CN101714749A - Electronic circuit breaker - Google Patents

Abstract

The present invention provides an electronic circuit breaker, capable of obtaining fluctuation status of a load current in an overcurrent area without an additional measuring device so as to set overcurrent tripping characteristics easily. The electronic circuit breaker comprises switch contact points used to switch on/off a circuit; a tripping device used to switch off the switch contact points; a current detection circuit used to detect the current of a circuit; a characteristics setting part used to set the overcurrent tripping characteristics for switching off the switch contact points corresponding to the overcurrent flowing across the circuit; and a control device used to output a tripping signal to the tripping device according to the overcurrent tripping characteristics and the detection current detected by the current detection circuit. The electronic circuit breaker also comprises a on-time measuring part used to time the on-time corresponding to the detection current; and a most on-time storage part used to store a most on-time measured by the on-time measuring part corresponding to the detection current.

Description

electronic circuit breaker

technical field

The invention relates to an electronic circuit breaker, which detects the load current flowing through the circuit, and performs disconnection protection for the circuit according to the time limit characteristic in the overcurrent region.

Background technique

Existing electronic circuit breakers can set the overcurrent tripping characteristics after setting the circuit breaker according to the connection status of the load equipment connected to the load side circuit and the usage status of the load equipment (for example, refer to Patent Document 1 figure 1).

Patent Document 1: JP-A-2001-128354

Contents of the invention

In the conventional electronic circuit breaker shown above, since the overcurrent trip characteristic can be set according to the usage status of the load equipment, it can be installed in the following circuit, that is, after installing the circuit breaker, it is expected that A circuit in which the load current fluctuates due to, for example, additional connection of load equipment or changes in the operating mode of the load equipment.

However, when multiple load devices such as motors are connected to the load side circuit, if they are operated simultaneously or delayed depending on the operation mode, the load current will fluctuate greatly instantaneously due to the starting current of the motor. To set the fluctuation state of the load current in the overcurrent region necessary for setting the overcurrent tripping characteristic, it is necessary to separately install a measuring device to measure the fluctuation state of the load current, and it becomes difficult to set the overcurrent tripping characteristic.

The present invention is proposed to solve the above problems, and its object is to provide an electronic circuit breaker that can grasp the fluctuation state of the load current in the overcurrent region without installing an additional measuring device, thereby easily setting overcurrent trip characteristic.

The electronic circuit breaker of the present invention has: a switch contact that turns on/off the circuit; a trip device that turns off the switch contact; a current detection unit that detects the current in the circuit; an overcurrent trip characteristic setting a part which sets an overcurrent tripping characteristic for opening the switch contact corresponding to an overcurrent flowing through the circuit; The device outputs a trip signal, and the electronic circuit breaker is characterized in that it has: an energization time measurement part, which counts the energization duration corresponding to the detection current; and a maximum energization time storage part, which stores The maximum energization duration measured corresponding to the detection current.

The effect of the invention

According to the present invention, by measuring the maximum energization duration measured corresponding to the load current flowing in the circuit, it is possible to grasp the fluctuation state of the load current in the overcurrent region, and it is possible to easily set the overcurrent trip characteristic .

Description of drawings

FIG. 1 is a block diagram showing the configuration of an electronic circuit breaker in Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of a method for obtaining an effective value of current by sampling in the electronic circuit breaker according to Embodiment 1 of the present invention.

3 is a diagram showing display contents displayed on a display unit of the electronic circuit breaker according to Embodiment 1 of the present invention.

Fig. 4 is a flowchart showing the operation of the electronic circuit breaker in Embodiment 1 of the present invention.

5 is a block diagram showing the configuration of an electronic circuit breaker in Embodiment 2 of the present invention.

6 is an explanatory diagram showing the relationship between the maximum load time limit characteristic and the overcurrent trip characteristic of the electronic circuit breaker according to Embodiment 2 of the present invention.

7 is a flowchart showing the operation of the electronic circuit breaker in Embodiment 2 of the present invention.

8 is a flowchart showing the operation of the electronic circuit breaker in Embodiment 3 of the present invention.

9 is an explanatory diagram of a method of obtaining an effective value of a load current by sampling in the electronic circuit breaker according to Embodiment 4 of the present invention.

10 is a flowchart showing the operation of the electronic circuit breaker in Embodiment 4 of the present invention.

