JP7805810B2 - Fault detection circuit and circuit breaker - Google Patents
Fault detection circuit and circuit breakerInfo
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- JP7805810B2 JP7805810B2 JP2022019022A JP2022019022A JP7805810B2 JP 7805810 B2 JP7805810 B2 JP 7805810B2 JP 2022019022 A JP2022019022 A JP 2022019022A JP 2022019022 A JP2022019022 A JP 2022019022A JP 7805810 B2 JP7805810 B2 JP 7805810B2
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Description
本発明は、接続端子の接続不良を検出する接続不良検出回路、及び接続不良検出回路を備えた回路遮断器に関する。 The present invention relates to a connection failure detection circuit that detects connection failures in connection terminals, and a circuit breaker equipped with a connection failure detection circuit.
回路遮断器の電路を接続する接続端子は、端子ネジにより電線側の圧着端子を座金に圧接して機械的接続及び電気的接続が成される構成が普及している。このような端子では、端子ネジが緩むと座金と圧着端子との接触状態が不安定となり、アーク放電が発生し過熱する問題があった。
この対策として、端子ネジの緩みが発生したら、それを検出して電路を遮断する回路遮断器がある。例えば、特許文献１では端子ネジと端子座の間に所定の電位差が発生したら、接続不良発生と判断して遮断機構部を遮断動作させた。
The common connection terminals for connecting the electrical paths of circuit breakers are configured so that the crimp terminal on the wire side is pressed against a washer by a terminal screw to establish mechanical and electrical connections. With this type of terminal, if the terminal screw becomes loose, the contact between the washer and the crimp terminal becomes unstable, causing arc discharge and overheating.
To address this issue, there are circuit breakers that detect loose terminal screws and shut off the electrical path. For example, in Patent Document 1, when a predetermined potential difference occurs between the terminal screw and the terminal base, it is determined that a connection failure has occurred and the circuit breaker operates to shut off the electrical path.
しかしながら、上記特許文献１の技術は、接続端子に発生する電位差によりフォトカプラをオン動作させて、その出力により接続不良を検出した。そのため、検出部位の電位差がフォトカプラの動作電圧に至らなければ検出できないため、初期段階での検出が難しい問題があった。また、接続不良により発生する電位差は電路電流の大きさにより変化するため、感度にばらつきがあり、電路電流が大きくなると誤動作することがあった。 However, the technology in Patent Document 1 detects a connection fault by turning on a photocoupler using the potential difference generated at the connection terminal and detecting the fault through its output. This makes it difficult to detect a connection fault in the early stages, as it cannot be detected unless the potential difference at the detection point reaches the photocoupler's operating voltage. Furthermore, because the potential difference generated by a connection fault varies depending on the magnitude of the circuit current, there is variation in sensitivity, and a malfunction can occur when the circuit current becomes large.
そこで、本発明はこのような問題点に鑑み、発生した電位差がフォトカプラの動作電圧に至らない電圧でも接続不良を検知でき、更に電路電流の影響を受け難い接続不良検出回路及び回路遮断器を提供することを目的としている。 In light of these problems, the present invention aims to provide a connection failure detection circuit and circuit breaker that can detect connection failures even when the generated potential difference does not reach the operating voltage of the photocoupler, and that is less susceptible to the influence of circuit current.
上記課題を解決する為に、請求項１の発明は、電路を接続する接続端子の接続不良を検出する接続不良検出回路であって、接続端子で発生する電位差を検出する電位差検出回路と、検出した電位差が所定の閾値を超えたら接続不良発生と判断する判定部とを有し、電位差検出回路が、検出した電位差を増幅する差動増幅回路と、電路電流を計測する電流計測部と、差動増幅回路の増幅率を変更制御する増幅率制御部と、を有し、増幅率制御部は、電路電流に対して差動増幅回路の増幅率を所定の率で反比例させる制御を実施し、判定部は、差動増幅回路が増幅した電位差を閾値と比較して判定することを特徴とする。
この構成によれば、検出した電位差を差動増幅回路で増幅して判断するため、従来のように検出した電位差が、フォトカプラをオンさせる電圧に至らなくても検出が可能となり、接続不良を初期の段階で検知できる。
加えて、差動増幅回路の増幅率、即ち接続不良を検出する感度が電路電流に反比例するため、電路電流の増加に伴って増大する電圧降下に起因する誤動作を削減できる。
In order to solve the above problem, the invention of claim 1 is a poor connection detection circuit that detects poor connections in connection terminals that connect electric circuits, and includes a potential difference detection circuit that detects a potential difference generated at the connection terminal, and a judgment unit that determines that a poor connection has occurred if the detected potential difference exceeds a predetermined threshold, and the potential difference detection circuit includes a differential amplifier circuit that amplifies the detected potential difference, a current measurement unit that measures the electric circuit current, and an amplification factor control unit that changes and controls the amplification factor of the differential amplifier circuit, and the amplification factor control unit controls the amplification factor of the differential amplifier circuit to be inversely proportional to the electric circuit current at a predetermined factor, and the judgment unit compares the potential difference amplified by the differential amplifier circuit with a threshold value to make a judgment.
With this configuration, the detected potential difference is amplified by a differential amplifier circuit and then judged, so that it is possible to detect the potential difference even if it does not reach the voltage that turns on the photocoupler as in the conventional case, and poor connection can be detected at an early stage.
In addition, since the amplification factor of the differential amplifier circuit, i.e., the sensitivity for detecting connection defects, is inversely proportional to the circuit current, it is possible to reduce malfunctions caused by voltage drops that increase with an increase in the circuit current.
