KR100876651B1 - Method of leakage current break and measurement leakage current use phase calculation - Google Patents

Abstract

The present invention relates to a leakage current, in particular, by accurately measuring the resistive leakage current (Igr) and the capacitive leakage current (Igc) by using the leakage current measured in a state where the power is not shut off, and accurately determine the leakage of the cause of the accident. In addition, the present invention relates to a leakage current measurement and an earth leakage blocking method by calculating a phase angle that prevents unnecessary power interruption and prevents fire and short circuit accidents by applying this method to an earth leakage breaker.

The present invention provides a process for detecting the voltage value and the voltage phase between the power line and the neutral line of the device under measurement without interrupting the power supply, and the leakage current vector sum (Io) and the current phase flowing out of the power line and the neutral line. Two phases of detection, the line voltage value and the voltage phase, the leakage current vector sum value Io and the current phase, the phase angle θ, the resistive leakage current Igr, the capacitive leakage current Igc, It characterized in that it comprises three steps of calculating the insulation resistance value (M Ω) and outputs it to the liquid crystal display.

Live state, current transformer (ZCT), vector sum, phase angle, resistive leakage current, capacitive leakage current, insulation resistance.

Description

Leakage current measurement and leakage current interruption method by phase angle calculation {Method of leakage current break and measurement leakage current use phase calculation}

1 is a diagram showing a case in which the vector sum Io is the same but the magnitudes of the resistive leakage current and the capacitive leakage current are different.

2 is a general equivalent circuit of a low voltage line and a leakage current vector diagram thereof.

3 is a diagram for explaining a phase difference between a resistive leakage current Igr and a capacitive leakage current Igc.

4 is a configuration diagram for measuring insulation resistance in a conventional manner.

5 is a schematic diagram of a clamp leakage meter for measuring a leakage current.

6 is a screen measured using a conventional leakage ammeter.

7 is a block diagram of a leakage current measuring device by calculating the phase angle of the present invention.

Figure 8 is a flow chart of the leakage current measurement operation by calculating the phase angle of the present invention.

9 is a configuration diagram of an earth leakage breaker by calculating a phase angle of the present invention.

10 is a characteristic graph for the operation of the ground fault interrupting method and the conventional ground fault interrupter according to the present invention;

11 is a flowchart illustrating the operation of the earth leakage breaker by calculating the phase angle of the present invention.

It is an example of the measured value displayed on the liquid crystal display part of the leakage current measuring apparatus by phase angle calculation of this invention.

<Description of Major Symbols in Drawing>

20: voltage application part 22: decompression transformer

24: Harmonic and noise canceling filter 1 26: Voltage phase detection unit

28: phase angle calculator 40: current sensing clamp

42 current sensing circuit 44 amplification circuit

46: Harmonic and Noise Rejection Filter 2 48: Current Measuring A / D Converter

50: current phase detection unit 52: leakage current analysis circuit

54 liquid crystal display 56 earth leakage breaker control circuit

The present invention relates to leakage current measurement and ground fault interruption. The risk of an accident by separately measuring the resistive leakage current (Igr) and the capacitive leakage current (Igc) by using the leakage current measured without shutting off the power supply. In addition to the leakage current measuring device that can easily determine the degree of the leakage current (Igr), the leakage current measurement and leakage interruption method by the phase angle calculation that applies this method also to the leakage current circuit breaker It is about.

In general, when the covering of wires and the insulation of electrical equipment are aged or damaged, the insulator is damaged so that the leakage current flows from the wire path to the ground through the location. If the human body touches the place where the leakage current flows, there is a risk of electric shock.In the area where the excessive leakage current flows, overheating occurs due to the arc, and it is ignited by the flammable material around it, which causes the leakage material.

On the other hand, in order to prevent the occurrence of a short circuit accident, Article 52 (Insulation performance of low voltage line) of Article 2006-65 of 2006. The insulation resistance between the voltage-side wire and the middle conductor or earth shall be at least 0.2MΩ. " It is described.

If insulation resistance is more than 0.2MΩ in 220V commercial power supply, the leakage current is (220V / 0.2MΩ = 0.0011A) 1.1mA or less, so if the leakage current can be measured accurately in live state without power off, insulation resistance between wire and earth However, a commercially available live leakage leak clamp (Leakage Clamp) has a technical disadvantage in that it is impossible to accurately measure the leakage current.

Hereinafter, the contents regarding the conventional leakage current measurement will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a case in which the vector sum Io is the same but the magnitudes of the resistive leakage current and the capacitive leakage current are different.