Detailed ways

Embodiment 1

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

In FIG. 1, an electronic circuit breaker 100 is composed of the following components: a switch contact 2, which turns on/off an AC circuit 1; The current signal proportional to the load current of the AC circuit 1; the current detection circuit 4, which converts the current output signal of the converter 3 into an analog voltage signal; the A/D conversion circuit 5, which converts the analog voltage signal from the current detection circuit 4 The voltage signal is converted into a digital signal; the load current calculation part 6 calculates the current value flowing in each phase of the AC circuit 1 according to the digital signal from the A/D conversion circuit 5; the characteristic setting part 7 is set by The overcurrent tripping characteristic and the rated current constituted by the relationship between the tripping time and the load current value; the control device 8, which includes a microcomputer (CPU), according to the overcurrent tripping characteristic and the load set by the characteristic setting part 7 The current value calculated by the current calculation part 6 outputs an overcurrent trip signal; the trip circuit 9 disconnects the switch contact 2 according to the trip signal from the control device 8; the energization time measurement part 10 calculates the load current and the maximum energization time storage unit 11 stores the maximum energization duration measured by the energization time measurement unit 10 in correspondence with each load current value. time.

In addition, the control device 8 is connected with: a display unit 12, that is, a display unit, which, as shown in FIG. 3 , displays an overcurrent trip characteristic curve 20 and a maximum load time limit characteristic curve 21. The overcurrent tripping characteristic set by the characteristic setting part 7, the maximum load time limit characteristic curve 21 graphically shows the difference between the maximum energization duration stored in the maximum energization time storage part 11 and each load current value using, for example, a curve or the like. relationship, that is, the maximum load time limit characteristics; and the communication interface (communication I/F) 13, that is, a communication unit, which is used to display the data of the overcurrent trip characteristics and the maximum load time limit characteristics set by the characteristic setting part 7 to the outside, for example External devices such as devices send and receive settings for overcurrent tripping characteristics. The display unit 12 is constituted by, for example, a liquid crystal display device or the like.

The current detection circuit 4 is composed of the following components: a rectification circuit 4a, which converts the AC current output signal from the converter 3 into a DC signal; a load circuit 4b, which converts the output current signal of the rectification circuit 4a into a voltage signal; And a waveform conversion circuit 4c, which is used to obtain the effective value of the output voltage signal generated in the load circuit 4b. Furthermore, current detection means is constituted by the current detection circuit 4 , the current transformer 3 , and the A/D conversion circuit 5 .

In addition, a plurality of loads 14a, 14b such as motors and lamps are connected to the load side of the electronic circuit breaker 100 .

A calculation method of the load current by the load current calculation unit 6 will be described with reference to FIG. 2 . The detected current of the AC circuit 1 is converted from an analog value to a digital value by the A/D conversion circuit 5 . The detection period of the current signal, that is, the sampling period is Δt. Since it is necessary to obtain an effective value of the load current, the frequency of the AC power supply of the AC circuit 1 is, for example, 50 Hz for a period corresponding to 5 cycles, and for a period corresponding to 6 cycles in the case of 60 Hz, the number of samples is m. In the second-order moving average, I ² =(∑i ² )/m is obtained as the square value of the effective value of the sampling current. The square root of ^I2 is the effective value I of the load current.

The display on the display unit 12 is shown in FIG. 3 , with the horizontal axis being the load current value and the vertical axis being the operating time of the circuit breaker 100 , and the overtime value set by the characteristic setting unit 7 is displayed on the same display screen. A current tripping characteristic curve 20, and a maximum load time limit characteristic curve 21, which graphically shows data constituted by the maximum energization duration stored in the maximum energization time storage unit 11 relative to each load current value . When the load current value of the AC circuit 1 calculated by the load current calculation unit 6 exceeds the boundary line of the overcurrent trip characteristic 20 , a trip signal is output from the control device 8 to the trip circuit 9 to open the switch contact 2 .

In addition, as the display content, the numerical values of the maximum energization duration corresponding to each load current value of the maximum load time-limit characteristic 21 may be collectively displayed.

Next, the operation will be described.

