JP5212005B2 - Electronic circuit breaker - Google Patents

Description

  The present invention relates to an electronic circuit breaker that detects a load current flowing through an electric circuit and protects the electric circuit by means of time characteristics in an overcurrent region.

  The conventional electronic circuit breaker can set the overcurrent trip characteristic after the circuit breaker is installed according to the connection status of the load device connected to the load side circuit and the usage status of the load device. . (For example, see Patent Document 1 and FIG. 1)

JP 2001-128354 A

As described above, in the conventional electronic circuit breaker, it is possible to set the overcurrent trip characteristic according to the usage state of the load device. It is installed in the electric circuit where the fluctuation of the load current is assumed due to the change of the operation pattern of the equipment.
However, when a plurality of load devices such as motors are connected to the load-side circuit, the load current fluctuates instantaneously and greatly depending on the motor start current when operated simultaneously or with a delay time depending on the operation pattern. In order to grasp the fluctuation state of the load current in the overcurrent region necessary for setting the current trip characteristic, it is necessary to install another measuring device and measure the fluctuation state of the load current. It was difficult to set the trip characteristics.

  The present invention has been made to solve the above-described problems, and can easily set the overcurrent trip characteristic by grasping the fluctuation state of the load current in the overcurrent region without installing another measuring device. An electronic circuit breaker that can be obtained is obtained.

An electronic circuit breaker according to the present invention includes an open / close contact that opens and closes an electric circuit, a tripping device that opens the open / close contact, current detection means that detects an electric current of the electric circuit, and an open / close contact according to an overcurrent flowing through the electric circuit An overcurrent tripping characteristic setting unit for setting an overcurrent tripping characteristic for opening the circuit, and a control device for outputting a trip signal to the tripping device based on the overcurrent tripping characteristic and the current detected by the current detecting means, An energization time measuring unit for timing the energization duration according to the detected current, a maximum energization time storage unit for storing the maximum energization duration measured according to the detected current by the energization time measuring unit, and the maximum energization Display means for displaying the maximum load time characteristic composed of the maximum energization duration corresponding to the detected current stored in the time storage unit and the overcurrent tripping characteristic together .

  According to this invention, by measuring the maximum energization duration measured according to the load current flowing through the electric circuit, it becomes possible to grasp the fluctuation state of the load current in the overcurrent region, and the overcurrent tripping characteristic is easily obtained. Can be set.

Embodiment 1 FIG.
1 is a block diagram showing a configuration of an electronic circuit breaker according to Embodiment 1 of the present invention, FIG. 2 is an explanatory diagram of a method for obtaining an effective value of current by sampling, FIG. 3 is an enlarged view of a main part of a display unit, FIG. 4 is a flowchart showing the operation of the electronic circuit breaker.

  In FIG. 1, an electronic circuit breaker 100 includes an open / close contact 2 that opens and closes an AC circuit 1, and a current transformer 3 that is provided in the AC circuit 1 and outputs a current signal proportional to a load current flowing through the AC circuit 1. The current detection circuit 4 that converts the current output signal of the current transformer 3 into an analog voltage signal, the A / D conversion circuit 5 that converts the analog voltage signal from the current detection circuit 4 into a digital signal, and the A / D Based on the digital signal from the conversion circuit 5, the load current calculation unit 6 that calculates the current value flowing in each phase of the AC circuit 1, the overcurrent trip characteristic and the rated current consisting of the relation of the trip time with respect to the load current value A characteristic setting unit 7 to be set, and a microcomputer (CPU) that outputs an overcurrent trip signal based on the overcurrent trip characteristic set by the characteristic setting unit 7 and the current value by the load current calculation unit 6 are included. Time when the load current value of the AC circuit 1 calculated by the load current calculator 6 and the trip circuit 9 that opens the switching contact 2 by the trip signal from the control device 8 by the trip signal from the control device 8 continues to flow. And a maximum energization time storage unit 11 that stores the maximum energization duration measured according to each load current value by the energization time measurement unit 10.

