JP2004286670A - Commercial power supply neutral grounding side detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a neutral grounding side power supply line of a commercial power supply is not found. <P>SOLUTION: This detector comprises an electromagnetic wave generating means T1 power-supplied from the power source lines 17, 18 of the commercial power source to generate an electromagnetic wave, a sensor ANT1 for detecting the electromagnetic wave, a shielding member 20 interposed between the sensor ANT1 and the electromagnetic wave generating means T1, and passing the electromagnetic wave, means K1, K2 for switching-connecting the member 20 selectively to the power source lines 17, 18, and a detecting means 19 for comparing each detection value of the sensor ANT1 when switching-connecting the shielding member 20 selectively to the power source lines 17, 18 by the switching means K1, K2 to detect the neutral grounding side power source line of the commercial power source. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a commercial power supply neutral point ground side detection device that detects a commercial power supply neutral point ground side power supply line among two power supply lines of a commercial power supply.
[0002]
[Prior art]
The commercial power supply requires a neutral point ground, and the necessity and purpose of the neutral point ground are in the following points (1) to (3).
{Circle around (1)} The occurrence of abnormal voltage due to the failure of the power supply system is suppressed, and the rise of sound relative earth voltage is prevented.
(2) The operation of the protective relay at the time of ground fault is ensured quickly to prevent the spread of disaster.
(3) In the arc extinguishing reactor grounding method, the earth fault arc at the time of the one-line ground fault is extinguished, and the power transmission can be continued without interrupting the line.
[0003]
As a typical neutral point grounding method for performing neutral point grounding, there is a direct grounding method. In this direct grounding method, as shown in FIG. The neutral point is grounded with a conductor so that the impedance is as low as possible. This direct grounding scheme is employed because of its technical and economic advantages in terms of system insulation. The neutral point grounding method includes a resistance grounding method, an arc-extinguishing reactor grounding method, and a resistance reactor parallel grounding method in addition to the direct grounding method.
[0004]
Since a commercial power supply used in a general company or home employs such a neutral point grounding method, a HOT line and a NEUT line always exist, and a neutral point ground side power supply line exists. Therefore, it has been considered to use such a neutral-ground-side power supply line of a commercial power supply for various uses.
[0005]
[Problems to be solved by the invention]
As described above, it is considered that the neutral ground power supply line of the commercial power supply is used for various purposes. I don't know.
[0006]
In view of the foregoing, an object of the present invention is to provide a commercial power supply neutral point ground side detection device that can detect a neutral point ground side power supply line of a commercial power supply.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 includes an electromagnetic wave generating unit that is supplied with power from two power lines of a commercial power supply and generates an electromagnetic wave, a sensor that detects the electromagnetic wave from the electromagnetic wave generating unit, and a sensor that detects the electromagnetic wave. A shielding member interposed between the electromagnetic wave generating means and the electromagnetic wave generating means, through which electromagnetic waves can pass, switching means for selectively switching the shield member to the two power supply lines, and switching the shielding member by the switching means. Detecting means for comparing each detection value of the sensor when selectively connected to two power supply lines and detecting a commercial power supply neutral point ground side power supply line of the two power supply lines. It is.
[0008]
The invention according to claim 2 is the commercial power supply neutral point grounding side detecting device according to claim 1, wherein the electromagnetic wave generating means is a transformer.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 3 shows an embodiment of the present invention. The commercial power supply neutral point ground side detection device 11 of this embodiment is connected between the commercial power supply line 13 of the equipment 12 connected to the commercial power supply and the commercial power supply, or connected to the commercial power supply in parallel with the equipment 12. (Connected to a power outlet different from the power outlet to which the commercial power line 13 is connected), detecting the neutral grounded power line on the commercial power source and connecting it to the shield point of the device 12 to prevent electromagnetic waves emitted from the device 12 Reduce. The device 12 is provided with a shield member between a portion that generates an electromagnetic wave and the outside, and this shield member is connected to a commercial power supply neutral point ground side power line as a shield point of the device 12 without being grounded.
[0010]
FIG. 1 shows the configuration of the present embodiment. The plug 15 is connected to the commercial power supply, and the plug 16 is connected to the commercial power supply line 13 of the device 12. Therefore, the commercial power is connected to the commercial power line 13 of the device 12 via the plug 15, the power lines 17, 18 and the plug 16, and the shield terminal 16a of the plug 16 is connected to the shield point of the device 12. Alternatively, the plug 15 is connected to a commercial power source in parallel with the device 12 (connected to a power outlet different from the power outlet to which the commercial power line 13 is connected), and the shield terminal 16 a of the plug 16 is connected to a shield point of the device 12. You.
