JPH05288790A - Overhead earth wire current sensor disconnection detector - Google Patents

Abstract

PURPOSE:To improve reliability of a system by connecting a power supply for applying an AC voltage a cross a current sensor coil, a relay for turning on or off voltage, and a resistor for measuring current which flows and then judging presence or absence of disconnection according to a phase difference of voltage which appears in the resistor. CONSTITUTION:A current sensor coil 1 is connected to an overhead earth wire, current which is proportional to current which flows in the overhead earth wire is allowed to flow to the coil 1, and voltage at both edges of the resistor 2 is measured by a measuring device 3, thus measuring current of the overhead earth wire. When detecting disconnection, a disconnection detection part 7 closes the switch of a relay 4 and applies a voltage of an AC power supply 6 to the coil 1 through a resistor 5. When the coil 1 is not disconnected, the phase of voltage which is applied to both edges of the coil 1 differs from that of current which flows. However, no phase difference is generated between voltage and current. The phase difference between the voltage and current is measured by a detection part 7, thus judging presence or absence of disconnection. A frequency of the AC power supply 6 which is not integer-multiples of the commercial frequency is used.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a device for detecting disconnection of a current sensor of an overhead ground wire of a transmission line accident point detection system using OPGW.

[0002]

2. Description of the Related Art A transmission line accident point detection system using an OPGW locates an accident point on the overhead ground line by installing a current sensor at every several towers along the transmission line and measuring the current value there. It is a thing. However, if the current sensor does not output, is there really no current flowing?
I can't tell if it's broken. If the current sensor is disconnected, there is a high possibility that the fault location will be abandoned.

Therefore, it is necessary to detect the disconnection of the current sensor.

FIG. 5 shows a current sensor section. In order to detect the disconnection of the current sensor, a method of switching between current measurement and disconnection detection by a switch 4 such as a relay and detecting disconnection as another circuit can be easily considered as shown in FIG. .

However, in the above-mentioned method, the reliability of the relay is low, so that the relay may break with a higher probability than the disconnection of the current sensor, and this method cannot be used.

Therefore, it is necessary to develop a highly reliable current sensor disconnection detection device.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide a highly reliable current sensor disconnection detecting device.

[0008]

That is, the gist of the present invention is to provide an overhead ground wire current sensor equipped with a current sensor coil, a resistance attached to both ends of the current sensor coil, and a voltage measuring device for measuring the voltage across the resistance. It consists of a power supply that applies an AC voltage to both ends of the coil, a relay that turns the voltage on and off, and a resistor for measuring the flowing current. An overhead ground wire current sensor disconnection detection device characterized by being configured to determine the presence or absence.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the current sensor coil 1 is attached to an overhead ground wire. A current flows through the current sensor coil 1 in proportion to the current flowing through the overhead ground wire, the current flows through the resistor 2, and the voltage across the resistor 2 is measured by the voltage measuring device 3
The current of the overhead ground wire is measured by measuring at.

When the wire breakage is detected, the wire breakage detection device 7 closes the switch of the relay 4, applies the voltage of the AC power supply 6 through the resistor 5, and applies the current sensor coil 1. When the current sensor coil 1 is not broken, the circuit is as shown in FIG. 2, and the phase of the voltage applied across the current sensor coil 1 is different from the phase of the flowing current. When the current sensor coil 1 is broken, the circuit is as shown in FIG. 3, and there is no phase difference between voltage and current. The disconnection detection unit 7 measures the phase difference between the voltage and the current, and determines the presence or absence of disconnection.

The frequency of the AC power source 6 is preferably a frequency that is not an integral multiple of the commercial frequency (50 or 60 Hz). This makes it possible to remove noise due to the commercial frequency.

FIG. 4 shows the construction of the disconnection detecting section 7.

The voltage across the current sensor coil 1 is input to the AD converter 8, converted into a digital signal, and sent to the digital filter 9. Digital filter 9
Passes only the frequency component of the AC power supply 6 in the sent digital signal.

On the other hand, similarly, the voltage across the resistor 5 is AD
It is input to the converter 8, converted into a digital signal, and sent to the digital filter 9. Digital filter 9
Passes only the frequency component of the AC power supply 6 in the sent digital signal. These two digital signals are sent to the phase difference calculation device 10 to calculate the phase difference. This signal is sent to the disconnection judging device 11. When performing the disconnection determination, the disconnection determination device 11 closes the switch of the relay 4 and determines the presence or absence of the disconnection based on the signal sent from the phase difference calculation device 10.

[0016]

As described above, according to the present invention, it is possible to realize an apparatus for diagnosing disconnection of a current sensor without impairing the reliability of the current sensor and without being affected by noise of commercial frequency. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a disconnection detection device of the present invention.

FIG. 2 is a circuit diagram when the current sensor coil is not broken in the present invention.

FIG. 3 is a circuit diagram when the current sensor coil is broken in the present invention.

FIG. 4 is a block diagram of an embodiment of a wire breakage detection unit used in the present invention.

FIG. 5 is a configuration diagram of a current sensor unit of an overhead ground wire.

FIG. 6 is an example of a disconnection detection device that can be easily considered.

[Explanation of symbols]

 1 Current Sensor Coil 2 Resistance 3 Voltage Measuring Device 4 Relay 5 Continuity Test Device 6 AC Power Supply 7 Disconnection Detection Unit 8 AD Converter 9 Digital Filter 10 Phase Difference Calculator 11 Disconnection Determination Device

Claims (3)

[Claims] 1. An overhead ground wire current sensor equipped with a current sensor coil, a resistance attached to both ends of the current sensor coil, and a voltage measuring device for measuring a voltage across the resistance, wherein an AC voltage is applied to both ends of the current sensor coil. It is configured by connecting an applied power source, a relay for turning on and off a voltage, and a resistor for measuring a flowing current, and is configured to judge whether or not the current sensor coil is broken by the phase difference of the voltage appearing in the resistor. An overhead ground wire current sensor disconnection detection device. 2. The overhead ground wire current sensor disconnection detection device according to claim 1, wherein the AC power supply applied to both ends of the current sensor coil is composed of an AC power supply having a frequency that is not an integral multiple of the commercial frequency. 3. A mechanism for determining the presence / absence of a wire break in a current sensor coil, an AD converter for measuring the voltage across the resistor, a digital filter that passes only a specific frequency, and the voltage levels of the two resistors. 3. The overhead ground wire current sensor disconnection detection device according to claim 1, comprising a phase difference calculation device for calculating a phase difference and a relay on / off control device.