  Further, as shown in FIG. 3, the control device 8 stores the overcurrent trip time characteristic set in the characteristic setting unit 7 in a graph and the overcurrent trip time characteristic curve 20 and the maximum energization time storage unit 11. The relationship between the maximum energization duration with respect to each load current value, that is, the display unit 12 that displays the maximum load time characteristic curve 21 in which the maximum load time characteristic is displayed as a graph, for example, is set by the display means and the characteristic setting unit 7. Communication interface (communication I / F) 13 for transmitting the overcurrent trip time characteristic and the maximum load time characteristic data to an external device such as an external display device and receiving the setting of the overcurrent trip time characteristic That is, the communication means is connected. The display unit 12 is configured by, for example, a liquid crystal display device.

The current detection circuit 4 includes a rectifier circuit 4a that converts an AC current output signal from the current transformer 3 into a DC signal, a load circuit 4b that converts an output current signal of the rectifier circuit 4a into a voltage signal, and a load circuit 4b. It comprises a waveform conversion circuit 4c for obtaining the effective value of the induced output voltage signal. The current detection circuit 4, the current transformer 3, and the A / D conversion circuit 5 constitute current detection means.
In addition, a plurality of loads 14 a and 14 b such as a motor and an electric lamp are connected to the load side of the electronic circuit breaker 100.

A load current calculation method in the load current calculation unit 6 will be described with reference to FIG. The detected current of the electric circuit 1 is converted from an analog value to a digital value by the A / D conversion circuit 5. The detection period of this current signal, that is, the sampling period is Δt. Since it is necessary to obtain an effective value for the load current, the effective value of the sampling current is obtained by performing a square moving average with a sampling number m during a period corresponding to 5 cycles when the AC power supply frequency of the AC circuit 1 is 50 Hz, and 6 cycles when 60 Hz, for example. I ² = (Σi ² ) / m is obtained as the square value of. The square root of I ² is the effective value I of the load current.

As shown in FIG. 3, the display unit 12 displays the load current value on the horizontal axis, the operating time of the circuit breaker 100 on the vertical axis, the overcurrent trip characteristic curve 20 set in the characteristic setting unit 7, and the maximum The maximum load time characteristic curve 21 in which data including the maximum energization duration for each load current value stored in the energization time storage unit 11 is displayed as a graph is displayed on the same display screen. When the load current value of the AC circuit 1 calculated by the load current calculation unit 6 exceeds the boundary of the overcurrent trip characteristic 20, a trip signal is output from the control device 8 to the trip circuit 9, and the switching contact 2 is opened. Is done.
As the display content, it is also possible to display the maximum energization duration value for each load current value of the maximum load time characteristic 21 together.

Next, the operation will be described.
The operation of the control device 8 will be mainly described with reference to the flowchart of FIG. Since the energization time data T1 is included in the processing routine, the data T1 is cleared in the initial process (step 30). The load current calculation unit 6 obtains the load current value I1 (step 31), the overcurrent trip time limit process is executed based on the load current value I1 (step 32), and the overcurrent tripping set by the characteristic setting unit 7 is performed. If the load current value I1 exceeds the boundary of the overcurrent trip characteristic 20 and the overcurrent trip operation is performed, for example, the control device 8 is compared with the overcurrent trip characteristic 20 shown in FIG. The trip signal is output from the trip circuit 9 to the trip circuit 9 to execute the circuit breaker breaking operation (step 42).

  When the load current value I1 does not exceed the boundary of the overcurrent trip characteristic 20 and the overcurrent trip operation is not performed, it is determined whether the calculated load current value I1 has changed from the previous load current value (step 34). When the load current value I1 has not changed, a time obtained by adding the elapsed time Δt from the previous calculation process in the load current calculation unit 6 to the current process to the energization duration T1 is defined as an energization duration T1 = T1 + Δt. The energization duration time is updated (step 35). When the load current value I1 changes from the previous value, the energization continuation time is updated with the energization continuation time T1 as the elapsed time Δt (step 36).

  Next, the past maximum energization duration Tmax (I1) for the load current value I1 is read from the maximum energization time storage unit 11 (step 37), the current energization duration T1 for the load current value I1 and the past maximum energization duration Tmax. (I1) is compared (step 38), and when the energization duration of the current load current value exceeds the past maximum energization duration, the past maximum energization duration is updated (Tmax (I1) = T1). (Step 39) The maximum energization duration Tmax (I1) for the load current value is stored in the maximum energization time storage unit 11 (Step 40). As the display data of the maximum load time characteristic on the display unit 12, the maximum energization duration value for each load current value stored in the maximum energization time storage unit 11 is read, and the maximum load time characteristic is obtained from the load current value and the maximum energization duration time. The curve 21 is displayed (step 41). Thereafter, a new load current value is calculated (step 31).

