JP6897603B2 - Cable disconnection sign detection device - Google Patents

Description

The present invention is an invention relating to detection of disconnection of a cable connected to a load and energizing the load.

Conventionally, in the configuration of an electric circuit in which a cable is connected to some kind of load and a current is applied to the load through the cable, power is not naturally supplied to the load when the cable is broken.

For example, in a heating device that heats an object to be heated, a cable is connected between a heater that is a heat source and a power supply circuit or a control circuit. If such a cable is broken, the heater cannot be controlled and predetermined heating cannot be performed.

Therefore, in order to detect a sign of disconnection of the cable, the cable installed in the movable part is more resistant to the voltage supply lead wire (the original lead wire actually required) and this original lead wire. By providing a dummy lead wire with inferior flexibility and detecting the presence or absence of disconnection of this dummy lead wire, it is predicted that the original lead wire disconnection time is approaching and the risk of disconnection is high. The device to be used is shown in Patent Document 1.

Japanese Unexamined Patent Publication No. 5-340985

In the apparatus shown in Patent Document 1, it is necessary to prepare a special cable provided with a lead wire for a dummy having inferior bending resistance, and a versatile cable cannot be used. Further, since it is a binary determination that the original lead wire breakage is predicted only by the presence or absence of the dummy lead wire breakage, it is not possible to adjust the sensitivity for detecting the sign of the cable breakage. In addition, it is not possible to detect an abnormality such as a disconnection of the load.

Therefore, an object of the present invention is to provide a device that does not require a special cable and detects a sign of disconnection of the cable.

The cable disconnection sign detection device as an example of the present disclosure is a device that detects a sign of disconnection of a cable connected to a load and energizing the load, and includes a current detection unit and an alarm unit. The cable contains multiple current paths connected in parallel. The current detection unit detects the current flowing in at least one of the plurality of current paths. Then, the alarm unit compares the value detected by the current detection unit with the threshold value, detects the energized state of the plurality of current paths, determines the presence or absence of disconnection of the plurality of current paths, and determines that there is a disconnection. , Issue an alarm.

In this configuration, a lead wire for a dummy having poor bending resistance is not required, and an ordinary cable can be used. Further, instead of determining whether or not the dummy lead wire is broken, the current flowing in at least one of the plurality of current paths is detected, and the current is energized in the plurality of current paths based on the comparison between this and the threshold value. Since the state is detected, it is possible to adjust the sensitivity of detecting the sign of the cable by setting the threshold value. Furthermore, abnormalities such as load disconnection can be detected.

Further, in one example of the present disclosure, it is a device for detecting a sign of disconnection of a cable connected to a load and energizing the load, and includes a current detection unit and an alarm unit. The cable contains multiple current paths connected in parallel. The current detector detects the sum or difference of the currents flowing in at least two of the plurality of current paths. Then, the alarm unit compares the value detected by the current detection unit with the threshold value, detects the energized state of the plurality of current paths, determines the presence or absence of disconnection of the plurality of current paths, and determines that there is a disconnection. , Issue an alarm.

In this configuration, since the energized state of the plurality of current paths is detected based on the combination of the currents flowing in the plurality of current paths, it is possible to detect the combination of the presence or absence of disconnection of the plurality of current paths.

Further, in one example of the present disclosure, the device is a device that detects a sign of disconnection of a plurality of cables that are connected to a plurality of connection portions of the load and conduct current to the load, and the current detection unit and the alarm unit are used. Be prepared. The cable includes a first cable connected to the first connection of the load and a second cable connected to the second connection of the load. The first cable is composed of a plurality of first current paths connected in parallel, and the second cable is composed of a plurality of second current paths connected in parallel. The current detection unit detects the sum or difference between the current flowing in at least one of the plurality of first current paths and the current flowing in at least one of the plurality of second current paths. Then, the alarm unit compares the value detected by the current detection unit with the threshold value, and detects the energized state of the plurality of first current paths and the energized state of the plurality of second current paths, thereby detecting a plurality of first currents. The presence or absence of disconnection of the path and the plurality of second current paths is determined, and when it is determined that there is a disconnection, an alarm is issued.

In this configuration, for the first cable and the second cable connected to the load, the energized state of the plurality of current paths is detected based on the combination of the currents flowing in the plurality of current paths, respectively, so that the plurality of currents of the first cable are detected. It is possible to detect a combination of a path and a plurality of current paths of the second cable with or without disconnection.