Referring to FIG. 1, the leakage current vector sum Io is equal to 5.1 mA, but the magnitudes of the resistive leakage current Igr and the capacitive leakage current Igc are not equal. In the magnitude of the resistive leakage current (Igr), the left side is 5 mA but the right side is 1 mA. In the magnitude of the capacitive leakage current (Igc), the characteristics are different as the left side is 1 mA and the right side is 5 mA, but both have a leakage current vector sum (Io). The same is displayed at 5.1mA.

The resistive leakage current (Igr) is the actual leakage caused by the aging or damage of the line, but the capacitive leakage current (Igc) is higher than the leakage current and the commercial frequency due to the capacitance component of the capacitance existing between the line and the ground. It is caused by the harmonic leakage current generated from the switching mode power supply (SMPS) used in DC power supply such as inverter, computer and printer which controls voltage by switching method at frequency, so the accurate measured value of resistive leakage current (Igr) Corresponds to the measured value to confirm the soundness. In this case, the sum of the capacitive leakage current and the harmonic leakage current is referred to as Igc.

2 is a general equivalent circuit of a low voltage line and a leakage current vector diagram thereof.

In FIG. 2, the phase of the resistive leakage current Igr is the same as the line voltage V, but the capacitive leakage current Igc is 90 degrees ahead of the phase of the line voltage Vo and the magnitude of the capacitive leakage current Igc. As a result, the phase angle θ becomes large.

Existing leakage current meters only measure and display the magnitude of the vector sum (Io) of the resistive leakage current (Igr) and the capacitive leakage current (Igc), so it is possible to measure the magnitude of the actually dangerous resistive leakage current caused by the aging of the line. The current situation is that it is difficult to make accurate short circuit judgment.

3 is a diagram illustrating a phase difference between the resistive leakage current Igr and the capacitive leakage current Igc.

Referring to FIG. 3, since the resistive leakage current Igr is in phase without voltage and phase difference, and the capacitive leakage current Igc is 90 degrees ahead of the voltage, the resistive leakage current Igr and the capacitive leakage current Igc. When are present together, the size and phase angle of the vector sum are determined according to the respective sizes.

In FIG. 3, the phase angle θ is 0 degrees because the resistive leakage current Igr is the denominator and the capacitive leakage current Igc is the tangent angle of the molecule, so that only the resistive leakage current Igr is 0 degrees, and the capacitive leakage current Igc is obtained. If it is, the maximum is 90 degrees.

4 is a configuration diagram for measuring insulation resistance in a conventional manner.

In general, the insulation resistance measuring instrument (Megger) adopts a method of measuring insulation between the line and the ground by generating a voltage of about 500V from the measuring instrument's own circuit and applying it to the line. That is, if the leakage current is measured as 1mA by applying 500V supplied from the insulation resistance measuring instrument (Megger), the insulation resistance is (500V ÷ 1mA) 0.5MΩ.

The megger of FIG. 4 can accurately measure the insulation resistance, but should be measured in the state of power failure, so that the measurement can be made in the insulation resistance meter when measuring in an industrial site in which information communication equipment or an automated production line is operated for 24 hours. Equipment rated for lower than the voltage to be sent may damage the machine itself. Therefore, all power cords inserted into the machine must be removed from the outlet and measured.

5 is a schematic diagram of a clamp leakage meter for measuring a leakage current.

The principle of measuring the leakage current is to measure the difference between the input current and the output current applied to the load by installing an image current transformer (ZCT) outside the power line (L) and the neutral line (N).

In FIG. 5, when the input current is 90 mA and the output current is 80 mA, a leakage current of 10 mA is generated. However, 10mA (90mA-80mA), which is the difference between input and output, is not a leakage current, and a resistive leakage current (Igr) or capacitive leakage current (Igc) can be generated arbitrarily, so its vector sum (Io) is 10mA. Is displayed.

Therefore, the conventional clamp leakage meter (Clamp Leakage Meter) is a vector sum (Io) of the resistive leakage current (Igr) and the capacitive leakage current (Igr) distributed between the line and the ground, so that substantially caused by the line degradation It is impossible to measure only dangerous resistive leakage current. Therefore, if the leakage current of a large value is measured first by using a clamp leakage meter (Clamp Leakage Meter), it is inconvenient because the insulation resistance must be repeatedly measured by the insulation resistance meter (Megger) described in FIG.