  According to the present embodiment, the maximum energization time storage unit 11 that stores the maximum energization duration Tmax (I1) measured by the energization time measurement unit 10 according to each load current value I1 flowing through the electric circuit 1 is provided. As a result, the maximum load time characteristic which is the fluctuation state of the load current in the overcurrent region due to the operation of the plurality of load devices connected to the electric circuit 1 can be grasped, and the overcurrent tripping characteristic can be easily set.

  Also, since the maximum load time characteristic curve 21 and the overcurrent trip characteristic curve 20 are displayed together on the display unit 12, the overcurrent trip characteristic can be set more easily.

  Moreover, since the communication interface 13 for transmitting / receiving each data constituting the maximum load time characteristic and the overcurrent trip characteristic with the external device is provided, the overcurrent trip characteristic can be easily set even from a remote place. .

  In the present embodiment, the maximum energization duration corresponding to each load current value I1 is set as the maximum load time characteristic, but each load current value is replaced with, for example, a percentage value relative to the rated current of the circuit breaker. Thus, by providing ranges for load current values such as 100% or more and less than 200% or 200% or more and less than 300%, the amount of data consisting of each load current value range and the maximum energization duration is reduced. Also good.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing the configuration of the electronic circuit breaker 101 according to the second embodiment of the present invention, and FIG. 6 is an explanation showing the relationship between the maximum load time characteristic and the overcurrent trip characteristic of the electronic circuit breaker 101. 7 and 7 are flowcharts showing the operation of the electronic circuit breaker 101.

  In the first embodiment, although fluctuations in the load current value can be easily grasped, the calculation methods related to the times of the actual overcurrent trip characteristics and the maximum load time characteristics are different, so the overcurrent trip characteristics and the maximum load time characteristics Is not consistent. In the present embodiment, the thermal history is reflected in the maximum load time characteristic, and the electronic circuit breaker 101 does not have the energization time measuring unit 10 as shown in FIG. Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

As shown in FIG. 6, the overcurrent trip characteristic of the electronic circuit breaker 101 is composed of overcurrent trip characteristic curves of a long time characteristic, a short time characteristic, and an instantaneous characteristic depending on the magnitude of the load current. In the present embodiment, an operation in the long time characteristic region will be described. The long-time characteristic is set in advance by the characteristic setting unit 7. For example, the trip operation time Te for the long-time is set as Te = K / Ie ² . Here, Ie is a load current value, Te is a tripping operation time for a long time, and K is a constant. Further, K corresponds to a line segment 0-Ie ^{2 in} FIG. 6 and a rectangular area S0 surrounded by the line segment 0-Te, that is, S0 = K = Te × Ie ² .

The operation of the electronic circuit breaker 101 compares the effective value Ie of the load current with a predetermined rated current I0 to determine whether the rated current I0 is exceeded. At this time, in order to simplify the processing, Ie ² which is the square value of the load current effective value may be compared with I ₀ ² which is the square value of the rated current. When the load current effective value exceeds the rated current, the current product integration means calculates a current product obtained by multiplying the square value Ie ² of the load current effective value by the sampling period Δt, and integrates and accumulates this current product. Thus, the accumulated current value S1 is calculated. The accumulated current value S1 is S1 = Σ (Δt × Ie ² ), and the breaking operation of the electronic circuit breaker 101 is executed when the accumulated current value S1 exceeds the area S0.

  When the effective load current value is equal to or lower than the rated current, the residual current correction means subtracts the thermal history Δt · P corresponding to cooling from the accumulated current value S1. Here, P is a constant and is a heat dissipation coefficient within a unit time.