Further, in one example of the present disclosure, the device is a device that detects a sign of disconnection of a plurality of cables that are connected to a plurality of connection portions of the load and conduct current to the load, and the current detection unit and the alarm unit are used. Be prepared. The cable includes a first cable connected to the first connection of the load and a second cable connected to the second connection of the load. The first cable is composed of a plurality of first current paths connected in parallel, and the second cable is composed of a plurality of second current paths connected in parallel. The current detection unit detects the sum or difference of the currents flowing in at least one of the second current paths with respect to the sum or difference of the currents flowing in at least two current paths in the first current path. Then, the alarm unit compares the value detected by the current detection unit with the threshold value, and detects the energized state of the plurality of first current paths and the energized state of the plurality of second current paths, thereby detecting a plurality of first currents. The presence or absence of disconnection of the path and the plurality of second current paths is determined, and when it is determined that there is a disconnection, an alarm is issued.

In this configuration, for the first cable and the second cable connected to the load, the energized state of the plurality of current paths is detected based on the combination of the currents flowing in the plurality of current paths, respectively, so that the plurality of currents of the first cable are detected. It is possible to detect a combination of a path and a plurality of current paths of the second cable with or without disconnection.

Further, in one example of the present disclosure, the threshold value is determined based on the value detected by the current detection unit in the initial state.

In this configuration, the disconnection is detected by the amount of change from the initial state, and it is possible to detect the disconnection sign by more accurate determination.

According to the present invention, a sign of cable disconnection can be detected without the need for a special cable.

FIG. 1 is a diagram showing the configuration of the entire heating device including the cable disconnection sign detection device according to the embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. FIG. 3 is a diagram showing the relationship between the threshold value and the measured current value. FIG. 4 is a flowchart showing the processing contents of the control unit 20 shown in FIG. FIG. 5 is a circuit diagram of a heating device having a configuration of a current path different from that of the heating device shown in FIG. 1 and detected by the current detection unit 4. FIG. 6 is a diagram showing the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. FIG. 7 is a circuit diagram of a heating device having a different configuration of the cable 31 from the heating device shown in FIG. FIG. 8 shows the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, the current flowing in the third current path CA13, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. It is a figure which shows. FIG. 9 is a circuit diagram of a heating device having a different configuration of the current detection unit from the example shown in FIG. 7. FIG. 10 shows the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, the current flowing in the third current path CA13, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. It is a figure which shows. FIG. 11 is a circuit diagram of a heating device in which the current detection unit 4 detects currents flowing through the three current paths CA11, CA12, and CA13 constituting the cable 31. FIG. 12 shows the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, the current flowing in the third current path CA13, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. It is a figure which shows. FIG. 13 is a circuit diagram of a heating device different from the example shown in FIG. FIG. 14 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, and CA2 and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. FIG. 15 is a circuit diagram of a heating device different from the example shown in FIG. FIG. 16 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, and CA2 and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. FIG. 17 is a circuit diagram of a heating device different from the example shown in FIG. FIG. 18 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, and CA22 and the measurement result of the current detection unit 4 in the disconnection state at a predetermined location. FIG. 19 is a circuit diagram of a heating device different from the example shown in FIG. FIG. 20 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, and CA22 and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. FIG. 21 is a circuit diagram of a heating device different from the example shown in FIG. FIG. 22 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, and CA22 and the measurement result of the current detection unit 4 in the disconnection state at a predetermined location. FIG. 23 is a circuit diagram of a heating device different from the example shown in FIG. FIG. 24 is an example of a device in which a three-phase AC power supply is connected to the heater 2, which is a three-phase AC load, via a cable. FIG. 25 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, CA22, CA31, and CA32 and the detection results of the current detection units CT1, CT2, and CT3 in the disconnected state at a predetermined location.

Hereinafter, embodiments for carrying out the present invention will be described with reference to some figures.

-Application example First, an example to which the present invention is applied will be described with reference to FIG. FIG. 1 is a diagram showing the configuration of the entire heating device including the cable disconnection sign detection device according to the embodiment of the present invention.

As shown in FIG. 1, the cable disconnection sign detection device 201 according to the present embodiment is a device that is connected to a heater 2 which is a load and detects a sign of disconnection of cables 31 and 32 that apply a current to the heater 2. Is. In the example shown in FIG. 1, the cable 31 includes a plurality of current paths CA11 and CA12 connected in parallel. The cable disconnection sign detection device 201 compares the current detection unit 4 that detects the current flowing through one of the plurality of current paths CA11 and CA12 with the current detection unit 4 and the threshold value detected by the current detection unit 4. By detecting the energized state of the plurality of current paths CA11 and CA12, it is determined whether or not the plurality of current paths CA11 and CA12 are disconnected, and when it is determined that the current paths are disconnected, an alarm unit 10 is provided to output an alarm.

