JP5178570B2 - Electric circuit switching device, outlet box, and electric circuit switching method - Google Patents

Description

  The present invention detects the current flowing in the electric circuit, and when the overcurrent caused by lightning surge or overload flows from the power source side to the electric circuit, the electric circuit is cut off and opened, and the safety of the connected load device is improved. If secured, the present invention relates to an electric circuit opening / closing device, an outlet box, and an electric circuit opening / closing method that recloses and closes an interrupted electric circuit.

  Conventionally, a plurality of techniques for detecting a voltage value or a current value supplied from a power source to a load side via an electric path and controlling an interruption operation or a return operation of the electric circuit based on at least one of both values have been disclosed. For example, Patent Document 1 is configured so that a delay circuit does not respond to a power failure for a short time, and when power is restored in a time shorter than the time constant of the relay coil, the load side is immediately interrupted without being interrupted. It is described that power supply is resumed in the electric tool or the like. In addition, when power is restored after a power failure that has continued for a certain period, the break contact of the CR relay is closed, so if the voltage on the load side of the earth leakage breaker is detected by power restoration, the load is actually connected. It states that the trip will occur regardless of whether or not it has been done.

  Further, in Patent Document 2, even when power is restored after a relatively short power failure by detecting the current flowing in the circuit during the timed circuit, a load is applied to the circuit within a certain time after power restoration. If it is detected that the connection is detected, the power supply is turned off to ensure safety. A technique for eliminating the annoyance that must be performed is disclosed.

  Further, in Patent Document 3, a trip signal is output when there is no overcurrent at the time of trip, and further, when a trip occurs after the circuit breaker is turned on by a feed signal that is output when there is no overcurrent at trip. Further, a technology is disclosed that outputs a closing signal when an overcurrent occurs, and outputs a breaker closing signal when an overcurrent occurs when a trip occurs when power is restored after a power failure.

  According to these technologies, even if power supply to the load device is resumed by the return operation after the shut-off operation, the load device, for example, the tip of an electric drill rotates, etc. When there is a possibility that an influence will occur, the influence can be reduced as much as possible by interrupting the electric circuit again.

JP-A-9-115412 JP 2003-032874 A JP 2006-156103 A

  However, in the case of the technique of Patent Document 1, even if the operator takes safety measures such as disconnecting the power tool or other load from the outlet or turning off the switch to ensure safety, regardless of the measure. There was a problem in that the circuit breaker trips at least once, so that the return operation is uniformly required regardless of whether or not safety measures have already been taken.

  Further, in the case of the technology of Patent Document 2, the technology of Patent Document 1 does not cause a trip even at the time of a power failure, and further maintains a turned-on state when there is no detected current in the electric circuit when power is restored. Although the required recharging operation can be omitted, not only the short-circuit current associated with the fault of the connected load, but also the transient overcurrent such as the inrush current associated with the normal start that is specific to the connected load can be restored. Even in such a case, there is a problem in that an unnecessary trip operation may occur because a configuration for tripping is provided anyway if there is a detected current in the electric circuit.

  Further, in the case of the technique of Patent Document 3, since a closing signal is output based on the determination result of whether or not the detected current is transient at the time of a trip, the technique of Patent Document 2 could not be determined. An excessive overcurrent can be determined, and the number of unnecessary trip operations can be reduced. However, in the case of Patent Document 3, the determination condition is whether or not a preset current threshold value is exceeded. Therefore, among transient transient currents, especially for inrush currents, the waveform at startup depends on the load status of the connected load. There is a problem in that the judgment accuracy is lowered because proper judgment cannot be made, such as a situation where the rise of the current rises steeply and exceeds the current threshold is expected, and even the rise characteristics at normal startup are judged inappropriate. .

  Therefore, in view of the above problems, in the present invention, when a startup characteristic at normal startup is detected, the circuit is once interrupted by a circuit breaker, and then the power switch provided for the connected load device is turned off. It is an object of the present invention to provide an electric circuit switching device, an outlet box, and an electric circuit switching method that make it easy to ensure a state where safety measures are taken.

