JP6147599B2 - Degradation / disconnection detection method for feeder lines - Google Patents

Description

  The present invention relates to a method for detecting deterioration or disconnection of a power supply line, and more particularly to a method for detecting deterioration or disconnection of a power supply line using a through-type current sensor. The present invention relates to a method for detecting deterioration or disconnection of a power supply line that is suitable for application to a power supply line such as an ejector motor.

  Current sensors that detect currents flowing through power supply lines such as electric wires and cables are conventionally known as shown in Patent Documents 1 to 3, and are roughly classified into a clamp type and a split type. The sensor is also detected by being pinched by the sensor or penetrating the sensor ring without cutting the power supply line. Such a sensor is known for an alternating current for detecting a current generated by electromagnetic induction of a toroidal core by a detection method and for a direct current in which a cut core and a hall element are combined. In the direct current sensor, a magnetic flux proportional to a through current flowing in a conductor or a feeder line is converged by an iron core, and passes through a hall element inserted in a gap. At this time, a Hall voltage is generated by the Hall effect, and this Hall voltage is detected. This direct current can also be used for alternating current.

JP 2010-249605 A JP 2007-333443 A JP 2006-300915 A JP 2012-247191 A JP-A-5-8690

  Generally, if a power supply line that supplies power from a power supply device to a load device breaks, the load device may be adversely affected, and it is also dangerous to stop suddenly. Has been detected. That is, as shown in Patent Document 4, when a current flows through a conductor or feed line inserted in the ring of the feedthrough type current sensor, a magnetic field having a magnitude proportional to the current is generated around the feed line. To do. When the strength of the magnetic field changes, a voltage is generated in the through-type current sensor, but when this cannot be detected, it is determined that no current is flowing, and thereby it is possible to detect “disconnection”.

  Further, Patent Document 5 proposes a disconnection detecting device for an automobile lamp. This detection device includes an annular core around which a detection coil is wound. For example, two lines of a brake lamp power supply line are wound around the iron core in opposite directions. Therefore, when the two power supply lines are conducting, the magnetic field is balanced and no voltage is generated in the detection coil. When one of the power supply lines is disconnected, the balance is lost and the power is output to the detection coil. Thereby, it can be known that one side is disconnected.

  As described above, the disconnection state can be known even by a conventional detection device. However, in the conventional detection method, “whether it is completely disconnected or not disconnected” can be known selectively, and it may not be sufficient. Hereinafter, such a case will be described. In some cases, it is necessary to supply power from a power supply device that is fixedly installed to a load device that is movably provided via a feeder line. For example, an injection molding machine includes a fixed mold and a movable mold that is opened and closed with respect to the fixed mold, and a molded product is molded between these molds. However, the molded product is configured such that the movable mold is opened and the projecting device is driven by an electric motor to eject the molded product. Since the protruding device that is a load device is provided on the movable side mold, it moves every molding cycle for obtaining a molded product, and the distance from the power supply device changes. In view of this, such a feeder line is provided with a “bent portion formed of slack, play, etc.” in the middle to absorb the change in the interval.

Since the bent portion is provided as described above, an excessive tensile force does not act on the power supply line, but a repeated load of bending and stretching acts on the bent portion for each molding cycle. As a result, core wires or strands such as portions where the radius of curvature of the bent portion is small and portions where stress is locally concentrated gradually deteriorate due to broken lines or breakage. Even if the resistance increases due to such deterioration, the current continues to flow because a predetermined voltage is applied. As a result, the deteriorated portion generates heat, and in the worst case, it burns out and causes a fire. However, the conventional detection method described above cannot detect deterioration such as partial breakage of the core wire as long as current flows. The actual situation is that this is detected and replaced after disconnection, or is periodically replaced with a new power supply line.
Accordingly, an object of the present invention is to provide a method for detecting deterioration or disconnection of a power supply line, which can detect not only disconnection of the power supply line but also deterioration due to breakage of a core wire or the like.

  In order to achieve the above-mentioned object, the present invention provides a pair of power lines of the same phase that are connected in parallel with the same electrical resistance when power is supplied from the power supply device to the load device with a single-phase or three-phase power supply line Power is supplied by branching to a pair feeder that is a feeder. The pair feeder is inserted into one ring-type through-type current sensor. One of the pair feeders is inserted from one side of the ring and the other is inserted from the other side. Since they are inserted in opposite directions in the ring, the magnetic field generated around the wires is canceled if there is no abnormality in the pair feeders, and no voltage is generated in the through-type current sensor. When one or the other of the pair feeders is disconnected or partially damaged, the resistance of the damaged wire changes and the flowing current changes. The balance of the magnetic field is lost, and an induced electromotive force is generated in the through-type current sensor. That is, a voltage is detected. As a result, it is possible to detect deterioration or disconnection of the pair power supply lines, that is, the power supply lines.