• Configuration Example Next, the configuration of the heating device according to the embodiment of the present invention will be described with reference to the drawings. As described above, FIG. 1 is a diagram showing the configuration of the entire heating device including the cable disconnection sign detection device according to the embodiment of the present invention.

As shown in FIG. 1, the heating device 101 includes a power supply 1, a heater 2, cables 31, 32, a current detection unit 4, and an opening / closing unit 5. The heater 2 corresponds to the "load" according to the present invention. The heater 2 is connected to the power supply 1 via cables 31 and 32. The cables 31 and 32 are current paths connecting the power supply 1 and the heater 2. In this example, the power supply 1 is a single-phase AC power supply, and the heater 2 is a load of two terminals. An opening / closing portion 5 is inserted in series with the cable 31. Further, the cable 31 includes two current paths CA11 and CA12. The current detection unit 4 detects the current flowing through the current path CA12. The current detection unit 4 is, for example, a current transformer, and a resistor is connected to the secondary side to output a voltage proportional to the detected current.

The control unit 20 controls the opening / closing unit 5 and controls for detecting a sign of disconnection of the cable.

The opening / closing unit 5 is, for example, a solid state switch, and is opened / closed by the output signal of the output unit 16.

The setting unit 12 inputs a set value manually or by communication from the outside, and stores the value in the storage unit 13. The current measuring unit 11 measures the current based on the detected value of the current detecting unit 4. The determination unit 14 determines whether or not it is in an abnormal state based on the value stored in the storage unit 13 and the value measured by the current measurement unit 11. When the determination unit 14 determines that it is in an abnormal state, the abnormality output unit 15 issues an alarm by relay output, light emission of an indicator, setting of a communication flag, or the like.

FIG. 2 is a diagram showing the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. In FIG. 2, i11 is a current flowing through the first current path CA11, i12 is a current flowing through the second current path CA12, and iCT is a detected value of the current detecting unit 4 (measured value of the current measuring unit 11). Both are relative values when the current flowing through the heater 2 is 1.0.

If there is no disconnection in any of the current paths, the measured current value is 0.5. When the first current path CA11 is disconnected, the current flowing through the heater 2 flows only through the second current path CA12, so that the current flowing through the second current path CA12 is 1.0. When the second current path CA12 is disconnected, the measured current value becomes 0. The measured current value becomes 0 even when the heater itself is disconnected.

The setting unit 12 shown in FIG. 1 stores the upper and lower limit values, for example, 0.25 and 0.75, in advance in the storage unit 13. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. FIG. 3 is a diagram showing the relationship between the threshold value and the measured current value. If the measured current value exceeds 0.25 and is less than 0.75, it is considered normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is 0.75 or more, it is considered that the first current path CA11 is disconnected. If the measured current value is less than 0.25, it is considered that the second current path CA12 is disconnected. That is, this is detected as a sign that the cable 31 is broken.

Since the measured current value is less than 0.25 even when the heater 2 is disconnected, the disconnection of the second current path CA12 and the disconnection of the heater 2 are indistinguishable in the present embodiment.

FIG. 4 is a flowchart showing the processing contents of the control unit 20 shown in FIG. First, the current value storage flag is reset and the state of the output unit is determined (S1 → S2). If the state of the output unit is ON, that is, if the switch is ON, the measured current value is read (S3). Then, based on this value, the threshold value is determined and registered, and the current value storage flag is set (S4 → S5 → S6). In the example shown in FIG. 3, if the initial measured current value is 0.5, a value (0.75, 0.25) obtained by adding or subtracting the relative fluctuation amount of 0.25 is registered as a threshold value.

In the normal state, the loop of S7 → S2 → S3 → S4 → S7 is repeated. After that, when the measured current value reaches a value in the abnormal range, an abnormal output is performed (S7 → S8). If the current value storage flag is reset in another routine, the measured current value at that time is updated as the initial current value.

Next, an example of detecting a sign of disconnection by detecting the current flowing through the two current paths will be shown.

FIG. 5 is a circuit diagram of a heating device having a configuration of a current path different from that of the heating device shown in FIG. 1 and detected by the current detection unit 4. In this example, the current detection unit 4 detects the difference between the currents flowing in the two current paths CA11 and CA12.

FIG. 6 is a diagram showing the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. In FIG. 6, i11 is a current flowing through the first current path CA11, i12 is a current flowing through the second current path CA12, and iCT is a detected value of the current detection unit 4. Both are relative values when the current flowing through the heater 2 is 1.0.

