JP2023023625A - Connection failure detection circuit and circuit breaker - Google Patents

Abstract

To provide a connection failure detection circuit and a circuit breaker for detecting a poor connection even at voltage value where generated potential difference does not reach operating voltage of a photocoupler and unaffected by electric path current.SOLUTION: A connection failure detection circuit 2 includes: a first differential amplifier 21 which detects generated potential difference at an individual connection terminal 6 of a terminal part 10; a second differential amplifier 22 which combines the first differential amplifiers 21 installed in any two connection terminals 6 with mutually different polarity on a same electric circuit and extracts difference of their outputs; and a determination part 23 which determines the presence of a poor connection when the output voltage of the second differential amplifier 22 exceeds a certain value. A circuit breaker 1 includes an output part 3 which generates an interruption signal according to the output of the determination part 23. At occurrence of poor connection, the circuit breaker 1 executes shut-off operation.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection failure detection circuit for detecting connection failure of an electric circuit connecting portion, and a circuit breaker equipped with the connection failure detection circuit.

A terminal of a circuit breaker has a structure in which a crimp terminal on the wire side is crimped onto a washer by a terminal screw to achieve mechanical connection and electrical connection. In such a terminal, when the terminal screw is loosened, the contact state between the washer and the crimp terminal becomes unstable, causing arc discharge and overheating.
As a countermeasure, there is a circuit breaker that detects loosened terminal screws and cuts off the electric circuit. For example, in Patent Document 1, when a predetermined potential difference occurs between the terminal screw and the terminal seat, it is determined that a connection failure has occurred, and the disconnecting mechanism is operated to disconnect.

JP 2012-243666 A

However, in the technique of Patent Document 1, the photocoupler is turned on by the potential difference generated at the connection terminal, and the connection failure is detected from the output. Therefore, there is a problem that detection cannot be performed unless the potential difference at the detection portion reaches the operating voltage of the photocoupler. In addition, since the potential difference to be detected varies depending on the magnitude of the circuit current, the sensitivity varies.

In view of such problems, the present invention provides a connection failure detection circuit and a circuit breaker that can detect a connection failure even if the generated potential difference is a voltage value that does not reach the operating voltage of the photocoupler, and is not affected by the circuit current. is intended to provide

In order to solve the above-mentioned problems, the invention of claim 1 is a connection failure detection circuit for detecting a connection failure of a terminal portion having a plurality of connection terminals for electrically connecting electric paths, wherein the electric paths are connected from different polarities. Each connection terminal has a potential difference detection circuit that detects the potential difference generated at the connection terminal, and a potential difference detection circuit that is provided at any two connection terminals with different polarities on the same electric path. It is characterized by having a differential amplifier circuit for extracting the difference between the outputs in combination, and a judgment unit for judging that connection failure occurs when the output voltage of the differential amplifier circuit exceeds a certain value.
According to this configuration, it is judged from the relative difference between the two connecting terminals that are combined, not from the potential difference within the terminals, and if a potential difference of a certain value or more occurs between the connecting terminals, it is judged that a connection failure has occurred. do. Therefore, connection failure can be detected without being affected by the electric circuit current. In addition, since the differential amplifier circuit extracts the potential difference, detection is possible even if the voltage does not reach the voltage that turns on the photocoupler as in the conventional art, and connection failure can be detected at an early stage.

According to a second aspect of the invention, in the configuration of the first aspect, the electrical path is composed of three electrical path members, and the terminal portion has three connection terminals, each of which has a potential difference detection circuit. and has three differential amplifier circuits for combining two different outputs of the three potential difference detection circuits and extracting the difference between the outputs, and the determination unit includes the output voltage of at least one of the differential amplifier circuits. exceeds a certain value, it is determined that a connection failure has occurred.
According to this configuration, if a connection failure occurs in any one connection terminal of the terminal section consisting of three connection terminals and the potential difference becomes larger than that of the other connection terminals, it is detected. Therefore, even if the terminal portion is composed of three terminals, it is possible to reliably detect connection failure.

