JPH05312878A - Inspection jig for wiring condition of power socket with grounding pole - Google Patents

Abstract

PURPOSE:To simpify and facilitate inspection of the wiring conditions to a power socket from a distribution pannel by locating a wire connected to a pole U, and inspecting that current is easy to flow through which one of other wires. CONSTITUTION:An input voltage measuring part locates a line A1 connected to a pole U by voltage between socket terminals selected by a switch. A grounding resistance differential detecting part blocks the connection with a terminal A1 to measure the electric potential difference between both poles V, G (A2, A3 connection line), and grounding potential is compensated to make it zero (0). Thereafter A1 terminal is connected, and it is inspected that through which lines A2, A3 current is easy to flow from the line A1. Then, it is applied to the pole U (A1 line) and inspection is made with AC voltage. Consequently, the intensity of grounding resistance of each pole V, G can be measured with the accuracy corresponding to 1 ohm difference. A line V and line G connection judgement part compares the differential potential between the grounding resistances of poles V and G with neutral potential to display whether lines A2, A3 are properly connected to the poles V, G of a distribution pannel, respectively and whether the grounding resistance difference between both poles V, G is unable to judge at 1 ohm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring to a power outlet with a grounding electrode for single-phase alternating current, whether or not there is an erroneous cross connection between an ungrounded electrode of a transformer and a grounded electrode of a distribution board, Also, the present invention relates to a jig capable of easily and easily inspecting the wiring condition such as the presence / absence of misconnection between the ground electrode of the transformer and the grounded electrode of the distribution board.

[0002]

2. Description of the Related Art A metal base and a casing of an OA device installed in an office building and operated by a single-phase alternating current must be grounded so that a ground resistance is equal to or lower than a predetermined value (E ₃ ground). It is stipulated in the electrical equipment technical standards. Therefore, install a grounded electrode on the distribution board in the building so that the grounding resistance is below a specified value, and connect the drive power supply from the grounding electrode of this distribution board to each OA equipment. Wiring to the ground electrode of is provided. On the other hand, for the single-phase transformer that supplies power to the distribution board, one of its output-side poles is grounded so that its potential does not fluctuate more than a predetermined value from the ground potential (E ₂ ground).
That is stipulated in the electrical equipment technical standards.

FIG. 4 is a diagram showing an example of the wiring state of a properly wired power outlet with a grounding electrode, in which 1 is a single phase 10
0V transformer, 2 is a distribution board, 3 is a power outlet with a grounding electrode, the U pole of the distribution board is not grounded anywhere, and the V pole of the distribution board is connected to the E ₂ grounded pole of the transformer The G pole of the distribution board is not connected to the transformer and is grounded at E ₃ at the position of the distribution board.

The respective poles of the power outlet with a ground electrode must be correctly connected to the U, V, and G poles of the distribution board, but in reality, they are the U pole, V pole, and G
It is not easy to reliably discriminate the wires that have been connected to the poles and have extended to the outlet mounting position, and to correctly connect them to the outlet poles. If incorrect connection is made, it may cause a burnout accident of the office automation equipment or a malfunction of the equipment.

Therefore, it is necessary to inspect whether the wiring that has conventionally been extended from the distribution board to the power outlet with a ground electrode is actually connected to the U, V or G pole of the distribution board. After checking, it was to connect to the corresponding pole of the outlet, or to check whether the wiring connected to each pole of the outlet is correct.

[0006]

Conventionally, in order to inspect the wiring connection state to a power outlet with a ground electrode, generally,
I used a so-called tester. For example, when the potential difference between the potential of the wiring extended from the distribution board and the potential near the outlet near the ground potential, such as the floor of the building, is examined with a tester, there is a significant potential difference. The wiring is only from the U pole of the switchboard, so you can see it immediately. However, it is not easy to discriminate between the line connected to the V pole and the line connected to the G pole. For that reason, a special tester that can distinguish this has been commercially available in the past, but due to the increase in the number of inspection steps and the large current value sent for testing, it has become possible to install it on the distribution board in recent years. There were problems such as the possibility of operating the breaker and causing a power failure.

In order to solve the above problems, the present applicant has
Japanese Patent Application No. 2-288484 has already proposed a jig for inspecting the wiring condition of a power outlet with a ground electrode, but when actually tried in various conditions, it leaked from another power source between the V pole and the G pole. It was found that there are cases where the discriminating ability of both electrodes is insufficient, such as when there is a ground potential that is thought to be due to the above, that it is difficult to manufacture in part, and sometimes it malfunctions.