Here, as the maximum load time characteristic, if the load current value Ie flows during the continuous energization time T1, the accumulated current value S1 is a rectangular area surrounded by the line segment 0-Ie ² and the line segment 0-T1. And S1 = Ie ² · T1.
When the load current value fluctuates from Ie to I1, the accumulated current value S1 is calculated as S1 = S2 + Δt · I1 ² from the accumulated current value S2 at the previous calculation and the load current I1 detected this time by the current product integrating means. Calculated with Energization duration T2 at the next load current I1, the load current is calculated in a timed conversion means by T2 = S1 / I1 ^2, is greater than the previous maximum energization duration corresponding to the load current I1, the new maximum power The duration is stored in the maximum energization time storage unit 11. As the maximum load time characteristic with respect to the load current I1, a characteristic consistent with the overcurrent tripping operation in the long time characteristic of the electronic circuit breaker 101 can be obtained.

Next, the operation will be described.
The operation of the control device 8 will be described with reference to the flowchart of FIG. Since steps 30, 31, and 37 to 42 are the same as those in the first embodiment, the description thereof is omitted. First, the load current calculation unit 6 obtains the load current I1 (step 31), compared with the rated current I _0, the load current value determines whether an overcurrent condition (step 50).

When I1> I0 and the load current value I1 exceeds the rated current I0, the accumulated current value S1 obtained by integrating the current products within the elapsed time by the current product integrating means as the long time delay trip processing is obtained as S1 = S2 + ( Δt × I1 ² ) (step 51). Here, S2 is the accumulated current value S1 at the previous calculation, and the initial value is zero.

  Next, it is compared with a predetermined constant K calculated from the set value of the long time delay trip characteristic preset by the characteristic setting unit 7 (step 52). If S1> K, the electronic circuit breaker 101 A shut-off operation is executed (step 42).

In the case of S1 ≦ K, in order to convert the accumulated current value S1 within the elapsed time as the thermal history into the energization duration value T1 with respect to the current load current value I1, the process proceeds to load current time period conversion processing, and the load current and it calculates the T1 = S1 / I1 ² by timed conversion means, obtains the energization duration value T1 for the load current I1 (step 53).

  Next, the past maximum energization duration Tmax (I1) for the load current value I1 is read from the maximum energization time storage unit 11 (step 37), and the current energization duration T1 for the load current value I1 and the past maximum energization duration. Time Tmax (I1) is compared (step 38). When the energization duration T1 of the current load current value I1 exceeds the past maximum energization duration Tmax (I1), the past maximum energization duration Tmax (I1) is updated (Tmax (I1) = T1) ( Step 39), the maximum energization duration Tmax (I1) for the load current value I1 is stored in the maximum energization time storage unit 11 (Step 40).

  Then, as display data for displaying the maximum load time characteristic on the display unit 12, the maximum energization duration for each load current value stored in the maximum energization time storage unit 11 is read, and each load current value and its maximum energization continuation are read. The maximum load time characteristic 21 consisting of time is displayed on the display unit 12 (step 41). Thereafter, a new load current value is calculated (step 31).

  Further, when the energization duration T1 of the current load current value I1 is equal to or less than the past maximum energization duration Tmax (I1), the update process of the maximum energization time storage unit 11 is not performed.

  Further, it is determined whether or not the load current value is in an overcurrent state (step 50). When the load current value I1 is equal to or less than the rated current I0 in the state of I1 ≦ I0, the process proceeds to a residual current product correction process. As the residual current product correction processing, the residual current product correction means calculates the heat dissipation correction value Δt · P proportional to the duration from the previous processing when the load current value I1 becomes less than the rated current I0, and the past rated current The heat dissipation correction value Δt · P is subtracted from the accumulated current value S2 of the thermal history accumulated within the elapsed time in the overcurrent state exceeding the calculated value to calculate the corrected accumulated current value S1 (step 54). Note that P is a constant and is a heat dissipation coefficient within a unit time, and the residual current product correction processing corresponds to the heat dissipation cooling of the load electric circuit 1.

  It is determined whether or not the accumulated current value S1 is S1 <0 (step 55). If S1 <0, the current and previous accumulated current values are initialized, that is, S1 = S2 = 0 (step 56), and the load The process proceeds to current time conversion processing (step 53). If S1 ≧ 0, the process proceeds to the load current time conversion process as it is (step 53).

  According to the present embodiment, the maximum energization time storage unit 11 that stores the maximum energization duration Tmax (I1) measured by the energization time measurement unit 10 according to each load current value I1 flowing through the electric circuit 1 is provided. As a result, the maximum load time characteristic which is the fluctuation state of the load current in the overcurrent region due to the operation of the plurality of load devices connected to the electric circuit 1 can be grasped, and the overcurrent tripping characteristic can be easily set.

