JP2015073356A - Heat generation detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat generation detecting device capable of detecting a cuprous oxide growth exothermic phenomenon occurring in a DC circuit.SOLUTION: A heat generation detecting device includes: a current detection part 5 which detects a current flowing through a DC circuit; and a control part 6 which operates a drive part 4 for interrupting the DC circuit if a current detected by the current detection part 5 is a current different from both a first current preset as the current when the DC circuit is interrupted at a connection 2 of wiring forming the DC current, and a second current preset as the current when the DC circuit is not interrupted.

Description

  The present invention relates to a heat generation detection device.

  In the connection portion of the wiring forming the electric circuit, the contact resistance increases due to aging, vibration, heat cycle, and the like. The connection portion with increased contact resistance generates heat when energized. Copper oxide is generated by heat generation in the connection portion containing copper. When cuprous oxide is produced as the copper oxide, the cuprous oxide itself generates heat when energized. During energization, copper metal may grow while being transformed into cuprous oxide due to heat generation of cuprous oxide. This phenomenon is called cuprous oxide growth exothermic phenomenon. The heat generating part of cuprous oxide is locally about 1000 ° C.

  Patent Document 1 below describes a circuit breaker for wiring. The circuit breaker for wiring includes voltage detection means, a trip circuit for performing a circuit breaking operation, and a control unit that operates the trip circuit based on the detection result of the voltage detection means.

JP 2001-327065 A Japanese Utility Model Publication No. 63-6833

  The circuit breaker described in Patent Document 1 cannot detect the cuprous oxide growth exothermic phenomenon generated in the DC circuit.

  The present invention has been made to solve the above-described problems. An object of the present invention is to provide a heat generation detecting device capable of detecting a cuprous oxide breeding heat generation phenomenon generated in a DC circuit.

  The heat generation detection device according to the present invention includes a current detection unit that detects a current flowing in a DC circuit, and a current detected by the current detection unit when the DC circuit is cut off at a connection part of a wiring that forms the DC circuit. When the current is different from both the first current preset as the current and the second current preset as the current when the DC circuit is not shut off, the drive unit that shuts off the DC circuit is operated. And a control unit to be provided.

  According to the present invention, it is possible to detect a cuprous oxide growth exothermic phenomenon generated in a DC circuit.

It is a circuit diagram which shows the DC circuit provided with DC power supply, a connection part, and load. It is a graph which shows the electric current which flows into the DC circuit shown in FIG. It is a circuit block diagram which shows the heat_generation | fever detection apparatus in Embodiment 1 of this invention. It is a circuit block diagram which shows the heat_generation | fever detection apparatus in Embodiment 2 of this invention.

  The present invention will be described in detail with reference to the accompanying drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. The overlapping description will be simplified or omitted as appropriate.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a DC circuit for operating a load 1. FIG. 1 shows a simple DC circuit comprising a load 1, a wiring connection 2 forming a DC circuit, and a DC power supply 3. FIG. 2 is a graph showing a current flowing through the DC circuit shown in FIG. In FIG. 2, a waveform A shows a current in a state where the DC circuit is cut off. Waveform B shows the current when the cuprous oxide heat is not generated in the energized state. Waveform C shows the current when the cuprous oxide heat is generated in the energized state. The cuprous oxide heat generation means that the cuprous oxide itself generates heat when energized. Hereinafter, the principle of the present invention will be described with reference to FIGS.

  In FIG. 1, when the connection part 2 is open, the DC circuit is cut off. Open means a state in which the connection part 2 is opened or disconnected. When the connection unit 2 is open, the load 1 does not operate because it is not energized. At this time, the supply current from the DC power supply 3 is substantially 0 A as shown by the waveform A shown in FIG. That is, when the connection part 2 is open, no current flows through the DC circuit.

  In FIG. 1, when the connection part 2 is short-circuited, the DC circuit is energized. A short means a state in which the circuit is not interrupted. When the connection unit 2 is short-circuited, the load 1 operates by supplying a current from the DC power source 3. At this time, the current has a constant value as shown by a waveform B in FIG. For example, when a voltage of DC 100 V is supplied from the DC power supply 3 to a load having a resistance value of 50Ω, a current of 2 A flows through the DC circuit including the connection unit 2 when the connection unit 2 is short-circuited.