請求項２の発明は、電路を接続する接続端子の接続不良を検出する接続不良検出回路であって、接続端子で発生する電位差を検出する電位差検出回路と、検出した電位差が所定の閾値を超えたら接続不良発生と判断する判定部とを有し、電位差検出回路が、検出した電位差を増幅する差動増幅回路と、電位差検出対象の接続端子の温度を計測する端子温度計測部と、周囲の環境温度を計測する周囲温度計測部と、温度差と電路電流の関係を記憶する温度差情報記憶部と、差動増幅回路の増幅率を変更制御する増幅率制御部と、を有し、増幅率制御部は、接続端子の温度と環境温度との温度差を求め、温度差から電路電流を換算し、換算した電路電流に対して差動増幅回路の増幅率を所定の率で反比例させる制御を実施し、判定部は、差動増幅回路が増幅した電位差を閾値と比較して判定することを特徴とする。
この構成によれば、検出した電位差を差動増幅回路で増幅して判断するため、従来のように検出した電位差が、フォトカプラをオンさせる電圧に至らなくても検出が可能となり、接続不良を初期の段階で検知できる。
加えて、温度から電路電流を推測するため、電流計測のための変流器等を設置する必要がない。そして、接続不良を検出する感度を電路電流に反比例させることができるため、電路電流の増加に伴って増大する電圧降下に起因する誤動作を削減できる。
The invention of claim 2 is a connection failure detection circuit that detects connection failures of connection terminals that connect electric circuits, and includes a potential difference detection circuit that detects a potential difference generated at the connection terminal, and a judgment unit that determines that a connection failure has occurred if the detected potential difference exceeds a predetermined threshold, and the potential difference detection circuit includes a differential amplifier circuit that amplifies the detected potential difference, a terminal temperature measurement unit that measures the temperature of the connection terminal that is the target of potential difference detection, an ambient temperature measurement unit that measures the surrounding environmental temperature, a temperature difference information storage unit that stores the relationship between the temperature difference and the electric circuit current, and an amplification factor control unit that changes and controls the amplification factor of the differential amplifier circuit, and the amplification factor control unit determines the temperature difference between the temperature of the connection terminal and the environmental temperature, converts the electric circuit current from the temperature difference, and controls the amplification factor of the differential amplifier circuit to be inversely proportional to the converted electric circuit current at a predetermined rate, and the judgment unit compares the potential difference amplified by the differential amplifier circuit with a threshold value to make a judgment .
With this configuration, the detected potential difference is amplified by a differential amplifier circuit and then judged, so that it is possible to detect the potential difference even if it does not reach the voltage that turns on the photocoupler as in the conventional case, and poor connection can be detected at an early stage.
In addition, since the circuit current is estimated from the temperature, there is no need to install a current transformer or other device to measure the current.Furthermore, since the sensitivity for detecting connection defects can be made inversely proportional to the circuit current, it is possible to reduce malfunctions caused by voltage drops that increase as the circuit current increases.
請求項３の発明は、電路を接続する接続端子の接続不良を検出する接続不良検出回路であって、接続端子で発生する電位差を検出する電位差検出回路と、検出した電位差が所定の閾値を超えたら接続不良発生と判断する判定部とを有し、電位差検出回路が、検出した電位差を増幅する差動増幅回路と、電位差検出対象の接続端子の温度を計測する端子温度計測部と、温度と差動増幅回路の増幅率の関係を記憶する温度補正情報記憶部と、差動増幅回路の増幅率を変更制御する増幅率制御部と、を有し、増幅率制御部は、接続端子の計測温度を基に、温度補正情報記憶部を参照して温度が上昇したら差動増幅回路の増幅率を下げる制御を実施し、判定部は、差動増幅回路が増幅した電位差を閾値と比較して判定することを特徴とする。
この構成によれば、検出した電位差を差動増幅回路で増幅して判断するため、従来のように検出した電位差が、フォトカプラをオンさせる電圧に至らなくても検出が可能となり、接続不良を初期の段階で検知できる。
加えて、温度上昇に伴う接触抵抗の上昇、即ち電位差の上昇を加味して接続端子の温度に反比例するよう差動増幅回路の増幅率を制御するため、誤動作を削減できる。
The invention of claim 3 is a poor connection detection circuit that detects poor connections in connection terminals that connect electric circuits, and includes a potential difference detection circuit that detects a potential difference generated at the connection terminal, and a judgment unit that determines that a poor connection has occurred if the detected potential difference exceeds a predetermined threshold, and the potential difference detection circuit includes a differential amplifier circuit that amplifies the detected potential difference, a terminal temperature measurement unit that measures the temperature of the connection terminal that is the target of potential difference detection, a temperature correction information storage unit that stores the relationship between temperature and the amplification factor of the differential amplifier circuit, and an amplification factor control unit that changes and controls the amplification factor of the differential amplifier circuit, and the amplification factor control unit refers to the temperature correction information storage unit based on the measured temperature of the connection terminal and controls to lower the amplification factor of the differential amplifier circuit if the temperature rises, and the judgment unit compares the potential difference amplified by the differential amplifier circuit with a threshold to make a judgment .
With this configuration, the detected potential difference is amplified by a differential amplifier circuit and then judged, so that it is possible to detect the potential difference even if it does not reach the voltage that turns on the photocoupler as in the conventional case, and poor connection can be detected at an early stage.
In addition, the gain of the differential amplifier circuit is controlled to be inversely proportional to the temperature of the connection terminals, taking into account the increase in contact resistance, i.e., the increase in potential difference, that accompanies a temperature rise, thereby reducing malfunctions.
請求項４の発明は、１次側端子及び２次側端子と、両端子の間に配設された電路を遮断する遮断機構部とを有し、電路に過電流が流れたら遮断機構部が遮断動作する回路遮断器であって、請求項１乃至３の何れかに記載の接続不良検出回路が、１次側端子及び２次側端子のうちの少なくとも一方に設けられ、接続不良検出回路が接続不良発生と判断したら、遮断機構部が遮断動作することを特徴とする。
この構成によれば、接続端子の電位差が従来のようにフォトカプラをオンさせる電圧に至らなくても接続不良発生を検出して遮断動作するため、接続不良の発生を初期の段階で検出して遮断動作でき、回路遮断器の劣化を防止できる。
The invention of claim 4 is a circuit breaker having a primary terminal, a secondary terminal, and a breaking mechanism unit that breaks the electric circuit arranged between the two terminals, and the breaking mechanism unit performs a breaking operation when an overcurrent flows in the electric circuit, characterized in that a poor connection detection circuit according to any one of claims 1 to 3 is provided in at least one of the primary terminal and the secondary terminal, and when the poor connection detection circuit determines that a poor connection has occurred, the breaking mechanism unit performs a breaking operation .