  In order to solve the above problems, an electric circuit switchgear according to the invention of claim 1 includes an electric circuit that connects a power source and a load device, a current detection unit that detects a current flowing through the electric circuit, and a detection signal of the current detection unit. When the power supply that has lost power is restored, the power supply from the power supply to the load device is started via the electrical circuit, after a predetermined first set time has elapsed. An opening time limit means, an electric circuit state switching means for switching the electric circuit to a turned-on state or a cut-off state by an input predetermined switching signal, and the switching signal is generated based on a detection signal of the current detection means, and the electric circuit state And a control means for controlling the switching operation of the switching means, wherein when the control means starts supplying power from the power source to the load device via the electric circuit, A startup current waveform that rises to a steady current value as the device starts up is detected by the current detection means and stored in the waveform storage means, and a predetermined startup waveform characteristic related to the startup is calculated in advance based on the stored startup current waveform. Based on the detection signal waveform detected by the current detection means during the first set time when the switching contact is closed when the power supply that has been cut off and the power supply that has failed is restored, a predetermined detection related to the rising edge is performed. Detection waveform characteristic calculation means for calculating a waveform characteristic, waveform characteristic determination means for determining whether or not the startup waveform characteristic and the detection waveform characteristic match, and a detection signal was not detected during the first set time In this case, the input state of the electric circuit state switching means is maintained, a detection signal is detected during the first set time, and both waveform characteristics are made uniform by the waveform characteristic determination means. If it is determined that the waveform characteristics are not, the circuit state switching means is shut off, a detection signal is detected during the first set time, and the waveform characteristics determination means determines that both waveform characteristics match. The circuit state switching means that has been once interrupted is turned on again after a predetermined second set time has elapsed, and the switching signal is sent so that the circuit state switching means performs the switching operation in these three cases. Switching signal generating means for generating.

  In the electric circuit switchgear according to the invention of claim 2, the starting waveform characteristic calculating means stores the starting start point and the starting current that increases from the starting start point on the stored starting current waveform. A predetermined starting elapsed point until a predetermined current value not exceeding is calculated in advance as a starting waveform characteristic, and the detection waveform characteristic calculating means detects a detection start point and the starting waveform on the detected signal waveform A detection elapsed point corresponding to the startup elapsed point calculated by the characteristic calculation unit is calculated as a predetermined detection signal waveform characteristic, and the waveform characteristic determination unit calculates a difference in current value between the startup elapsed point and the detection elapsed point. When the calculated difference is equal to or less than a preset allowable value, it is determined that both waveforms match.

  A power outlet box according to a third aspect of the present invention is configured such that a power outlet socket for inserting a power plug provided in the load device is provided in the electric circuit according to the first or second aspect.

  According to a fourth aspect of the present invention, there is provided an electric circuit opening / closing method provided in series at an electric circuit connecting a power source and a load device, current detecting means for detecting a current flowing through the electric circuit, and an output terminal of a detection signal of the current detecting means. A time-limit means for opening the open / close contact when a power failure is restored, when a predetermined first set time elapses after power supply from the power source to the load device is started via the electrical path. Based on the predetermined switching signal, the circuit state switching unit that switches the circuit to the on state or the cutoff state, and the switching signal is generated based on the detection signal of the current detection unit, and the switching operation of the circuit state switching unit is controlled. An electric circuit opening / closing method using the control means, wherein when the control means starts supplying power from the power source to the load equipment via the electric circuit, A startup waveform characteristic calculation process for detecting a startup current waveform rising to a value by the current detection unit and storing it in a waveform storage unit, and calculating in advance a predetermined startup waveform characteristic related to the startup based on the stored startup current waveform; A detection waveform for calculating a predetermined detection waveform characteristic related to the rising edge based on the detection signal waveform detected by the current detection means during the first set time when the switching contact is closed when the power supply that has failed is restored. A characteristic calculation process; a waveform characteristic determination process for determining whether or not the startup waveform characteristic and the detected waveform characteristic match; and if no detection signal is detected during a first set time, the electric circuit state switching means The detection state is detected during the first set time, and it is determined by the waveform characteristic determination process that the two waveform characteristics do not match. In the case where the circuit state switching means is cut off, a detection signal is detected during the first set time, and if it is determined by the waveform characteristic judgment processing that both waveform characteristics match, the cutoff operation is performed once. Switching signal generation processing for generating the switching signal so as to cause the electric circuit state switching unit to perform the switching operation in these three cases, wherein the electric circuit state switching unit is turned on again after a predetermined second set time has elapsed. , Is performed.

