JP3815699B2

JP3815699B2 - Insulation detector

Info

Publication number: JP3815699B2
Application number: JP26523396A
Authority: JP
Inventors: 治夫近藤; 裕司平薮; 健司中田
Original assignee: Tempearl Industrial Co Ltd
Current assignee: Tempearl Industrial Co Ltd
Priority date: 1996-09-13
Filing date: 1996-09-13
Publication date: 2006-08-30
Anticipated expiration: 2016-09-13
Also published as: JPH1090323A

Description

【０００１】
【産業上の利用分野】
本発明は、電気器具の絶縁抵抗測定を接地線引出し形差込プラグの接地線又は接地形差込プラグの接地極と本体金属部間の導通抵抗の大きさが規定レベル以下か否かを検出して、自動で且つ安全に行う絶縁判定器に関わる。
【０００２】
【従来の技術及び発明が解決しようとする課題】
従来、電気器具の絶縁抵抗測定には、絶縁抵抗計が使用されていた。
【０００３】
しかし、絶縁抵抗計は設定及び表示値を評価する電気的知識が必要であり、測定に多くの時間がかかっていた。
【０００４】
さらに、絶縁抵抗計は高圧直流電圧を発生させる電極が外部に露出しているため、感電の危険性が高かった。
【０００５】
また、電気器具の導通抵抗測定は行われないことが多く、そのとき導通抵抗が大きい場合は、接地線引出し形差込プラグの接地線又は接地形差込プラグの接地極を大地に接続していても不意なる絶縁抵抗不良の際の感電保護が出来ない場合があった。
【０００６】
【発明の目的】
そこで本件の発明の目的とするところは、電気器具を接続し、スイッチをＯＮにする操作のみで、電気器具の絶縁抵抗及び導通抵抗を自動で且つ安全に測定する特徴をもった絶縁判定器を提供しようとするものである。
【０００７】
【目的を解決するための手段】
上述の目的を達成するため本件の発明では、請求項１は、電源電圧の一端をコンセントの接地極及びアース端子で構成される接地部に接続し、前記電源電圧の他端と前記接地部間に挿入された抵抗Ａと抵抗Ｂで構成される分圧器Ａと、前記電源電圧の前記他端と前記接地部に挿入された抵抗Ｃと接地線引出し形差込プラグ又は接地形差込プラグを有した電気器具の前記接地線引出し形差込プラグの接地線又は前記接地形差込プラグの接地極と前記電気器具本体金属部間の導通抵抗で構成される分圧器Ｂと、前記分圧器Ａの出力電圧と分圧器Ｂの出力電圧の入力を比較するコンパレータＡと、分圧器Ｂの出力電圧が分圧器Ａの出力電圧より大きいときコンパレータＡの不良判定出力により動作する接地機能不良表示回路と、分圧器Ｂの出力電圧が分圧器Ａの出力電圧より小さいときコンパレータＡの合格判定出力により起動するＤＣ−ＤＣコンバータで構成される電圧発生部Ａと、電圧発生部Ａの一端を前記接地部に接続し、電圧発生部Ａの他端と前記コンセント刃受部間に挿入された抵抗Ｄ、抵抗Ｅで構成される分圧器Ｃと、前記刃受部と前記接地部間に接続された前記電気器具の絶縁抵抗と、電圧発生部Ａの前記他端と前記接地部間に挿入された抵抗Ｆ、抵抗Ｇで構成される分圧器Ｄと、分圧器Ｃの出力電圧と前記接地部間に挿入された抵抗Ｈ、抵抗Ｉの分圧に比例する分圧器Ｅと、分圧器Ｄの出力電圧と分圧器Ｅの出力電圧の入力を比較するコンパレータＢと、分圧器Ｄの出力電圧が分圧器Ｅの出力電圧より大きいときコンパレータＢの不良判定出力により動作する絶縁抵抗不良表示回路と、分圧器Ｄの出力電圧が分圧器Ｅの出力電圧より小さいときコンパレータＢの合格判定出力により動作する絶縁抵抗及び接地機能合格表示回路と、前記電気器具の差込プラグを構成部品のコンセントに接続し、接地線引出し形差込プラグの場合は、その接地線を構成部品のアース端子に接続し、測定リード線によって前記電気器具本体金属部と構成部品のシャーシ端子を接続し、スイッチをＯＮ操作することにより測定を行う測定手段とからなることを特徴として絶縁判定器を提供したものである。それにより、導通抵抗判定値及び絶縁抵抗判定値は電源電圧の変動の影響をほとんど受けず安定している。
【０００８】
【実施例の説明】