  Thus, normally, the current flowing in the DC circuit shows either the waveform A or the waveform B shown in FIG. On the other hand, if a cuprous oxide growth exothermic phenomenon occurs in the connection portion 2 due to deterioration over time or poor connection, even if the connection portion 2 is short-circuited, the current is slightly as shown by the waveform C in FIG. descend. This is because the generated cuprous oxide has a slight resistance value. Cuprous oxide heat generation continues stably as long as the DC circuit is energized. When energization is continued in the cuprous oxide heat generating portion, the heat generating portion expands, and the resistance value gradually increases. As the resistance value increases, the current decreases as shown by waveform C. Waveform C is a current waveform characteristic of the heated cuprous oxide. A current waveform such as waveform C does not appear only due to poor connection or circuit on / off. The resistance value of the cuprous oxide and the rate of change of the resistance value in the energized state are values determined by various conditions such as the supply voltage from the DC power supply 3, the current flowing in the DC circuit, and the structure of the connection portion 2. For this reason, the current waveform when cuprous oxide heat generation occurs can also be determined in advance. This current waveform can be set as a current waveform generated in the DC circuit when cuprous oxide generates heat. Thus, in the present invention, cuprous oxide heat generated in the DC circuit during energization is detected based on a current change in the DC circuit.

  Cuprous oxide heat generation can also be detected based on a change in voltage applied to the connection portion 2. However, if there are multiple connections in the DC circuit, it is difficult to predict which of the connections will cause the cuprous oxide growth heat generation phenomenon, so a voltage detector must be provided for each connection. There is.

  FIG. 3 is a circuit block diagram showing the heat generation detection device in the present embodiment. FIG. 3 shows a state where the heat generation detection device is attached to the DC circuit. Hereinafter, the configuration of the heat generation detection device will be described with reference to FIG.

  The circuit diagram shown in FIG. 3 shows a DC circuit for operating the load 1. As in FIG. 1, the DC circuit includes a wiring connection 2 that forms the DC circuit. In addition, the DC circuit is provided with a drive unit 4 that operates to cut off the energization of the circuit.

  As shown in FIG. 3, the heat generation detection device includes a current detection unit 5 and a control unit 6. The current detection unit 5 is connected to the control unit 6. The control unit 6 includes a threshold circuit 7, an integrating circuit 8, and an output circuit 9. The control unit 6 is connected to the drive unit 4.

  Next, the operation of each unit will be described. The current detector 5 detects a circuit current flowing through the DC circuit. The current value detected by the current detection unit 5 is input to the threshold circuit 7 of the control unit 6. The threshold circuit 7 outputs a signal when the input current value is included in the set current region. The threshold circuit 7 does not output a signal when the input current value is not included in the set current range. That is, the threshold circuit 7 determines whether or not the current value detected by the current detection unit 5 is included in the set current region. The set current region is a current region set in advance based on a circuit current that decreases when cuprous oxide heat is generated. The lower limit of the set current region is set to be higher than the current when the connection unit 2 is open during normal operation. The upper limit of the set current region is set lower than the current when the connection part 2 is short-circuited at normal times.

  The signal output from the threshold circuit 7 is input to the integrating circuit 8. The integrating circuit 8 outputs a signal when the input of the signal from the threshold circuit 7 continues for a set time or longer. On the other hand, the integrating circuit 8 does not output a signal when the signal input from the threshold circuit 7 does not continue for a set time or longer. In other words, the integration circuit 8 determines whether or not the determination result indicating that the current value is included in the set current range remains unchanged for the set time. The set time is a predetermined time set in advance.

  The signal output from the integrating circuit 8 is input to the output circuit 9. The output circuit 9 outputs a signal to the drive unit 4 when the signal from the integrating circuit 8 is input. The drive unit 4 operates when a signal from the output circuit 9 is input, and cuts off the energization of the DC circuit.

  Next, the detection operation by the heat generation detection device in the present embodiment will be described using a specific example. Here, a case where cuprous oxide having a resistance value of 2.5Ω is generated in the connection part 2 of the DC circuit where the supply voltage is DC 100V and the resistance value of the load 1 is 10Ω is taken as an example. The reduction rate of the circuit current due to cuprous oxide heat generation is set to 0.01 A / s. The set current region in the threshold circuit 7 is 9 to 7A. The set time in the integrating circuit 8 is 10 s.

  When the cuprous oxide generates heat and does not generate heat, a current of 10 A flows through the DC circuit including the connection 2. The current detector 5 detects a circuit current of 10A. This circuit current is input to the threshold circuit 7. However, since 10A is not included in 9-7A which is the set current region, the threshold circuit 7 does not output a signal.