When there is no disconnection in any of the current paths, the current flowing through the first current path CA11 and the second current path CA12 is 0.5, and the measured current value is 0. When the first current path CA11 is disconnected, the current flowing through the heater 2 flows only through the second current path CA12, so that the current flowing through the second current path CA12 is 1.0 and the measured current value is 1.0. When the second current path CA12 is disconnected, the current flowing through the heater 2 flows only through the first current path CA11, so that the current flowing through the first current path CA11 is 1.0 and the measured current value is -1.0. .. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 5, the setting unit 12 shown in FIG. 1 stores, for example, 0.5 and −0.5 as upper and lower limit values in advance in the storage unit 13. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds −0.5 and is less than 0.5, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is 0.5 or more, it is considered that the first current path CA11 is disconnected. If the measured current value is less than −0.5, it is considered that the second current path CA12 is disconnected. That is, these are detected as a sign that the cable 31 is disconnected.

Next, an example of detecting a sign of disconnection when one cable is composed of three current paths will be described.

FIG. 7 is a circuit diagram of a heating device having a different configuration of the cable 31 from the heating device shown in FIG. In this example, the cable 31 is composed of three current paths CA11, CA12, and CA13. The current detection unit 4 detects the current flowing through the current path CA13.

FIG. 8 shows the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, the current flowing in the third current path CA13, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. It is a figure which shows. In FIG. 8, i11 is a current flowing through the first current path CA11, i12 is a current flowing through the second current path CA12, i13 is a current flowing through the third current path CA13, and iCT is a detected value of the current detection unit 4. Both are relative values when the current flowing through the heater 2 is 1.0.

When there is no disconnection in any of the current paths, the current flowing through the first current path CA11, the second current path CA12, and the third current path CA13 is 1/3, and the measured current value is 1/3. When the first current path CA11 is disconnected, the current flowing through the heater 2 flows through the second current path CA12 and the third current path CA13, so that the current flowing through the third current path CA13 is 0.5 and the measured current value is 0. It becomes .5. When the second current path CA12 is disconnected, the current flowing through the heater 2 flows through the first current path CA11 and the third current path CA13, so that the current flowing through the third current path CA13 is 0.5 and the measured current value is 0. It becomes .5. When the third current path CA13 is disconnected, the current flowing through the third current path CA13 becomes 0, and the measured current value becomes 0. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 7, the setting unit 12 shown in FIG. 1 stores in advance 0.166, which is an intermediate value between 1/3 and 0, as the lower limit value in the storage unit 13, and 0 as the upper limit value. 0.416, which is an intermediate value between .5 and 1/3, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds 0.166 and is less than 0.416, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is 0.416 or more, it is considered that the first current path CA11 or the second current path CA12 is disconnected. If the measured current value is less than 0.166, it is considered that the third current path CA13 is disconnected. That is, these are detected as a sign that the cable 31 is disconnected.

Since the measured current value becomes 0 even when the heater 2 is disconnected, the disconnection of the third current path CA13 and the disconnection of the heater 2 are indistinguishable in the present embodiment.

FIG. 9 is a circuit diagram of a heating device having a different configuration of the current detection unit from the example shown in FIG. 7. In this example, the cable 31 is composed of three current paths CA11, CA12, and CA13. The current detection unit 4 detects the sum of the current flowing in the current path CA12 and the current flowing in the current path CA13.

FIG. 10 shows the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, the current flowing in the third current path CA13, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. It is a figure which shows. In FIG. 10, i11 is a current flowing through the first current path CA11, i12 is a current flowing through the second current path CA12, i13 is a current flowing through the third current path CA13, and iCT is a detected value of the current detection unit 4. Both are relative values when the current flowing through the heater 2 is 1.0.

When there is no disconnection in any of the current paths, the current flowing through the first current path CA11, the second current path CA12, and the third current path CA13 is 1/3, and the measured current value is 2/3. When the first current path CA11 is disconnected, the current flowing through the heater 2 flows through the second current path CA12 and the third current path CA13, so that the measured current value is 1.0. When the second current path CA12 is disconnected, the current flowing through the heater 2 flows through the first current path CA11 and the third current path CA13, so that the measured current value is 0.5. When the third current path CA13 is disconnected, the current flowing through the heater 2 flows through the first current path CA11 and the second current path CA12, so that the measured current value is 0.5. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 9, the setting unit 12 shown in FIG. 1 stores in advance 0.583, which is an intermediate value between 2/3 and 0.5, as a lower limit value in the storage unit 13, and stores an upper limit value. 0.833, which is an intermediate value between 1.0 and 2/3, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds 0.583 and is less than 0.833, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is 0.833 or more, it is considered that the first current path CA11 is disconnected. If the measured current value is less than 0.583, it is considered that the second current path CA12 or the third current path CA13 is disconnected. That is, these are detected as a sign that the cable 31 is disconnected.