According to the flowchart of FIG. 4 , the operation of the control device 8 will be mainly described. Since the energization time data T1 is present in the processing flow, the data T1 is cleared to zero in the initial processing (step 30). The load current value I1 is obtained by the load current calculation part 6 (step 31), and based on the load current value I1, the overcurrent trip time limit processing (step 32) is performed, and the overcurrent trip characteristic set by the characteristic setting part 7, For example, the overcurrent tripping characteristic 20 shown in FIG. 3 is compared (step 33), and when the load current value I1 exceeds the boundary line of the overcurrent tripping characteristic 20, and the overcurrent tripping operation is performed, the tripping circuit 9 is sent from the control device 8 A trip signal is output, and the circuit breaker is disconnected (step 42).

When the load current value I1 does not exceed the boundary line 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 does not change, the time elapsed time Δt from the previous calculation process of the load current calculation unit 6 to the current process is added to the energization duration T1, and the obtained time is defined as the energization time. Duration T1=T1+Δt, update the energization duration (step 35). When the load current value I1 has changed from the previous value, the energization duration T1 is set as the time elapsed amount Δt, and the energization duration is updated (step 36 ).

Then, the past maximum energization duration Tmax (I1) corresponding to the load current value I1 is read from the maximum energization time storage unit 11 (step 37), and the current energization duration T1 relative to the load current value I1 and the past The maximum energization duration Tmax (I1) is compared (step 38), 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), store the maximum energization duration Tmax(I1) corresponding to the load current value in the maximum energization time storage unit 11 (step 40). As the display data of the maximum load time-limit characteristic output to the display unit 12, the maximum energization duration value corresponding to 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. to display the maximum load time limit characteristic curve 21 (step 41). Then, calculation of a new load current value is performed (step 31).

According to this embodiment, since the maximum energization time storage unit 11 is provided for storing the maximum energization duration Tmax(I1) measured by the energization time measurement unit 10 corresponding to each load current value I1 flowing in the AC circuit 1, it is possible to The overcurrent tripping characteristic can be easily set by grasping the fluctuation state of the load current in the overcurrent region caused by the operation of a plurality of load devices connected to the AC circuit 1 , that is, the maximum load time limit characteristic.

In addition, since the maximum load time-limit characteristic curve 21 is displayed on the display unit 12 together with the overcurrent trip characteristic curve 20, the overcurrent trip characteristic can be set more easily.

In addition, since the communication interface 13 is provided for receiving/transmitting each data constituting the maximum load time limit characteristic and the overcurrent trip characteristic with an external device, the overcurrent trip characteristic can be easily set remotely.

In addition, in the present embodiment, the maximum energization duration corresponding to each load current value I1 is configured as the maximum load time-limit characteristic, but it may be configured such that each load current value is replaced by, for example, a value corresponding to the rated current of the circuit breaker. The percentage value of the load current value is divided into the range of greater than or equal to 100% and less than 200%, greater than or equal to 200% and less than 300%, so that it is composed of the range of each load current value and the corresponding maximum power-on duration The amount of data is reduced.

Embodiment 2

5 is a block diagram showing the configuration of the electronic circuit breaker 101 in Embodiment 2 of the present invention, and FIG. 6 is an explanatory diagram showing the relationship between the maximum load time limit characteristic and the overcurrent tripping characteristic of the electronic circuit breaker 101. 7 is a flowchart showing the operation of the electronic circuit breaker 101 .

In Embodiment 1, although the fluctuation of the load current value can be easily grasped, since the time-dependent calculation method of the actual overcurrent trip characteristic and the maximum load time limit characteristic is different, the overcurrent trip characteristic and the maximum load time limit There is a mismatch between features. In this embodiment, the thermal history is reflected in the maximum load time-limit characteristic, and as shown in FIG. 5 , the electronic circuit breaker 101 does not have the energization time measurement unit 10 . Since the other configurations are the same as those in Embodiment 1, description thereof will be omitted.

The overcurrent tripping characteristic of the electronic circuit breaker 101 is shown in FIG. 6 . According to the magnitude of the load current, each overcurrent tripping characteristic curve consists of a long time limit characteristic, a short time limit characteristic and an instantaneous characteristic. In this embodiment, the operation in the region of the long-term characteristic will be described in particular. The long-time characteristic is set in advance by the characteristic setting unit 7, for example, the long-time trip operation time Te is set as Te=K/Ie ² . Here, Ie is the load current value, Te is the long-term trip action time, and K is a constant. In addition, K is an area S0 of a rectangle surrounded by the line segment 0-Ie and the line segment 0-Te in FIG. 6 , that is, corresponds to S0=K=Te×Ie ² .