  On the other hand, when cuprous oxide having a resistance value of 2.5Ω is generated in the connection portion 2, the circuit current at the start of energization is 8A. The current detector 5 detects a circuit current of 8A. This circuit current is input to the threshold circuit 7. At this time, since 8A is included in 9-7A which is the set current region, the threshold circuit 7 outputs a signal. The signal output from the threshold circuit 7 is input to the integrating circuit 8. While the circuit current is a value in the range of 9 to 7 A that is the set current region, a signal is continuously input from the threshold circuit 7 to the integrating circuit 8. Since the current decrease rate due to the heat generation of cuprous oxide is 0.01 A / s, the circuit current after 10 s is 7.9 A. For this reason, the signal continues to be input to the integrating circuit 8 even after 10 seconds. When the signal input from the threshold circuit 7 continues for 10 s, which is the set time, the integrating circuit 8 outputs a signal. The signal output from the integrating circuit 8 is input to the output circuit 9. The output circuit 9 outputs a signal to the drive unit 4 when the signal from the integrating circuit 8 is input. The drive unit 4 operates when a signal from the output circuit 9 is input, and cuts off the energization of the DC circuit. Thereby, the cuprous oxide formed in the connection portion 2 is not energized. As a result, the exothermic phenomenon ends.

  In the specific example described above, the setting current region in the threshold circuit 7 is described as 9 to 7A. However, the set current region can be changed in consideration of various conditions of the DC circuit, a margin of current flowing through the DC circuit, and the like. Further, by shortening the set time in the integrating circuit 8, it is possible to quickly detect the cuprous oxide growth exothermic phenomenon and shut off the DC circuit.

  As described above, the heat generation detection device according to the present embodiment detects a cuprous oxide breeding heat generation phenomenon that occurs at a connection portion or the like in the DC circuit based on the current flowing through the DC circuit. As a result, the DC circuit can be cut off, and burnout of the electrical circuit equipped with the DC circuit connecting portion and the DC circuit can be prevented.

  As described above, in the present embodiment, the cuprous oxide growth exothermic phenomenon is detected by detecting the current characteristic of the heated cuprous oxide. For this reason, it is possible to prevent erroneous detection of a current change caused by a connection failure of a wiring or a circuit on / off. As a result, cuprous oxide growth exotherm can be detected with high accuracy.

Embodiment 2. FIG.
FIG. 4 is a circuit block diagram showing the heat generation detection apparatus in the present embodiment. FIG. 4 shows a state where the heat generation detection device is attached to the DC circuit. Hereinafter, the difference from the first embodiment will be mainly described, and the same parts as those of the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  In the present embodiment, the control unit 6 includes a current decrease rate calculation circuit 10. The current value detected by the current detection unit 5 is input to the current decrease rate calculation circuit 10. The current decrease rate calculation circuit 10 calculates the current decrease rate (A / s) from the current change over a fixed time.

  The current decrease rate calculated by the current decrease rate calculation circuit 10 is input to the threshold circuit 7. The threshold circuit 7 outputs a signal when the input current decrease rate is included in a preset decrease rate range. The threshold circuit 7 does not output a signal when the input current decrease rate is not included in the decrease rate range. Thus, the threshold circuit 7 determines whether or not the current decrease rate calculated by the current decrease rate calculation circuit 10 is included in the decrease rate range. The reduction rate range is a range set in advance based on the reduction rate of the circuit current that changes when cuprous oxide heat is generated. That is, in the first embodiment, the occurrence of cuprous oxide heat generation is detected based on the value of the reduced circuit current, whereas in this embodiment, the occurrence of cuprous oxide heat generation is detected based on the current decrease rate of the circuit current. To detect.

  A signal output from the threshold circuit 7 is input to the output circuit 9. When the signal from the threshold circuit 7 is input, the output circuit 9 outputs a signal to the drive unit 4. The drive unit 4 operates when a signal from the output circuit 9 is input, and cuts off the energization of the DC circuit.

  Next, the detection operation by the heat generation detection device of the present embodiment will be described using a specific example. Here, a case where cuprous oxide having a resistance value of 2.5Ω is generated in the connection part 2 of the DC circuit where the supply voltage is DC 100V and the resistance value of the load 1 is 10Ω is taken as an example. The rate of current reduction due to cuprous oxide heat generation is 0.01 A / s. The current decrease rate calculation circuit 10 calculates the current decrease rate from the current change during 30 s. The reduction rate range in the threshold circuit 7 is 0.005 to 0.02 A / s.