According to the third aspect of the invention, in the configuration of the first aspect, the electric circuit is composed of two electric circuit members, and the terminal portion has two connection terminals, each of which has a potential difference detection circuit. and has one differential amplifier circuit for extracting the difference between the outputs of the two potential difference detection circuits, and the judging section judges that a connection failure has occurred when the output voltage of the differential amplifier circuit exceeds a certain value. Characterized by
According to this configuration, the terminal section including the two connection terminals determines that a connection failure has occurred when a difference occurs in the potential difference between the two connection terminals. Therefore, connection failure can be detected with a simple configuration.

The invention of claim 4 is a circuit breaker in which the terminal portions on the primary side and the secondary side are composed of three connecting terminals, and at least one of the terminal portions on the primary side and the secondary side has a 2, and has an output unit for outputting a cutoff signal when the connection fault detection circuit determines that a connection fault has occurred, and performs a cutoff operation according to the cutoff signal.
According to this configuration, when a connection failure occurs in the terminal portion, it is detected from the relative difference in voltage effect between the terminals, and the disconnection operation is performed. Therefore, the detection operation of poor connection does not vary depending on the magnitude of the electric circuit current.

The invention according to claim 5 is a circuit breaker in which the terminal portions on the primary side and the secondary side are composed of two connection terminals, and at least one of the terminal portions on the primary side and the secondary side has a 3, and has an output unit for outputting a cutoff signal when the connection fault detection circuit determines that a connection fault has occurred, and performs cutoff operation according to the cutoff signal.
According to this configuration, when a connection failure occurs in the terminal portion, it is detected from the relative difference in voltage effect between the terminals, and the disconnection operation is performed. Therefore, the detection operation of poor connection does not vary depending on the magnitude of the electric circuit current.

According to the poor connection detection circuit and the circuit breaker of the present invention, in the two connection terminals combined rather than the potential difference in the terminals, it is judged from the relative difference between the terminals, and the potential difference between the connection terminals is equal to or greater than a certain value. If a potential difference occurs, it is determined that a connection failure has occurred. Therefore, connection failure can be detected without being affected by the electric circuit current. In addition, since the differential amplifier circuit extracts the potential difference, detection is possible even if the voltage does not reach the voltage that turns on the photocoupler as in the conventional art, and connection failure can be detected at an early stage.

FIG. 4 is an explanatory diagram of a circuit breaker equipped with a poor connection detection circuit; FIG. 4 is an explanatory diagram showing a configuration of a connection terminal; FIG. 10 is an explanatory diagram showing another form of the poor connection detection circuit and the circuit breaker;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a circuit breaker equipped with a poor connection detection circuit according to the present invention. Reference numeral 1 denotes a circuit breaker, and 2 denotes a connection failure detection circuit.
A circuit breaker 1 shows a case where an electric circuit member is composed of a three-wire electric circuit, and here shows a configuration used for a single-phase three-wire electric circuit (hereinafter simply referred to as “electric circuit”) 4 . The poor connection detection circuit 2 is mounted on a circuit board (not shown) and built into the housing H of the circuit breaker 1 .

In the circuit breaker 1, a terminal portion 10 constituting a primary side terminal 11 and a secondary side terminal 12 electrically connecting an electric circuit 4 has three connection terminals, and an L1 pole which is a voltage pole, and It is composed of an L2 pole and an N pole, which is a neutral pole.
Inside the housing H of the circuit breaker 1, there are provided a contact portion 13 for opening and closing an electric circuit that spans between the primary side terminal 11 and the secondary side terminal 12, and an opening/closing mechanism portion (not shown) for opening and closing the contact portion 13. ) are installed. A handle (not shown) for opening and closing is provided on the upper portion of the housing H. As shown in FIG. However, in FIG. 1, the inside of the housing H is seen through for explanation.

The poor connection detection circuit 2 includes first differential amplifiers 21 (21a, 21b, and 21c) as three potential difference detection circuits connected to each connection terminal of the secondary side terminal 12, and a different first differential amplifier 21. From the output voltage of the second differential amplifier 22 (22a, 22b, 22c), which are three differential amplifier circuits for forming three pairs and inputting the outputs of the formed pairs, and the second differential amplifier 22, and a judgment unit 23 for judging connection failure.
The circuit breaker 1 includes an output section 3 that outputs a break signal for breaking the circuit breaker 1 when the judgment section 23 judges that connection failure has occurred. In response to this breaking signal, the opening/closing mechanism of the circuit breaker 1 performs breaking operation.

