Detailed Description
Next, an embodiment of an electronic circuit breaker according to the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts.
Embodiment 1.
Fig. 1 is a block diagram showing an electronic circuit breaker according to embodiment 1 of the present invention, fig. 2 is a functional block diagram showing a function of a microcomputer in the electronic circuit breaker shown in fig. 1, fig. 3 is an explanatory diagram showing a method for obtaining an effective value of a sampled current, fig. 4 is a flowchart showing a process of the microcomputer, fig. 5 is an explanatory diagram showing a method for transmitting a remaining time in a higher-level remaining time input circuit and a remaining time output circuit shown in fig. 1, (a) a method based on a pulse width, (b) a method based on an analog voltage, and (c) a method based on a frequency of pulses.
As shown in fig. 1, the electronic circuit breaker 100 in the present embodiment is constituted by: an opening/closing contact 2 inserted into the ac circuit 1 to open/close the ac circuit 1; a current detector 3 provided in the ac circuit 1 and outputting a detection current proportional to a load current flowing in the ac circuit 1; a rectifying circuit 4 connected to the secondary side of the current detector 3 for rectifying the detection current; a power supply circuit 5 that outputs a constant voltage to be used for operating an electronic circuit in the electronic circuit breaker by the current output from the rectifier circuit 4; a waveform conversion circuit 6 connected to the output side of the rectifier circuit 4, for converting the detected current of the current detector 3 into an analog voltage signal; a microcomputer 10 (hereinafter referred to as microcomputer 10) as a control device that performs a process of trip characteristics based on the analog voltage signal of the waveform conversion circuit 6; and a trip circuit 7 for driving the trip device 8 by each trip signal from the microcomputer 10 to separate the opening and closing contacts 2.
The microcomputer 10 is constituted by: CPU (central processing unit) 11, ROM (read-only memory) 12 and RAM (random access memory), which constitute a microcomputer; an a/D (Analog to digital) conversion circuit 14 that converts the analog voltage signal of the waveform conversion circuit 6 into a digital signal; a higher-level remaining time input circuit 15 connected to an electronic circuit breaker provided on the upper side of the distribution line, the higher-level remaining time being input from the upper-level electronic circuit breaker; a remaining time output circuit 16 for outputting a remaining time until a trip signal described in detail later is output to an electronic circuit breaker provided on a lower side of the distribution line; and a trip output port 17 for driving the trip circuit 7 based on an output of the trip signal from the trip determination unit 18 d.
Next, a functional module to be processed by software of the microcomputer 10 will be described.
As shown in fig. 2, the software process 18 by the CPU 11 of the microcomputer 10 is constituted by: an effective value calculation unit 18a that calculates an effective value of the current flowing through the ac circuit 1 based on the digital signal output from the a/D conversion circuit 14; an LTD time limit characteristic calculation unit 18b that performs time limit characteristic processing based on the effective value of the current calculated by the effective value calculation unit 18a, and calculates an accumulated current value LTD; a remaining time calculation unit 18c that calculates a remaining time until the trip signal is output, based on the accumulated current value LTD acquired from the LTD time limit characteristic calculation unit 18 b; and a trip determination unit 18d for determining the remaining time R from the remaining time calculation unit 18c based on the accumulated current value LTD obtained from the LTD time limit characteristic calculation unit 18b 1 And the upper remaining time R obtained from the upper remaining time input circuit 15 2 An instruction to separate the opening/closing contact 2 is sent to the trip output port 17.
Next, the processing of the effective value calculation unit 18a in the microcomputer 10 will be described.
First, a method for calculating the effective value of the load current will be described with reference to fig. 3. The detected current of the ac circuit 1 detected by the current detector 3 is converted into an analog voltage signal based on the detected current by the waveform conversion circuit 6, and then converted from the analog voltage signal to a digital value by the a/D conversion circuit 14. The detection period of the detection current, that is, the sampling period is Δt. Since the effective value calculation unit 18a needs to obtain the effective value of the load current flowing through the ac circuit 1, the effective value I calculated by moving the square of the sampled digital value, that is, dividing the square of the digital value by the accumulated number of samples m is obtained during 100msec corresponding to 5 cycles at 50Hz and 6 cycles at 60Hz, for example, in the ac power supply frequency of the ac circuit 1 2 =(Σi 2 ) And/m. Furthermore, effective value I 2 For example, the calculation is performed with a calculation cycle Δt of 10msec to 25 msec. In addition, in practice, the effective value I 2 Is the effective value of the load current, but here I will be 2 Called the effective value, and is processed.
Next, the processing of the LTD time limit characteristic calculation unit 18b, the remaining time calculation unit 18c, and the trip determination unit 18d will be described.
As shown in fig. 4, if the microcomputer 10 is started up by the power supply from the power supply circuit 5, first, in step S101, the effective value I is performed 2 The operation of (2) proceeds to step S102. The process of step S101 is performed by the effective value calculation unit 18 a.