The present invention solves the above-mentioned various problems of the related art, and
It has a high ability to distinguish the wiring from the pole and the G pole,
It is an object of the present invention to provide a wiring condition inspection jig for a power outlet with a ground electrode that is easy to operate, safe, and can be easily manufactured by using commercially available electronic components that are inexpensive and have good performance.

[0009]

In order to achieve the above object, in the present invention, the U pole and the transformer connected to the non-grounded pole of the transformer of the single-phase AC power supply, respectively, of the distribution board Connect each pole of the power outlet with a grounding pole to be connected to the V pole connected to the grounding pole and the G pole not connected to the transformer and grounded by the distribution board from the distribution board. In order to properly connect to the actual wiring, first, the voltage between the respective actual wirings is examined, and a line showing a large voltage between any of the other two lines is regarded as a line connected to the U pole. Then, determine which of the two remaining wires from the wire considered to be connected to the U pole, through which the current is likely to flow, in the live line state (AC 1 for wiring from the distribution board).
00V is applied), and the power outlet with a grounding pole is designed to determine that the one with the easier current flow is the line connected to the V pole and the one with the less current flow is the line connected to the G pole In the wiring condition inspection jig, a series resistance of 1 MΩ or more is connected to a portion where a user comes into contact or may come into contact when the inspection jig is used, and the current flowing through the human body is harmlessly limited. In addition, a circuit for discriminating between the line connected to the V pole and the line connected to the G pole is used in a state in which the influence of the ground potential that may occur between the V and G2 poles due to leakage from another power source is compensated. , The difference between which of the two wires considered to be connected to the U pole and the remaining two wires, through which the current easily flows, is discriminable until the resistance difference corresponds to 1Ω. Also,
AC current flowing through the grounding point when using a jig is 3 mA
The voltage of the AC power supply applied between the two poles and the U pole as a power supply of the circuit for suppressing the power failure due to the malfunction of the earth leakage breaker and discriminating the lines connected to the V and G poles by suppressing the voltage below. Is used after half-wave rectification, and the effect of AC component on the measured value corresponding to the ground resistance difference is removed by a low-pass filter.

[0010]

Actually, in many cases, after the wiring from the distribution board is once connected to the outlet with the ground electrode, it is often checked whether or not the connection is correct by the jig of the present invention. If incorrect wiring is found, the wiring will be redone. Therefore, before connecting to the outlet, the wiring itself was explained as to check which pole of the distribution board is connected to the wiring.

In the jig of the present invention, AC 100V (or 2
The line to which the voltage of 00V) is applied is handled, but even if the user touches a live part (including a part that may be touched when replacing the battery) with almost the same potential as the U pole during the measurement work. Since the series resistance is set to 1 MΩ or more everywhere, the value of the current flowing through the human body to the grounded portion is small, there is no discomfort during work, and it is extremely safe.

With the safe measuring circuit as described above, first, the voltage between the three wires is measured, and the wire having a higher voltage than any of the other two wires is regarded as the wire connected to the U pole. (Or two wires with a small voltage between them are connected to the V and G poles,
The remaining wire is considered to be the wire connected to the U pole). To measure the input voltage for this purpose, a voltage direct reading circuit, which is isolated from the resistance difference detection unit for discriminating which line is connected to the V or G pole, is used, and the numerical display is digitally displayed on the LCD. A commercially available electronic device was used.

If the line connected to the U pole can be identified, which of the remaining two lines the current is likely to flow through is checked, and the line with the easier current flow is determined by the line connected to the V pole. It is determined that there is (grounding resistance difference detection), but as described above, there was a case where a ground potential that is thought to be due to leakage from another power source was generated between the V pole and the G pole. .. It was found that the actual value of the ground potential should be regarded as ± 1.4 V for the direct current component and 3.2 V _PP for the alternating current component (commercial frequency and high frequency) even if a margin is taken into account in many actual measurement results. If the difference in ground resistance is very small, measurement becomes impossible. With the jig of the present invention, a resistance difference of 1Ω can be detected.
If the judgment cannot be made without a difference of 1Ω or less, firstly, if the G pole of the distribution board shares the ground pole with the ground pole of the transformer,
Secondly, when the steel frame or other metal body of the building whose electric resistance with the ground is 1Ω or less is used for the G pole of the distribution board and the grounding pole of the transformer, the third is the grounding of the transformer. This is the case where the earth-to-ground electrical resistance between the pole (E ₂ ground) and the grounding pole (E ₃ ground) of the distribution board is 1Ω or less. In the first and second cases, both are special grounding methods, and their share in the total power supply work for OA equipment is small. In the third case, it is impossible unless a special grounding method such as burying a copper plate is used. If it is not possible to make a judgment with this jig, it can be discriminated by the method of temporary wiring for construction on the floor from the G pole to the power outlet with a ground electrode as in the conventional case.