In addition, FIG. 6 is an example of a screen measured using a conventional leakage current meter, and shows that the resistive leakage current Igr and the capacitive leakage current Igr are not provided separately and are represented only by the vector sum Io.

As mentioned above, the megger used for measuring leakage current is measured after the power is cut off, so it is not applicable to telecommunication equipment or 24 hours a day low voltage line with automated production line. It is difficult to apply to the equipment because it can be damaged at DC 500V or higher, and the clamp leakage meter is measured in live state, but it is provided as vector sum of leakage current (Io) to prevent electric shock and fire due to actual leakage. It is not possible to measure only the resistive leakage current (Igr) which is dangerous, and to measure this, it is very inconvenient to measure the leakage current since the power supply must be shut off and an insulation resistance meter (Megger) is used.

The present invention is to solve the above-described problems, the object of the present invention is to cut off the power to low-voltage line installed telecommunication equipment or automated production line operating 24 hours, there is a risk of electric shock accident and fire due to the actual leakage The present invention provides a leakage current measurement method and a leakage current interruption method by calculating a phase angle to easily determine whether an abnormality of a corresponding device is detected by accurately measuring a resistive leakage current (Igr) at a time.

In addition, the object of the present invention is to use the resistive leakage current (Igr), the capacitive leakage current (Igc), the insulation resistance (MΩ) by using the leakage current measured by the line voltage and the image current transformer (ZCT) in the state that the power is not cut off. ) Measurement and analysis of measurement information such as phase angle (θ) can be used to prevent electric shock and fire accidents caused by a short circuit or to be resistant to capacitive leakage current and to be sensitive to resistive short circuit current. The present invention provides a leakage current measurement and an earth leakage blocking method by calculating a phase angle applicable to a circuit.

It is also an object of the present invention to implement a leakage current measuring method by applying a leakage current measuring method, and to provide a leakage current measuring method and a leakage current blocking method by calculating a phase angle that implements a ground fault circuit breaker by applying a ground fault interrupting method.

Leakage current measuring method by calculating the phase angle of the present invention for achieving the above object is one step of detecting the voltage value and the voltage phase between the power supply line and the neutral line of the device under measurement without interrupting the power supply, and Phase angle (θ) using two steps of detecting the leakage current vector sum value Io and the current phase flowing out of the neutral line, and using the line voltage value and the voltage phase, the leakage current vector sum value Io and the current phase. ), The resistive leakage current Igr, the capacitive leakage current Igc, and the insulation resistance value MΩ are calculated and output to the liquid crystal display.

In addition, the above-described step 1 is connected to the power line and the neutral line to measure the line voltage of the device under measurement, receiving a voltage from a voltage applying unit, and reducing the AC 220V voltage in a decompression transformer, and harmonics and noise removing filter 1 Receiving the output of the decompression transformer and passing only the 50/60 Hz voltage, which is a commercial power frequency, and removing and outputting harmonics and noise; and receiving the output of the harmonics and noise removing filter 1 to receive the voltage phase at the voltage phase detection unit. Detecting and providing the phase angle calculator to the phase angle calculator; and converting the analog voltage value provided by the harmonic and noise reduction filter 1 into a voltage value between the analog line and the digital resistance line by the voltage measurement A / D converter. It features.

Also. In the above-described two steps, in order to measure the voltage between the lines and the leakage current, the steps of measuring the current difference by using the current sensing clamp on the outside of the power line and the neutral line, and transmitting from the current sensing clamp in the current sensing circuit Sensing the amount of current to be amplified in the amplification circuit, and passing only 50/60 Hz current, which is a commercial power source frequency, in the harmonic and noise removal filter 2, and removing harmonics and noise, and in the current phase detection unit in the harmonic and noise removal filter 2 Detecting and transmitting a phase of the provided current to a phase angle calculator, and converting an analog current value provided by the harmonic and noise removing filter 2 into a digital leakage current vector sum value Io in a current measuring A / D converter. And transmitting to the leakage current analysis circuit.

Also. In the above-described three steps, the insulation resistance calculation unit divides the line voltage value received from the voltage measuring A / D converter by the resistive leakage current value Igr received from the leakage current analysis session, and calculates the insulation voltage. Calculating a phase angle using the obtained voltage phase and current phase, and calculating a resistive leakage current (Igr) and a capacitive leakage current (Igc) using the leakage current vector sum value (Io) and the phase angle. And outputting to a display unit.