FIG. 2 shows the configuration of the connection terminal 6 of the secondary side terminal 12 to which the first differential amplifier 21 is connected. The configuration of the connection terminal 6 itself is common to each connection terminal 6 of the primary side terminal 11 and the secondary side terminal 12 .
The connection terminal 6 has a washer 61, a terminal screw 62, and a nut 63, and is connected to a crimp terminal 65 fixed to the end of an electric wire 62, which is an electric circuit.
The positive input terminal 20 a of the pair of positive and negative input terminals 20 a and 20 b of the first differential amplifier 21 is connected to the washer 61 , and the negative input terminal 20 b is connected to the crimp terminal 65 . Thus, the potential difference between the washer 61 of the connection terminal 6 and the crimp terminal 65 is input.

Incidentally, the part where the voltage is detected may be between the washer 61 and the nut 63 or between the washer 61 and the terminal screw 62 . Further, when the poor connection detection circuit 2 is provided at the primary side terminal 11, the parts to which the pair of positive and negative input terminals of the first differential amplifier 21 are connected are reversed.
Further, the circuit breaker 1 has three first differential amplifiers 21 because the terminal section 10 is composed of three terminals. Since there are three combinations of the first differential amplifiers 21 forming pairs, the number of the second differential amplifiers 22 is also three in order to cover the combinations.

The poor connection detection circuit 2 configured as described above operates as follows. For example, assume that the amplification degrees of the first differential amplifier 21 and the second differential amplifier 22 are 100, and the absolute value of the threshold voltage of the determination unit 23 is 5V. Assuming that the potential difference between the washer 61 and the crimp terminal 65 is 10 mV in a normal connection state, the output of the first differential amplifier 21 is 1V.
However, since this value is a numerical value for a normal connection state, all three terminals are approximately 10 mV, and the outputs of the first differential amplifier 21 are all 1 V, which is the same voltage. Therefore, no potential difference occurs in the differential input of the second differential amplifier 22, and the output voltage becomes a value close to 0 V even if the amplification degree is 100. Therefore, since the determination threshold value of 1 V is not reached, the determination unit 23 does not determine that connection failure has occurred.

Also, even if the current in the electric circuit 4 increases and the detected potential difference of the first differential amplifier 21 of the L1 pole terminal increases to 20 mV, for example, the detected potential difference of the connection terminal 6 of the other pole also increases due to the current increase. Since the voltage increases, the operating input of the second differential amplifier 22 continues to have a value close to 0 V, and the output voltage does not change significantly. Therefore, it is not determined that connection failure has occurred.

However, for example, if a connection failure occurs at the connection terminal 6 of the L2 pole and the detected potential difference changes from 10 mV to 20 mV, a difference of 10 mV from the other connection terminals 6 occurs.
In this case, the outputs of the L1 and N-pole first differential amplifiers 21a and 21b are 1 V, whereas a difference of 20 mV occurs in the differential input of the L2-pole first differential amplifier 21c. becomes 2V.
Since the two second differential amplifiers 22a and 22c to which this voltage is input have a difference of 1V in the differential inputs, the absolute value of the output voltage greatly exceeds the set threshold of 5V. Therefore, the determination unit 23 determines that a connection failure has occurred and outputs a predetermined signal to the output unit 3. Upon receiving this signal, the output unit 3 outputs a cutoff signal, and the circuit breaker 1 performs a cutoff operation.