  In addition, the calculation method of the maximum energization duration corresponding to each load current value of the maximum load time characteristic is a method that takes into account the thermal history, so that the overcurrent pull-in including the thermal history of the electronic circuit breaker 101 is performed. It is possible to acquire the maximum load time characteristic 21 that is consistent with the removal operation, and the overcurrent trip characteristic can be set accurately.

  Also, since the maximum load time characteristic curve 21 and the overcurrent trip characteristic curve 20 are displayed together on the display unit 12, the overcurrent trip characteristic can be set more easily.

  Moreover, since the communication interface 13 for transmitting / receiving each data constituting the maximum load time characteristic and the overcurrent trip characteristic with the external device is provided, the overcurrent trip characteristic can be easily set even from a remote place. .

  In the present embodiment, only the case of the long time characteristic is described, but the calculation method of the maximum energization duration time of the maximum load time characteristic 21 is also described for each overcurrent trip process in the case of the short time characteristic and the instantaneous characteristic. It may be the same as the method.

  In addition, the maximum energization duration corresponding to each load current value I1 is configured to have the maximum load time characteristic, but each load current value is replaced with, for example, a percentage value with respect to the rated current of the circuit breaker to be 100% or more 200 By providing a range of load current values such as less than%, 200% or more and less than 300%, the amount of data consisting of the range of each load current value and the maximum energization duration corresponding thereto may be reduced.

Embodiment 3 FIG.
FIG. 8 is a flowchart showing the operation of the electronic circuit breaker 102 according to the third embodiment of the present invention. The block diagram showing the configuration of the electronic circuit breaker 102 is the same as FIG. In the present embodiment, the energization time measurement unit 10 is added to the second embodiment, and when the load current value is equal to or lower than the rated current, the maximum energization duration time in the maximum load time characteristic is calculated as in the first embodiment. It does not reflect the thermal history. Other configurations and operations are the same as those of the second embodiment, and thus description thereof is omitted.

Next, the operation will be described.
The operation of the control device 8 will be described with reference to the flowchart of FIG. Steps 30, 31, and 37 to 56 are the same as those in the second embodiment. First, the load current calculation unit 6 obtains the load current I1 (step 31), compared with the rated current I _0, the load current value determines whether an overcurrent condition (step 50).

When I1> I0 and the load current value I1 exceeds the rated current I0, the overcurrent excess flag F is turned on (step 60). The accumulated current value S1 obtained by integrating the current products within the elapsed time is calculated by S1 = S2 + (Δt × I1 ² ) by the current product integrating means as the long time delay trip process (step 51). Here, S2 is the accumulated current value S1 at the previous calculation, and the initial value is zero.

  Next, it is compared with a predetermined constant K calculated from the set value of the long time delay trip characteristic preset by the characteristic setting unit 7 (step 53). If S1> K, the electronic circuit breaker 102 A shut-off operation is executed (step 42).

In the case of S1 <K, in order to convert the accumulated current value S1 within the elapsed time as the thermal history into the energization duration value T1 with respect to the current load current value I1, T1 = S1 / I1 by the load current time conversion means. ² is calculated to obtain the energization duration value T1 for the load current value I1 (step 53).

  Next, the past maximum energization duration Tmax (I1) for the load current value I1 is read from the maximum energization time storage unit 11 (step 37), and the current energization duration T1 for the load current value I1 and the past maximum energization duration. Time Tmax (I1) is compared (step 38). When the energization duration T1 of the current load current value I1 exceeds the past maximum energization duration Tmax (I1), the past maximum energization duration Tmax (I1) is updated (Tmax (I1) = T1) ( Step 39), the maximum energization duration Tmax (I1) for the load current value is stored in the maximum energization time storage unit 11 (Step 40).

  Then, as display data for displaying the maximum load time characteristic on the display unit 12, the maximum energization duration for each load current value stored in the maximum energization time storage unit 11 is read, and the load current value and its maximum energization duration are read out. Further, the maximum load time characteristic curve 21 is displayed on the display unit 12 (step 41). Thereafter, a new load current value is calculated (step 31).

  Further, when the energization duration T1 of the current load current value I1 is equal to or less than the past maximum energization duration Tmax (I1), the update process of the maximum energization time storage unit 11 is not performed.