[0011]
The power transformer T1 has its primary side connected between the power lines 17 and 18, and 100V AC between the power lines 17 and 18 is transformed to 12V by the power transformer T1. The output voltage of the power transformer T1 is full-wave rectified by the diode bridge circuit D1 and smoothed by the capacitors C1 and C2 to become a DC voltage of 16 V, and is supplied to the control device 19 as control means, and the relay K1 The voltage is applied to one end of the coil of K2, and further applied to the anode of the light emitting diode LED via the resistor R1.
[0012]
The other ends of the coils of the relays K1 and K2 and the cathode of the light emitting diode LED are connected to an output terminal of the control device 19, and two fixed terminals of the switching contact of the relay K2 are connected to power supply lines 17 and 18, respectively. The switching piece at the switching contact of the relay K2 is connected to the normally open fixed terminal of the relay K1, and the switching piece of the relay K1 is connected to the shield terminal 16a of the plug 16 via the resistor R2. A shield panel 20 is provided between the power transformer T1 and a sensor ANT1 for measuring an electromagnetic wave generated by the power transformer T1. The shield panel 20 has a large number of holes through which electromagnetic waves from the transformer T1 can pass, and is made of, for example, a net-like or lattice-like metal, and is connected to the shield terminal 16a of the plug 16.
[0013]
In the measurement mode, the control device 19 operates the relay K1 to sequentially switch the switching piece of the relay K2 between the power supply line 17 side and the power supply line 18 side, thereby connecting the shield terminal 20a of the shield panel 20 and the plug 16 to the resistance. The power supply lines 17 and 18 are sequentially switched and connected via R2. The sensor ANT1 measures an electromagnetic wave arriving from the power transformer T1 through a hole in the shield panel 20. The electromagnetic wave measured by the sensor ANT1 from the power transformer T1 through the hole of the shield panel 20 is connected to the commercial power supply neutral point ground side power line of the power lines 17 and 18 via the resistor R2. In this case, the number is smaller than when the shield panel 20 is connected via the resistor R2 to the power supply line which is not the commercial power supply neutral point ground side power supply line among the power supply lines 17 and 18.
[0014]
The controller 19 detects the commercial power supply neutral point ground side power supply line of the power supply lines 17 and 18 from the electromagnetic wave measurement signal from the sensor ANT1. By connecting the switching piece of the relay K2 to the neutral power supply line on the commercial power supply so as to connect the power supply line on the neutral point, the electromagnetic wave emitted from the device 12 is reduced.
[0015]
FIG. 2 shows the configuration of the control device 19.
The DC / DC converters 21 and 22 generate + 5V and -5V from the above 16V DC voltage and supply them to each unit of the control device 19. The sensor ANT1 measures an electromagnetic wave arriving from the power transformer T1 through the hole of the shield panel 20 and outputs a detection signal indicating the intensity of the electromagnetic wave. The detection signal from the sensor ANT1 is amplified by the amplifiers AMP1 and AMP2. The A / D converter 23 converts the analog signal into a digital signal.
[0016]
FIG. 6 is a functional block diagram showing a part of the functions of the microcomputer 24 in a block form. The microcomputer 24 turns on the relay K1 and turns off the relay K2 so that the switching section of the relay K2 is switched to the power supply line 18 side, and the data detection block (BLOCK) 28 outputs the signal from the A / D converter 23. The detection signal is sampled a plurality of times, and these sampled values are added by an adder 29 and stored in a register 30 as a memory as a first detection signal MA1.
[0017]
Further, the microcomputer 24 samples the detection signal from the A / D converter 23 a plurality of times by the data detection block 28 with the relays K1 and K2 turned on and the switching section of the relay K2 switched to the power supply line 17 side. Then, these sampled values are added by an adder 29 and stored as a second detection signal MA2 in a register 31 as a memory.
[0018]
The microcomputer 24 compares the first detection signal MA1 in the register 30 with the second detection signal MA2 in the register 31 by the comparator 32 to determine the magnitude of the comparison. Out of the power transformer T1, the power line passing through the hole of the shield panel 20 and having less electromagnetic waves measured by the sensor ANT1 (when the larger one of the detection signals MA1 and MA2 is obtained, the switching piece of the relay K2 is connected). The final state of the relay K2 (the state of the relay K2 in the operation mode) is determined by determining (detecting) the power supply line that is in use as the commercial power supply neutral point ground side power supply line.
[0019]
The drivers 25 to 27 drive the coils of the relays K1 and K2 and the light emitting diodes LED according to the control signal from the microcomputer 24. In the operation mode, the microcomputer 24 relays via the driver 25 so that the power line determined as the above-described commercial power supply neutral point ground side power line is connected to the shield terminal 16a of the plug 16 (the shield point of the device 12). By controlling K2 to the final state, electromagnetic waves emitted from the device 12 are reduced, and the light emitting diode LED is turned on during operation via the driver 27.
