JPH1094159A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the setting of a rated current value, etc., without operating an adjuster lend. SOLUTION: Since this circuit breaker has a compulsive rating setter 30 which nullifies the set value by a property setter 19 and changes a rated current value automatically, an operator can perform the adjustment automatically even if he does not adjust the rating setter 19 each time, and the degree of freedom in setting a rated current can be raised by that amount. Moreover, because the rating compulsory setter 30 has a maximum rating setting button, it is selected to the maximum rated current, so the trip operation can be avoided, and for example, when a trip operation is to be avoided, it is convenient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker for protecting a main circuit when an overcurrent flowing in the main circuit is detected and the main circuit is cut off by a trip device.
The present invention relates to a circuit breaker suitable for controlling a trip device by a digital signal processing unit.

[0002]

2. Description of the Related Art Generally, in a circuit breaker 1 of this type, as shown in FIG. 7, a power supply terminal 4 and a load terminal 5 are provided inside a mold case 2 and a mold case 3. Is provided, and a main circuit contact 7 is provided for each phase at an intermediate position of the main circuit 6. The main circuit 6 is also provided with a current transformer (CT) 8, an overcurrent relay section 9, and a trip device 10. Reference numeral 11 denotes an arc extinguishing device.

[0003] Such a circuit breaker 1 is shown in FIG.
When the main circuit contact 7 is in a closed state as shown in FIG. 2 and an overcurrent flows in any one of the main circuits 6a to 6c of each phase, the overcurrent is passed through the current transformers 8a to 8c. Relay unit 9a
To 9c, the overcurrent relay units 9a to 9c instruct the trip device 10, and the trip device 10 opens the main circuit contacts 7a to 7c together, whereby the main circuit 6 of each phase is opened.
Block a to 6c. In this case, as shown in FIG. 9, the circuit breaker has a time limit characteristic Z in which the trip device does not operate at the rated current In and operates when a current larger than the rated current In flows. That is, the time limit characteristic Z is
Generally, when the overcurrent tripping current Ir exceeds the rated current In by a predetermined ratio, the long time limit operation a, the short time limit operation b, and the instantaneous operation c are respectively performed according to the magnitude of the load current.

In the prior art, a digital signal processing unit having a microcomputer is mounted on a circuit breaker.
Various proposals have been made to control the time limit characteristic by a digital signal processing unit.

For example, Japanese Patent Application Laid-Open No. Hei 5-236
633 (hereinafter, referred to as a first prior art) and JP-A-1-270722 (hereinafter, referred to as a second prior art).

In the first prior art, when an analog signal corresponding to a current value (or an average value) flowing through each phase of a main circuit is detected by a current detecting means, the signal is converted into a digital signal via an A / D converter. By being taken into the processing section, the digital signal processing section performs control based on the time limit characteristic. In this case, the digital signal processing unit controls the characteristics so that the degree of freedom in setting the timed operation characteristics can be increased in order to facilitate protection coordination.

On the other hand, in the second prior art, an analog signal corresponding to a current flowing through each phase of the main circuit is sampled,
When the sampled analog signal is taken into the digital signal processing unit via the A / D converter, the digital signal processing unit obtains, for example, an amount corresponding to the effective value of the current of each phase by digital calculation, The time limit characteristic is controlled based on the digital signal value.

Further, in the third prior art, as shown in FIG. 10, in addition to a digital signal processing section, a characteristic setting section 19 for adjusting a rated current and the like is provided, and an adjustment knob forming the characteristic setting section 19 is provided. To change the rated current value, or, as shown by the white arrow in FIG. 12, the overcurrent tripping current value A of the timed characteristic, the long timed operation region B, and the short timed operation region C. Can be changed.
In adjusting the characteristic setting section 19, usually, the adjustment knob is operated after grasping the total load current of the applied circuit.

FIG. 10 is basically similar in configuration to the second prior art. In FIG. 10, the main circuits 6a to 6a
c, the load current flowing through the current transformers 8a to 8c and the rectifier 12
a to 12c, burden circuits 13a to 13c, an amplifier 14, and a power supply circuit 20. When the analog signal is detected and amplified by an analog signal processing unit, the analog signal is converted to an A / D converter 16 of a digital signal processing unit 15. Is converted into a digital signal, and is taken into the microcomputer 17.

The microcomputer 17 controls the tripping operation of the tripping device 10 based on the received digital signal. At this time, when the tripping device 10 cuts off the main circuits 6a to 6c by detecting an overcurrent (tripping). Operation), the alarm display section 18 is operated by a command from the microcomputer 17 to display an alarm. On the other hand, when the setting value is adjusted by the characteristic setting unit 19, the microcomputer 17
Based on the set value, the rated current can be changed or the time limit characteristic of the trip device 10 can be adjusted.