That is, in order to achieve the above-mentioned object, the invention according to claim 1 supplies each phase coming out from the power supply device when supplying power from the power supply device to the load device through a single-phase or three-phase power supply line. The electric wires are branched into a pair of feed lines, which are two feed lines having the same electrical resistance connected in parallel to each other, and merged again from the pair of feed lines into one, and the portion that becomes the one is the load Connected to the device to supply power , provided with a ring-shaped through-type current sensor, one of the pair of feeders is inserted from one side of the ring and the other is inserted from the other side of the ring. Currents flow in opposite directions to each other, and a voltage is detected by the through-type current sensor so as to detect deterioration or disconnection of the pair feeders. According to the second aspect of the present invention, when power is supplied from the power supply device to the load device by a single-phase or three-phase power supply line, the electric resistance connected in parallel with respect to the power supply lines of each phase coming out of the power supply device Are split into a pair of feeders, which are the same two feeders, merged again from the pair of feeders into one, and the one part is connected to the load device to supply power, Two or more ring-shaped through-type current sensors are provided, and one of the pair of feeders is inserted through the first through-type current sensor and the other through the second through-type current sensor. By detecting a voltage difference generated in the through-type current sensor, it is configured to detect deterioration or disconnection of the pair feeder.

  According to a third aspect of the present invention, in the method according to the first or second aspect, the power supply line is between the power supply device and a load device in which a positional relationship between the power supply device changes repeatedly with time. Applied to be configured.

As described above, according to the present invention, when power is supplied from a power supply device to a load device with a single-phase or three-phase power supply line, the electric power lines connected to each other in parallel with respect to the power supply lines of the respective phases coming out of the power supply device. Branch to a pair of feeders that are two feeders with the same resistance, merge again from the pair of feeders into one, and connect the portion that became one to a load device to feed power, A ring-shaped through-type current sensor is provided, and one of the pair feeders is inserted from one side of the ring and the other is inserted from the other side of the ring so that currents flow in opposite directions in the ring. Since each pair of feeders has the same electrical resistance, currents of the same magnitude flow, and the magnetic field generated around the wires is canceled in the ring. That is, no voltage is detected in the through-type current sensor. However, when one of the pair feeders is disconnected or the electrical resistance changes due to deterioration, a magnetic field is generated in the ring, and the voltage is detected by the through current sensor. That is, not only disconnection but also deterioration can be reliably detected. According to another invention, a pair of through-type current sensors is provided, and one of the pair of feed lines is inserted through one through-type current sensor and the other is inserted through the other through-type current sensor. By detecting the voltage difference between the pair of through-type current sensors, it is possible to detect the deterioration or disconnection of the pair feeders.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic wiring diagram which shows the electric power feeding state which concerns on embodiment of this invention, The (a), (b) is a figure which shows various embodiment, respectively.

  Embodiments of the present invention will be described below. Since the principle of the feed line deterioration / breakage detection method according to the present invention is the same in both three-phase and single-phase and can be implemented in the same manner, a simpler single-phase embodiment will be described below. FIG. 1A shows the present embodiment. In the same figure, the code | symbol S shows the fixed power supply device and M has each shown the electric motor which is a load apparatus. The ejector device of the injection molding machine as described above is driven by the motor M, for example. The motor M and the ejector device are mounted on the movable base B and are reciprocally driven in the direction of the arrow Y in accordance with the molding cycle. .

  A power supply device S has a two-phase feed line. One phase of the power supply line is branched into the first power supply line 1 and the second power supply line 2 on the way, and is joined again to form a single line and is connected to the motor M. Similarly, the power supply line of the other phase also exits from the power supply device S, becomes a third power supply line 3 and a fourth power supply line 4 in a form that branches in the middle, and then joins again as one line. It is connected to the motor M. The first and second feeder lines 1 and 2 are electric wires formed from the same material with the same length and the same cross-sectional area, and have the same electric resistance. Similarly, the third and fourth feeder lines 3 and 4 are electric wires formed from the same material with the same length and the same cross-sectional area, and have the same electric resistance. The first and second feeder lines 1 and 2 and the third and fourth feeder lines 3 and 4 are also pair feeder lines. Although the power supply device S is fixed, the load device M moves. Therefore, a “bending portion U including slack, play, etc.” is provided in the middle of the power supply line. Since the first and second feeders 1 and 2, that is, the pair feeders are wired close to each other, other physical influences such as electromagnetic influences and temperatures received from the outside are practical. be equivalent to. That is, they are wired in parallel so as to satisfy the same electromagnetic and physical conditions. Similarly, the third and fourth feeders 3 and 4 that are other pair feeders are wired in the same manner. In the pair feeder, the electric resistance is the same as described above, the voltages applied to both ends of the pair feeder are equal, and the electromagnetic and physical influences around the wiring are the same, so the flowing currents are equal.