Since various parts including ICs having a good performance price ratio are on the market today, the performance price ratio of the jig itself of the present invention can be made sufficiently good by appropriately selecting and using them. I was able to do it.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a schematic structure of a wiring condition inspection jig for an outlet with a ground electrode according to the present invention.
Is from the U pole to the V pole through the wiring resistance and the detection resistance, and from the U pole through the detection resistance, wiring resistance, and the ground resistance at the E ₂ ground pole and E ₃ ground pole, and the ground potential due to leakage from another power source. To explain the principle of a circuit for discriminating between a V pole and a G pole, in which a direct current (actually, half-wave rectification) is caused to flow to the G pole under the influence of, and the one in which the current easily flows is determined to be the V pole. It is a figure. In principle, terminals A ₁ , A ₂ and A ₃ should be connected to the wires connected to the U pole, V pole and G pole respectively, and should be measured by the input voltage measurement unit and the ground resistance difference detection unit. , If it is found that it is not (misconnection), the connection shall be changed. On the side of the jig, actually connect the wire connected to the U pole to
High AC voltage (actually 100V or 200V) due to incorrect connection such as connecting to ₂ terminals or A ₃ terminal
Is applied to any of the above terminals, a diode is bidirectionally connected to the input section so that a high-sensitivity element or member that can withstand only low voltage, such as an operational amplifier, will not be damaged by fire. Actually, a voltage larger than the voltage drop at the time of forward conduction of the diode is protected by being not applied to the operational amplifier.

In the input section, in order to handle the input, that is, to set the state for measuring the input voltage between the terminals, or to detect the ground resistance difference between the lines connected to the V and G poles. Select whether or not to switch to. The circuit of the ground resistance difference detection unit has terminals A ₁ , A ₂ , and A ₃
Connected after the DC power supply for the control unit and status display unit (whether it is correctly connected to the V and G poles, indicating that the resistance difference is less than 1Ω and undetectable) is connected and ready for measurement As described above, by using the LED that is turned on by the DC power source and the relay that operates according to the light emission, first, A ₂ ,
The opening / closing is controlled so that the connection with A ₃ and the connection with A ₁ are made next.

In the grounding resistance difference detecting section, first, the DC component of the potential difference between the V and G poles (connection line) is measured in a state where the A ₁ terminal is cut off (even if there is an AC component, it is in the low range). Then, the DC compensation circuit of the ground potential is adjusted so that it is compensated and becomes zero. Next, with the A ₁ terminal (and therefore the U pole connecting line) connected, a current easily flows from the line connected to the U pole through any of the other two lines (V pole connecting line and G pole connecting line). Whether or not the alternating current applied to the U pole is half-wave rectified is used as a direct current power source and checked. By doing this, other than the above 2
The current flowing through the line contains an AC component, but voltage fluctuations due to that are removed and compensated by a low-pass filter (a second-order Butterworth active filter with a cut-off frequency of 0.5 Hz) to ensure the same magnitude. The difference in the voltage generated in the detection resistor can be measured with a DC voltage to determine which pole the ground resistance is large or small with an accuracy corresponding to the difference of 1Ω.

The V-line / G-line connection determination unit amplifies and outputs the difference between the ground resistances of the V-pole and the G-pole to 50 mV / Ω. The output potential is compared with the neutral potential by the comparator, and the line connected to the V pole of the distribution board is correctly connected to the A ₂ terminal of the jig, and the line connected to the G pole is correctly connected to the A ₃ terminal. Whether or not the ground resistance difference between the V pole and the G pole is 1 Ω or less cannot be discriminated is displayed by the three LEDs of the status display section through the control section so that each case can be discriminated in an easy-to-understand manner.