The operation of the electronic circuit breaker 101 is to compare the effective value Ie of the load current with a predetermined rated current I ₀ and determine whether or not Ie exceeds I ₀ . At this time, in order to simplify the processing, the square value Ie ² of the effective value of the load current may also be compared with the square value I ₀ ² of the rated current. When the effective value of the load current exceeds the rated current, the current accumulator unit multiplies the square value ^Ie2 of the effective value of the load current by the sampling period Δt to calculate the current product, and at the same time accumulates the current product to calculate the cumulative current value S1. The accumulated current value S1 is S1=Σ(Δt×Ie ² ). When the accumulated current value S1 exceeds the area S0, the electronic circuit breaker 101 performs a breaking operation.

When the effective value of the load current is less than or equal to the rated current, the thermal history Δt·P corresponding to cooling is subtracted from the accumulated current value S1 by the residual current correction unit. Here, P is a constant and is the heat dissipation coefficient per unit time.

Here, as the maximum load time limit characteristic, if the load current value Ie flows through the period of the continuous energization time T1, the cumulative current value S1 becomes the area of the rectangle surrounded by the line segment 0-Ie and the line segment 0-T1, which can be expressed as S1 =Ie ² ·T1.

In addition, when the load current value changes from Ie to I1, the accumulative current value S2 in the last calculation and the load current I1 detected this time are calculated according to S1=S2+Δt×I1 ² through the current accumulator unit. Calculate the accumulated current value S1. Then, the energization duration T2 of the load current I1 is calculated by the load current time limit conversion unit according to T2=S1/I1 ² , and when T2 is larger than the maximum energization duration corresponding to the past load current I1, as a new The maximum energization duration is stored in the maximum energization time storage section 11 . In addition, as the maximum load time-limit characteristic with respect to the load current I1, a characteristic matching the overcurrent tripping operation under the long-time 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 based on the flowchart of FIG. 7 . Since steps 30, 31, and 37 to 42 are the same as those in Embodiment 1, description thereof will be omitted. First, the load current I1 is obtained by the load current computing unit 6 (step 31), and is compared with the rated current _I0 to determine whether the load current value is in an overcurrent state (step 50).

When I1>I ₀ , that is, when the load current I1 exceeds the rated current I ₀ , it is treated as a long-term trip, and the current accumulator unit calculates the cumulative current value S1 according to S1=S2+(Δt×I1 ² ) (step 51), wherein the The accumulated current value S1 is obtained by integrating the current product over the elapsed time. Here, S2 is the accumulated current value S1 at the time of last calculation, and the initial value is zero.

Then, it is compared with a predetermined constant K (step 52). This constant K is calculated based on the set value of the long-time tripping characteristic set in advance by the characteristic setting part 7. In the case of S1>K, The electronic circuit breaker 101 performs a breaking action (step 42).

In the case of S1≤K, in order to convert the thermal history, that is, the accumulated current value S1 in the elapsed time, into the energization duration value T1 corresponding to the current load current value I1, transfer to the load current time limit conversion process, and the load current time limit The conversion unit calculates T1=S1/I1 ² to obtain the energization duration value T1 corresponding to the load current value I1 (step 53).

Then, the past maximum energization duration Tmax (I1) corresponding to the load current value I1 is read from the maximum energization time storage unit 11 (step 37), and the current energization duration T1 relative to the load current value I1 and the past The maximum energization duration 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), storing the maximum energization duration Tmax(I1) corresponding to the load current value I1 in the maximum energization time storage unit 11 (step 40).

Then, as display data for displaying the maximum load time-limit characteristic in the display unit 12, the maximum energization duration stored in the maximum energization time storage unit 11 relative to each load current value is read, and the load current value and its The maximum load time-limit characteristic 21 formed by the maximum energization duration is displayed on the display unit 12 (step 41). Then, calculation of a new load current value is performed (step 31).