FIG. 11 is a circuit diagram of a heating device in which the current detection unit 4 detects currents flowing through the three current paths CA11, CA12, and CA13 constituting the cable 31. In this example, the cable 31 is composed of three current paths CA11, CA12, and CA13. The current detection unit 4 detects a value obtained by subtracting the current flowing through the current path CA11 from the added value of the current flowing through the current path CA12 and the current flowing through the current path CA13.

FIG. 12 shows the relationship between the current flowing in the first current path CA11, the current flowing in the second current path CA12, the current flowing in the third current path CA13, and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. It is a figure which shows. In FIG. 12, i11 is a current flowing through the first current path CA11, i12 is a current flowing through the second current path CA12, i13 is a current flowing through the third current path CA13, and iCT is a detected value of the current detection unit 4. Both are relative values when the current flowing through the heater 2 is 1.0.

When there is no disconnection in any of the current paths, the current flowing through the first current path CA11, the second current path CA12, and the third current path CA13 is 1/3, and the measured current value is 1/3. When the first current path CA11 is disconnected, the current flowing through the heater 2 flows through the second current path CA12 and the third current path CA13, so that the measured current value is 1.0. When the second current path CA12 is disconnected, the current flowing through the heater 2 flows through the first current path CA11 and the third current path CA13, so that the measured current value becomes 0. When the third current path CA13 is disconnected, the current flowing through the heater 2 flows through the first current path CA11 and the second current path CA12, so that the measured current value becomes 0. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 11, the setting unit 12 shown in FIG. 1 stores in advance 0.166, which is an intermediate value between 1/3 and 0, as the lower limit value in the storage unit 13, and 1 as the upper limit value. 0.666, which is an intermediate value between .0 and 1/3, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds 0.166 and is less than 0.666, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is 0.666 or more, it is considered that the first current path CA11 is disconnected. If the measured current value is less than 0.166, it is considered that the second current path CA12 or the third current path CA13 is disconnected. That is, these are detected as a sign that the cable 31 is disconnected.

FIG. 13 is a circuit diagram of a heating device different from the example shown in FIG. In this example, the current detection unit 4 determines the difference between the current flowing in the current path CA12 of the two current paths CA11 and CA12 constituting the first cable 31 and the current flowing in the current path CA2 forming the second cable. To detect.

FIG. 14 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, and CA2 and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. In FIG. 14, i11 is a current flowing through the current path CA11, i12 is a current flowing through the current path CA12, i2 is a current flowing through the current path CA2, and iCT is a detected value of the current detection unit 4. Both are relative values when the current flowing through the heater 2 is 1.0.

If there is no disconnection in any of the current paths, the current flowing in the current paths CA11 and CA12 is 0.5, and the current flowing in the current path CA2 is 1.0, so that the measured current value is -0.5. .. When the current path CA11 is disconnected, the current flowing through the heater 2 flows through the current path CA12 and the current path CA2, so that the measured current value becomes 0. When the current path CA12 is disconnected, the current flowing through the heater 2 flows through the current path CA11 and the current path CA2, so that the measured current value is −1.0. When the current path CA2 is disconnected, the measured current value becomes 0. Even when the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 13, the setting unit 12 shown in FIG. 1 stores in advance in the storage unit 13, −0.25, which is an intermediate value between −0.5 and 0, as an upper limit value. Further, as the lower limit value, -0.75, which is an intermediate value between -0.5 and -1.0, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value is −0.75 or more and less than −0.25, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is -0.25 or more, it is considered that one of the current paths CA11 and CA2 is broken. Further, if the measured current value is less than −0.75, it is considered that the current path CA12 is disconnected. These are detected as a sign that the cable 31 is broken.

FIG. 15 is a circuit diagram of a heating device different from the example shown in FIG. In this example, the current detection unit 4 sums the current flowing in the current path CA12 of the two current paths CA11 and CA12 constituting the first cable 31 and the current flowing in the current path CA2 forming the second cable 31. To detect.