In this way, it is judged from the relative difference between the two connecting terminals 6 that are combined rather than the potential difference in the terminals, and if a potential difference of a certain value or more occurs between the connecting terminals 6, it is judged that a connection failure has occurred. do. Therefore, connection failure can be detected without being affected by the electric circuit current. In addition, since the second differential amplifier 22 extracts the potential difference, detection is possible even if the voltage does not turn on the photocoupler as in the conventional art, and connection failure can be detected at an early stage.
In the terminal section 10 having three terminals, if a connection failure occurs in any one of the connection terminals 6 and the potential difference becomes larger than that of the other terminals, the terminal section 10 is composed of three terminals in order to detect it. It is possible to reliably detect a connection failure even if it is

FIG. 3 shows a circuit breaker 1a in which a primary side terminal 11 and a secondary side terminal 12, which are the terminal section 10, are composed of two terminals. A poor connection detection circuit 2 is provided at the secondary side terminal 12 in the same manner as in the above embodiment.
In the case of the two-terminal circuit breaker 1a, one terminal unit 10 has two first differential amplifiers 21, so only one second differential amplifier 22 to which this output is input may be used. It becomes the structure provided with the differential amplifier. Also, the determination unit 23 determines the connection failure based only on the output voltage of this one second differential amplifier 22 . The determination threshold is the same as in the above embodiment.
Thus, in the terminal section 10 having two terminals, if a difference occurs in the potential difference between the two connection terminals 6, it is determined that a connection failure has occurred. Therefore, connection failure can be detected with a simple configuration.

In the above-described embodiment, the poor connection detection circuit 2 is provided at the secondary terminal 12, but it may be provided at the primary terminal 11 or both.
In addition, although the case where the connection failure detection circuit 2 is assembled to the circuit breaker 1 has been described, it can also be applied to, for example, a terminal block that does not have an interruption mechanism. It can function effectively by ringing.
Furthermore, although the configuration for detecting the potential difference between the crimp terminal 65 and the washer 61 has been described, it can also be applied to other terminal configurations, such as quick-connect terminals, by detecting the potential difference between the wire to be inserted and the terminal fitting. can do.

DESCRIPTION OF SYMBOLS 1, 1a... Circuit breaker, 2... Connection failure detection circuit, 3... Output part, 4... Electric circuit (electric circuit member), 6... Connection terminal, 10... Terminal part, 11... Primary side Terminal 12 Secondary side terminal 13 Contact point 21 First differential amplifier (potential difference detection circuit) 22 Second differential amplifier (differential amplifier circuit) 23 Judgment part .

Claims (5)

A connection failure detection circuit for detecting a connection failure of a terminal portion having a plurality of connection terminals for electrically connecting an electric circuit,
The electric circuit is composed of a plurality of electric circuit members having different polarities,
a potential difference detection circuit for detecting a potential difference generated at each of the connection terminals;
a differential amplifier circuit that combines the potential difference detection circuits provided at any two of the connection terminals with different polarities in the same electrical path and extracts the difference in the outputs thereof;
and a determination unit that determines that a connection failure has occurred when the output voltage of the differential amplifier circuit exceeds a predetermined value. The electrical path is composed of three electrical path members, and the terminal section has three connection terminals, each of which is provided with the potential difference detection circuit,
having three differential amplifier circuits for extracting a difference between outputs by combining two different outputs of the three potential difference detection circuits;
2. The poor connection detection circuit according to claim 1, wherein said determining unit determines that a poor connection has occurred when the output voltage of at least one of said differential amplifier circuits exceeds a predetermined value. The electrical path is composed of two electrical path members, and the terminal portion has two connection terminals, each of which is provided with the potential difference detection circuit,
having one differential amplifier circuit for extracting a difference between outputs of the two potential difference detection circuits;
2. The defective connection detection circuit according to claim 1, wherein said determining unit determines that a defective connection has occurred when the output voltage of said differential amplifier circuit exceeds a predetermined value. A circuit breaker in which the terminal portions on the primary side and the secondary side are composed of three connection terminals,
The connection failure detection circuit according to claim 2 is provided in at least one of the terminal portions on the primary side and the secondary side, and
an output unit that outputs a cutoff signal when the connection failure detection circuit determines that a connection failure has occurred;
A circuit breaker, characterized in that it performs a breaking operation in response to the breaking signal. A circuit breaker in which the terminal portions on the primary side and the secondary side are composed of two connection terminals,
The connection failure detection circuit according to claim 3 is provided in at least one of the terminal portions on the primary side and the secondary side, and
an output unit that outputs a cutoff signal when the connection failure detection circuit determines that a connection failure has occurred;
A circuit breaker, characterized in that it performs a breaking operation in response to the breaking signal.

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