With this configuration, a poor connection can be detected and a cut-off operation can be performed even if the potential difference between the connection terminals does not reach the voltage that turns on the photocoupler as in the past, so that a poor connection can be detected at an early stage and a cut-off operation can be performed, preventing deterioration of the circuit breaker.
本発明によれば、検出した電位差を差動増幅回路、或いはコンパレータで増幅して判断するため、従来のように検出した電位差がフォトカプラをオンさせる電圧に至らなくても検出が可能となり、接続不良を初期の段階で検知できる。
また、電路電流に応じて差動増幅回路の増幅率或いはコンパレータの基準電位を変化させるため、電路電流の影響を受け難い。
According to the present invention, the detected potential difference is amplified and judged using a differential amplifier circuit or a comparator, so that detection is possible even if the detected potential difference does not reach the voltage that turns on the photocoupler as in the conventional case, and poor connection can be detected at an early stage.
Furthermore, since the amplification factor of the differential amplifier circuit or the reference potential of the comparator is changed in response to the current in the electrical path, it is less susceptible to the influence of the current in the electrical path.
以下、本発明を具体化した実施の形態を、図面を参照して詳細に説明する。図１は本発明に係る接続不良検出回路を備えた回路遮断器の説明図であり、１は回路遮断器、２は接続不良検出回路である。接続不良検出回路２を回路遮断器１の２次側端子に設けた構成を示している。
回路遮断器１は、３線式の電路に使用される構成を示し、例えば単相３線式電路に使用される構成を示している。
尚、接続不良検出回路２は、図示しない回路基板に組み付けられて、回路遮断器１のハウジングＨ内に組み込まれている。また、接続不良検出回路２は全ての２次側端子に設けられているが、説明の都合上１端子のみの記載としている。
[0016] The present invention will be described in detail below with reference to the accompanying drawings, in which: [0017] Fig. 1 is an explanatory diagram of a circuit breaker equipped with a connection failure detection circuit according to the present invention, in which reference numeral 1 denotes the circuit breaker and reference numeral 2 denotes the connection failure detection circuit. [0018] The present invention shows a configuration in which the connection failure detection circuit 2 is provided on the secondary terminal of the circuit breaker 1.
The circuit breaker 1 is configured to be used in a three-wire electrical circuit, for example, a single-phase three-wire electrical circuit.
The connection failure detection circuit 2 is mounted on a circuit board (not shown) and incorporated into the housing H of the circuit breaker 1. Although the connection failure detection circuit 2 is provided for all secondary side terminals, for convenience of explanation, only one terminal is shown.
回路遮断器１は、電路４を電気的に接続する１次側端子１１、２次側端子１２を構成する接続端子１０がそれぞれ３つの端子を有しており、電圧極であるＬ１極、Ｌ２極と、中性極であるＮ極により構成されている。
回路遮断器１のハウジングＨ内には、１次側端子１１と２次側端子１２の間に掛け渡された電路を開閉する接点部１３、接点部１３を遮断操作する遮断機構部（図示せず）が組み込まれている。また、ハウジングＨの上部には接点部１３をオン／オフ操作するハンドル（図示せず）が設けられている。
尚、図１では説明のためハウジングＨ内を透視した図としている。
The circuit breaker 1 has a connection terminal 10 that constitutes a primary terminal 11 and a secondary terminal 12 that electrically connect the electric circuit 4, each of which has three terminals, consisting of voltage poles L1 and L2, and a neutral pole N.
The housing H of the circuit breaker 1 contains a contact 13 that opens and closes the electrical circuit spanning between the primary terminal 11 and the secondary terminal 12, and a breaker mechanism (not shown) that breaks the contact 13. A handle (not shown) that turns the contact 13 on and off is provided on the top of the housing H.
1 is a perspective view of the inside of the housing H for the sake of explanation.
接続不良検出回路２は、接続端子１０で発生する接触抵抗に基づく電位差を検出する電位差検出回路である差動増幅回路２１、接続不良を判定する判定部２２、判定結果を受けて所定の信号を出力する出力部２３、閾値を記憶する閾値記憶部２６を有している。また、２１ａは差動増幅回路２１を構成するオペアンプを示している。判定部２２、出力部２３、及び閾値記憶部２６はＭＣＵ（Micro Controller Unit）３により構成されている。
そして、出力部２３から出力される信号により遮断機構部が接点部１３を開操作し、回路遮断器１は遮断動作する。
The connection failure detection circuit 2 includes a differential amplifier circuit 21, which is a potential difference detection circuit that detects a potential difference based on the contact resistance generated at the connection terminal 10, a determination unit 22 that determines a connection failure, an output unit 23 that outputs a predetermined signal in response to the determination result, and a threshold value storage unit 26 that stores a threshold value. Reference numeral 21a denotes an operational amplifier that constitutes the differential amplifier circuit 21. The determination unit 22, the output unit 23, and the threshold value storage unit 26 are configured by an MCU (Micro Controller Unit) 3.
Then, the breaking mechanism opens the contacts 13 in response to a signal output from the output unit 23, and the circuit breaker 1 performs a breaking operation.