  In the electric circuit switching method according to the fifth aspect of the present invention, in the startup current waveform stored in the startup waveform characteristic calculation process, the startup start point and the startup current that increases from the startup start point have the steady current value. A predetermined starting elapsed point until a predetermined current value that does not exceed is calculated in advance as a starting waveform characteristic, and the detection waveform characteristic calculating process detects a detection start point and the starting waveform on the detected detection signal waveform. A detection elapsed point that coincides with an elapsed time of the activation elapsed point calculated in the characteristic calculation process is calculated as a predetermined detection signal waveform characteristic, and the waveform characteristic determination process determines a current value at the activation elapsed point and the detection elapsed point. When the difference is less than or equal to a preset allowable value, it is determined that both waveforms match.

  According to the first to fifth aspects of the present invention, since it is determined whether or not the startup waveform characteristic calculated in advance matches the detected waveform characteristic detected at the time of power recovery, not only can it be confirmed that the load device is in a normal state. When the startup characteristics at normal startup are detected, it is easy to secure time to take safety measures such as turning off the load equipment with a power switch etc. after the circuit is once interrupted by the circuit state switching means. The electric circuit state switching means can be switched to the on state more safely.

It is a block diagram which shows the electric circuit switch apparatus which concerns on this invention. It is a block diagram which shows the structure of a control means. (A) is a waveform diagram showing a startup current waveform, (b) is a detection signal waveform, and (c) is a waveform diagram showing straight lines obtained from the startup current waveform and the detection signal waveform. The operation state of each part when the power failure is restored, (a) shows the power supply status at the time of power failure and power recovery, and (b) when the detection signal is not detected at the time of power restoration , (C) is the operation timing of each part indicating that the detection signal is detected at the time of power recovery and the two waveforms do not match, and (d) is the operation timing of each part indicating the case where the detection signal is detected at the time of power recovery and the both waveforms match. FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an electric circuit switching device 1 according to the present invention. In FIG. 1, 7 is an electric circuit connecting the power source 3 and the load device 5, 9 is a current transformer as current detection means for detecting a current flowing through the electric circuit 7, and 13 is an output of a detection signal of the current transformer 9. A predetermined first set time set in advance from the time when power supply from the power supply 3 to the load device 5 is started via the electric path 7 when the power supply 3 that has failed is restored. The time-limit means 15 that opens after the elapse of t1 includes a shut-off mechanism that disconnects the contact point by the trip coil and inputs the circuit 7 to the shut-off state by inputting a predetermined switching signal corresponding to the excitation current of the trip coil, After a lapse of a predetermined second set time t2 preset from the time, a charging mechanism is provided to stop the excitation by the trip coil, close the contact, return the electric circuit 7 to the connected state, and turn the electric circuit 7 on or off. Condition Breaker as path state switching means for switching to, 21 generates a switching signal based on the detection signal of the current transformer 9, the control means for controlling the switching operation of the breaker 15, it is.

  For example, commercial AC power having a predetermined frequency is supplied from the power source 3 to the electric path 7 as drive power for the load device 5 such as an electric drill. Here, it is assumed that the load device 5 includes a power switch that starts or stops the drive motor by a pressing operation of the user. When the power switch is in the ON state, the time when power supply to the load device 5 is started is equal to the time when the power supply 3 that has failed is restored.

  In the state where the power of the power source 3 is stably supplied continuously, the circuit breaker 15 is subjected to a lightning strike when the current flowing through the electric circuit 7 becomes higher than a preset breaking current value Ith (see FIG. 3A). As a basic operation corresponding to an abnormal current such as electric leakage or electric leakage, it is configured to promptly cut off.

  As shown in FIG. 2, the control means 21 is a CPU 41 that controls the operation of each unit in accordance with the input command, a memory 43 that stores a program describing a command used by the CPU 41, and a detection signal input to the CPU 41. And an input / output I / F 45 that outputs an operation control signal to each unit. The CPU 41 generates an abnormal current such as a lightning surge based on the A / D conversion function that converts the detection signal of the current transformer 9 into digital data via the input / output I / F 45 and the A / D converted detection signal. In addition to calculating the presence / absence of the circuit breaker 15, it is configured to have an operation function for outputting a switching signal for interrupting the circuit breaker 15 when it occurs.