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

In addition, it is judged whether the load current value is in an overcurrent state (step 50), and in the state of _I1≤I0 , that is, when the load current value I1 is less than or equal to the rated current _I0 , transfer to the residual current product correction process. As the residual current product correction processing, the heat dissipation correction value Δt P is calculated by the residual current product correction unit, which is proportional to the duration of the state in which the load current value I1 is smaller than the rated current _I0 from the previous processing, and since the past The heat dissipation correction value Δt·P is subtracted from the thermal history accumulated over the elapsed time of the overcurrent state exceeding the rated current, that is, the cumulative current value S2, to calculate the corrected cumulative current value S1 (step 54). In addition, P is a constant, which is the heat dissipation coefficient per unit time, and the residual current product correction process corresponds to the heat dissipation and cooling of the AC circuit 1 .

Determine whether the accumulated current value S1 is S1<0 (step 55), and if it becomes S1<0, initialize the current and previous accumulated current values, that is, set to S1=S2=0 (step 56) , transfer to load current time limit conversion processing (step 53). In the case of S1≧0, the process proceeds directly to the load current time limit conversion process (step 53).

According to this embodiment, since the maximum energization time storage unit 11 is provided for storing the maximum energization duration Tmax(I1) measured by the energization time measurement unit 10 corresponding to each load current value I1 flowing in the AC circuit 1, it is possible to The overcurrent tripping characteristic can be easily set because the maximum load time limit characteristic is grasped, which is the maximum load time limit characteristic, which is the variation state of the load current in the overcurrent region caused by the operation of a plurality of load devices connected to the AC circuit 1 .

In addition, by considering the thermal history in the calculation method of the maximum energization duration corresponding to each load current value of the maximum load time-limit characteristic, it is possible to obtain the electronic circuit breaker 101 matching with the overcurrent tripping operation including the thermal history. The maximum load time limit characteristic of 21 can accurately set the over-current tripping characteristic.

In addition, since the maximum load time-limit characteristic curve 21 is displayed on the display unit 12 together with the overcurrent trip characteristic curve 20, the overcurrent trip characteristic can be set more easily.

In addition, since the communication interface 13 is provided for receiving/transmitting each data constituting the maximum load time limit characteristic and the overcurrent trip characteristic with an external device, the overcurrent trip characteristic can be easily set remotely.

In addition, in this embodiment, only the case of the long-time characteristic is described, but for the case of the short-time characteristic and the instantaneous characteristic, the calculation method of the maximum energization duration of the maximum load time characteristic 21 and each overcurrent tripping process may be The method is the same.

In addition, it is configured to use the maximum energization duration corresponding to each load current value I1 as the maximum load time limit characteristic, but it may also be configured such that each load current value is replaced by, for example, a percentage value relative to the rated current of the circuit breaker. The load current value is divided into a range of greater than or equal to 100% and less than 200%, greater than or equal to 200% and less than 300%, so that the amount of data consisting of the range of each load current value and the maximum energization duration corresponding to it is reduced. .

Embodiment 3

FIG. 8 is a flowchart showing the operation of electronic circuit breaker 102 in Embodiment 3 of the present invention. The block diagram showing the structure of the electronic circuit breaker 102 is the same as that of FIG. 1 . In this embodiment, the energization time measuring unit 10 is added to the second embodiment, and when the load current value is less than or equal to the rated current, as in the first embodiment, when calculating the maximum energization duration of the maximum load time-limit characteristic Heat history is not reflected. The other configurations and operations are the same as those in Embodiment 2, so descriptions thereof are omitted.

Next, the operation will be described.

The operation of the control device 8 will be described based on the flowchart of FIG. 8 . Steps 30, 31, 37-56 are the same as those in the second embodiment. First, the load current I1 is obtained by the load current computing unit 6 (step 31), and is compared with the rated current _I0 to determine whether the load current value is in an overcurrent state (step 50).

When I1> _I0, that is, when the load current I1 exceeds the rated current _I0 , the overcurrent flag F is turned on (step 60). Then, as a long-term tripping process, the cumulative current value S1 is calculated by the current accumulator unit according to S1=S2+(Δt×I1 ² ) (step 51), wherein the cumulative current value S1 is the current product accumulated over the elapsed time and obtained. Here, S2 is the accumulated current value S1 at the time of last calculation, and the initial value is zero.

Then, it is compared with a predetermined constant K (step 52). This constant K is calculated based on the set value of the long-time tripping characteristic set in advance by the characteristic setting part 7. In the case of S1>K, The electronic circuit breaker 102 performs a breaking action (step 42).