図２は、接続不良検出回路２が接続された２次側端子１２の接続端子１０の構成を示している。尚、接続端子１０自体の構成は、１次側端子１１及び２次側端子１２の個々の接続端子１０において共通である。
接続端子１０は、座金６１、端子ネジ６２、ナット６３を有し、電路４である電線６０の端部に固着された圧着端子６５が、座金６１に密着するように端子ネジ６２とナット６３とで圧接される。
差動増幅回路２１を構成するオペアンプ２１ａは、正極側入力端子２０ａ、負極側入力端子２０ｂのうち、正極側入力端子２０ａが座金６１に接続され、負極側入力端子２０ｂが圧着端子６５に接続されている。こうして、接続端子１０の座金６１と圧着端子６５の間の電位差が入力される。
尚、電圧を検出する部位は、座金６１とナット６３の間、座金６１と端子ネジ６２の間であってもよい。
2 shows the configuration of the connection terminal 10 of the secondary terminal 12 to which the connection failure detection circuit 2 is connected. The configuration of the connection terminal 10 itself is common to the individual connection terminals 10 of the primary terminal 11 and the secondary terminal 12.
The connection terminal 10 has a washer 61, a terminal screw 62, and a nut 63, and a crimp terminal 65 fixed to the end of an electric wire 60, which is an electric circuit 4, is pressed against the washer 61 by the terminal screw 62 and the nut 63 so as to be in close contact with the washer 61.
The operational amplifier 21a constituting the differential amplifier circuit 21 has a positive input terminal 20a and a negative input terminal 20b, of which the positive input terminal 20a is connected to a washer 61 and the negative input terminal 20b is connected to a crimp terminal 65. In this way, the potential difference between the washer 61 and the crimp terminal 65 of the connection terminal 10 is input.
The voltage may be detected between the washer 61 and the nut 63 or between the washer 61 and the terminal screw 62 .
上記の如く構成された接続不良検出回路２は以下のように動作する。接続端子１０において発生した電位差が差動増幅回路２１に入力され、抵抗素子Ｒ１，Ｒ２の比で設定された増幅度（ゲイン）により、例えば１０倍に増幅されて判定部２２に出力される。
尚、差動増幅回路２１の増幅率Ｇは、Ｒ２／Ｒ１或いは１＋Ｒ２／Ｒ１で設定され、オペアンプ２１ａに対する抵抗素子Ｒ１，Ｒ２の接続形態により何れかとなる。
The poor connection detection circuit 2 configured as described above operates as follows: The potential difference generated at the connection terminal 10 is input to the differential amplifier circuit 21, amplified by, for example, 10 times with the gain set by the ratio of the resistance elements R1 and R2, and output to the determination unit 22.
The amplification factor G of the differential amplifier circuit 21 is set to R2/R1 or 1+R2/R1, and depends on the connection of the resistance elements R1 and R2 to the operational amplifier 21a.
閾値記憶部２６は接続不良発生と判定する閾値を記憶しており、判定部２２は差動増幅回路２１から出力された電圧情報が、閾値記憶部２６が記憶している閾値を超えたら接続不良発生と判断し、出力部２３から所定の信号を出力させる。
遮断機構部はこの信号を受けて遮断動作し、接点部１３が開放されて電路４が遮断される。
The threshold memory unit 26 stores a threshold value for determining whether a connection failure has occurred, and the judgment unit 22 determines that a connection failure has occurred when the voltage information output from the differential amplifier circuit 21 exceeds the threshold value stored in the threshold memory unit 26, and outputs a predetermined signal from the output unit 23.
Upon receiving this signal, the circuit breaking mechanism performs a circuit breaking operation, opening the contact 13 and breaking the electrical circuit 4 .
このように、検出した電位差を差動増幅回路２１で増幅して判断するため、従来のように検出した電位差が、フォトカプラをオンさせる電圧に至らなくても検出が可能となり、接続不良を初期の段階で検知して電路を遮断できる。結果、回路遮断器１の劣化を防止できる。
尚、閾値記憶部２６が記憶する閾値は、固定値でなく監視する接続端子１０の接触抵抗の実測値を基準に設定すると良く、接触抵抗の初期値が１ｍΩと１０ｍΩとでは、同一の電路電流でも電圧降下量が１桁異なるため、接触抵抗の初期値が大きい接続端子１０は閾値を比較的大きく設定するのが望ましい。こうすることで、経年劣化に起因する接触抵抗の増加があっても、誤動作も削減できる。
In this way, the detected potential difference is amplified and judged by the differential amplifier circuit 21, so that it is possible to detect the potential difference even if it does not reach the voltage that turns on the photocoupler as in the conventional case, and it is possible to detect a connection failure at an early stage and cut off the electrical circuit, thereby preventing deterioration of the circuit breaker 1.
It is preferable that the threshold value stored in the threshold memory unit 26 is set based on the actual measured value of the contact resistance of the connection terminal 10 being monitored, rather than a fixed value, and since the amount of voltage drop differs by an order of magnitude even with the same circuit current when the initial contact resistance is 1 mΩ and 10 mΩ, it is desirable to set a relatively large threshold value for connection terminals 10 with a large initial contact resistance. This can reduce malfunctions even if the contact resistance increases due to deterioration over time.
図３は接続不良検出回路２の別の形態を示している。上記図１の形態とは電路電流の情報を基に差動増幅回路２１の増幅率が変化する点が異なっている。
具体的に、電路４に設けた変流器７から電流情報を入手して電路電流を計測する電流計測部２４、差動増幅回路２１の増幅率を制御する増幅率制御部２５を備え、差動増幅回路２１の増幅率を設定する抵抗素子Ｒ１，Ｒ２をデジタルポテンショメータ９で構成し、抵抗値を変更して差動増幅回路２１の増幅率を制御可能としている。２６ａは電流値と増幅率の対応関係を記憶する電流情報記憶部であり、電路電流と差動増幅回路２１の増幅率を所定の率で反比例させる情報を記憶している。
増幅率制御部２５は、計測した電路電流情報を基に対応する増幅率を読み取り、電路電流が増加するとＲ１，Ｒ２を制御して増幅率を下げる。
Fig. 3 shows another embodiment of the connection failure detection circuit 2. It differs from the embodiment shown in Fig. 1 in that the amplification factor of the differential amplifier circuit 21 changes based on information about the current flowing through the electrical path.