In addition, the earth leakage blocking method by calculating the phase angle of the present invention is connected to both ends of the power line and the neutral line to detect the line voltage value and the voltage phase, and connected to the outside of the power line and the neutral line leakage current vector sum value (Io ) And 6 phases of detecting the current phase, the line voltage value and the voltage phase, the leakage current vector sum value Io and the current phase, and the phase angle θ, the resistive leakage current Igr, and the capacitive leakage. And calculating a current Igc and an insulation resistance value MΩ and determining the magnitude of the resistive leakage current and the capacitive leakage current to cut off the power supply in the leakage current analysis circuit.

In addition, the above-described seven steps of the present invention includes the steps of receiving the line voltage value in the voltage measurement A / D converter in the insulation resistance calculation unit, receiving the resistive leakage current value Igr from the leakage current analysis circuit, and Calculating an insulation potential by dividing the resistive leakage current (Igr), calculating a phase angle using the voltage phase and the current phase received by the phase angle calculator, and a leakage current vector sum value (Io) and the phase angle. Calculating a resistive leakage current (Igr) and a capacitive leakage current (Igc) and outputting the same to the leakage current analysis circuit unit; and in the leakage current analysis circuit, the resistive leakage current (Igr) and the capacitive leakage current (Igc) values And distinguishing and controlling the operation of the ground fault circuit breaker.

In addition, the leakage current analysis circuit of the present invention operates the circuit breaker control circuit when the resistive leakage current Igr value reaches the capacitance-specific reference value, and the capacitive leakage current Igc value is the resistive leakage current Igr. When the value is between 3 and 5 times, it characterized in that it comprises operating the earth leakage breaker control circuit.

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

It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted.

To accurately measure the insulation of a line to prevent electric shocks and fires caused by a short circuit, the capacitive leakage current (Igc) caused by the impedance component of the line-to-earth capacitance and the harmonic leakage current generated by the device itself Except for the components, the resistive leakage current (Igr) flowing between the low voltage line and the ground due to aging of the line or damage to the insulator must be accurately measured and calculated in a live state, and the present invention implements this.

That is, the present invention can accurately measure the resistive leakage current (Igr) and the capacitive leakage current (Igc) in the live state, thereby preventing electric shock accidents and fires caused by leakage.

7 is a configuration diagram of the leakage current measuring apparatus by calculating the phase angle of the present invention.

Referring to FIG. 7, the voltage applying unit 20 for measuring the line voltage is connected to the power line and the neutral line of the device under measurement, receives the voltage, and provides the voltage to the decompression transformer 22. Reduce the AC 220V voltage to an appropriate low voltage.

 The harmonic and noise removal filter 1 (24) passes only a 50/60 Hz voltage, which is a commercial power supply frequency, and removes noise. The voltage phase detection unit 26 grasps the phase of the voltage provided from the harmonic and noise removal filter 1 (24). To the phase angle calculator 28.

The voltage measuring A / D converter 30 converts the analog voltage value provided from the harmonic and noise removing filter 1 24 into a digital signal and transmits the converted digital signal to the insulation resistance calculator 32.

On the other hand, the current sensing clamp 40 (image transformer: ZCT) measures the current difference between the power line and the neutral line of the device to be measured, the current sensing circuit 42 grasps the amount of current measured by the current sensing clamp 40 The amplification circuit 44 amplifies, and the harmonics and noise removing filter 2 46 passes only a 60 Hz current which is a commercial power supply frequency.

The current measuring A / D converter 48 converts the analog current value provided by the harmonic and noise canceling filter 2 46 into a digital value and transmits it to the leakage current analysis circuit 52.

The insulation resistance calculator 32 calculates insulation resistance using the line voltage provided from the voltage measuring A / D converter 30 and the resistive leakage current Igr provided from the leakage current analysis circuit 52 to calculate the liquid crystal as follows. Output to display unit 54.

Insulation resistance (MΩ) = voltage of the power line and neutral wire / resistive leakage current (Igr)

In addition, the current phase detection unit 50 detects a phase from the current provided by the harmonic and noise removing filter 2 46 and transmits the phase to the phase angle calculation unit 28.

The phase angle calculator 28 calculates the phase angle by using the voltage phase value provided from the voltage phase detector 26 and the current phase value provided from the current phase detector 50, and the leakage current analysis circuit 52 performs the phase. The resistive leakage current Igr and the capacitive leakage current Igc are calculated by using the leakage current vector sum Io measured by the phase angle and the current measurement A / D converter 48 provided by each calculation unit 28. Output to the liquid crystal display unit 54.