  When the cuprous oxide generates heat and does not generate heat, a current of 10 A flows through the DC circuit including the connection 2. Since 10A keeps flowing at a normal time, the current decrease rate calculated by the current decrease rate calculation circuit 10 is 0 A / s. This current reduction rate is input to the threshold circuit 7. However, since 0 A / s is not included in the decrease rate range 0.005 to 0.02 A / s, the threshold circuit 7 does not output a signal.

  On the other hand, when cuprous oxide having a resistance value of 2.5Ω is generated in the connection portion 2, the circuit current at the start of energization is 8A. When the energized state is maintained, the circuit current gradually decreases as a waveform C shown in FIG. The current reduction rate calculation circuit 10 calculates a current reduction rate of 0.01 A / s at this time. This current reduction rate is input to the threshold circuit 7. Since the current decrease rate 0.01 A / s is included in the decrease rate range 0.005 to 0.02 A / s, the threshold circuit 7 outputs a signal. The signal output from the threshold circuit 7 is input to the output circuit 9. When the signal from the threshold circuit 7 is input, the output circuit 9 outputs a signal to the drive unit 4. The drive unit 4 operates when a signal from the output circuit 9 is input, and cuts off the energization of the DC circuit. Thereby, the cuprous oxide formed in the connection portion 2 is not energized. As a result, the exothermic phenomenon ends.

  In the specific example described above, the reduction rate range in the threshold circuit 7 is described as 0.005 to 0.02 A / s. However, the current decrease rate during heat generation of cuprous oxide is a value that can be determined by various conditions such as the supply voltage, the current flowing in the DC circuit, and the structure of the connection portion 2. For this reason, it is necessary to set an optimal reduction rate range in the threshold circuit 7 in advance. Further, the current decrease rate calculation circuit 10 calculates the current decrease rate from the current change during 30 s, but it is possible to detect cuprous oxide heat generation more quickly by shortening this time.

  As described above, the heat generation detection device according to the present embodiment detects a cuprous oxide growth heat generation phenomenon that has occurred at a connection portion or the like in a DC circuit, based on the current decrease rate when cuprous oxide heat generation occurs. For this reason, even when the current temporarily changes for some reason, no erroneous detection is performed. As a result, it is possible to accurately detect the occurrence of cuprous oxide heat generation.

  As described above, in Embodiments 1 and 2, the case where cuprous oxide heat is generated in one connection portion 2 is taken as an example. However, the present invention can also be applied to a DC circuit having a plurality of connection portions. Since the heat generation detection device in the present invention detects the cuprous oxide growth heat generation phenomenon based on the circuit current or the current drop rate, it detects heat generation even when a cuprous oxide growth heat generation phenomenon occurs in any of a plurality of connecting portions. it can. For this reason, interruption | blocking operation | movement can be performed with respect to the DC circuit provided with the some connection part. As a result, it is possible to prevent burning of electrical equipment or the like equipped with a DC circuit connection part and a DC circuit. In addition, since the heat generation detection device according to the present invention detects the circuit current, unlike the detection method based on the voltage applied to the connection portion, it is not necessary to provide a detector for each connection portion. For this reason, only one current detector 5 may be used as a detector. As a result, it is possible to realize a heat generation detection device that detects cuprous oxide heat generation and interrupts the DC circuit with a simpler configuration.

  In the first and second embodiments, when the load 1 is changed, the resistance value in the DC circuit changes. As a result, the normal current, the current when the cuprous oxide heat is generated, and the current decrease rate when the cuprous oxide heat is generated change. For example, consider a case where cuprous oxide having a resistance value of 2.5Ω is generated in the connection portion 2 of the DC circuit having a supply voltage of DC 100V and a load resistance value of 10Ω. In this case, a current of 10 A flows through the DC circuit normally, and a current of 8 A flows when cuprous oxide heat is generated. Here, when the load 1 is changed to one having a resistance value of 20Ω, the normal current becomes 5A. Moreover, since the resistance value of cuprous oxide also changes, the current when cuprous oxide heat generation occurs and the current decrease rate when cuprous oxide heat generation occurs change. For this reason, when cuprous oxide heat generation occurs after the load 1 is changed, the occurrence of cuprous oxide heat generation cannot be detected using various set values set in the threshold circuit 7 before the change. In this case, heat generation of cuprous oxide can be detected by linking the resistance value of the load 1 and the setting of the threshold circuit 7. Specifically, in the first embodiment, the set current region of the threshold circuit 7 may be changed in accordance with the change of the load 1. In the second embodiment, the reduction rate range of the threshold circuit 7 may be changed in accordance with the change of the load 1.