Specifically, it includes a current measurement unit 24 that obtains current information from a current transformer 7 provided in the electric circuit 4 and measures the circuit current, and an amplification factor control unit 25 that controls the amplification factor of the differential amplifier circuit 21, and the resistance elements R1 and R2 that set the amplification factor of the differential amplifier circuit 21 are configured with a digital potentiometer 9, and the amplification factor of the differential amplifier circuit 21 can be controlled by changing the resistance value. 26a is a current information storage unit that stores the correspondence between the current value and the amplification factor, and stores information that makes the circuit current and the amplification factor of the differential amplifier circuit 21 inversely proportional to a predetermined rate.
The gain control unit 25 reads the corresponding gain based on the measured circuit current information, and when the circuit current increases, controls R1 and R2 to reduce the gain.
このように、電路電流が増加すると差動増幅回路２１の増幅率を下げる。即ち、接続不良を検出する感度が電路電流に反比例する。よって、電路電流の増加に伴って増加する電圧降下に起因する誤動作を削減できる。 In this way, the amplification factor of the differential amplifier circuit 21 decreases as the circuit current increases. In other words, the sensitivity for detecting poor connections is inversely proportional to the circuit current. This reduces malfunctions caused by the voltage drop that increases with an increase in the circuit current.
図４は接続不良検出回路２の別の形態を示している。上記図３の形態とは電路電流情報ではなく温度情報を基に差動増幅回路２１の増幅率を制御する点が異なっている。
具体的に、接続端子１０の温度情報を入手する第１温度センサ８ａ、回路遮断器１の周囲温度の情報を入手する第２温度センサ８ｂ、接続端子１０の温度及び周囲温度（環境温度）を算出する温度計測部２７、電流値と増幅率の関係を記憶する電流情報記憶部２６ａ、温度と電路電流の関係を記憶する温度差情報記憶部２６ｂ、差動増幅回路２１の増幅率を制御する増幅率制御部２５ａを備えている。
増幅率制御部２５ａは、接続端子１０の温度と周囲の環境温度との差を算出して、算出した温度差情報を基に温度差情報記憶部２６ｂを参照して電路電流を換算し、更に電流情報記憶部２６ａを参照して換算した電流値から増幅率を決定する。そして、決定した増幅率になるようデジタルポテンショメータ９から成る抵抗素子Ｒ１，Ｒ２を制御する。
Fig. 4 shows another embodiment of the connection failure detection circuit 2. It differs from the embodiment shown in Fig. 3 in that the amplification factor of the differential amplifier circuit 21 is controlled based on temperature information rather than on current information on the electrical path.
Specifically, it is equipped with a first temperature sensor 8a that obtains temperature information of the connection terminal 10, a second temperature sensor 8b that obtains information on the ambient temperature of the circuit breaker 1, a temperature measurement unit 27 that calculates the temperature of the connection terminal 10 and the ambient temperature (environmental temperature), a current information memory unit 26a that stores the relationship between the current value and the amplification factor, a temperature difference information memory unit 26b that stores the relationship between the temperature and the circuit current, and an amplification factor control unit 25a that controls the amplification factor of the differential amplifier circuit 21.
The gain control unit 25a calculates the difference between the temperature of the connection terminal 10 and the ambient temperature, converts the circuit current based on the calculated temperature difference information by referring to the temperature difference information storage unit 26b, and determines the gain from the converted current value by referring to the current information storage unit 26a.Then, the resistance elements R1 and R2 formed by the digital potentiometer 9 are controlled to achieve the determined gain.
図５は、温度差情報記憶部２６ｂが記憶する電路電流（電路電流推測値）と温度差のとの関係を示し、実測値に基づいて設定されている。
このように、温度から電路電流を推測するため、電流計測のための変流器等を設置する必要がない。そして、接続不良を検出する感度を電路電流に反比例させることができるため、電路電流の増加に伴って増大する電圧降下に起因する誤動作を削減できる。
FIG. 5 shows the relationship between the circuit current (estimated circuit current value) and the temperature difference stored in the temperature difference information storage unit 26b, which is set based on the actual measured value.
In this way, since the circuit current is estimated from the temperature, there is no need to install a current transformer or other device for measuring current. Furthermore, since the sensitivity for detecting connection defects can be made inversely proportional to the circuit current, malfunctions caused by voltage drops that increase as the circuit current increases can be reduced.
図６は、接続不良検出回路２の別の形態を示している。図４の形態とは、１箇所の温度情報を基に増幅回路の増幅率を制御する点が異なっている。
具体的に、接続端子１０の温度情報を入手する温度センサ８ｃ、温度センサ８ｃの情報から温度を算出する温度計測部２７ａ、差動増幅回路２１の増幅率を制御する増幅率制御部２５ｂ、温度と増幅率の関係を記憶する温度補正情報記憶部２６ｃを備えている。
増幅率制御部２５ｂは、検出した接続端子１０の温度情報を基に温度補正情報記憶部２６ｃの情報を参照して増幅率を制御する。
Fig. 6 shows another embodiment of the connection failure detection circuit 2. This embodiment differs from the embodiment shown in Fig. 4 in that the amplification factor of the amplifier circuit is controlled based on temperature information from one location.
Specifically, it is equipped with a temperature sensor 8c that obtains temperature information of the connection terminal 10, a temperature measurement unit 27a that calculates the temperature from the information from the temperature sensor 8c, an amplification factor control unit 25b that controls the amplification factor of the differential amplifier circuit 21, and a temperature correction information storage unit 26c that stores the relationship between temperature and amplification factor.
The gain control unit 25b controls the gain based on the detected temperature information of the connection terminal 10 by referring to the information in the temperature correction information storage unit 26c.