The resistive leakage current Igr and the capacitive leakage current Igc are simply calculated from the following equation using the leakage current vector sum Io and the phase angle θ.

Resistive leakage current (Igr) = leakage current vector sum (Io) * Cosθ

Capacitive Leakage Current (Igc) = Leakage Current Vector Sum (Io) * Sinθ

8 is a flowchart illustrating a leakage current measurement operation by calculating a phase angle of the present invention.

First, in step 200, the voltage applying unit 20 is connected to a power line and a neutral line to receive a voltage and provides the voltage to the decompression transformer 22 to measure the line voltage, and in the decompression transformer 22, an appropriate AC 220V voltage at a low voltage. The harmonic and noise removal filter 1 (24) passes only a 60 Hz voltage, which is a commercial power supply frequency, and removes the noise.

In steps 210 to 230, the voltage phase detector 26 detects a phase from the voltage provided by the harmonic and noise removing filter 1 24 and provides the phase angle calculator 28.

In addition, the analog voltage value provided by the harmonic and noise removing filter 1 24 is converted into a digital signal by the voltage measuring A / D converter 30 and transmitted to the insulation resistance calculator 32.

In order to measure the voltage difference and the line current difference at the same time in step 240, a current sensing clamp 40 called a ZCT is connected to the outside of the power line and the neutral line of the device under measurement to measure the current difference between the power line and the neutral line. The current sensing circuit 42 senses the amount of current transmitted from the current sensing clamp 40 and amplifies it in the amplifying circuit 44. The harmonic and noise removing filter 2 46 passes only a 60 Hz current which is a commercial power supply frequency.

In step 250, the current phase detector 50 detects a phase of the current provided from the harmonic and noise removing filter 2 46 and transmits the phase to the phase angle calculator 28.

In step 260, the current measurement A / D converter 48 converts the analog current value provided by the harmonic and noise canceling filter 2 46 into a digital value and transmits it to the leakage current analysis circuit 52.

In operation 270, the phase angle calculator 28 calculates the phase angle θ using the voltage phase value provided from the voltage phase detector 26 and the current phase value provided from the current phase detector 50.

In step 280, the insulation resistance calculator 32 uses the digital line voltage value provided by the voltage measuring A / D converter 30 and the digital resistive leakage current Igr provided by the leakage current analysis circuit 52 to calculate the insulation resistance. It calculates and outputs it to the liquid crystal display 54.

Insulation resistance (MΩ) = voltage of the power line and neutral wire / resistive leakage current (Igr)

In step 290, the leakage current analysis circuit 52 uses the phase current? And the leakage current vector sum Io measured by the current measuring A / D converter 48 to provide a resistive leakage current ( Igr) and the capacitive leakage current Igc are calculated and output to the liquid crystal display 54.

The resistive leakage current Igr and the capacitive leakage current Igc are simply calculated from the following equation using the leakage current vector sum Io and the phase angle θ.

Resistive leakage current (Igr) = leakage current vector sum (Io) * Cosθ

Capacitive Leakage Current (Igc) = Leakage Current Vector Sum (Io) * Sinθ

Since the liquid crystal display 54 displays the leakage current vector sum Io, the phase angle θ, the resistive leakage current Igr, the capacitive leakage current Igc, and the insulation resistance MΩ in step 300, The device can determine whether there is a risk of electric shock or fire due to a short circuit without a power cut. It is also applied to the circuit breaker control circuit so that it is resistant to capacitive leakage current and sensitive to resistive leakage current.

9 is a configuration diagram of an earth leakage breaker by calculating a phase angle of the present invention.

9 is a circuit breaker control circuit 56 is added to the leakage current measuring apparatus of FIG. 7 except for the voltage measuring A / D converter 30, the insulation resistance calculator 32, and the liquid crystal display 54.

The leakage current analysis circuit 52 reacts sensitively to the resistive leakage current Igr causing the accident, and controls the leakage breaker control circuit 56 so as to be resistant to the directional leakage current Igc.

Referring to FIG. 9, the voltage applying unit 20 for measuring the line voltage is connected to a power supply line and a neutral line to receive a voltage and provide the voltage to the decompression transformer 22, and the decompression transformer 22 supplies an AC 220V voltage. Lower to an appropriate low voltage.

 The harmonic and noise removal filter 1 (24) passes only a 50/60 Hz voltage, which is a commercial power supply frequency, and removes noise. The voltage phase detection unit 26 grasps the phase of the voltage provided from the harmonic and noise removal filter 1 (24). To the phase angle calculator 28.