  The pair feed line is provided with a through current sensor 10 according to the present embodiment. The through-type current sensor 10 includes a ring-shaped iron core and a coil wound around the iron core, and the conductive wires a and b drawn from the coil are connected to a predetermined resistor 14. The potential difference between the resistors 14 is detected by a comparator 11 with a dead zone. Therefore, when the magnetic field changes in the ring-shaped iron core, an induced electromotive force is generated in the coil and a current flows through the conductors a and b. Then, a potential difference is generated between the resistors 14 and is detected by the comparator 11. The output of the comparator 11 is output to a terminal 12 for detecting disconnection or deterioration of the feeder line.

  The first and second feeders 1 and 2 are inserted through the ring portion of the through-type current sensor 10, but the current flowing through the first feeder 1 and the second feeder 2 flow. Currents are inserted so as to flow in opposite directions. That is, the first feeder 1 is inserted so as to penetrate the ring portion of the through-type current sensor 10 from the left to the right, and the second feeder 2 is U-turned and penetrates from the right to the left. So that it is inserted. A similar through-type current sensor 10 ′ is attached to the third and fourth feed lines 3 and 4, which are the other pair feed lines, but is not shown in detail in FIG.

  Next, the operation will be described. When there is no abnormality such as partial breakage or disconnection in the core wires of the first and second feed lines 1 and 2, as described above, the first and second feed lines 1 and 2 have the same electrical resistance. In the first and second feed lines 1 and 2, a magnetic field proportional to the current is generated around each feed line. Since the currents flowing in the pair feeders are equal, the magnetic fields generated in the ring portion by the first and second feeders 1 and 2 are equal in magnitude. However, since the currents flow in the first and second feeder lines 1 and 2 in the ring portions in the opposite directions, the directions of the magnetic fields are reversed. This cancels the magnetic field. If it does so, a magnetic field will not change in a ring part and penetration type current sensor 10 will not react. Thereby, it is determined that the first and second feeders 1 and 2 are not abnormal.

  As the operation time elapses, the core wire of the bent portion U is fatigued by bending and stretching, and an abnormality such as partial breakage occurs. The first and second power supply lines 1 and 2 are wired in the same manner. However, if an abnormality such as a partial breakage occurs in any one of the causes for some reason, the electrical resistance of one damaged power supply line changes. As a result, the currents flowing through the pair feeders are different. Since the magnetic field is not canceled in the ring portion of the through-type current sensor 10, the magnetic field changes. An induced electromotive force is generated in the coil, current flows through the conductors a and b, and a potential difference is generated between the resistors 14. The comparator 11 detects the potential difference and outputs it to the terminal 12. Thereby, it is possible to detect that an abnormality such as a partial breakage has occurred in one of the first and second power supply lines 1 and 2. The first and second power supply lines 1 and 2 are both replaced with a new power supply line.

  Obviously, the abnormal state can be detected in the same manner by the through-type current sensor 10 'provided on the other pair of feeder lines. In the present embodiment, a single-phase AC power supply line has been described, but the same applies to a three-phase AC power supply.

  In the above embodiment, the first and second feeder lines 1 and 2 and the third and fourth feeder lines 3 and 4 are shown as being branched in the middle and wired in parallel to the two. As shown in FIG. 1A, two power supply devices S can be wired in parallel. Further, it is obvious that the present invention can be applied to a feeder line having no bent portion U.

1-4 1st to 4th feeder lines
10, 10 'Through-type current sensor U Bend
S Power supply device M Electric motor (load device)

Claims (3)

When power is supplied from the power supply device to the load device with a single-phase or three-phase power supply line, the two power supply lines connected in parallel with each other are connected to each other for each phase of the power supply line coming out of the power supply device. Branch to a certain pair of feeders, merge again from the pair of feeders to make one, and connect the part that became one to the load device to feed power, and provide a ring-shaped through-type current sensor One of the pair feeders is inserted from one side of the ring and the other is inserted from the other side of the ring so that currents flow in opposite directions in the ring, and the voltage is detected by the feed-through current sensor. To detect deterioration or disconnection of the pair of feeder lines. When power is supplied from the power supply device to the load device with a single-phase or three-phase power supply line, the two power supply lines connected in parallel are the same in each phase of the power supply line coming out of the power supply device. The first and second ring-shaped through-types are branched into a pair of feeders, merged again from the pair of feeders into one, and the portion that becomes one is connected to the load device to supply power. A voltage difference generated in the first and second through-type current sensors by providing a current sensor, with one of the pair feeders being inserted into the first through-type current sensor and the other through the second through-type current sensor. A method of detecting deterioration or disconnection of a power feed line, wherein the deterioration or disconnection of the pair power feed line is detected by detecting. 3. The method according to claim 1, wherein the power supply line is applied between the power supply device and a load device in which a positional relationship between the power supply device repeatedly changes with time. Disconnection detection method.

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