本発明の絶縁判定器の概要を次に示す。本発明の絶縁判定器は、接地線引出し形差込プラグ又は接地形差込プラグを有した電気器具を接続し、スイッチをＯＮ操作することにより、前記電気器具の接地線引出し形差込プラグの接地線又は接地形差込プラグの接地極と前記電気器具本体金属部間の導通抵抗を測定し、前記導通抵抗が規定値を超えたときは、前記電気器具の接地線引出し形差込プラグの接地線又は接地形差込プラグの接地極による接地機能が不良である事を表示し、前記導通抵抗が規定値以下のときは、高圧直流電圧を発生させて前記電気器具の絶縁抵抗を測定し、前記絶縁抵抗が規定値未満のときは絶縁抵抗が不良である事を表示し、前記絶縁抵抗が規定値以上のときは絶縁抵抗及び前記接地機能が合格である事を表示するようにしたものである。
【０００９】
また、前記電気器具の差込プラグを構成部品のコンセントに接続し、接地線引出し形差込プラグの場合はその接地線を構成部品のアース端子に接続し、測定リード線によって前記電気器具本体金属部と構成部品のシャーシ端子を接続し、スイッチをＯＮ操作する測定手段を有するものである。
【００１０】
また、コンセントの接地極及びアース端子で構成される接地部とシャーシ端子間に接続される請求項１に記載の導通抵抗を導通抵抗判定回路によって測定し、前記導通抵抗が規定値を超えたときは、請求項１に記載の接地機能が不良である事を表示し、前記導通抵抗が規定値以下のときは、高圧直流電圧を発生させてその電圧をコンセントの刃受部と前記接地部間に接続される前記絶縁抵抗に印加することにより発生する電流から前記絶縁抵抗を絶縁抵抗判定回路によって測定し、前記絶縁抵抗が規定値未満のときは絶縁抵抗が不良である事を表示し、前記絶縁抵抗が規定値以上のときは絶縁抵抗及び前記接地機能が合格である事を表示するようにしたものである。接地部とシャーシ端子間に接続される導通抵抗が規定値を超えていれば絶縁抵抗測定をおこなわないので、絶縁判定器単体でスイッチをＯＮにしても導通抵抗値は無限大で絶縁抵抗測定用の高圧直流電圧は発生しないことより、絶縁判定器単体状態において安全に取扱うことができる。また、絶縁抵抗測定用の高圧直流電圧は、コンセントの刃受部に発生させており、刃受部は容易に触れることが出来ない構造となっているため、安全に取扱うことができる。
【００１１】
次に本発明の絶縁判定器を図面を用いて詳細に説明を行う。電気器具１の接地線引出し形差込プラグ７（図２参照）又は、接地形差込プラグ８（図３参照）をコンセント１５に接続し、７の接地線４をアース端子１２に接続し、測定リード線９によって１の本体金属部をシャーシ端子１１に接続し、スイッチ１０をＯＮ操作する測定手段を有する。
【００１２】
次に図１によって測定方法を詳細に説明する。電気器具１の差込プラグが接地線引出し形差込プラグ７の場合は、コンセント１５に差し込むことによって７の電極６とコンセントの刃受部１４が接続される。さらに７の接地線４をアース端子１２に接続する。また、１の差込プラグが接地形差込プラグ８の場合は、１５に差し込むことによって６と１４が接続されると同時に８の接地極５と１５の接地極１３が接続される。測定リード線９によって１の本体金属部とシャーシ端子１１に接続する。接続後、スイッチ１０をＯＮ操作することにより測定ができる。尚、１はスイッチ２と電気回路３によって形成され、６はそれぞれ２と３の一端に接続され、２と３の他端は互いに接続されている。差込プラグは、前記のように７と８があり、両者に対応するため１５は接地極付とし、さらに接地線４用にアース端子１２を設けた。
【００１３】
１５の接地極１２と１３は内部で接続されており、以降”接地部”と呼ぶ。接地部と１１の間には、４及び５から１の本体金属部の接続部そして９により回路が形成される。その回路両端の抵抗を導通抵抗１６と呼ぶこととする。１６は１から外部へ引き出される４及び５の接地機能のパラメータであり、１６が零Ωに近いほど接地機能は良好である。
【００１４】
１５の刃受部は内部で接続されている。１４と接地部間には、６から１の本体金属部を介して４及び５による回路が形成される。その回路両端の抵抗が絶縁抵抗となる。
【００１５】
図１のブロック図の説明をする。電源電圧１９の負側電圧２１は接地部に接続され、１９の正側電圧２０と接地部間に挿入された抵抗２３，抵抗２４の分圧出力２５と、２０と接地部に挿入された抵抗２２及び１１と１２間の導通抵抗１６の分圧出力１１と、１１が＋側へ、２５が−側へ入力されるコンパレータ２６と、１１が２５より大きいとき，２６の不良判定出力２７により動作するアース線不良表示回路６０と、１１が２５より小さいとき、２６の合格判定出力２８により導通抵抗測定を行う。２６に入力される１１と２５は同じ電圧源を分圧しているため、２６の判定は電源電圧の変動に左右されない。２６の２８によって起動するＤＣ−ＤＣコンバータと３０によって発生する負側電圧３３は接地部に接続され、３０によって発生する正側電圧３４と接地部間に挿入された抵抗３１、抵抗３２及び１７により発生する３１と３２間の分圧出力３５と、３４と接地部間に挿入された抵抗３６、抵抗３７による分圧出力４０と、３５と接地部間に挿入された抵抗３８、抵抗３９による分圧出力４１と、４０が−側へ、４１が＋側へ入力されるコンパレータ５１と、４０が４１より大きいとき、５１の不良判定出力５２により動作する絶縁抵抗不良表示回路６１と、４０が４１より小さいとき、５１の合格判定出力５３により動作する絶縁抵抗及び接地機能合格表示回路６２により絶縁抵抗測定を行う。