On the other hand, the current sensing clamp 40 measures the current difference between the power line and the neutral line of the device under measurement, the current sensing circuit 42 grasps the amount of current measured by the current sensing clamp 40 and amplified by the amplification circuit 44 The harmonic and noise removing filter 2 46 passes only a 60 Hz current which is a commercial power supply frequency.

The current measuring A / D converter 48 converts the analog current value provided by the harmonic and noise canceling filter 2 46 into a digital value and transmits it to the leakage current analysis circuit 52.

In addition, the current phase detection unit 50 detects the phase of the current provided from the harmonic and noise removing filter 2 (46) and transmits it to the phase angle calculator (28).

The phase angle calculator 28 calculates the phase angle by using the voltage phase value provided from the voltage phase detector 26 and the current phase value provided from the current phase detector 50, and the leakage current analysis circuit 52 performs the phase. The resistive leakage current Igr and the capacitive leakage current Igc are calculated using the phase angles provided by the calculation units 28 and the leakage current vector sum Io measured by the current measurement A / D converter 48. .

The resistive leakage current Igr and the capacitive leakage current Igc are simply calculated from the following equation using the leakage current vector sum Io and the phase angle θ.

Resistive leakage current (Igr) = leakage current vector sum (Io) * Cosθ

Capacitive Leakage Current (Igc) = Leakage Current Vector Sum (Io) * Sinθ

The leakage current analysis circuit 52 controls the ground fault breaker control circuit 56 to cut off the power supply when the ground fault breaker is required by using the resistive leakage current Igr and the capacitive leakage current Igc.

In the present invention, the leakage current analysis circuit 52 cuts off 70 to 80% of the capacitance by using a vector sum (Io) as in the prior art. The present invention distinguishes the resistive leakage current (Igr) from the capacitive leakage current (Igc). Therefore, the power supply is cut off when the resistive leakage current causing the accident is high, and the power supply is not cut off when only the capacitive leakage current is high.

10 is a graph comparing the characteristics of the operation of the earth leakage breaker according to the present invention and the conventional earth leakage breaker.

10 shows the resistive leakage current Igr, and the length shows the capacitive leakage current Igc.

10A and 10B show the operation characteristics of the conventional ground fault circuit breaker, and in the case of A, a 15 mA earth leakage breaker can be seen to cut off power based on the vector sum Io. That is, the ground fault circuit breaker was operated at about 11 mA, either capacitive leakage current or resistive leakage current.

In the case of B, a 30 mA earth leakage breaker, like A, turns off the power based on the vector sum (Io). In other words, the circuit breaker was operated at about 27mA for either capacitive leakage current or resistive leakage current.

In the case of B, this is an example of blocking at 90% of the reference dose.

Therefore, the conventional circuit breaker has a problem in that the power is cut off unnecessarily.

C and D in Fig. 10 are examples of the case where the earth leakage breaker of the present invention is applied.

In the case of C, as in the case of the conventional A earth leakage breaker, a 15 mA earth leakage breaker for home use operates the earth leakage breaker at 11 mA, which may cause an electric accident or fire, but in the case of the capacitive leakage current Igc, Unlike the conventional case, the circuit breaker operates at about 55 mA.

That is, the earth leakage breaker of the present invention applies the resistive leakage current as it is, but cuts off the power when the magnitude of the capacitive leakage current is about 5 times larger than the resistive leakage current Igc.

In the example of D, a 30 mA earth leakage circuit breaker commonly used in factories, such as a conventional earth leakage circuit breaker, operates an earth leakage circuit breaker when the resistive earth leakage current (Igc) is 22 mA, but in the case of a capacitive leakage current (Igc), it is weak. Leakage cut-off operation at 76mA.

Looking at the example of the D graph as shown in C, the earth leakage breaker of the present invention applies the resistive earth leakage current as it is, but cuts off the power supply when the magnitude of the capacitive leakage current is about 3 times or more.

As described above, the present invention operates sensitively to high resistive leakage current related to an accident but does not operate sensitively to capacitive leakage current.

11 is a flowchart illustrating an operation of a leakage current circuit breaker by calculating a phase angle of the present invention.

First, in step 500, the voltage applying unit 20 is connected to a power supply line and a neutral line to receive a voltage and provides the voltage to the decompression transformer 22 to measure the line voltage. The harmonic and noise removal filter 1 (24) passes only a 60 Hz voltage, which is a commercial power supply frequency, and removes the noise.