  In addition, when power supply from the power supply 3 to the load device 5 is started from the power source 3, the control unit 21 generates a startup current waveform that flows through the electrical path 7 and rises to a steady current value with the startup of the load device 5. And is stored in the memory 43 which is also a waveform storage means, and is provided with a startup waveform characteristic calculation means 23 for performing a process for calculating in advance a predetermined startup waveform characteristic related to the rising edge based on the stored startup current waveform. Yes.

  The startup waveform characteristic calculating means 23 flows through the electric circuit 7 when the power supply is started by the pressing operation of the power switch of the load device 5 and the drive motor is driven in a state where the power of the power supply 3 is stably supplied continuously. The startup current is detected by the current transformer 9, and the detected signal waveform input via the input / output I / F 45 is converted into a startup current waveform by the CPU 41 and stored in a predetermined storage area allocated to the memory 43. It is configured. In addition, the switching contact 11 of the time limit means 13 is configured to close when detecting the starting current.

  In the case of the load device 5, for example, as shown in FIG. 3A, the startup current waveform is represented on an orthogonal coordinate in which the elapsed time [ms] is defined on the X axis and the startup current value [A] is defined on the Y axis. It is assumed that the current value IT1 (= 0) at the start time T1, the current value IT2 at the elapsed time T2, and the steady current value Ia at the steady state after passing through the overshoot portion that is the inrush current portion.

  Based on this startup current waveform, the startup waveform characteristic calculation means 23 has a startup start point P1 (T1, IT1), a startup elapsed point P2 (T2, IT2), and the calculated startup start point P1 on the waveform. A straight line L0 passing through the activation elapsed point P2 is calculated in advance as the activation waveform characteristic. The startup elapsed point P2 is a current threshold value 90% of the steady current value Ia (= IT2) so that the current value IT2 of the startup current that increases from the startup start point P1 after startup is a current value that does not exceed the steady current value Ia. ) And the elapsed time T2 that coincides with (), the calculation processing is performed by the CPU 41.

  Further, the control means 21 performs a predetermined detection on the rise based on the detection signal waveform detected by the current transformer 9 during the first set time t1 when the switching contact 11 is closed when the power supply 3 that has failed is restored. A detection waveform characteristic calculation means 25 for performing processing for calculating the waveform characteristic is provided.

  The detection waveform characteristic calculation means 25 starts supplying power to the load device 5 during the first set time t1 when the timer built in the time limit means 13 starts timing and closes the switching contact 11 when power is restored. The drive current of the drive motor flowing through the electric circuit 7 is detected by the current transformer 9, and the detected signal waveform input via the input / output I / F 45 is converted into data by the CPU 41 and assigned to the memory 43. It is configured to store in a storage area.

  For example, in the case of the detection signal waveform 01 shown in FIG. 3B, the detection waveform characteristic calculation means 25 detects the detection start point P1 ′ (T1, IT1 ′) and the detection elapsed point on the waveform based on the detection signal waveform 01. A straight line L1 passing through P2 ′ (T2, IT2 ′) and the calculated detection start point P1 ′ and detection elapsed point P2 ′ is calculated as a detection waveform characteristic.

  Further, the detection waveform characteristic calculation means 25 similarly detects, for example, the detection start point P1 ″ (T1, IT1 ′) on the waveform based on the detection signal waveform 02 in the case of the detection signal waveform 02 of FIG. '), The detection elapsed point P2 ″ (T2, IT2 ″), and a straight line L2 passing through the calculated detection start point P1 ″ and the detection elapsed point P2 ″ is calculated as a detection waveform characteristic. In FIGS. 3A and 3B, it is assumed that the start point P1 is equal to the detection start points P1 'and P1' '.

  Furthermore, the control means 21 includes a waveform characteristic determination means 27 that performs a process for determining whether or not the startup waveform characteristic and the detected waveform characteristic match.