The input voltage measuring unit outputs the voltage between the outlet terminals selected by the switch at a level of 1/100,
An RMS converter composed of a commercially available IC is used to measure the DC level (1VDC / 10) corresponding to the true effective value of the voltage between terminals.
0 VAC) and read on a commercial LCD display from a minimum value of 0.0V to a maximum value of 199.9V. As described above, when using this jig, it is necessary to first find the wire connected to the U pole. Therefore, in this input voltage measurement unit, the work for that purpose is performed first. If it is found, it is ensured that the remaining two wires are respectively connected to either the V pole or the G pole. Then, the work of detecting the difference in ground resistance with respect to the V and G2 poles is advanced. As described above, the numerical display unit has an LCD for digital display and displays the input voltage between the terminals. Prior to detecting the difference in ground resistance between the V pole and the G pole, first, the voltage between the two poles is measured, and the ground potential DC component is removed by leakage from another power source that appears between these two poles.
The numerical display is also used for compensation. It goes without saying that the numerical value display unit incorporates an A / D converter.

The power supply unit is necessary for the operation of each unit of this jig.
Generates a stable DC voltage. In this example, AA
A voltage of ± 5 V is generated from four manganese dry batteries.
The jig operates continuously for 50 hours or more with one battery exchange.

FIG. 3 is a diagram showing only a main part of a detailed circuit of an embodiment of the jig of the present invention.

[0022]

As described above, according to the present invention, it is possible to safely and easily inspect whether or not the wiring from the distribution board to the power outlet with a ground electrode is properly connected to each pole of the outlet. An inspection jig with a good price ratio can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a wiring state inspection jig for an outlet with a grounding electrode according to the present invention.

FIG. 2 is a diagram illustrating a principle of discriminating and determining that a line in which a current easily flows is a line connected to a V pole when a current is viewed from a line connected to a U pole.

FIG. 3 is a diagram showing only a main part of a detailed circuit of an embodiment of a jig of the present invention.

FIG. 4 is a diagram showing an example of a wiring state of a correctly wired power outlet with a ground electrode.

[Explanation of symbols]

1 ... Single-phase 100V transformer, 2 ... Distribution board, 3 ... Power outlet with grounding electrode, U pole ... Distribution board pole V pole connected to ungrounded pole of transformer of single-phase AC power supply ... Distribution board pole connected to the grounding pole of the transformer G pole: Distribution board pole not connected to the transformer and grounded by the distribution board

Claims (3)

[Claims] 1. A U-pole connected to a non-grounded pole of a transformer of a single-phase AC power supply, a V-pole connected to a grounding pole of a transformer, and a transformer of a distribution board, respectively. First, in order to properly connect the respective poles of the power outlet with a grounding electrode to be connected to the G pole, which is grounded in the distribution board, to the actual wirings from the respective poles of the distribution board, first, the respective actual wirings. By checking the voltage between them, the line showing a large voltage between any of the other two lines is regarded as the line connected to the U pole, and then the line considered to be connected to the U pole. From the two remaining lines, it is checked through which line the current easily flows, in the live line state, the one in which the current easily flows is the line connected to the V pole, and the one in which the current hardly flows is the line connected to the G pole. In the wiring condition inspection jig of the power outlet with a grounding electrode that is judged, the user touches or touches when using the inspection jig. A series resistance of 1 MΩ or more is connected to the location where there is a risk that the current flowing in the human body will be harmlessly limited, and a circuit that distinguishes between the line connected to the V pole and the line connected to the G pole will be provided. , V, G due to leakage from another power source
The remaining 2 from the line that is considered to be connected to the U pole while compensating for the effect of the ground potential that may occur between the 2 poles.
The difference in which line the current easily flows through is the resistance difference of 1Ω
A wiring condition inspection jig for a power outlet with a grounding electrode, which is characterized in that it can be discriminated until it is compatible with. 2. The ground according to claim 1, wherein when the jig is used, the AC current flowing through the grounding point is suppressed to 3 mA or less, and the earth leakage breaker mounted on the distribution board is not operated. Wiring condition inspection jig for power outlets with poles. 3. A ground resistance difference is obtained by half-wave rectifying an AC power supply voltage applied between the 2 pole and the U pole as a power supply of a circuit for discriminating wires connected to V and G poles. The wiring condition inspection jig for a power outlet with a ground electrode according to claim 1, wherein the influence of an alternating current component on the measured value corresponding to is removed by a low-pass filter.