND gate NG becomes "0" when the outputs of the zero comparators ZA1 and ZA2 both become "1" bell, and as a result, the light emitting diode LEDA emits light. In this way, the outputs of the zero comparators ZA1 and ZA2 are both at the "1" level, that is, the state in which the entire circuit is balanced can be automatically known by the light emission of the light emitting diode LED. This shows that the measurement state can be entered.
That is, according to the present invention, the above-mentioned points are improved in the voltage drop method.

In the above-described embodiment, the case where two zero comparators ZA1 and ZA2 are used and their ORs are taken to detect the balanced state of the circuit has been described.
The provision of the zero comparator ZA2 side is for detecting a change in the voltage on the detection side when the line impedance is too high due to noise or the like and the response is long, and for example, this is detected voltage Ex. Is high speed, or when the noise can be considered to be within a certain range, the system of the zero comparator ZA2 may be omitted and only the circuit of ZA1 may be practically used. Also,
If the device of FIG. 1 is configured so that the output of the A / D converter is automatically held when the circuit is in a balanced state, there is an advantage that measurement values can be read easily.

[Effect of device]

As described above, according to the present invention, the accident detection device can be easily operated by the voltage drop method and can easily know the balance state of the circuit only by the light emission of the light emitting element such as the light emitting diode by pressing the switch Sw. Can be obtained. Moreover, since the balance state is detected by the light emission of the light emitting element in this way, it is suitable for field work such as in a dark area.

[Brief description of drawings]

1 is a connection diagram of an embodiment of the device according to the present invention, FIG. 2 is a diagram for explaining the device of FIG. 1, FIG. 3 is a diagram for explaining the operation of the device of FIG. FIG. 4 is a view for explaining the operation of a conventional device of this type. DS ... probing device, L ... telephone line, Es ... reference voltage source, CG ... comparative integrator, g ... accident point, G ... ground point, A /
D ... Analog / digital converter, P ... Display, SA ...
Differential voltage detection circuit, ZA1, ZA2 ... Zero comparator,
DA ... Differentiating circuit, LED ... Light emitting diode.

Claims (1)

[Scope of utility model registration request] 1. A pair of terminals to which both ends of an electric line are connected, a reference voltage is integrated to output a constant voltage, and the output voltage is supplied from one terminal of the pair of terminals to the electric line. And a measuring means for directly reading the voltage generated between the grounding point G and the other terminal of the pair of terminals, and an accident detection device configured to obtain an accident point of an electric line from the directly read value. An electric line accident detection device is provided with a balance state detection circuit including a light emitting element that emits light when the difference between the reference voltage and the line applied voltage is within a certain range.