In the case of S1<K, in order to convert the thermal history, that is, the cumulative current value S1 within the elapsed time, into the current-on duration value T1 corresponding to the current load current value I1, the load current time limit conversion unit calculates T1=S1/ I1 ² , obtain the energization duration value T1 corresponding to the load current value I1 (step 53).

Then, the past maximum energization duration Tmax (I1) corresponding to the load current value I1 is read from the maximum energization time storage unit 11 (step 37), and the current energization duration T1 relative to the load current value I1 and the past The maximum energization duration 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) corresponding to 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-limit characteristic on the display unit 12, the maximum energization duration corresponding to each load current value stored in the maximum energization time storage unit 11 is read, and the load current value and its maximum The maximum load time limit characteristic curve 21 is displayed on the display unit 12 for the energization duration (step 41). Then, calculation of a new load current value is performed (step 31).

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

In addition, it is judged whether the load current value is in an overcurrent state (step 50), and in the state of _I1≤I0 , that is, when the load current value I1 is less than or equal to the rated current _I0 , it is confirmed whether the overcurrent flag F is open (step 61) , when the overcurrent flag F is ON (F=1), the process proceeds to the residual current product correction process. When the overcurrent flag F is off (F=0), the residual current product correction process is not executed, and the process proceeds to the subsequent energization time counting process.

When the overcurrent flag F is ON (F=1), it transfers to residual current product correction processing. As the residual current product correction processing, the heat dissipation correction value Δt P is calculated by the residual current product correction unit, which is proportional to the duration of the state in which the load current value I1 is smaller than the rated current _I0 from the previous processing, and since the past The heat dissipation correction value Δt·P is subtracted from the thermal history accumulated over the elapsed time of the overcurrent state exceeding the rated current, that is, the cumulative current value S2, to calculate the corrected cumulative current value S1 (step 54). In addition, P is a constant, which is the heat dissipation coefficient per unit time, and the residual current product correction process corresponds to the heat dissipation and cooling of the AC circuit 1 .

When the accumulated current value S1 becomes S1<0, the current and previous accumulated current values are initialized, that is, set to S1=S2=0 (step 56), and the overcurrent flag F is turned off ( F=0), transfer to the timing process of the energization duration corresponding to the load current value less than or equal to the rated current value.

When the accumulated current value S1 is S1≧0, it proceeds directly to the counting process of the energization duration corresponding to the load current value less than or equal to the rated current value.

As the timing process of the energization duration corresponding to the load current value less than or equal to the rated current value, it is judged whether the load current value I1 is the same as the last load current value (step 34), and when the load current value I1 is the same, the energization The processing time elapsed amount Δt is added to the continuation time T1, and the obtained time is set as the current energization duration T1=T1+Δt, and the energization duration is updated (step 35). When the load current value I1 has changed from the previous value, the energization duration is set to time elapsed T1 = Δt, and the energization duration T1 is updated (step 36 ). Then, using the energization duration T1 for the load current value I1 calculated by this elapsed time update process, the maximum energization time calculation process for the load current value I1 is executed (steps 37 to 40), and the updated maximum load Time limit characteristic display processing (step 41).

According to this embodiment, since the maximum energization time storage unit 11 is provided for storing the maximum energization duration Tmax(I1) measured by the energization time measurement unit 10 corresponding to each load current value I1 flowing in the AC circuit 1, it is possible to The overcurrent tripping characteristic can be easily set because the maximum load time limit characteristic is grasped, which is the maximum load time limit characteristic, which is the variation state of the load current in the overcurrent region caused by the operation of a plurality of load devices connected to the AC circuit 1 .

In addition, by considering the thermal history in the calculation method of the maximum energization duration corresponding to each load current value in the maximum load time-limit characteristic, it is possible to obtain an overcurrent tripping action matching the electronic circuit breaker 102 including the thermal history. The maximum load time limit characteristics can accurately set the over-current tripping characteristics.

In addition, the processing of the control device 8 can be reduced by adopting a simple method in which the thermal history is not considered in the timing processing of the energization duration corresponding to the load current value equal to or less than the rated current value.

In addition, since the maximum load time-limit characteristic curve 21 is displayed on the display unit 12 together with the overcurrent trip characteristic curve 20, the overcurrent trip characteristic can be set more easily.