In step S102, the effective value I calculated in step S101 is determined 2 Whether or not it is greater than the 1 st prescribed value, e.g. rated current set value I 0 2 At the effective value I 2 If the value is greater than the 1 st prescribed value, the process proceeds to step S103, and the effective value I is 2 If the value is less than or equal to the 1 st predetermined value, the process proceeds to step S104.
In step S103, the effective value I 2 Is greater than rated current set value I 0 2 Therefore, the addition processing of the accumulated current value LTD is performed according to the formula (1), and the flow advances to step S105.
LTD = previous timeLTD+(ΔT×I 2 )···(1)
In step S104, the effective value I 2 Since the value is less than or equal to the 1 st predetermined value, the subtraction processing of the accumulated current value LTD is performed according to the equation (2), and the process returns to step S101.
Ltd=previous value of LTD- Δt× (I 0 2 -I 2 )···(2)
Further, Δt is the effective value I calculated in the effective value calculating unit 18a as described above 2 Since the calculation period of (a) is usually a fixed value, it can be handled as Δt=1 in software to simplify the calculation.
In step S105, it is the effective value I 2 Since the integrated current value LTD reaches the trip threshold K in a state of being larger than the 1 st predetermined value, the remaining time R, which is the time until the electronic circuit breaker 100 is opened, is performed 1 Is calculated in step S106.
As the remaining time R 1 In a specific example of the calculation method of (a), the calculation formulas shown in the formulas (3), (4) and (5) are considered.
R 1 =K/I 2 -ΣΔT···(3)
R 1 =(K-LTD)/I 2 ···(4)
R 1 =K-LTD···(5)
Here, ΣΔt of equation (3) shows the effective value I 2 Is greater than rated current set value I 0 2 Is a time for the state of the (c) to continue.
In step S106, the remaining time R calculated in step S105 is used 1 The remaining time output circuit 16 outputs the remaining time, and the process advances to step S107.
In step S107, a determination is made as to whether or not the integrated current value LTD is greater than or equal to the trip threshold K. When the accumulated current value LTD is equal to or greater than the trip threshold K, the open/close contact 2 should be immediately opened, and the flow of the process proceeds to step S109, in which the trip output port 17 is set to the H level, and the trip circuit 7 is driven to operate the trip device 8, so that the open/close contact 2 is separated, and the ac circuit 1 is opened.
On the other hand, in the case where the accumulated current value LTD is smaller than the trip threshold K, the flow advances to step S108.
In step S108, the remaining time R calculated in step S105 is determined 1 And (3) whether the operation is greater than the 2 nd prescribed value. At the remaining time R 1 If the remaining time R is greater than the predetermined value, the routine returns to step S101 1 If the value is less than or equal to the predetermined value, the process proceeds to step S110.
In step S110, the upper remaining time R, which is the remaining time of the upper electronic circuit breaker 200 input to the upper remaining time input circuit 15, is read 2 The process advances to step S111.
In step S111, the remaining time R is determined 1 Whether or not it is greater than or equal to the upper remaining time R 2 . At the remaining time R 1 Is greater than or equal to the upper residual time R 2 In the case of (a), the process proceeds to step S109, and the remaining time R is set 1 Less than the upper residual time R 2 In the case of (2), the process returns to step S101.
In step S108, the remaining time R is determined 1 The reason for whether the remaining time R is greater than the predetermined value is that only the remaining time R is passed 1 Whether or not it is greater than the upper residual time R 2 When it is determined that the breaking operation is performed, if the remaining time until the breaking operation is very long, for example, the remaining time R 1 10 minutes, upper residual time R 2 In the case of 11 minutes, the breaking operation may be performed.
Next, a method of transferring the remaining time between the upper electronic circuit breaker and the lower electronic circuit breaker, that is, details of the remaining time output circuit 16 and the upper remaining time input circuit 15 will be described with reference to fig. 5.
As a method for transmitting the remaining time, a method is conceivable in which an upper electronic circuit breaker and a lower electronic circuit breaker are connected by a signal line, and the remaining time is transmitted. Specifically, the method is a method of changing the pulse width corresponding to the remaining time from, for example, 0msec to 10msec as shown in fig. 5 (a), a method of changing the analog voltage signal from 0.5V to 5V according to the remaining time as shown in fig. 5 (b), a method of changing the frequency from, for example, 100Hz to 10kHz according to the remaining time as shown in fig. 5 (c), and the like.
Further, since the upper electronic circuit breaker and the lower electronic circuit breaker are connected by the ac circuit 1, a method of superimposing a pulse corresponding to the remaining time on the ac circuit 1, for example, changing the pulse width from 0msec to 10msec, is also conceivable.