【００１６】

以上のように、実施例に記載した絶縁判定器は、電気器具の絶縁抵抗測定をおこなうまえに、導通抵抗測定を実施し、導通抵抗が規定値以下であることを確認しているので、測定者が導通抵抗測定を忘れることはなく、電気器具の安全管理が向上し、また、接続及び測定の簡略化が実現され、作業時間の短縮ができるとともに、接地部とシャーシ端子間に接続される導通抵抗が規定値を超えていれば絶縁抵抗測定をおこなわないので、絶縁判定器単体でスイッチをＯＮにしても導通抵抗値は無限大で絶縁抵抗測定用の高圧直流電圧は発生しないことより、絶縁判定器単体状態において安全に取扱うことができ、さらには導通抵抗判定値及び絶縁抵抗判定値は電源電圧の変動の影響をほとんど受けず安定しているものである。
【００１７】
【発明の効果】
以上のように本発明では請求項１により、導通抵抗判定値及び絶縁抵抗判定値は電源電圧の変動の影響をほとんど受けず安定している絶縁判定器を提供することができる。
【図面の簡単な説明】
【図１】請求項１の実施例
【図２】請求項１の実施例
【図３】請求項１の実施例
【符号の説明】
１電気器具
２スイッチ
３電気回路
４接地線
５接地極
６電極
７接地線引出し形差込プラグ
８接地形差込プラグ
９測定リード線
１０スイッチ
１１シャーシ端子
１２アース端子
１３接地極
１４刃受部
１５コンセント
１６導通抵抗
１７絶縁抵抗
１８導通抵抗判定回路
１９電源
２０正側電圧
２１負側電圧
２２抵抗
２３抵抗
２４抵抗
２５分圧出力
２６コンパレータ
２７不良判定出力
２８合格判定出力
３０ＤＣ−ＤＣコンバータ
３１抵抗
３２抵抗
３３負側電圧
３４正側電圧
３５分圧出力
３６抵抗
３７抵抗
３８抵抗
３９抵抗
４０分圧出力
４１分圧出力
５０絶縁抵抗判定回路
５１コンパレータ
５２不良判定出力
５３合格判定出力
６０接地機能不良表示回路
６１絶縁抵抗不良表示回路
６２絶縁抵抗及び接地機能合格表示回路
７０絶縁判定器
７１判定表示部[0001]
[Industrial application fields]
The present invention detects the insulation resistance of an electrical appliance by detecting whether the magnitude of the conduction resistance between the ground wire of the ground wire lead-in plug or the ground electrode of the ground plug and the metal part of the main body is below a specified level. In addition, the present invention relates to an insulation determination device that performs automatically and safely.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, an insulation resistance meter has been used to measure the insulation resistance of electric appliances.
[0003]
However, the insulation resistance meter requires electrical knowledge to evaluate the setting and display value, and it took a lot of time for measurement.
[0004]
Furthermore, the insulation resistance meter has a high risk of electric shock because the electrodes that generate high-voltage DC voltage are exposed to the outside.