FIG. 16 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, and CA2 and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. In FIG. 16, i11 is a current flowing through the current path CA11, i12 is a current flowing through the current path CA12, i2 is a current flowing through the current path CA2, and iCT is a detected value of the current detection unit 4. Both are relative values when the current flowing through the heater 2 is 1.0.

If there is no disconnection in any of the current paths, the current flowing in the current paths CA11 and CA12 is 0.5, and the current flowing in the current path CA2 is 1.0, so the measured current value is 1.5. is there. When the current path CA11 is disconnected, the current flowing through the heater 2 flows through the current path CA12 and the current path CA2, so that the measured current value is 2.0. When the current path CA12 is disconnected, the current flowing through the heater 2 flows through the current path CA11 and the current path CA2, so that the measured current value is 1.0. When the current path CA2 is disconnected, the measured current value becomes 0. Even when the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 15, the setting unit 12 shown in FIG. 1 stores 1.25, which is an intermediate value between 1.5 and 1 as a lower limit value, in advance in the storage unit 13, and sets 2 as an upper limit value. 1.75, which is an intermediate value between .0 and 1.5, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value is 1.25 or more and less than 1.75, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is 1.75 or more, it is considered that the current path CA11 is broken. If the measured current value is less than 1.25, it is considered that the current path CA12 or the current path CA2 is disconnected, that is, these are detected as a sign that the cable 31 is disconnected.

FIG. 17 is a circuit diagram of a heating device different from the example shown in FIG. In this example, the current detection unit 4 includes the current flowing through the current path CA12 among the two current paths CA11 and CA12 constituting the first cable 31 and the two current paths CA21 and CA22 constituting the second cable 32. The sum with the current flowing in the current path CA22 is detected.

FIG. 18 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, and CA22 and the measurement result of the current detection unit 4 in the disconnection state at a predetermined location. In FIG. 18, i11 is a current flowing through the current path CA11, i12 is a current flowing through the current path CA12, i21 is a current flowing through the current path CA21, i22 is a current flowing through the current path CA22, and iCT is a value detected by the current detection unit 4. is there. Both are relative values when the current flowing through the heater 2 is 1.0.

When there is no disconnection in any of the current paths, the current flowing through the current paths CA11, CA12, CA21, and CA22 is 0.5, so the measured current value is 1.0. When the current path CA11 is disconnected, the current flowing through the heater 2 flows through the current path CA12, so that the measured current value is 1.5. When the current path CA12 is disconnected, the current flowing through the heater 2 flows through the current path CA11, so that the measured current value is 0.5. When the current path CA21 is disconnected, the current flowing through the heater 2 flows through the current path CA22, so that the measured current value is 1.5. When the current path CA22 is disconnected, the measured current value becomes 0.5. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 17, the setting unit 12 shown in FIG. 1 stores in advance 0.75, which is an intermediate value between 1.0 and 0.5, as a lower limit value in the storage unit 13, and stores an upper limit value. 1.25, which is an intermediate value between 1.0 and 1.5, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds 0.75 and is less than 1.25, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is less than 0.75, it is considered that one of the current paths CA12 and CA22 is broken. If the measured current value is 1.25 or more, it is considered that one of the current paths CA11 and CA21 is disconnected. That is, these are detected as a sign that the cable 31 is disconnected.

FIG. 19 is a circuit diagram of a heating device different from the example shown in FIG. In this example, the current detection unit 4 includes the current flowing through the current path CA12 among the two current paths CA11 and CA12 constituting the first cable 31 and the two current paths CA21 and CA22 constituting the second cable 32. The difference from the current flowing in the current path CA22 is detected.

FIG. 20 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, and CA22 and the measurement result of the current detection unit 4 in the disconnected state at a predetermined position. In FIG. 20, i11 is a current flowing through the current path CA11, i12 is a current flowing through the current path CA12, i21 is a current flowing through the current path CA21, i22 is a current flowing through the current path CA22, and iCT is a value detected by the current detection unit 4. is there. Both are relative values when the current flowing through the heater 2 is 1.0.

If there is no disconnection in any of the current paths, the current flowing through the current paths CA11, CA12, CA21, and CA22 is 0.5, so the measured current value is 0. When the current path CA11 is disconnected, the current flowing through the heater 2 flows through the current path CA12, so that the measured current value is 0.5. When the current path CA12 is disconnected, the current flowing through the heater 2 flows through the current path CA11, so that the measured current value is −0.5. When the current path CA21 is disconnected, the current flowing through the heater 2 flows through the current path CA22, so that the measured current value is −0.5. When the current path CA22 is disconnected, the measured current value becomes 0.5. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 19, the setting unit 12 shown in FIG. 1 previously stores -0.25, which is an intermediate value between 0 and -0.5, as the lower limit value in the storage unit 13, and stores the upper limit value. 0.25, which is an intermediate value between 0 and 0.5, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds −0.25 and is less than 0.25, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is less than -0.25, it is considered that one of the current paths CA12 and CA21 is broken. If the measured current value is 0.25 or more, it is considered that one of the current paths CA11 and CA22 is broken. That is, these are detected as a sign that the cable 31 is disconnected.