  As described above, in the first embodiment, the integrating circuit 8 outputs a signal when the input of the signal from the threshold circuit 7 continues for a set time or more, and does not output a signal when the input does not continue for the set time or longer. . However, it is also possible to reverse the condition for the integrating circuit 8 to output a signal and the condition for not outputting a signal. That is, the signal may be continuously output when the signal input from the threshold circuit 7 does not continue for the set time or more, and the signal output may be stopped when the signal is continued for the set time or longer. However, in this case, the output circuit 9 is set so as to output a signal when no signal is input from the integrating circuit 8.

  As described above, in the first and second embodiments, the threshold circuit 7 outputs a signal when the input value is within a preset range, and does not output a signal when the input value is not within the range. However, it is also possible to reverse the condition for the threshold circuit 7 to output a signal and the condition for not outputting a signal. That is, the signal may not be output when the input value is within the range, and the signal may be output when the input value is not within the range. However, in this case, the integration circuit 8 in the first embodiment outputs a signal when a state in which no signal is input from the threshold circuit 7 continues for a set time or longer, and a state in which no signal is input continues for a set time or longer. If not, it is set not to output a signal. In this case, the output circuit 9 in the second embodiment does not output a signal while the signal from the threshold circuit 7 is being input, and outputs a signal when the signal from the threshold circuit 7 is no longer input. Set to do.

  Moreover, it is good also as providing an alerting | reporting means in the heat_generation | fever detection apparatus in Embodiment 1 and 2. For example, it is possible to notify the user of an abnormal state by providing an indicator lamp or LED that is turned on when the drive unit 4 is operated. Thereby, restoration work such as removal of cuprous oxide can be promoted.

  DESCRIPTION OF SYMBOLS 1 Load 2 Connection part 3 DC power supply 4 Drive part 5 Current detection part 6 Control part 7 Threshold circuit 8 Accumulation circuit 9 Output circuit 10 Current reduction rate calculation circuit

The heat generation detection device according to the present invention includes a current detection unit that detects a current flowing in a DC circuit, and a current detected by the current detection unit when the DC circuit is cut off at a connection part of a wiring that forms the DC circuit. When the current is different from both the first current preset as the current and the second current preset as the current when the DC circuit is not shut off, the drive unit that shuts off the DC circuit is operated. A threshold value circuit that determines whether or not the current detected by the current detection unit is included in a preset current range, and a determination result by the threshold circuit is preset. And an output circuit that operates the drive unit based on a determination result by the integration circuit, and the lower limit of the current range is higher than the first current. , Current range The upper limit is lower than the second current.
Further, the heat generation detection device according to the present invention includes a current detection unit that detects a current flowing in the DC circuit, and a current detected by the current detection unit is cut off at a connection part of a wiring that forms the DC circuit. A drive unit that cuts off the DC circuit when the current is different from both the first current set in advance as the current and the second current set as the current when the DC circuit is not cut off. A control unit for operating the current reduction rate calculation circuit for calculating a current reduction rate of the current detected by the current detection unit, and a current reduction rate calculated by the current reduction rate calculation circuit in advance. And a threshold circuit that determines whether or not the set reduction rate range is included, and an output circuit that operates the drive unit based on a determination result by the threshold circuit.

Claims (3)

A current detector for detecting the current flowing in the DC circuit;
The current detected by the current detection unit is the first current preset as the current when the DC circuit is cut off at the connection part of the wiring forming the DC circuit and the DC circuit is cut off. A control unit that operates the drive unit that shuts off the DC circuit when the current is different from any of the second currents that are preset as the current when
A fever detection device comprising: The controller is
A threshold circuit for determining whether or not the current detected by the current detector is included in a preset current region;
An integration circuit for determining whether or not the determination result by the threshold circuit has not changed for a preset time; and
An output circuit for operating the driving unit based on a determination result by the integrating circuit;
With
The heat generation detecting device according to claim 1, wherein a lower limit of the current region is higher than the first current, and an upper limit of the current region is lower than the second current. The controller is
A current reduction rate calculating circuit for calculating a current reduction rate of the current detected by the current detection unit;
A threshold circuit for determining whether or not the current reduction rate calculated by the current reduction rate calculation circuit is included in a preset reduction rate range;
An output circuit for operating the drive unit based on a determination result by the threshold circuit;
The heat generation detecting device according to claim 1, comprising:

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