In the case of the detection signal waveform 01 shown in FIG. 3B, the waveform characteristic determination unit 27 includes the activation elapsed point P2 calculated by the activation waveform characteristic calculation unit 23 and the detection elapsed point P2 ′ calculated by the detection waveform characteristic calculation unit 25. Is used to calculate the difference G (= IT2−IT2 ′) between the current value IT2 and the current value IT2 ′ at the elapsed time T2, and the difference G is preset as in the following conditional expression (1). If it is within the allowable value mI, it is determined that both waveforms match.
−mI ≦ difference G ≦ + mI (1)

Since the current threshold IT2 is set to 90% of the steady current value Ia, the allowable value mI satisfies the following conditional expression (2) so that the upper limit value of the difference G does not exceed the steady current value Ia. And
mI <0.1 × steady current value Ia (2)

  Similarly, in the case of the detection signal waveform 02 in FIG. 3B, the difference G between the current value IT2 and the current value IT2 ″ at the elapsed time T2 is similarly calculated using the activation elapsed point P2 and the detection elapsed point P2 ″. (= IT2−IT2 ″) is calculated, and when the difference G is within the preset allowable value mI as in the conditional expression (1), it is determined that both waveforms match.

  Further, when the detection signal is not detected within a predetermined first set time t1 from the time of power recovery, the control means 21 maintains the circuit breaker 15 in the on state, and during the predetermined first set time t1. When the detection signal is detected and the waveform characteristic determination means 27 determines that the two waveforms do not match, the circuit breaker 15 is operated to be interrupted. In addition, when the detection signal is detected during the first set time t1 and the waveform characteristic determination means 27 determines that the two waveforms match, the circuit breaker 15 that has been cut off once is set to a predetermined second time. A switching signal generation means 29 is provided for performing a process of generating a switching signal so that the circuit breaker 15 performs switching operations in these three cases, which are re-input after the set time t2.

The operation of closing and closing the electric circuit 7 (electric circuit switching method) by the electric circuit switching device 1 having the above-described configuration is performed as follows. FIG. 4 is a timing diagram showing various operations of each part of the circuit switching device 1 when the power supply 3 that has been interrupted due to lightning or connected load devices recovers.
The figure (a) shows the power supply state at the time of power failure and power recovery of the power source 3, and (b) in the figure, when no detection signal is detected at the time of power recovery, (c) is detected at the time of power recovery. When a signal is detected and the two waveforms do not match, FIG. 4D shows a case where the detection signal is detected at the time of power recovery and the two waveforms match.
1A to 1D, A is a power waveform of the power source 3, B is an open / close state of the switching contact 11, C is an output state of the current transformer 9, D is an output state of a switching signal, and E is a cut-off. The switching state of the device 15 is shown respectively.

In FIG. 5B, since the detection signal waveform is not detected during the first set time t1, it is highly possible that the load device 5 is not connected to the electric circuit 7 at the time of power recovery, and the interruption operation is not performed. .
Here, in a state where the power of the power source 3 is stably supplied continuously except at the time of power recovery, the switching contact 11 of the time limit means 13 is not used except when the start-up waveform characteristic calculation means 23 detects the start-up current. If the load device 5 connected to the electric circuit 7 is normal because it is open, the shutoff operation is not performed regardless of the pressing operation of the power switch by the user.

  In FIG. 5C, since the detection signal waveform is detected during the first set time t1, the load device 5 is connected, and the detection signal waveform flowing through the load device 5 is the startup current calculated in advance. Since it does not coincide with the waveform (in the case of the detection signal waveform 02 in FIG. 3), it is highly possible that some abnormality has occurred in the load device 5, so that the blocking operation is performed.

  In FIG. 4D, the load device 5 is connected, and the detection signal waveform flowing through the load device 5 matches the normal startup current waveform (in the case of the detection signal waveform 01 in FIG. 3). In order to ensure safety, the second setting is used in order to take safety measures such as turning off the power switch for the connected load device 5 after the electric circuit 7 is once interrupted by the circuit breaker 15 to ensure safety. The interruption state is maintained only for the time t2. Then, safety measures are taken or the power is turned on again after the second set time t2.