FIG. 21 is a circuit diagram of a heating device different from the example shown in FIG. In this example, the current detection unit 4 has the difference between the currents flowing through the two current paths CA11 and CA12 constituting the first cable 31 and the current path CA22 of the two current paths CA21 and CA22 constituting the second cable 32. Detects the difference from the current flowing through.

FIG. 22 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, and CA22 and the measurement result of the current detection unit 4 in the disconnection state at a predetermined location. In FIG. 22, i11 is a current flowing through the current path CA11, i12 is a current flowing through the current path CA12, i21 is a current flowing through the current path CA21, i22 is a current flowing through the current path CA22, and iCT is a value detected by the current detection unit 4. is there. Both are relative values when the current flowing through the heater 2 is 1.0.

When there is no disconnection in any of the current paths, the current flowing through the current paths CA11, CA12, CA21, and CA22 is 0.5, so the measured current value is 0.5. When the current path CA11 is disconnected, the current flowing through the heater 2 flows through the current path CA12, so that the measured current value is 1.5. When the current path CA12 is disconnected, the current flowing through the heater 2 flows through the current path CA11, so that the measured current value is −0.5. When the current path CA21 is disconnected, the current flowing through the heater 2 flows through the current path CA22, so that the measured current value is 1.0. When the current path CA22 is disconnected, the measured current value becomes 0. When the heater itself is disconnected, the measured current value becomes 0.

In the example shown in FIG. 21, the setting unit 12 shown in FIG. 1 stores 0.25, which is an intermediate value between 0 and 0.5, as a lower limit value in advance in the storage unit 13, and 0 as an upper limit value. 0.75, which is an intermediate value between .5 and 1.0, is stored in advance. The determination unit 14 uses the value of the storage unit 13 as a threshold value and determines the magnitude relationship with the measured current value. Then, if the measured current value exceeds 0.25 and is less than 0.75, it is considered to be normal. That is, it is determined that there is no disconnection in the current path. If the measured current value is less than 0.25, it is considered that one of the current paths CA12 and CA22 is broken. If the measured current value is 0.75 or more, it is considered that one of the current paths CA11 and CA21 is broken. That is, these are detected as a sign that the cable 31 is disconnected.

FIG. 23 is a circuit diagram of a heating device different from the example shown in FIG. In this example, a current detection unit is provided not only on the first cable 31 side shown in FIG. 1 but also on the second cable 32 side, and a sign of cable disconnection is detected from the detection results of these two current detection units. It is a thing. In this heating device, the presence or absence of disconnection of the current paths CA21 and CA22 of the second cable 32 can be detected by the same principle as the example shown in FIG. 1, and thereby, a sign of disconnection of the second cable 32 can also be detected. ..

Similarly, the configuration of the current detection unit shown in FIGS. 5, 7, 9, 11, 13, 13, 15, 17, 19, 21, 21 and the like is provided on the second cable 32 side. From the detection results of the two current detectors, it is possible to detect a sign of cable disconnection.

The examples shown above have shown a device in which two cables are connected to a load having two terminals, but the same can be applied to a device in which cables are connected to a load having three or more terminals. For example, FIG. 24 is an example of a device in which a three-phase AC power supply is connected to a heater 2, which is a three-phase AC load, via a cable. In this example, the heater 2 is connected to each line of the three-phase AC power supply via two current paths. Then, the current detection units CT1, CT2, and CT3 are connected to one of the two current paths of each phase, respectively.

FIG. 25 is a diagram showing the relationship between the current flowing through the current paths CA11, CA12, CA21, CA22, CA31, and CA32 and the detection results of the current detection units CT1, CT2, and CT3 in the disconnected state at a predetermined location. In FIG. 24, i11 is a current flowing through the current path CA11, i12 is a current flowing through the current path CA12, i21 is a current flowing through the current path CA21, i22 is a current flowing through the current path CA22, i31 is a current flowing through the current path CA31, and i32. Is the current flowing through the current path CA32, iCT1 is the detection value of the current detection unit CT1, iCT2 is the detection value of the current detection unit CT2, and iCT3 is the detection value of the current detection unit CT3. Both are relative values when the phase current flowing through the heater 2 is 1.0.