According to the present embodiment, there is provided: an opening/closing contact 2 inserted into the ac circuit 1; a current detector 3 that detects a current flowing in the ac circuit 1; and a microcomputer 10 that detects an effective value of the detection current of the current detector 3 at a predetermined detection period, calculates an accumulated current value LTD obtained by accumulating a product of a square value of the effective value of the detection current and the detection period in a period in which the effective value of the detection current exceeds a 1 st predetermined value corresponding to the rated current, and separates the opening/closing contact 2 based on the accumulated current value, the microcomputer 10 including: a remaining time calculation unit for calculating a remaining time R from the detected current to the opening/closing contact 2 1 Calculating; a higher-level remaining time input circuit 15 connected to the other electronic circuit breaker and input the remaining time R of the other electronic circuit breaker 1 I.e. upper residual time R 2 The method comprises the steps of carrying out a first treatment on the surface of the And a trip determination unit 18d that is based on the remaining time R 1 Upper residual time R 2 And the accumulated current value LTD determines whether to separate the opening/closing contacts 2, the electronic circuit breaker 100 can perform the breaking operation earlier than the electronic circuit breaker 200 in the upper stage in the state where the overload state is detected.
When the effective value of the detected current exceeds the 1 st predetermined value, the trip determination unit 18d performs the remaining time R 1 And upper residual time R 2 In the remaining time R 1 Is greater than the upper residual time R 2 Since the opening/closing contact 2 is separated when the overload state is detected, the electronic circuit breaker 100 can be disconnected from the upper electronic circuitThe circuit breaker 200 performs the circuit breaking operation earlier.
The trip determination unit 18d determines the remaining time R 1 When the remaining time is greater than the 2 nd prescribed value, the remaining time R is performed 1 And upper residual time R 2 Therefore, if there is a sufficiently long time until the circuit is broken, the electronic circuit breaker 100 does not perform an unnecessary breaking operation.
The remaining time R calculated by the remaining time calculating unit 18c is provided 1 The remaining time output circuit 16 outputs the remaining time R of the electronic circuit breakers 301 and 302 which are lower than the remaining time R of the electronic circuit breakers 1 This can prevent the electronic circuit breakers 301 and 302 from performing a breaking operation before the electronic circuit breakers themselves.
Embodiment 2.
Next, an electronic circuit breaker 101 according to embodiment 2 of the present invention will be described.
Fig. 6 is a block diagram of the electronic circuit breaker according to embodiment 2, fig. 7 is a functional block diagram showing the function of the microcomputer in the electronic circuit breaker shown in fig. 6, and fig. 8 is a flowchart showing the processing of the microcomputer.
As shown in fig. 6 and 7, the remaining time output circuit 16 provided in embodiment 1 is omitted. Similarly, as shown in fig. 8, step S106 provided in embodiment 1 is deleted in the processing of the microcomputer. Since the other structures are the same as those of embodiment 1, the same reference numerals are given to the constituent elements having the same functions as those of embodiment 1, and the description thereof will be omitted.
According to the present embodiment, in the electronic circuit breaker connected to the lower side of the power supply system, there is a case where the circuit breaker is not present in the lower side than the electronic circuit breaker itself. In this case, since it is not necessary to output the remaining time to the lower electronic circuit breaker, the electronic circuit breaker having no remaining time output circuit as shown in the present embodiment is employed, and thus the cost of the circuit breaker system can be reduced.
In addition, the device comprises: the contact 2 is opened and closed,which is inserted into the ac circuit 1; a current detector 3 that detects a current flowing in the ac circuit 1; and a microcomputer 10 for detecting the detection current of the current detector 3 at a predetermined detection period, calculating an accumulated current value LTD obtained by accumulating the product of the detection period and the square value of the effective value of the detection current in a period in which the detection current exceeds a 1 st predetermined value corresponding to the rated current, and separating the opening/closing contact 2 based on the accumulated current value, the microcomputer 10 comprising: a remaining time calculation unit for calculating a remaining time R from the detected current to the opening/closing contact 2 1 Calculating; a higher-level remaining time input circuit 15 connected to the other electronic circuit breaker and input the remaining time R of the other electronic circuit breaker 1 I.e. upper residual time R 2 The method comprises the steps of carrying out a first treatment on the surface of the And a trip determination unit 18d that is based on the remaining time R 1 Upper residual time R 2 And the accumulated current value LTD, and determines whether to separate the opening/closing contacts 2, the electronic circuit breaker 101 can perform the breaking operation earlier than the electronic circuit breaker 200 in the upper stage in the state where the overload state is detected.
The trip determination unit 18d determines the remaining time R 1 When the remaining time is greater than the 2 nd prescribed value, the remaining time R is performed 1 And upper residual time R 2 Therefore, if there is a sufficiently long time until the circuit is broken, the electronic circuit breaker 101 does not perform an unnecessary breaking operation.