In operation 510 to 530, the voltage phase detector 26 detects a phase from the voltage provided by the harmonic and noise removing filter 1 24 and provides the phase angle calculator 28.

In step 540, the current sensing clamp 40 called a current transformer (ZCT) is connected to the outside of the power line and the neutral line of the device under test to measure the current difference between the power line and the neutral line. The current sensing circuit 42 senses the amount of current transmitted from the current sensing clamp 40 and amplifies it in the amplifying circuit 44. The harmonic and noise removing filter 2 46 passes only a 60 Hz current which is a commercial power frequency.

In operation 550, the current phase detector 50 detects a phase of the current provided from the harmonic and noise removing filter 2 46 and transmits the phase to the phase angle calculator 28.

In step 560, the current measurement A / D converter 48 converts the analog current value provided from the harmonic and noise canceling filter 2 46 into a digital value and transmits it to the leakage current analysis circuit 52.

In operation 570, the phase angle calculator 28 calculates the phase angle θ using the voltage phase value provided from the voltage phase detector 26 and the current phase value provided from the current phase detector 50.

In step 590, the leakage current analysis circuit 52 uses the phase current θ provided by the phase angle calculator 28 and the leakage current vector sum Io measured by the current measurement A / D converter 48 to generate a resistive leakage current ( Igr) and the capacitive leakage current (Igc) are calculated.

The resistive leakage current Igr and the capacitive leakage current Igc are simply calculated in the manner described above for the leakage current vector sum Io and the phase angle θ.

Resistive leakage current (Igr) = leakage current vector sum (Io) * Cosθ

Capacitive Leakage Current (Igc) = Leakage Current Vector Sum (Io) * Sinθ

In step 600, the leakage current analysis circuit 52 blocks when the 70-80% of the capacity is blocked by using the vector sum (Io) as in the prior art. The present invention provides a resistive leakage current (Igr) and a capacitive leakage current (Igc). ), The power supply is cut off when the resistive leakage current causing the accident is high, and the capacitive leakage current is cut off when the capacitive leakage current reaches about 3 ~ 5 times the resistance leakage current.

Fig. 12 shows an example of measured values displayed on the liquid crystal display of the leakage current measuring device by calculating the phase angle of the present invention.

On the screen of the liquid crystal display 54 of FIG. 12, when the user measures the leakage current in the device under measurement, the leakage current vector sum Io, the phase angle θ, the resistive leakage current Igr, and the capacitive leakage current Igc ), Insulation resistance (MΩ) can be seen at a glance.

The present invention calculates the phase angle of the voltage and the current with respect to the resistive leakage current and the capacitive leakage current existing between the line and the ground, and distinguishes the resistive leakage current (Igr) and the capacitive leakage current (Igc) in the actual line state. Easily determine the risk of leakage in actual line conditions

 So far, the configuration and operation of the embodiment of the present invention have been described. The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims but also by the equivalents of the claims.

According to the present invention, when the leakage current is measured, the leakage current vector sum (Io), the phase angle (θ), the resistive leakage current (Igr), the capacitive leakage current (Igc), and the insulation resistance (MΩ) are measured at once in the liquid crystal display. It is possible to accurately understand the line status of the device under measurement by one measurement, and it is very convenient to work by simply detecting the detection of the actual leakage, and it is possible to reduce the electric shock and fire accident caused by the leakage by detecting the accurate leakage. It has an effect.

In addition, the method of controlling the earth leakage breaker according to the present invention applies the measured resistive earth leakage current Igr to the control circuit of the earth leakage breaker so that it operates sensitively to the resistive earth leakage current Igr but insensitive to capacitive leakage current Igc. Accurate and safe earth leakage blocking effect is effective.

Therefore, the present invention can implement a leakage current measuring device that accurately measures the leakage current during operation without shutting off the power by using the leakage current measuring method, and also by applying the leakage blocking method, it is accurate and prevents the leakage of the short circuit accident. It is possible to implement a leakage current circuit breaker.