Similar to the examples shown in FIGS. 1 and 2, the lower limit threshold value to be compared with the detection value of the current detection unit CT1 is set to 0.25, and the upper limit threshold value is set to 0.75. The same applies to the current detection units CT2 and CT3. In this way, the signs of disconnection of the cables 31, 32, and 33 can be detected from the detection results of the three current detection units CT1, CT2, and CT3.

Finally, the description of the embodiments for carrying out the above invention is, needless to say, exemplary in all respects and not restrictive. Modifications and changes can be made as appropriate for those skilled in the art.

For example, a cable caulking portion is provided at a portion where the cable is branched into a plurality of current paths, but if the contact resistance of the cable caulking portion is not equal, the distribution ratio to the plurality of current paths is not equal. In that case, the threshold value may be set according to the actual diversion ratio to the plurality of current paths.

Further, in FIG. 4, an example in which the threshold value is determined based on the measured initial current value is shown, but the normal current value may change due to aging of the load, cable, cable connection, etc. , The threshold value may be reset based on the measured current value at a predetermined timing.

Further, in the above-described embodiment, the heating device using a heater as a load has been illustrated, but the same can be applied to a device using a motor or an electromagnet as a load.

Further, in each of the above-described embodiments, a current transformer (current transformer) is used for the current detection unit, but in addition, for example, a current detection resistor element is inserted into each current path, and the voltage drop is used as a base. Then, the current flowing in the current path may be detected. In this case, a rectifier circuit for determining the peak value of the current, a polarity determining unit for determining the polarity of the sine wave, and an arithmetic unit for adding or subtracting the peak values obtained for a plurality of current paths in consideration of the polarity may be provided. ..

CA11 ... 1st current path CA12 ... 2nd current path CA13 ... 3rd current path CA2 ... Current path CA21, CA22 ... Current path CA31, CA32 ... Current path CT1, CT2, CT3 ... Current detection unit 1 ... Power supply 2 ... Heater 4 ... Current detection unit 5 ... Opening / closing unit 10 ... Alarm unit 11 ... Current measurement unit 12 ... Setting unit 13 ... Storage unit 14 ... Judgment unit 15 ... Abnormal output unit 16 ... Output unit 20 ... Control unit 31 ... First cable 32 ... First 2 Cable 33 ... Cable 101 ... Heating device 201 ... Cable disconnection sign detection device

Claims (3)

It is a device that detects signs of disconnection of a plurality of cables that are connected to a plurality of connection portions of a load and apply a current to the load.
The cable includes a first cable connected to a first connection portion among the plurality of connection portions of the load, and a second cable connected to a second connection portion among the plurality of connection portions of the load. ,
The first cable is composed of a plurality of first current paths connected in parallel.
The second cable is composed of a plurality of second current paths connected in parallel.
A current detection unit that detects the sum or difference between the current flowing in at least one of the plurality of first current paths and the current flowing in at least one of the plurality of second current paths.
By comparing the value detected by the current detection unit with the threshold value and detecting the energized state of the plurality of first current paths and the energized state of the plurality of second current paths, the plurality of first current paths and the plurality of first current paths and the energized state are detected. An alarm unit that issues an alarm when it is determined whether or not there is a disconnection in the plurality of second current paths and it is determined that there is a disconnection.
Cable disconnection sign detection device equipped with. It is a device that detects signs of disconnection of a plurality of cables that are connected to a plurality of connection portions of a load and apply a current to the load.
The cable includes a first cable connected to a first connection portion among the plurality of connection portions of the load, and a second cable connected to a second connection portion among the plurality of connection portions of the load. ,
The first cable is composed of a plurality of first current paths connected in parallel.
The second cable is composed of a plurality of second current paths connected in parallel.
A current detector that detects the sum or difference of the currents flowing in at least one of the plurality of second current paths with respect to the sum or difference of the currents flowing in at least two of the plurality of first current paths. When,
By comparing the value detected by the current detection unit with the threshold value and detecting the energized state of the plurality of first current paths and the energized state of the plurality of second current paths, the plurality of first current paths and the plurality of first current paths and the energized state are detected. An alarm unit that issues an alarm when it is determined whether or not there is a disconnection in the plurality of second current paths and it is determined that there is a disconnection.
Cable disconnection sign detection device equipped with. The cable disconnection sign detection device according to claim 1 or 2, wherein the threshold value is determined based on a value detected by the current detection unit in the initial state.

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