Embodiment 3.
Next, an electronic circuit breaker 102 according to embodiment 3 of the present invention will be described.
Fig. 9 is a block diagram of an electronic circuit breaker according to embodiment 3, fig. 10 is a functional block diagram showing the function of a microcomputer in the electronic circuit breaker shown in fig. 9, and fig. 11 is a flowchart showing the processing of the microcomputer.
In embodiment 1, the remaining time of the output to the lower electronic circuit breaker must be the remaining time of the lower electronic circuit breaker itself. In this case, if the remaining time of the circuit breaker itself is longer than the remaining time of the upper circuit breaker itself, the circuit breaker may trip earlier than the lower circuit breaker itself.
In this embodiment, the remaining time output circuit 16 in embodiment 1 is changed to a minimum remaining time output circuit, and the software process in embodiment 1 is also changed, and the present embodiment has a higher-level remaining time input circuit as in embodiment 1. The same reference numerals are given to the constituent elements having the same functions as those of embodiment 1, and description will be omitted, focusing on differences from embodiment 1.
In fig. 9, which is a block diagram of the electronic circuit breaker 102, the point of difference from fig. 1 of embodiment 1 is that the remaining time output circuit 16 of embodiment 1 is changed to the minimum remaining time output circuit 19. Other structures are the same as those in fig. 1 of embodiment 1, and therefore, description thereof is omitted.
In fig. 10, which is a functional block diagram showing the function of a microcomputer in the electronic circuit breaker 102, the difference from fig. 2 of embodiment 1 is that the output from the remaining time calculating unit 18c is from the remaining time R 1 Change to minimum remaining time R 3 . Other structures are the same as those of fig. 2 of embodiment 1, and therefore, description thereof is omitted.
The following describes modification contents of the software process.
In embodiment 1, the remaining time R until the disconnection calculated in step S105 shown in fig. 4 is set to 1 Directly from the remaining time output circuit 16 through the following step S106.
On the other hand, as shown in fig. 11, in the remaining time calculating section 18c of the present embodiment, the upper remaining time R is read from the upper remaining time input circuit 15 2 The self-calculated remaining time R 1 And upper residual time R 2 Comparing, and taking the smaller value as the minimum residual time R 3 Output from the minimum remaining time output circuit 19.
In the present embodiment, the minimum remaining time R is set to 3 The remaining time calculated by the remaining time calculating unit 18c is described, but the remaining time R may be 1 And upper residual time R 2 Is input to a minimum remaining time output circuit 19, and the remaining time R is output by the minimum remaining time output circuit 19 1 And upper residual time R 2 Comparing, and taking the smaller value as the minimum residual time R 3 Output from the minimum remaining time output circuit 19.
According to the present embodiment, the upper remaining time R is read from the upper remaining time input circuit 15 in the remaining time calculating unit 18c 2 The remaining time R calculated by the remaining time calculating unit 18c itself 1 And upper residual time R 2 Comparing, and taking the smaller value as the minimum residual time R 3 Output from the minimum remaining time output circuit 19, the electronic circuit breaker 102 is thus at its own remaining time R 1 The upper residual time R 2 In a long case, the electronic circuit breaker 301 or 302 located lower than the electronic circuit breaker itself can be prevented from tripping.
In addition, the device comprises: an opening/closing contact 2 inserted into the ac circuit 1; a current detector 3 that detects a current flowing in the ac circuit 1; and a microcomputer 10 for detecting the detection current of the current detector 3 at a predetermined detection period, calculating an accumulated current value LTD obtained by accumulating the product of the detection period and the square value of the effective value of the detection current in a period in which the detection current exceeds a 1 st predetermined value corresponding to the rated current, and separating the opening/closing contact 2 based on the accumulated current value, the microcomputer 10 comprising: a remaining time calculation unit for calculating a remaining time R from the detected current to the opening/closing contact 2 1 Calculating; a higher-level remaining time input circuit 15 connected to the other electronic circuit breaker and input the remaining time R of the other electronic circuit breaker 1 I.e. upper residual time R 2 The method comprises the steps of carrying out a first treatment on the surface of the And a trip determination unit 18d that is based on the remaining time R 1 Upper residual time R 2 And the accumulated current value LTD determines whether to separate the opening/closing contact 2, the electronic circuit breaker 102 can perform the breaking operation earlier than the electronic circuit breaker 200 in the upper stage in the state where the overload state is detectedAnd (3) doing so.
Description of the reference numerals
2 on-off contacts, 3 current detector, 4 rectifying circuit, 5 power supply circuit,
a waveform conversion circuit 6, a trip circuit 7, a trip device 8,
a microcomputer of 10 is provided, which is a microcomputer,
15 upper residual time input circuit, 16 residual time output circuit,
18c remaining time calculation section, 18d trip determination section,
100 electronic circuit breaker.