  Further, it is determined whether or not the load current value is in an overcurrent state (step 50). When the load current value I1 is less than or equal to the rated current I0 with I1 ≦ I0, it is confirmed whether or not the overcurrent excess flag F is on. (Step 61) When the overcurrent excess flag F is ON (F = 1), the process proceeds to the residual current product correction process. When the overcurrent excess flag F is off (F = 0), the process proceeds to the next energization time counting process without executing the residual current product correction process.

  When the overcurrent excess flag is on (F = 1), the process proceeds to the residual current product correction process. As the residual current product correction processing, the residual current product correction means calculates the heat dissipation correction value Δt · P proportional to the duration from the previous processing when the load current value I1 becomes less than the rated current I0, and the past rated current The heat dissipation correction value Δt · P is subtracted from the accumulated current value S2 of the thermal history accumulated within the elapsed time in the overcurrent state exceeding the calculated value, thereby calculating the corrected accumulated current value S1 (step 56). Note that P is a constant and is a heat dissipation coefficient within a unit time, and the residual current product correction processing corresponds to the heat dissipation cooling of the load electric circuit 1.

When the accumulated current value S1 becomes S1 <0, the current and previous accumulated current values are initialized, that is, S1 = S2 = 0 (step 56), and the overcurrent excess flag f is turned off (F = 0). Then, the process shifts to a time counting process of the energization duration according to the load current value below the rated current value.
When the accumulated current value S1 is S1 ≧ 0, the process immediately shifts to a time-keeping process of the energization duration according to the load current value below the rated current value.

  As a process for measuring the duration of energization according to the load current value below the rated current value, it is determined whether the load current value I1 is the same as the previous load current value (step 34), and energization is performed when the load current value I1 is the same. The time obtained by adding the processing time elapsed Δt to the duration T1 is set as current energization duration T1 = T1 + Δt, and the energization duration is updated (step 35). When the load current value I1 changes from the previous value, the energization continuation time T1 is updated by setting the energization continuation time as the elapsed time T1 = Δt (step 36). Next, the maximum energization time calculation process for the load current value I1 is executed using the energization duration T1 for the load current value I1 calculated by the elapsed time update process (steps 37 to 40), and the updated maximum load time characteristic Display processing is performed (step 41).

  According to the present embodiment, the maximum energization time storage unit 11 that stores the maximum energization duration Tmax (I1) measured by the energization time measurement unit 10 according to each load current value I1 flowing through the electric circuit 1 is provided. As a result, the maximum load time characteristic which is the fluctuation state of the load current in the overcurrent region due to the operation of the plurality of load devices connected to the electric circuit 1 can be grasped, and the overcurrent tripping characteristic can be easily set.

  In addition, since the calculation method of the maximum energization duration according to each load current value of the maximum load time characteristic is a method including the thermal history, the overcurrent tripping including the thermal history of the electronic circuit breaker 102 is performed. It is possible to acquire the maximum load time characteristic that is consistent with the operation, and the overcurrent trip characteristic can be set accurately.

  In addition, the processing of the control device 8 can be reduced by adopting a simple method that does not take into account the thermal history for the time-keeping process of the energization duration according to the load current value below the rated current value.

  Also, since the maximum load time characteristic curve 21 and the overcurrent trip characteristic curve 20 are displayed together on the display unit 12, the overcurrent trip characteristic can be set more easily.

  Moreover, since the communication interface 13 for transmitting / receiving each data constituting the maximum load time characteristic and the overcurrent trip characteristic with the external device is provided, the overcurrent trip characteristic can be easily set even from a remote place. .

  In the present embodiment, only the case of the long time characteristic is described, but the calculation method of the maximum energization duration time of the maximum load time characteristic 21 is also described for each overcurrent trip process in the case of the short time characteristic and the instantaneous characteristic. It may be the same as the method.

  In addition, the maximum energization duration corresponding to each load current value I1 is configured to have the maximum load time characteristic, but each load current value is replaced with, for example, a percentage value with respect to the rated current of the circuit breaker to be 100% or more 200 By providing a range of load current values such as less than%, 200% or more and less than 300%, the amount of data consisting of the range of each load current value and the maximum energization duration corresponding thereto may be reduced.