[0005]
In addition, the continuity resistance of electrical appliances is often not measured, and if the continuity resistance is high at that time, the ground wire of the ground wire lead-in plug or the ground electrode of the ground plug is connected to the ground. However, there were cases where electric shock protection was not possible in the event of unexpected insulation resistance failure.
[0006]
OBJECT OF THE INVENTION
Therefore, the object of the present invention is to provide an insulation determination device having a feature of automatically and safely measuring the insulation resistance and conduction resistance of an appliance by simply connecting the appliance and turning on the switch. It is something to be offered.
[0007]
[Means for Solving the Purpose]
In order to achieve the above-mentioned object, in the present invention, claim 1 connects one end of a power supply voltage to a grounding portion composed of a grounding pole and a grounding terminal of an outlet, and connects the other end of the power supply voltage and the grounding portion. A voltage divider A composed of a resistor A and a resistor B inserted into the resistor, a resistor C inserted into the other end of the power supply voltage and the grounding portion, and a ground wire lead-in plug or a ground plug. A voltage divider B configured by a conduction resistance between the ground wire of the ground wire lead-in type plug or the grounding electrode of the ground type plug and the metal body of the electric device, and the voltage divider A A comparator A that compares the output voltage of the voltage divider B with the output voltage of the voltage divider B, and a ground function failure indication circuit that operates in accordance with the failure determination output of the comparator A when the output voltage of the voltage divider B is greater than the output voltage of the voltage divider A. Output voltage of voltage divider B When the output voltage of the voltage divider A is smaller than the output voltage of the voltage divider A, the voltage generator A is configured by a DC-DC converter that is activated by the pass determination output of the comparator A, and one end of the voltage generator A is connected to the ground unit. A voltage divider C composed of a resistor D and a resistor E inserted between the other end of the socket and the outlet blade receiving portion, an insulation resistance of the electric appliance connected between the blade receiving portion and the grounding portion, and a voltage A voltage divider D composed of a resistor F and a resistor G inserted between the other end of the generator A and the grounding portion, and a resistor H and a resistor I inserted between the output voltage of the voltage divider C and the grounding portion. A voltage divider E proportional to the divided voltage of the output voltage, a comparator B that compares the output voltage of the voltage divider D and the output voltage of the voltage divider E, and a comparator when the output voltage of the voltage divider D is greater than the output voltage of the voltage divider E. Insulation resistance failure that operates according to the failure judgment output of B A display circuit, an insulation resistance and ground function pass indication circuit that operates according to a pass judgment output of the comparator B when the output voltage of the voltage divider D is smaller than the output voltage of the voltage divider E, and an insertion plug of the electric appliance. Connect to an outlet, and in the case of a ground wire lead-in plug, connect the ground wire to the earth terminal of the component, connect the metal part of the electrical appliance main body and the chassis terminal of the component with the measurement lead wire, and switch It is provided with an insulation determination device characterized by comprising measurement means for performing measurement by turning ON the. As a result, the conduction resistance determination value and the insulation resistance determination value are stable without being affected by fluctuations in the power supply voltage.
[0008]
[Explanation of Examples]
The outline of the insulation determination device of the present invention is as follows. The insulation determination device of the present invention connects a ground wire lead-in type plug or an electric appliance having a ground type plug, and turns on the switch to turn on the ground wire lead-in type plug. Measure the continuity resistance between the ground wire or the grounding pole of the grounding type plug and the metal part of the main body of the electric appliance, and when the continuity resistance exceeds the specified value, Indicates that the grounding function of the grounding wire or the grounding plug of the grounding type plug is poor, and if the conduction resistance is less than the specified value, generate a high-voltage DC voltage and measure the insulation resistance of the appliance. When the insulation resistance is less than the specified value, it is displayed that the insulation resistance is defective, and when the insulation resistance is greater than the specified value, the insulation resistance and the grounding function are displayed as being passed. It is.
[0009]
In addition, the plug of the electric appliance is connected to an outlet of a component, and in the case of a ground wire lead-in plug, the ground wire is connected to the earth terminal of the component, and the electric appliance body metal is connected by a measurement lead wire. And a chassis terminal of a component part are connected, and a measuring means for turning on the switch is provided.