図７は、抵抗値と温度の関係を示しており、Ｒｔは基準温度ｔでの抵抗値、ＲＴは計測温度Ｔでの抵抗値を示している。図７に示すように、温度の上昇に伴い接触抵抗値（抵抗値）も上昇（検出する電位差も上昇）する。
温度補正情報記憶部２６ｃは、この温度変化に伴う抵抗値の変化を補正するために、差動増幅回路２１の増幅率と温度の関係を記憶している。増幅率制御部２５ｂは、この温度補正情報記憶部２６ｃの情報を参照して、温度上昇分により誤検知しないように差動増幅回路２１の増幅率を下げる制御を実施する。結果、判定閾値を上げて誤動作を防止する制御を実施している。
7 shows the relationship between resistance and temperature, where Rt is the resistance at reference temperature t and RT is the resistance at measurement temperature T. As shown in FIG. 7, as the temperature rises, the contact resistance (resistance) also rises (the detected potential difference also rises).
The temperature correction information storage unit 26c stores the relationship between the gain and temperature of the differential amplifier circuit 21 in order to correct for changes in resistance value due to temperature changes. The gain control unit 25b references the information in the temperature correction information storage unit 26c and performs control to lower the gain of the differential amplifier circuit 21 so as to prevent erroneous detection due to temperature increases. As a result, the determination threshold is raised to prevent malfunction.
このように、温度上昇に伴う接触抵抗の上昇、即ち電位差の上昇を加味して接続端子１０の温度に反比例するよう差動増幅回路２１の増幅率を制御するため、誤動作を削減できる。
尚、差動増幅回路２１の増幅率を変更制御する上記図４，６の形態では、２つの抵抗素子Ｒ１，Ｒ２の抵抗値を可変としたが、何れか一方のみデジタルポテンショメータとして可変とし、他方を固定値としても良い。
In this way, the gain of the differential amplifier circuit 21 is controlled to be inversely proportional to the temperature of the connection terminal 10, taking into account the increase in contact resistance, i.e., the increase in potential difference, that accompanies a temperature rise, thereby reducing malfunctions.
In the embodiments shown in FIGS. 4 and 6 for controlling and changing the amplification factor of the differential amplifier circuit 21, the resistance values of the two resistance elements R1 and R2 are variable. However, it is also possible to make only one of them variable as a digital potentiometer and the other a fixed value.
図８は、接続不良検出回路２の別の形態を示し、上記一連の形態とは電位差検出回路にコンパレータ回路３１を使用している点が相違している。尚、回路遮断器１の構成は上記形態と同様であるため説明を省略する。
具体的に、接続不良検出回路２は、接続端子１０の電位差を検出する電位差検出回路をコンパレータ回路３１で構成し、コンパレータ回路３１が出力するＨ／Ｌ信号から接続不良を判定する判定部２２、判定結果を受けて所定の信号を出力する出力部２３を備えている。３１ａはコンパレータ回路３１を構成するオペアンプ、Ｒ３，Ｒ４はコンパレータ回路のＨ／Ｌ出力の閾値（基準電位）を設定する抵抗素子である。
8 shows another embodiment of the connection failure detection circuit 2, which differs from the above series of embodiments in that a comparator circuit 31 is used in the potential difference detection circuit. Note that the configuration of the circuit breaker 1 is the same as that of the above embodiments, and therefore a description thereof will be omitted.
Specifically, the connection failure detection circuit 2 includes a comparator circuit 31 as a potential difference detection circuit that detects the potential difference of the connection terminal 10, a determination unit 22 that determines a connection failure from the H/L signal output by the comparator circuit 31, and an output unit 23 that outputs a predetermined signal in response to the determination result. 31a is an operational amplifier that forms the comparator circuit 31, and R3 and R4 are resistance elements that set the threshold value (reference potential) of the H/L output of the comparator circuit.
コンパレータ回路３１からＨ信号が出力されたら、判定部２２は接続不良発生と判断して出力部２３から遮断機構部を遮断動作させる信号を出力させる。結果、接点部１３が開動作して回路遮断器１は遮断動作する。
尚、上記形態と同様に、判定部２２及び出力部２３はＭＣＵ（Micro Controller Unit）３により構成されている。
When the comparator circuit 31 outputs an H signal, the determination unit 22 determines that a connection failure has occurred and outputs a signal to cause the breaking mechanism unit to perform a breaking operation from the output unit 23. As a result, the contact unit 13 opens and the circuit breaker 1 performs a breaking operation.
As in the above embodiment, the determination unit 22 and the output unit 23 are configured by an MCU (Micro Controller Unit) 3 .
このように、検出した電位差をコンパレータ回路３１で増幅し、増幅値を基準電位と比較して判断しても良い。差動増幅回路２１の場合と同様に僅かな電位差であっても接続不良を検出することが可能であり、従来のように検出した電位差がフォトカプラをオンさせる電圧に至らなくても容易に検出できる。よって、接続不良を初期の段階で検知して電路４を遮断でき、回路遮断器１の劣化を防止できる。 In this way, the detected potential difference can be amplified by the comparator circuit 31, and the amplified value can be compared with a reference potential to make a judgment. As with the differential amplifier circuit 21, it is possible to detect a connection fault even with a slight potential difference, and it can be easily detected even if the detected potential difference does not reach the voltage that turns on the photocoupler, as in the past. Therefore, a connection fault can be detected at an early stage, breaking the electrical circuit 4 and preventing deterioration of the circuit breaker 1.
図９は、コンパレータ回路３１を使用した接続不良検出回路の他の形態を示し、上記図８の構成とは基準電位を可変とした点が相違している。
具体的に、コンパレータ回路３１、判定部２２、出力部２３に加えて、電路電流を検出する変流器７、変流器７の検出電流情報から電路電流を算出する電流計測部２４、基準電位を変更する基準電位制御部２８、電流と基準電位の対応関係を記憶する基準電位情報記憶部２６ｄを備え、基準電位を設定する２つの抵抗素子Ｒ３，Ｒ４のうちの抵抗素子Ｒ３の抵抗値を変更できるデジタルポテンショメータ９ａとしている。基準電位情報記憶部２６ｄには、電路電流に基準電位が比例して変化する所定の関係が記憶されている。
FIG. 9 shows another embodiment of a connection failure detection circuit using a comparator circuit 31, which differs from the configuration of FIG. 8 in that the reference potential is variable.