[0011]

By the way, when a circuit breaker is installed, as shown in FIG. 11, in order to facilitate protection coordination between a higher-level device and a lower-level device, the thermal characteristic D of the higher-level device is reduced. A time limit characteristic Z which does not intersect with the operation characteristic E of the lower device and is located between the two characteristics D and E is employed.

In the first to third prior arts described above, since the time limit characteristic of the trip device 10 is controlled by using a microcomputer, accurate control can be performed and reliability can be improved. However, in the first prior art and the second prior art, since the characteristic setting unit is not provided, when the connection load connected to the main circuit increases or decreases, the rated current value and the time limit characteristic of the trip device are adjusted. There is a problem that is not considered.

On the other hand, the third prior art is provided with the characteristic setting section 19, so that the above problem can be solved. However, in the third prior art, the characteristic setting unit 19
By turning (or changing over) the adjustment knob, and selecting one of a finite number of characteristic values assigned to the adjustment knob, the time limit characteristic can be changed. The characteristic value scale provided on the container cover tends to be a coarse display due to the display space. For this reason, the difference between the desired set value and the actual set value is likely to be large, and it is difficult to confirm the setting accuracy. Therefore, there is a problem that the usability is not good.

In order to enhance the effectiveness of the adjustable function,
It is desirable that the adjustment range is not stepwise but continuously changed to finely adjust the set value of the rated current. For this reason, in some cases, a variable resistor is actually provided on the setting knob. However, such a device has a problem that the deviation between a desired setting value and an actual setting value is likely to be further increased, and it is difficult to cope with an increase or decrease in connection addition.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, it is an object of the present invention to easily set a rated current value and the like without operating the adjustment knob each time. It is to provide a circuit breaker which can be dealt with.

[0016]

According to the present invention, there is provided a main circuit contact for connecting a main circuit, a trip device for opening and closing the main circuit contact, and an analog signal processing for detecting a load current flowing in the main circuit as an analog signal. Unit, a digital signal processing unit that converts an analog signal from the analog signal processing into a digital signal, and controls a trip device based on the converted digital signal, and a rated current flowing in a main circuit and a trip device. A circuit breaker having a characteristic setting section for adjusting a time limit characteristic, wherein the function of the characteristic setting section is invalidated, and a rated compulsory setting section for automatically selecting a rated current and a time limit characteristic is provided. is there.

In the present invention, the rating compulsory setting unit obtains a rated current value based on at least a maximum rating setting means for selecting a preset maximum rated value and a magnitude of a load current flowing through the main circuit. Automatic rating setting means.

Further, in the present invention, in addition to the above-mentioned rated compulsory setting section, there is provided a compulsory setting state display section for displaying an operation state of the rated compulsory setting section. The content is displayed individually according to the setting means.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the circuit breaker according to the embodiment has main circuits 6a, 6b, 6c between power supply terminals 4a, 4b, 4c and load terminals 5a, 5b, 5c each having three phases.
Are provided, and are connected by main circuit contacts 7a, 7b, 7c. The main circuits 6a to 6c are provided with an analog signal processing unit including current transformers 8a to 8c, rectifier circuits 12a to 12c, burden circuits 13a to 13c, an amplifier circuit 14, and a power supply circuit 20. The load current flowing through the main circuits 6a to 6c of each phase is detected, amplified and output.

The burden circuits 13a to 13c convert full-wave rectified output signals output from the rectifier circuits 12a to 12c into analog voltage signals for each phase. The power supply circuit 20 outputs a positive voltage and a negative voltage to the burden circuits 13a to 13c and the rectifier circuits 12a to 12c.

The analog signal output from the amplifier circuit 14 is supplied to the A / D converter 16 of the digital signal processor 15.
The signals are converted into digital signals for each phase by a to 16c and taken into the microcomputer 17. The microcomputer 17 determines whether to operate the trip device 10 based on the magnitude of the received signal. In this case, when an overcurrent flows in any phase of the main circuits 3a to 3c, a command is issued to the trip device 10, and the trip device 10 closes both the main circuit contacts 7a to 7c, thereby causing a trip operation. In addition, as shown in FIG. 9, the time limit characteristic Z is controlled based on the magnitude of the load current. Then, at the time of this trip operation, the microcomputer 17 operates the alarm display unit 19.

Further, the microcomputer 17 has a characteristic setting section 19.
The rated current and the time limit characteristic of the circuit breaker can be changed based on the magnitude of the set value adjusted by the operation of the characteristic setting unit 19. The changed data is stored in a readable / writable memory (EEPROM) 21 and used as needed. Note that the characteristic setting unit 19
Is the mold cover 3 of the circuit breaker 1 as shown in FIG.
And a plurality of adjustment knobs, and an alarm display unit 18 is disposed near the adjustment knobs. In FIG. 1, I / O indicates an interface.