  Therefore, according to the electric circuit switching device 1 or the electric circuit switching method described above, when a characteristic relating to a normal startup is detected, the electric circuit 7 is once interrupted by the circuit breaker 15 and then re-entered after a predetermined time. Therefore, it is possible to easily secure the time for taking safety measures such as turning off the power switch for the connected load device 5. Further, it is possible to increase the determination accuracy and make it difficult to cause an unnecessary blocking operation.

In addition, this invention is not limited to the said embodiment, As shown below, it is also possible to change suitably the shape and structure of each part in the range which does not deviate from the meaning of this invention.
(1) The allowable value is not limited to ± 10%, and can be set to other values as long as it does not exceed the steady current value. Further, the upper limit value and the lower limit value may be different values.
(2) The electric circuit switchgear can also be configured as an electric outlet box by providing an electric outlet on the electric circuit with an outlet socket for inserting an outlet plug provided in the load device. In the case of this outlet box, the same effect as that of the electric circuit switchgear can be obtained.
(3) In the case of the detection signal waveform 01, the waveform characteristic determination means (process) uses the start passage point P2 and the detection elapsed point P3 ′, and uses the difference G between the elapsed time T2 and the elapsed time T2 ′ in the current value IT2. (= T2−T2 ′) is calculated, and when the difference G is within the preset allowable value mT as in the following conditional expression (3), it may be determined that both waveforms match.
−mT ≦ difference G ≦ + mT (3)
Since the current threshold IT2 is set to 90% of the steady current value Ia, the allowable value mT is such that the current value at the upper limit (= IT2 + mT) of the difference G does not exceed the steady current value Ia using the straight line L0. Thus, the following conditional expression (4) shall be satisfied.
mT <0.1 × elapsed time T2 (time at steady-state current value Ia) (4)
(4) The startup waveform characteristic and the detection waveform characteristic are not limited to the current value and time, and in the same way, at two points of the start point and the elapsed point, the slope of the straight line, the curve along the waveform shape, the waveform area, etc. A combination of these may be used.
(5) When a plurality of load devices are connected, the start waveform characteristic calculating means (process) may be configured to calculate in advance the start waveform characteristics at the normal start for each of the load devices individually or in combination. desirable.

  1 .... Circuit switch, 3 .... Power supply, 5 .... Load equipment, 7 .... Circuit, 9 .... Current transformer (current detection means), 11 .... Switch contact, 13 .... Time limit means, ... Circuit breaker (electric circuit state switching means), 21... Control means, 23... Startup waveform characteristic calculation means, 25... Detection waveform characteristic calculation means, 27. ..CPU, 43..Memory, 45..Input / output I / F, P1, P1 ', P1' '.. Start point, P2, P2', P2 '' .. Elapsed point, L0, L1, L2.・ Straight line, Ia ・ ・ Steady current value, Ith ・ ・ Shutdown threshold, T1 ・ ・ Start time (at power supply, power recovery), T2 ・ ・ Elapsed time, t1 ・ ・ First set time, t2 ・ ・ Second set time.

Claims (5)