Embodiment 4 FIG.
FIG. 9 is an explanatory diagram of a method for obtaining the effective value of the load current by sampling of the electronic circuit breaker 103 according to Embodiment 4 of the present invention, and FIG. 10 is a flowchart showing the operation of the electronic circuit breaker 103. The block diagram showing the configuration of the electronic circuit breaker 103 is the same as FIG.

  In the third embodiment, the calculation of the load current value I1 and the energization continuation time according to the load current value I1 is performed for each detection sampling period Δt of the current signal. However, in this embodiment, as shown in FIG. For each ΔT corresponding to a common multiple of the periods of 50 Hz and 60 Hz, which are AC power supply frequencies of 1, the calculation processing of the load current value I1 and the energization duration time corresponding to the load current value I1 is performed. Since other configurations are the same as those in the third embodiment, the description thereof is omitted.

Next, the operation will be described.
The operation of the control device 8 will be described with reference to the flowchart of FIG. Since this process is performed not every sampling period Δt of the current signal but every ΔT that is a common multiple of the 50 Hz and 60 Hz periods that are the AC power supply frequencies of the electric circuit 1, the current product integrating means is equivalent to the ΔT period that is the elapsed time. Since the current product is integrated, Σ (Δt · I1 ² ) is obtained, and the accumulated current value S1 is calculated by S1 = S2 + Σ (Δt · I1 ² ) (step 51a).

  Further, in the residual current product correction process, the load current value I1 becomes less than the rated current I0 by the residual current product correction means, and the duration ΔT period from the previous process is integrated. Therefore, the heat dissipation correction value is Σ (Δt · P Thus, the corrected accumulated current value S1 is calculated by subtracting the heat radiation correction value ΣΔt · P from the accumulated current value S2 of the previous thermal history (step 54a).

  The current-carrying time measurement processing corresponding to the load current value below the rated current value also determines whether the load current value I1 is the same as the previous load current value (step 34). The time obtained by adding the processing time elapsed ΔT to the time (T1) is set as the current energization duration (T1 = T1 + Δt), and the energization duration is updated (step 35a). When the load current value I1 changes from the previous value, the energization continuation time T1 is updated by setting the energization continuation time as the elapsed time and T1 = ΔT (step 36a). Other operations are the same as those in the third embodiment, and thus description thereof is omitted.

  According to the present embodiment, the maximum energization time storage unit 11 that stores the maximum energization duration Tmax (I1) measured by the energization time measurement unit 10 according to each load current value I1 flowing through the electric circuit 1 is provided. As a result, the maximum load time characteristic which is the fluctuation state of the load current in the overcurrent region due to the operation of the plurality of load devices connected to the electric circuit 1 can be grasped, and the overcurrent tripping characteristic can be easily set.

  In addition, since the calculation method of the maximum energization duration corresponding to each load current value of the maximum load time characteristic is a method that takes into account the thermal history, an overcurrent trip including the thermal history of the electronic circuit breaker 103 is obtained. It is possible to acquire the maximum load time characteristic 21 that is consistent with the removal operation, and the overcurrent trip characteristic can be set accurately.

  In addition, the processing of the control device 8 can be reduced by adopting a simple method that does not take into account the thermal history for the time-keeping process of the energization duration according to the load current value below the rated current value.

  In addition, since the calculation of the load current value I1 and the energization continuation time according to the load current value I1 is performed for each ΔT corresponding to a common multiple of the 50 Hz and 60 Hz periods of the AC power supply frequency of the circuit 1, Processing can be further reduced.

  Also, since the maximum load time characteristic curve 21 and the overcurrent trip characteristic curve 20 are displayed together on the display unit 12, the overcurrent trip characteristic can be set more easily.

  Moreover, since the communication interface 13 for transmitting / receiving each data constituting the maximum load time characteristic and the overcurrent trip characteristic with the external device is provided, the overcurrent trip characteristic can be easily set even from a remote place. .

  In the present embodiment, only the case of the long time characteristic is described, but the calculation method of the maximum energization duration time of the maximum load time characteristic 21 is also described for each overcurrent trip process in the case of the short time characteristic and the instantaneous characteristic. It may be the same as the method.