Claims (11)

delete In order to measure the line voltage of the device under measurement without interrupting the power supply, it is connected to the power line and the neutral line and inputs the voltage from the voltage applying section to reduce the AC 220V voltage in the decompression transformer, and the decompression transformer in the harmonic and noise removing filter 1. Receives the output of and passes only the 50 / 60Hz voltage, which is the commercial power frequency, removes harmonics and noise, and outputs it.The output of the harmonics and noise removal filter 1 is received, and the voltage phase detection unit detects the voltage phase. A first step of converting an analog voltage value provided by the harmonic and noise removing filter 1 into a digital line voltage value in a voltage measuring A / D converter and transmitting it to an insulation resistance calculator; Connected to the outside of the power line and the neutral line to detect a leakage current vector sum (Io) and a current phase; The phase angle θ, the resistive leakage current Igr, the capacitive leakage current Igc, and the insulation resistance value MM are obtained by using the line voltage value, the voltage phase, the leakage current vector sum value Io, and the current phase. ) And a three-step process of calculating the output to the liquid crystal display unit. The method of claim 2, The second process, Measuring a current difference by installing the power supply line and the neutral line outside of the power line using a current sensing clamp to measure the leakage current simultaneously with the measurement of the line voltage; Sensing the amount of current transmitted from the current sensing clamp in the current sensing circuit and amplifying it in the amplifying circuit, and passing only 50/60 Hz current of commercial power frequency in the harmonic and noise removing filter 2 and removing harmonics and noise; Detecting a phase of a current provided from the harmonic and noise removing filter 2 by a current phase detector and transmitting the phase to the phase angle calculator; And converting the analog current value provided by the harmonic and noise canceling filter 2 into a digital leakage current vector sum value (Io) in the current measuring A / D converter and transmitting it to the leakage current analysis circuit. Leakage current measurement method by calculation. The method of claim 2, The above three steps, Receiving the line voltage value from the voltage measuring A / D converter in the insulation resistance calculating unit and receiving the resistive leakage current value Igr from the leakage current analysis session; Calculating an insulation potential by dividing the line voltage value by a resistive leakage current (Igr); Calculating a phase angle using the voltage phase and the current phase received by the phase angle calculator; Calculating a resistive leakage current (Igr) and a capacitive leakage current (Igc) by using the leakage current vector sum value (Io) and the phase angle, and outputting the capacitive leakage current (Igc) to a liquid crystal display. Leakage current measurement method delete delete delete It is connected to both the power line and the neutral line, and receives the voltage from the voltage applying unit to reduce the AC 220V voltage in the decompression transformer, and receives the output of the decompression transformer from the harmonic and noise removal filter 1 to pass only the 50 / 60Hz voltage which is the commercial power frequency. 5 processes of removing the harmonics and noise, and receiving the output of the harmonics and noise removing filter 1, detecting the voltage phase from the voltage phase detection unit and providing the voltage phase to the phase angle calculator; A sixth process connected to the outside of the power line and the neutral line to detect a leakage current vector sum value (Io) and a current phase; The phase angle θ, the resistive leakage current Igr, and the capacitive leakage current Igc are calculated using the line voltage value, the voltage phase, the leakage current vector sum value Io, and the current phase. And a seven-step process of interrupting the power supply in the leakage current analysis circuit by determining the current and the magnitude of the capacitive leakage current. The method of claim 8, The above six steps, Measuring a current difference by installing the power supply line and the neutral line outside of the power line using a current sensing clamp to measure the leakage current simultaneously with the measurement of the line voltage; Sensing the amount of current transmitted from the current sensing clamp in the current sensing circuit and amplifying it in the amplifying circuit, and passing only 50/60 Hz current of commercial power frequency in the harmonic and noise removing filter 2 and removing harmonics and noise; Detecting a phase of a current provided from the harmonic and noise removing filter 2 by a current phase detector and transmitting the phase to the phase angle calculator; And converting the analog current value provided by the harmonic and noise canceling filter 2 into a digital leakage current vector sum value (Io) in the current measuring A / D converter and transmitting it to the leakage current analysis circuit. Leakage blocking method by calculation. The method of claim 8, The seven steps, Calculating a phase angle using the voltage phase and the current phase received by the phase angle calculator; Calculating a resistive leakage current (Igr) and a capacitive leakage current (Igc) by using the leakage current vector sum value (Io) and the phase angle and outputting the calculated leakage current to the leakage current analysis circuit unit; And controlling the operation of the ground fault circuit breaker by discriminating the resistance between the resistive leakage current (Igr) and the capacitive leakage current (Igc) values in the leakage current analysis circuit. The method of claim 10, The leakage current analysis circuit operates an earth leakage breaker control circuit when the resistive leakage current Igr value reaches a reference value for each capacitance, and the capacitive leakage current Igc value is equal to 3 of the resistive leakage current Igr value. And a circuit between 5 times and operating the ground fault interrupter control circuit.

Images