In the circuit breaker of the embodiment,
There is a rating compulsory setting unit 30 for invalidating the set value by the characteristic setting unit 19 and automatically changing the rated current value. That is, as shown in FIG.
Maximum rating setting button 31 and automatic rating setting button 32
And a forced setting release button 33. The maximum rating setting button 31 disables the function of the characteristic setting section 19,
A predetermined maximum rated current value is selected. Therefore, when the maximum rating setting button 31 is operated (turned on), the microcomputer 1
7 controls based on the maximum rated current value stored in the memory 21.

The automatic rating setting button 32 is operated (ON).
Then, similarly to the maximum rating setting button 31, the characteristic setting unit 1
9 is disabled, and the rated current is selected based on the magnitude of the load current flowing in the main circuits 6a to 6c at that time. In this case, at the time of selection, if the load current flowing at the time of operation is Io and the set rated current is In,
For example, the microcomputer 17 automatically calculates and calculates the rated current from the relationship of In = α · Io, and sets the calculated value. The value of α is (Io / 1.25) ≦ α <
(Io / 1.05). The present invention is not limited to this, and the rated current may be calculated and set based on the relationship of In = Io + β. In any case, the microcomputer 17 automatically obtains the rated current based on the current load current using the automatic rating setting button 32, and sets the obtained value as the rated current.

Further, the rating compulsory setting section 30 has a compulsory setting canceling button 33 for canceling the functions of the maximum rating setting button 31 and the automatic rating setting button 32 and utilizing the function of the characteristic setting section 19.

Returning to FIG. 1, the microcomputer 17 is connected to a forcible setting state display section 34, and a maximum rating setting button 31, an automatic rating setting button 32, and a forced setting release button 3
When any one of 3 is selected, the selected content is displayed. For example, the compulsory setting state display unit 3
4 is displayed in red when the maximum rating setting button 31 is operated, is displayed in green when the automatic rating setting button 32 is operated, and remains off when the forced setting release button 33 is operated. State and the selected button 31
Displayed according to the types of .about.33. The color display is controlled by the microcomputer 17 based on the data stored in the memory 21.

The data of the maximum rating setting button 31, the automatic rating setting button 32, the forced setting release button 33, and the data of the forced setting release button 33 by the rating compulsory setting section 30 are stored in the memory 21. Is written by the microcomputer 17 as needed.

Since the circuit breaker of the embodiment has the above-described configuration, the control operation of the microcomputer 17 will be described next with reference to FIGS.
This will be described with reference to FIG.

When power is supplied between the main circuits 6a to 6c by closing the main circuit contacts 7a to 7c, the microcomputer 17
First, it is checked whether the control parameters are in the normal setting state by the characteristic setting unit 19 (41). If the control parameters are in the normal setting state, the control parameters are read from the memory 21 (42), and the control parameters are Is displayed (43).

At this time, the microcomputer 17 checks whether or not it is in the command state by the rating compulsory setting unit 30 (in the case of the compulsory setting release command state) (44). The display of the section 34 is canceled (45), and it is checked whether or not the content of the characteristic setting section 19 and the content of the control parameter read out from the memory 21 match (46). And if they match,
The processing after B shown in FIG. 5 described later is executed, but if they do not match, the control parameters at that time are written into the memory 21 (47). In the process 44, if it is not in the forced setting release command state, the processes after A shown in FIG. 5 described later will be executed. That is, if the command is not in the forced setting release command state, the microcomputer 17 checks whether or not the command is in the maximum rated forced setting command state (51). At this time, it is checked whether or not the state is already in the maximum rating compulsory setting state (52).
If the maximum rating setting button 31 is already operated to enter the maximum rating compulsory setting state, the rated current is maximized based on this, and the time limit characteristic is controlled accordingly (5).
3), at the time when the maximum rating forced setting state has just been reached, the fact is displayed on the forced setting state display section 34 (56), and the maximum rating value is stored in the memory 21 as a selected new control parameter (57). .

In this case, it is checked whether or not the trip condition is satisfied (54). If the condition is satisfied, that is, if an overcurrent exceeding the maximum rated current value flows, the microcomputer 17 drives the trip device 10. , The main circuit contacts 7a to 7c trip. If the trip condition is not satisfied, the process 44 and subsequent steps are repeatedly executed as shown in FIG.