In addition, since the communication interface 13 is provided for receiving/transmitting each data constituting the maximum load time limit characteristic and the overcurrent trip characteristic with an external device, the overcurrent trip characteristic can be easily set remotely.

In addition, in this embodiment, only the case of the long-time characteristic is described, but for the case of the short-time characteristic and the instantaneous characteristic, the calculation method of the maximum energization duration of the maximum load time characteristic 21 and each overcurrent tripping process may be The method is the same.

In addition, it is configured to use the maximum energization duration corresponding to each load current value I1 as the maximum load time limit characteristic, but it may also be configured such that each load current value is replaced by, for example, a percentage value relative to the rated current of the circuit breaker. The load current value is divided into a range of greater than or equal to 100% and less than 200%, greater than or equal to 200% and less than 300%, so that the amount of data consisting of the range of each load current value and the maximum energization duration corresponding to it is reduced. .

Embodiment 4

9 is an explanatory diagram showing a method of obtaining an effective value of a load current by sampling in electronic circuit breaker 103 according to Embodiment 4 of the present invention, and FIG. 10 is a flowchart showing operations of electronic circuit breaker 103 . The block diagram showing the structure of the electronic circuit breaker 103 is the same as that of FIG. 1 .

In Embodiment 3, the calculation of the load current value I1 and the energization duration corresponding to the load current value I1 is performed every detection sampling period Δt of the current signal, but in this embodiment, as shown in FIG. 9 , every AC circuit The common multiple ΔT of the cycles of 50 Hz and 60 Hz, which is the AC power frequency of 1, is used to calculate the load current value I1 and the energization duration corresponding to the load current value I1 . Since the other configurations are the same as those in Embodiment 3, description thereof will be omitted.

Next, the operation will be described.

The operation of the control device 8 will be described based on the flowchart of FIG. 10 . This processing is not performed every sampling period Δt of the current signal, but every common multiple ΔT of the AC power frequency of the AC circuit 1, that is, the cycle of 50Hz and 60Hz, so the current accumulator unit compares with the elapsed time ΔT The current product corresponding to the period is accumulated to become Σ(Δt·I1 ² ), and the accumulated current value S1 is calculated from S1=S2+Σ(Δt·I1 ² ) (step 51a).

In addition, since the residual current product correction process also uses the residual current product correction unit to accumulate the duration of the load current value I1 being less than the rated current _I0 from the previous process, that is, the ΔT period, the heat dissipation correction value becomes Σ(Δt·P) Then, the heat dissipation correction value Σ(Δt·P) is subtracted from the cumulative current value S2 of the previous thermal history to calculate the corrected cumulative current value S1 (step 54a).

In the same manner as in the timing process of the energization duration corresponding to the load current value less than or equal to the rated current value, it is judged whether the load current value I1 is the same as the previous load current value (step 34), and when the load current value I1 is the same, The processing time elapsed amount ΔT is added to the energization duration (T1), and the obtained time is used as the current energization duration (T1=T1+ΔT), and the energization duration is updated (step 35a). When the load current value I1 has changed from the previous value, the energization duration T1 is updated by setting the energization duration as the elapsed time T1=ΔT (step 36 a ). Since other operations are the same as those in Embodiment 3, description thereof will be omitted.

According to this embodiment, since the maximum energization time storage unit 11 is provided for storing the maximum energization duration Tmax(I1) measured by the energization time measurement unit 10 corresponding to each load current value I1 flowing in the AC circuit 1, it is possible to The overcurrent tripping characteristic can be easily set because the maximum load time limit characteristic is grasped, which is the maximum load time limit characteristic, which is the variation state of the load current in the overcurrent region caused by the operation of a plurality of load devices connected to the AC circuit 1 .

In addition, by considering the thermal history in the calculation method of the maximum energization duration corresponding to each load current value of the maximum load time-limit characteristic, it is possible to obtain an overcurrent tripping action matching the electronic circuit breaker 103 including the thermal history. The maximum load time limit characteristic of 21 can accurately set the over-current tripping characteristic.

In addition, the processing of the control device 8 can be reduced by adopting a simple method in which the thermal history is not considered in the timing processing of the energization duration corresponding to the load current value equal to or less than the rated current value.

In addition, since the calculation of the load current value I1 and the energization duration corresponding to the load current value I1 is performed every common multiple ΔT of the AC power frequency of the AC circuit 1, that is, the cycle of 50 Hz and 60 Hz, the processing of the control device 8 can be further reduced. .