Specifically, in addition to the comparator circuit 31, the determination unit 22, and the output unit 23, the digital potentiometer 9a includes a current transformer 7 that detects the circuit current, a current measurement unit 24 that calculates the circuit current from the detected current information of the current transformer 7, a reference potential control unit 28 that changes the reference potential, and a reference potential information storage unit 26d that stores the correspondence relationship between the current and the reference potential, and can change the resistance value of the resistance element R3 of the two resistance elements R3 and R4 that set the reference potential. The reference potential information storage unit 26d stores a predetermined relationship in which the reference potential changes in proportion to the circuit current.
基準電位制御部２８は、計測した電路電流情報を基に基準電位情報記憶部２６ｄから対応する基準電位を読み取り、抵抗素子Ｒ３を制御する。例えば、電路電流の増加に対して抵抗素子Ｒ３の値を反比例させる制御を実施し、基準電位が上昇するよう制御される。
結果、電路電流が増加すると基準電位が上昇する。
The reference potential control unit 28 reads the corresponding reference potential from the reference potential information storage unit 26d based on the measured circuit current information, and controls the resistance element R3. For example, the reference potential control unit 28 controls the value of the resistance element R3 to be inversely proportional to an increase in the circuit current, thereby controlling the reference potential to increase.
As a result, an increase in the path current causes the reference potential to increase.
このように、基準電位が電路電流に比例するため、接続不良を検出する感度を電路電流に反比例させることができ、電路電流の増加に起因する電圧降下の増大による誤動作を削減できる。 In this way, because the reference potential is proportional to the circuit current, the sensitivity for detecting connection defects can be made inversely proportional to the circuit current, reducing malfunctions caused by increased voltage drop due to increased circuit current.
尚、図９では抵抗素子Ｒ３を可変として基準電位を変更しているが、電路電流の増加による誤動作を防止する構成としては、抵抗素子Ｒ３を温度に対して負特性を示す負特性サーミスタで構成し、この負特性サーミスタを電位差検出対象の接続端子１０の近傍に配置しても良い。こうすることで、温度上昇に伴い抵抗素子Ｒ３の値が小さくなり、基準電位を上昇させることができる。結果、温度上昇に伴う誤動作を防止できる。しかも、電流計測部２４、基準電位制御部２８を設ける必要が無い。
また上記実施形態は、何れも回路遮断器１の２次側端子１２に接続不良検出回路２を設けた場合を説明したが、接続不良検出回路２は１次側端子１１に設けても良いし双方に設けても良い。
更に、回路遮断器１に限らず、複数の接続端子を備えた端子台に対しても上記接続不良検出回路２は適用でき、接続不良が発生したら警報を発する等の機能を追加することで回路遮断器で無くても良好に作用させることができる。
9, the resistor element R3 is variable to change the reference potential. However, to prevent malfunction due to an increase in the circuit current, the resistor element R3 may be configured as a negative temperature coefficient thermistor, and this negative temperature coefficient thermistor may be placed near the connection terminal 10 for which the potential difference is to be detected. In this way, the value of the resistor element R3 decreases as the temperature rises, and the reference potential can be increased. As a result, malfunction due to an increase in temperature can be prevented. Furthermore, there is no need to provide a current measurement unit 24 or a reference potential control unit 28.
In addition, in all of the above embodiments, the poor connection detection circuit 2 is provided at the secondary terminal 12 of the circuit breaker 1, but the poor connection detection circuit 2 may be provided at the primary terminal 11 or at both.
Furthermore, the above-mentioned connection failure detection circuit 2 can be applied not only to the circuit breaker 1 but also to a terminal block having a plurality of connection terminals, and by adding a function such as issuing an alarm when a connection failure occurs, it can be made to function well even in devices other than circuit breakers.
１・・回路遮断器、２・・接続不良検出回路、４・・電路、９，９ａ・・デジタルポテンショメータ、１０・・接続端子、１１・・１次側端子。１２・・２次側端子、１３・・接点部、２１・・差動増幅回路、２１ａ・・オペアンプ、２２・・判定部、２３・・出力部、２４・・電流計測部、２５，２５ａ，２５ｂ・・増幅率制御部、２６・・閾値記憶部、２６ａ・・電流情報記憶部、２６ｂ・・温度差情報記憶部、２６ｃ・・温度補正情報記憶部、２６ｄ・・基準電位情報記憶部、２７・・温度計測部（端子温度計測部、周囲温度計測部）、２７ａ・・温度計測部、３１・・コンパレータ、３１ａ・・オペアンプ、Ｈ・・ハウジング。 1. Circuit breaker, 2. Connection failure detection circuit, 4. Electrical circuit, 9, 9a. Digital potentiometer, 10. Connection terminal, 11. Primary terminal, 12. Secondary terminal, 13. Contact section, 21. Differential amplifier circuit, 21a. Operational amplifier, 22. Judgment section, 23. Output section, 24. Current measurement section, 25, 25a, 25b. Amplification factor control section, 26. Threshold memory section, 26a. Current information memory section, 26b. Temperature difference information memory section, 26c. Temperature correction information memory section, 26d. Reference potential information memory section, 27. Temperature measurement section (terminal temperature measurement section, ambient temperature measurement section), 27a. Temperature measurement section, 31. Comparator, 31a. Operational amplifier, H. Housing.
Claims (4)
前記接続端子で発生する電位差を検出する電位差検出回路と、
検出した電位差が所定の閾値を超えたら接続不良発生と判断する判定部とを有し、
前記電位差検出回路が、検出した電位差を増幅する差動増幅回路と、
電路電流を計測する電流計測部と、
前記差動増幅回路の増幅率を変更制御する増幅率制御部と、を有し、
前記増幅率制御部は、前記電路電流に対して前記差動増幅回路の増幅率を所定の率で反比例させる制御を実施し、
前記判定部は、前記差動増幅回路が増幅した電位差を前記閾値と比較して判定することを特徴とする接続不良検出回路。 A connection failure detection circuit for detecting a connection failure of a connection terminal for connecting an electric circuit,
a potential difference detection circuit for detecting a potential difference occurring at the connection terminal;
a determination unit that determines that a connection failure has occurred when the detected potential difference exceeds a predetermined threshold value;
a differential amplifier circuit that amplifies the potential difference detected by the potential difference detection circuit ;
a current measurement unit that measures a circuit current;
an amplification factor control unit that changes and controls the amplification factor of the differential amplifier circuit;
the amplification factor control unit performs control to make the amplification factor of the differential amplifier circuit inversely proportional to the path current at a predetermined factor;
The connection failure detection circuit is characterized in that the determination unit compares the potential difference amplified by the differential amplifier circuit with the threshold value to make a determination.