[0010]
Further, when the conduction resistance according to claim 1 is measured by a conduction resistance determination circuit and is connected between a grounding portion composed of a grounding electrode and a grounding terminal of the outlet and the chassis terminal, and the conduction resistance exceeds a specified value. Indicates that the grounding function according to claim 1 is defective, and when the conduction resistance is not more than a specified value, a high-voltage direct current voltage is generated and the voltage between the blade receiving part of the outlet and the grounding part is generated. The insulation resistance is measured from the current generated by applying to the insulation resistance connected to the insulation resistance judgment circuit, and when the insulation resistance is less than a specified value, it is displayed that the insulation resistance is defective, When the insulation resistance is equal to or greater than a specified value, it is displayed that the insulation resistance and the grounding function are acceptable. Since the insulation resistance measurement is not performed if the conduction resistance connected between the grounding part and the chassis terminal exceeds the specified value, the conduction resistance value is infinite even if the switch is turned on with the insulation judgment unit alone, and for insulation resistance measurement Since the high-voltage DC voltage is not generated, it can be handled safely in the state of the insulation judgment unit alone. In addition, the high-voltage DC voltage for measuring the insulation resistance is generated in the blade receiving portion of the outlet, and the blade receiving portion has a structure that cannot be easily touched, so that it can be handled safely.
[0011]
Next, the insulation determination device of the present invention will be described in detail with reference to the drawings. Connect the ground wire lead-in type plug 7 (see FIG. 2) or the ground type plug 8 (see FIG. 3) of the electric appliance 1 to the outlet 15, and connect the ground wire 4 of 7 to the ground terminal 12. The main body metal part of 1 is connected to the chassis terminal 11 by the measurement lead wire 9 and the measurement means for turning on the switch 10 is provided.
[0012]
Next , the measurement method will be described in detail with reference to FIG. When the plug of the electric appliance 1 is the ground wire lead-in plug 7, the electrode 6 of 7 and the blade receptacle 14 of the outlet are connected by being inserted into the outlet 15. Further, the ground wire 4 is connected to the ground terminal 12. Further, when one plug is a ground-type plug 8, 6 and 14 are connected by being inserted into 15, and at the same time, eight ground electrodes 5 and 15 are connected. The measurement lead wire 9 connects to the main body metal part 1 and the chassis terminal 11. After connection, measurement can be performed by turning on the switch 10. Incidentally, 1 is formed by a switch 2 and an electric circuit 3, 6 is connected to one ends of 2 and 3, respectively, and the other ends of 2 and 3 are connected to each other. There are 7 and 8 plugs as described above, and 15 corresponds to both, and 15 is provided with a ground electrode, and a ground terminal 12 is provided for the ground wire 4.
[0013]
Fifteen ground electrodes 12 and 13 are connected internally, and are hereinafter referred to as “ground parts”. Between the grounding part 11, a circuit is formed by the connection parts 9 and 9 of the main body metal part 4 and 5 to 1. The resistance at both ends of the circuit is referred to as a conduction resistance 16. 16 is a parameter of the grounding functions 4 and 5 drawn from 1 to the outside, and the closer to 16 Ω, the better the grounding function.
[0014]
The 15 blade receivers are connected inside. Between 4 and the grounding portion, a circuit of 4 and 5 is formed through 6 to 1 body metal portions. The resistance at both ends of the circuit becomes the insulation resistance.
[0015]
The block diagram of FIG. 1 will be described. The negative side voltage 21 of the power supply voltage 19 is connected to the grounding part, the resistance 23 inserted between the 19 positive side voltage 20 and the grounding part, the divided output 25 of the resistor 24, and the resistance 20 inserted into the grounding part. 22 and the divided output 11 of the conduction resistor 16 between 11 and 12; the comparator 26 in which 11 is input to the + side; 25 is input to the-side; When the ground line defect display circuit 60 to be performed and 11 is smaller than 25, the conduction resistance is measured by 26 acceptance determination outputs 28. Since 11 and 25 input to 26 divide the same voltage source, the determination of 26 does not depend on the fluctuation of the power supply voltage. 26, the negative voltage 33 generated by the DC-DC converter 30 and 30 is connected to the ground part, and the positive voltage 34 generated by 30 and the resistors 31 and 32 and 17 inserted between the ground parts. The generated voltage-dividing output 35 between 31 and 32, the resistor 36 inserted between 34 and the grounding part, the voltage-dividing output 40 by the resistor 37, the resistance 38 inserted between 35 and the grounding part, and the voltage dividing by the resistor 39. Pressure output 41, comparator 51 to which 40 is input to the-side, 41 to the + side, insulation resistance failure display circuit 61 that operates according to the failure determination output 52 when 40 is greater than 41, and 40 to 41 When the value is smaller, the insulation resistance is operated by the acceptance judgment output 53 of 51, and the insulation resistance is measured by the ground function acceptance display circuit 62.