In addition, since the maximum load time-limit characteristic curve 21 is displayed on the display unit 12 together with the overcurrent trip characteristic curve 20, the overcurrent trip characteristic can be set more easily.

In addition, since the communication interface 13 is provided for receiving/transmitting each data constituting the maximum load time limit characteristic and the overcurrent trip characteristic with an external device, the overcurrent trip characteristic can be easily set remotely.

In addition, in this embodiment, only the case of the long-time characteristic is described, but for the case of the short-time characteristic and the instantaneous characteristic, the calculation method of the maximum energization duration of the maximum load time characteristic 21 and each overcurrent tripping process may be The method is the same.

In addition, it is configured to use the maximum energization duration corresponding to each load current value I1 as the maximum load time limit characteristic, but it may also be configured such that each load current value is replaced by, for example, a percentage value relative to the rated current of the circuit breaker. The load current value is divided into a range of greater than or equal to 100% and less than 200%, greater than or equal to 200% and less than 300%, so that the amount of data consisting of the range of each load current value and the maximum energization duration corresponding to it is reduced. .

Claims (6)

1. An electronic circuit breaker, which has: a switch contact, which makes the circuit on/off; a tripping device, which makes the switch contact open; a current detection unit, which detects the current in the circuit; a current trip characteristic setting section that sets an overcurrent trip characteristic for opening the switch contact corresponding to an overcurrent flowing through the circuit; and a control device based on the overcurrent trip characteristic and by The detection current detected by the current detection unit outputs a trip signal to the trip device, Its characteristics are that it has: An energization time measurement unit that counts an energization duration corresponding to the detected current; and a maximum energization time storage unit that stores the maximum energization duration measured by the energization time measurement unit corresponding to the detection current. 2. An electronic circuit breaker comprising: a switch contact that turns on/off a circuit; a tripping device that turns off the switch contact; a current detection unit that detects the circuit at a prescribed detection cycle the current in the circuit; an overcurrent trip characteristic setting section that sets an overcurrent trip characteristic for opening a switch contact corresponding to an overcurrent flowing through the circuit; and a control device that trips based on the overcurrent characteristics and the detection current detected by the current detection unit, outputting a trip signal to the trip device, Its characteristics are that it has: a maximum energization time storage unit that stores a maximum energization duration corresponding to the detected current; a current accumulator unit that calculates the detected current when the detected current detected by the current detection unit exceeds the rated current of the circuit breaker; The square value of the square value and the current product between the detection periods, and at the same time, the cumulative current value is calculated by accumulating the current product; the residual current product correction unit, which is when the detection current is less than or equal to the rated current , subtracting a thermal history value equivalent to cooling from the accumulated current value; and a load current time limit conversion unit that divides the accumulated current value obtained from the current accumulation meter unit or the residual current product correction unit by the accumulated current value The square value of the detected current is used to calculate the load current energization time, The energization duration stored in the maximum energization time storage unit is the load current energization time calculated by the load current time limit conversion unit. 3. The electronic circuit breaker of claim 2, wherein: having an energization time measuring section that counts an energization duration corresponding to the detection current detected by the current detection unit, The maximum energization duration stored in the maximum energization time storage unit is the load current energization time obtained by the load current time limit conversion unit when the detected current exceeds the rated current of the circuit breaker; When the above-mentioned rated current is used, it is the maximum energization duration measured by the energization time measurement unit. 4. The electronic circuit breaker according to any one of claims 1 to 3, characterized in that, A display unit is provided for displaying a maximum load time limit characteristic consisting of a maximum energization duration corresponding to a detected current stored in a maximum energization time storage unit together with an overcurrent trip characteristic. 5. The electronic circuit breaker according to any one of claims 1 to 3, characterized in that, A communication unit is provided for transmitting a maximum load time characteristic consisting of a maximum energization duration corresponding to a detected current stored in a maximum energization time storage unit to an external device, and an overcurrent trip characteristic. 6. The electronic circuit breaker of claim 4, wherein: A communication unit is provided for transmitting a maximum load time characteristic consisting of a maximum energization duration corresponding to a detected current stored in a maximum energization time storage unit to an external device, and an overcurrent trip characteristic.

Images