前記接続端子で発生する電位差を検出する電位差検出回路と、a potential difference detection circuit for detecting a potential difference occurring at the connection terminal;
検出した電位差が所定の閾値を超えたら接続不良発生と判断する判定部とを有し、a determination unit that determines that a connection failure has occurred when the detected potential difference exceeds a predetermined threshold value;
前記電位差検出回路が、検出した電位差を増幅する差動増幅回路と、a differential amplifier circuit that amplifies the potential difference detected by the potential difference detection circuit;
電位差検出対象の接続端子の温度を計測する端子温度計測部と、a terminal temperature measurement unit that measures the temperature of a connection terminal that is a potential difference detection target;
周囲の環境温度を計測する周囲温度計測部と、an ambient temperature measuring unit that measures the ambient temperature;
温度差と電路電流の関係を記憶する温度差情報記憶部と、a temperature difference information storage unit that stores the relationship between the temperature difference and the circuit current;
前記差動増幅回路の増幅率を変更制御する増幅率制御部と、を有し、an amplification factor control unit that changes and controls the amplification factor of the differential amplifier circuit;
前記増幅率制御部は、前記接続端子の温度と前記環境温度との温度差を求め、前記温度差から電路電流を換算し、換算した電路電流に対して前記差動増幅回路の増幅率を所定の率で反比例させる制御を実施し、the amplification factor control unit calculates a temperature difference between the temperature of the connection terminal and the ambient temperature, converts a circuit current from the temperature difference, and performs control such that the amplification factor of the differential amplifier circuit is inversely proportional to the converted circuit current at a predetermined rate;
前記判定部は、前記差動増幅回路が増幅した電位差を前記閾値と比較して判定することを特徴とする接続不良検出回路。The connection failure detection circuit is characterized in that the determination unit compares the potential difference amplified by the differential amplifier circuit with the threshold value to make a determination.
前記接続端子で発生する電位差を検出する電位差検出回路と、a potential difference detection circuit for detecting a potential difference occurring at the connection terminal;
検出した電位差が所定の閾値を超えたら接続不良発生と判断する判定部とを有し、a determination unit that determines that a connection failure has occurred when the detected potential difference exceeds a predetermined threshold value;
前記電位差検出回路が、検出した電位差を増幅する差動増幅回路と、a differential amplifier circuit that amplifies the potential difference detected by the potential difference detection circuit;
電位差検出対象の接続端子の温度を計測する端子温度計測部と、a terminal temperature measurement unit that measures the temperature of a connection terminal that is a potential difference detection target;
温度と前記差動増幅回路の増幅率の関係を記憶する温度補正情報記憶部と、a temperature correction information storage unit that stores a relationship between temperature and the amplification factor of the differential amplifier circuit;
前記差動増幅回路の増幅率を変更制御する増幅率制御部と、を有し、an amplification factor control unit that changes and controls the amplification factor of the differential amplifier circuit;
前記増幅率制御部は、前記接続端子の計測温度を基に、前記温度補正情報記憶部を参照して温度が上昇したら前記差動増幅回路の増幅率を下げる制御を実施し、the amplification factor control unit refers to the temperature correction information storage unit based on the measured temperature of the connection terminal, and performs control to reduce the amplification factor of the differential amplifier circuit when the temperature rises;
前記判定部は、前記差動増幅回路が増幅した電位差を前記閾値と比較して判定することを特徴とする接続不良検出回路。The connection failure detection circuit is characterized in that the determination unit compares the potential difference amplified by the differential amplifier circuit with the threshold value to make a determination.
前記請求項１乃至３の何れかに記載の接続不良検出回路が、前記１次側端子及び前記２次側端子のうちの少なくとも一方に設けられ、
前記接続不良検出回路が接続不良発生と判断したら、前記遮断機構部が遮断動作することを特徴とする回路遮断器。 A circuit breaker having a primary terminal, a secondary terminal, and a breaker mechanism that breaks an electric circuit disposed between the two terminals, wherein the breaker mechanism performs a break operation when an overcurrent flows in the electric circuit,
the connection failure detection circuit according to any one of claims 1 to 3 is provided on at least one of the primary side terminal and the secondary side terminal,
When the connection failure detection circuit determines that a connection failure has occurred, the breaking mechanism performs a break operation .
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002083532A (en) | 2000-09-06 | 2002-03-22 | Mitsubishi Electric Corp | Circuit breaker and temperature detector |
| JP2007285833A (en) | 2006-04-14 | 2007-11-01 | Ricoh Co Ltd | Connection abnormality detection device, connection abnormality detection method, and electrical device |
| JP2012243666A (en) | 2011-05-23 | 2012-12-10 | Kawamura Electric Inc | Contact failure detection circuit and circuit breaker |
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| JP5006123B2 (en) * | 2007-07-02 | 2012-08-22 | 河村電器産業株式会社 | Terminal connection failure detection circuit and circuit breaker |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002083532A (en) | 2000-09-06 | 2002-03-22 | Mitsubishi Electric Corp | Circuit breaker and temperature detector |
| JP2007285833A (en) | 2006-04-14 | 2007-11-01 | Ricoh Co Ltd | Connection abnormality detection device, connection abnormality detection method, and electrical device |
| JP2012243666A (en) | 2011-05-23 | 2012-12-10 | Kawamura Electric Inc | Contact failure detection circuit and circuit breaker |
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