An electric circuit connecting the power source and the load device;
Current detecting means for detecting a current flowing in the electric circuit;
A switching contact provided in series at the output terminal of the detection signal of the current detection means is connected to a predetermined power supply after the power supply from the power supply to the load device is started when the power supply is restored. A time-limit means that opens after the first set time has elapsed;
An electric circuit state switching means for switching the electric circuit to a turned-on state or a cut-off state according to an input predetermined switching signal;
Control means for generating the switching signal based on the detection signal of the current detection means and controlling the switching operation of the electric circuit state switching means;
An electric circuit switchgear comprising:
The control means includes
When power supply from the power source to the load device is started via the electric circuit, a start-up current waveform that rises to a steady current value with the start-up of the load device is detected by the current detection unit and stored in the waveform storage unit. A startup waveform characteristic calculating means for calculating in advance a predetermined startup waveform characteristic related to the rising edge based on the stored startup current waveform;
A detection waveform for calculating a predetermined detection waveform characteristic related to the rising edge based on the detection signal waveform detected by the current detection means during the first set time when the switching contact is closed when the power supply that has failed is restored. Characteristic calculation means;
Waveform characteristic determining means for determining whether or not the startup waveform characteristic and the detected waveform characteristic match;
When the detection signal is not detected during the first set time, the electric circuit state switching means is kept in the input state,
When a detection signal is detected during the first set time and the waveform characteristic determination unit determines that the two waveform characteristics do not match, the circuit state switching unit is operated to shut off,
When the detection signal is detected during the first set time and the waveform characteristic determining unit determines that the two waveform characteristics match, the circuit state switching unit that has been once cut off is set to a predetermined second state. Re-enter after the set time has elapsed,
Switching signal generating means for generating the switching signal so as to cause the electric circuit state switching means to perform the switching operation in these three cases,
An electric circuit switchgear characterized by the above. The startup waveform characteristic calculating means includes
On the stored start-up current waveform, a start-up start point and a predetermined start-up elapsed point until the start-up current increasing from the start-up start point reaches a predetermined current value that does not exceed the steady-state current value are set as start-up waveform characteristics. Calculated in advance,
The detected waveform characteristic calculating means includes
On the detected detection signal waveform, a detection start point and a detection elapsed point corresponding to the activation elapsed point calculated by the activation waveform characteristic calculating unit are calculated as predetermined detection signal waveform characteristics,
The waveform characteristic determining means includes
Calculating a difference between current values at the activation progress point and the detection progress point, and when the difference is equal to or less than a preset allowable value, it is determined that both waveforms match;
The electric circuit switchgear according to claim 1. In the electric circuit according to claim 1 or 2, an outlet socket for inserting an outlet plug provided in the load device is provided.
Outlet box characterized by that. An electric circuit connecting the power source and the load device;
Current detecting means for detecting a current flowing in the electric circuit;
A switching contact provided in series at the output terminal of the detection signal of the current detection means is connected to a predetermined power supply after the power supply from the power supply to the load device is started when the power supply is restored. A time-limit means that opens after the first set time has elapsed;
An electric circuit state switching means for switching the electric circuit to a turned-on state or a cut-off state according to an input predetermined switching signal;
Control means for generating the switching signal based on the detection signal of the current detection means and controlling the switching operation of the electric circuit state switching means;
Electric circuit opening and closing method using
The control means includes
When power supply from the power source to the load device is started via the electric circuit, a start-up current waveform that rises to a steady current value with the start-up of the load device is detected by the current detection unit and stored in the waveform storage unit. A startup waveform characteristic calculation process for calculating in advance a predetermined startup waveform characteristic related to the rising edge based on the stored startup current waveform;
A detection waveform for calculating a predetermined detection waveform characteristic related to the rising edge based on the detection signal waveform detected by the current detection means during the first set time when the switching contact is closed when the power supply that has failed is restored. A characteristic calculation process;
A waveform characteristic determination process for determining whether or not the startup waveform characteristic and the detected waveform characteristic match;
When the detection signal is not detected during the first set time, the electric circuit state switching means is kept in the input state,
When a detection signal is detected during the first set time and it is determined by the waveform characteristic determination process that the two waveform characteristics do not match, the circuit state switching unit is operated to shut off,
When the detection signal is detected during the first set time and it is determined by the waveform characteristic determination process that the two waveform characteristics match, the circuit state switching means that has been once cut off is set to a predetermined second Re-enter after the set time has elapsed,
A switching signal generating process for generating the switching signal so as to cause the electric circuit state switching means to perform the switching operation in these three cases,
An electric circuit opening and closing method characterized by the above. The startup waveform characteristic calculation process includes:
On the stored start-up current waveform, a start-up start point and a predetermined start-up elapsed point until the start-up current increasing from the start-up start point reaches a predetermined current value that does not exceed the steady-state current value are set as start-up waveform characteristics. Calculated in advance,
The detected waveform characteristic calculation process includes:
On the detected detection signal waveform, a detection start point and a detection elapsed point that coincides with an elapsed time of the startup elapsed point calculated in the startup waveform characteristic calculation process are calculated as predetermined detection signal waveform characteristics,
The waveform characteristic determination process includes
Calculating a difference between current values at the activation progress point and the detection progress point, and when the difference is equal to or less than a preset allowable value, it is determined that both waveforms match;
The electric circuit opening and closing method according to claim 4.

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