[0016]

As described above, the insulation determination device described in the examples performs the conduction resistance measurement before measuring the insulation resistance of the electric appliance, and confirms that the conduction resistance is not more than the specified value. Forgetting the continuity resistance measurement, the safety management of the electric appliance is improved, the connection and measurement are simplified, the working time can be shortened, and the connection is made between the grounding part and the chassis terminal. Since the insulation resistance measurement is not performed if the conduction resistance exceeds the specified value, the conduction resistance value is infinite even if the switch is turned on with the insulation determination unit alone, and the high-voltage DC voltage for insulation resistance measurement is not generated. The insulation determination unit can be safely handled in a single state, and further, the conduction resistance determination value and the insulation resistance determination value are hardly affected by fluctuations in the power supply voltage and are stable.
[0017]
【The invention's effect】
As described above, according to the first aspect of the present invention, it is possible to provide an insulation determination device in which the conduction resistance determination value and the insulation resistance determination value are hardly affected by fluctuations in the power supply voltage and are stable .
[Brief description of the drawings]
FIG. 1 embodiment of claim 1 FIG. 2 embodiment of claim 1 FIG. 3 embodiment of claim 1
DESCRIPTION OF SYMBOLS 1 Electric appliance 2 Switch 3 Electrical circuit 4 Grounding wire 5 Grounding electrode 6 Electrode 7 Grounding wire lead-in type plug 8 Grounding type insertion plug 9 Measurement lead wire 10 Switch 11 Chassis terminal 12 Grounding terminal 13 Grounding electrode 14 Blade receiving part 15 Outlet 16 Conduction resistance 17 Insulation resistance 18 Conduction resistance determination circuit 19 Power supply 20 Positive side voltage 21 Negative side voltage 22 Resistance 23 Resistance 24 Resistance 25 Voltage division output 26 Comparator 27 Defect determination output 28 Acceptance determination output 30 DC-DC converter 31 Resistance 32 Resistor 33 Negative voltage 34 Positive voltage 35 Divided output 36 Resistor 37 Resistor 38 Resistor 39 Resistor 40 Divided output 41 Divided output 50 Insulation resistance determination circuit 51 Comparator 52 Defect determination output 53 Acceptance determination output 60 Ground function failure display circuit 61 Insulation resistance defect display circuit 62 Insulation resistance and ground function pass display circuit 70 Edge determiner 71 determines a display unit

Claims

A voltage divider A comprising a resistor A and a resistor B inserted between the other end of the power supply voltage and the grounding portion; , a ground line of the ground line lead type attachment plug of the power supply voltage of the other end and said the inserted resistor C to the ground portion ground line lead type attachment plug or an appliance having a grounding-type attachment plug or comparator a comparing a voltage divider including B in the conducting resistance between the appliance body metal portion and a ground electrode of the ground type attachment plug, the input of the output voltage and the output voltage of the voltage divider B of the voltage divider a When the output voltage of the voltage divider B is larger than the output voltage of the voltage divider A, the ground function failure display circuit that operates according to the failure judgment output of the comparator A, and when the output voltage of the voltage divider B is smaller than the output voltage of the voltage divider A Comparator A combination A voltage generator A configured by a DC-DC converter that is activated by a determination output, and one end of the voltage generator A are connected to the grounding unit, and are inserted between the other end of the voltage generator A and the outlet blade receiving unit. A voltage divider C composed of resistors D and E, an insulation resistance of the electric appliance connected between the blade receiving portion and the ground portion, and between the other end of the voltage generator A and the ground portion. A voltage divider D composed of an inserted resistor F and resistor G; a voltage divider E proportional to the output voltage of the voltage divider C and the divided voltage of the resistor H and resistor I inserted between the ground parts; and a voltage divider Comparator B that compares the output voltage of D and the output voltage of voltage divider E, and an insulation resistance failure display circuit that operates according to the failure judgment output of comparator B when the output voltage of voltage divider D is greater than the output voltage of voltage divider E And the output voltage of the voltage divider D is the output voltage of the voltage divider E. Insulation resistance and grounding function acceptance display circuit that operates according to the acceptance judgment output of the comparator B, and the plug of the electric appliance is connected to the outlet of the component part. It comprises a measuring means for measuring by connecting a grounding wire to a grounding terminal of a component, connecting the metal part of the electric appliance main body and a chassis terminal of the component by a measurement lead wire, and turning on a switch. isolation determiner to.