[0020]
Here, the detection signal from the sensor ANT1 is amplified by the amplifiers AMP1 and AMP2 to become waveforms A and B synchronized with the commercial power supply frequency as shown in FIG. This waveform A is a waveform when the shield panel 20 is connected to the commercial power supply neutral point ground side power line of the power lines 17 and 18 via the resistor R2, and the waveform B is a waveform when the shield panel 20 is connected to the resistor R2. This is a waveform when the power supply lines 17 and 18 are connected to the power supply line which is not the commercial power supply neutral point ground side power supply line.
[0021]
The microcomputer 24 sets the A / A during about 200 mSEC from the time when the signal voltage input from the amplifier AMP2 via the A / D converter 23 drops to 2.5 V with the relay K1 = ON and the relay K2 = OFF. The output value of the D converter 23 is sampled a plurality of times by the data detection block 28, for example, 10 times, and these sampled values are added by the adder 29. The result of the addition is stored in the register 30 as the first detection signal MA1. .
[0022]
The microcomputer 24 starts a predetermined time after the signal voltage input from the amplifier AMP2 via the A / D converter 23 drops to 2.5 V with the relay K1 = ON and the relay K2 = ON. During approximately 200 mSEC, the output value of the A / D converter 23 is sampled a plurality of times, for example, 10 times, by the data detection block 28, and these sampled values are added by the adder 29. Is stored as the detection signal MA2. As for the signal input from the A / D converter 23 to the microcomputer 24, the numerically larger signal is the commercial power supply neutral point ground side power supply line, and the numerically smaller signal is the commercial power supply neutral point ground side power supply line. Not on the power line side.
[0023]
When sampling the 8-bit output value of the A / D converter 23 ten times and storing it in the register 30 or the register 31, the microcomputer 24 lowers the output value of the A / D converter 23 from 4V to 4V. (For example, about 10 mSEC), the data is detected by the data detection block 28, and these sampled values are added by the adder 29 and stored in the register 30 or the register 31 as the first detection signal MA1 or the second detection signal MA2. I do. The sequence of the present embodiment is as shown in FIG. FIG. 7 shows a sequence from the input of the analog signal from the sensor ANT1 to the final state determination of the relay K2 according to the present embodiment.
[0024]
According to this embodiment, a power transformer T1 as an electromagnetic wave generating means that generates electromagnetic waves when supplied with power from two power lines 17 and 18 of a commercial power supply, a sensor ANT1 that detects the electromagnetic waves from the power transformer T1, A shield panel 20 as a shield member which is interposed between the sensor ANT1 and the power transformer T1 and through which electromagnetic waves can pass; and a switching means for selectively switching and connecting the shield panel 20 to two power lines 17 and 18. Of the sensor ANT1 when the shield panel 20 is selectively switched and connected to the two power lines 17 and 18 by the relays KI and K2. And a microcomputer 24 as a detecting means for detecting a commercial power supply neutral point ground side power supply line. So equipped, it is possible to automatically detect the neutral grounding side power line of the commercial power supply.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to detect a neutral-point ground-side power supply line of a commercial power supply.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a circuit configuration of an embodiment of the present invention.
FIG. 2 is a block diagram showing a control device of the embodiment.
FIG. 3 is a perspective view showing a use state of the embodiment.
FIG. 4 is a waveform chart showing an output signal of the amplifier according to the embodiment.
FIG. 5 is a diagram showing a sequence according to the embodiment.
FIG. 6 is a functional block diagram showing a part of the functions of the microcomputer according to the embodiment as blocks.
FIG. 7 is a diagram showing a sequence according to the embodiment.
FIG. 8 is a connection diagram showing a transformer of a commercial frequency power supply.
[Explanation of symbols]
15, 16 Plug 16a Shield terminal K1, K2 Relay R2 Resistance L1, L2 Coil T1 Power transformer ANT1 Sensor 19 Control device 20 Shield panel

Claims (2)

Electromagnetic wave generating means for generating electromagnetic waves supplied from two power lines of a commercial power supply, a sensor for detecting electromagnetic waves from the electromagnetic wave generating means, and being interposed between the sensor and the electromagnetic wave generating means and capable of passing electromagnetic waves A switching member for selectively switching the shield member to the two power lines, and the sensor when the shield member is selectively connected to the two power lines by the switching member. And a detecting means for comparing each of the detected values to detect a commercial power supply neutral point ground side power supply line of the two power supply lines. 2. The commercial power supply neutral point grounding side detecting device according to claim 1, wherein said electromagnetic wave generating means is a transformer.

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