  In addition, the maximum energization duration corresponding to each load current value I1 is configured to have the maximum load time characteristic, but each load current value is replaced with, for example, a percentage value with respect to the rated current of the circuit breaker to be 100% or more 200 By providing a range of load current values such as less than%, 200% or more and less than 300%, the amount of data consisting of the range of each load current value and the maximum energization duration corresponding thereto may be reduced.

It is a block diagram which shows the structure of the electronic circuit breaker in Embodiment 1 of this invention. It is explanatory drawing of the method of obtaining the effective value of the electric current by the sampling of the electronic circuit breaker in Embodiment 1 of this invention. It is a principal part enlarged view of the display part of the electronic circuit breaker in Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the electronic circuit breaker in Embodiment 1 of this invention. It is a figure explaining the relationship between an overcurrent and a time characteristic. It is a block diagram which shows the structure of the electronic circuit breaker in Embodiment 2 of this invention. It is explanatory drawing which shows the relationship between the maximum load time limit characteristic and overcurrent trip characteristic of the electronic circuit breaker in Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the electronic circuit breaker in Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the electronic circuit breaker in Embodiment 3 of this invention. It is explanatory drawing of the method of obtaining the effective value of the load current by the sampling of the electronic circuit breaker in Embodiment 4 of this invention. It is a flowchart which shows operation | movement of the electronic circuit breaker in Embodiment 4 of this invention.

Explanation of symbols

2 switching contacts, 3 current transformer, 4 current detection circuit, 5 A / D conversion circuit,
7 characteristic setting unit, 8 control device, 9 trip circuit, 10 energization time measurement unit,
11 Maximum energization time storage unit, 100 Electronic circuit breaker.

Claims (4)

An open / close contact for opening and closing the electric circuit, a tripping device for opening the open / close contact, a current detecting means for detecting a current in the electric circuit, and an overcurrent trip for opening the open / close contact in response to an overcurrent flowing through the electric circuit. An overcurrent tripping characteristic setting unit for setting a tripping characteristic; a control device for outputting a tripping signal to the tripping device based on the overcurrent tripping characteristic and a current detected by the current detecting means; and An energization time measuring unit that measures the energization duration according to the current, a maximum energization time storage unit that stores the maximum energization duration measured according to the detected current by the energization time measurement unit, and the maximum energization time storage unit An electronic circuit breaker comprising: display means for displaying the maximum load time characteristic composed of the maximum energization duration corresponding to the detected current stored in and the overcurrent trip characteristic . An open / close contact that opens and closes the electric circuit, a tripping device that opens the open / close contact, current detection means that detects a current of the electric circuit at a predetermined detection period, and an open / close contact that opens according to an overcurrent flowing through the electric circuit An overcurrent trip characteristic setting unit for setting an overcurrent trip characteristic; a control device that outputs a trip signal to the trip unit based on the overcurrent trip characteristic and a current detected by the current detection unit; and A maximum energization time storage unit for storing the maximum energization duration according to the detected current, and a square value of the detected current and the detection cycle when the detected current by the current detecting means exceeds the rated current of the circuit breaker Current product integrating means for calculating a current product and calculating the accumulated current value by accumulating the current product, and a thermal history corresponding to cooling from the accumulated current value when the detected current falls below the rated current. value Residual current product correcting means for subtracting, and load current time conversion means for calculating the load current energizing time by dividing the accumulated current value obtained from the current product integrating means or the residual current product correcting means by the square value of the detected current When, and a display means for displaying together the maximum load time characteristics and the overcurrent tripping characteristic comprising the maximum the maximum in accordance with the stored detected electric current to the conduction time storage unit of the energization duration, the maximum the energization time duration to be stored in the current time storage unit, an electronic circuit breaker, characterized in that said load current supply time computed by the load current timed conversion means. It has an energization time measuring unit that measures the energization duration according to the current detected by the current detection means, and the maximum energization duration stored in the maximum energization time storage unit is when the detected current exceeds the rated current of the circuit breaker The load current energization time obtained by the load current time conversion means is set as the maximum energization duration time by the energization time measuring unit when the detected current becomes equal to or less than the rated current. Electronic circuit breaker. A communication means for transmitting a maximum load time characteristic and an overcurrent trip characteristic composed of a maximum energization duration corresponding to a detected current stored in a maximum energization time storage unit to an external device is provided. The electronic circuit breaker according to any one of claims 1 to 3 .

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