On the other hand, if it is not the maximum rating compulsory setting command state in the process 51, as shown by D in FIG.
It is checked whether or not the automatic rating setting button 32 has already been set to the automatic rating setting state (61), and if so, the processing after 53 is executed as shown by B in FIG. That is, the microcomputer 17 calculates the rated current I obtained in advance.
The time limit characteristic is controlled based on n, and a predetermined operation is performed according to the time limit characteristic (53 to 55). Further, when the microcomputer 17 has just entered the automatic rating setting state, the microcomputer 17 displays the automatic rating setting state on the compulsory setting state display unit 34 (62), and also obtains the load current Io from the predetermined relational expression. The rated current In is calculated and calculated based on the above, the calculated rated current value is stored in the memory 21 as a new control parameter, and the processes subsequent to 53 are executed in the same manner as described above. Therefore, in this case, the time limit characteristic is controlled based on the rated current In obtained by the calculation.

As described above, in this embodiment, apart from the normal rating setting section 19, the rating setting section 30 for invalidating the set value by the characteristic setting section 19 and automatically selecting the rated current value is provided. Therefore, it is possible to automatically adjust the rating setting section 19 without the operator having to adjust the rating setting section 19 one by one, thereby increasing the degree of freedom in setting the rated current.

Further, since the rating compulsory setting section 30 has a maximum rating setting button 31 and is selected with the maximum rating current, the possibility of trip operation can be avoided.
Usability is improved when it is not necessary to perform a trip operation. In addition, since the rating compulsory setting unit 30 has an automatic rating setting button 32, which obtains the rated current In based on the load current Io and controls the time limit characteristic based on this, as shown in FIG. Even if the load current is changed by increasing or decreasing the load 100N, it is not necessary to grasp the content in advance as in the related art, and it is possible to eliminate the trouble associated with the increase and decrease of the connection load 100N. In addition to this, it is also possible to prevent the connection load from burning, and the usability is further improved in this respect.

Further, the rating compulsory setting section 30 has a compulsory setting release button 33, and if necessary, a maximum rating setting button 3
1 and the automatic rating setting button 32 and the characteristic setting section 19 can be selectively used, so that the degree of freedom of usability is increased.

Further, the forced setting state display section 34 selectively displays the maximum rating setting state, the automatic rating setting state, and the contents according to the state in which these are released, so that the operator can select the current mode. Can be discriminated, and can be accurately displayed to the surroundings.

In the illustrated embodiment, the rating compulsory setting unit 30
As an example, the compulsory setting state display section 34 for displaying the contents of the above is configured to display each color by a light emitting diode, but the present invention is not limited to this, and a liquid crystal display can be used instead. In that case, the current rated current value can be displayed as it is, and the display can be further clarified. Further, in the illustrated embodiment, an example has been shown in which the microcomputer 17 performs an operation based on the coefficients α and β fixed in advance by the automatic rating setting button 32 of the rating compulsory setting unit 30. However, the count value is determined by means such as a switch. You may comprise so that adjustment to an arbitrary value is possible.

[0039]

As described above, claims 1 to 5 of the present invention.
According to No. 3, since the function of the characteristic setting unit is invalidated and a rating compulsory setting unit for automatically selecting the rated current and the time limit characteristic is provided, the operator does not need to adjust the rating setting unit each time. It can be adjusted automatically, which has the effect of increasing the degree of freedom in setting the rated current.

In particular, according to the second aspect, the rating compulsory setting unit includes at least a maximum rating setting means for selecting a preset maximum rating value, and a rated current based on the magnitude of the load current flowing through the main circuit. Automatic rating setting means for determining the value, and the maximum rating setting means is configured to avoid the risk of trip operation, so that it is easy to use when trip operation is not required, and Since the automatic time-limit characteristic is controlled by the rated current based on the load current by the automatic rating setting means,
Even if the load current changes due to an increase or decrease in the connection load, it can be easily dealt with, and the trouble associated with the increase or decrease in the connection load can be saved, and the connection load can be prevented from burning. There is an effect that can be.

According to a third aspect of the present invention, there is provided a forced setting state display section for displaying an operation state of the rated forced setting section, in addition to the rated forced setting section, wherein the forced setting state display section includes a maximum rating setting means. And the automatic rating setting means are selectively displayed, so that the operator can discriminate the current mode, and there is an effect that the display can be accurately displayed to the surroundings.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a circuit breaker of the present invention.

FIG. 2 is an enlarged view showing a main part of the circuit breaker as viewed from above.

FIG. 3 is an explanatory diagram showing an increase / decrease state of a connection load.

FIG. 4 is a flowchart in the case of a mode by a characteristic setting unit showing control contents of a digital signal processing unit.

FIG. 5 is a flowchart in the case of a mode using a rating compulsory setting button showing control contents.

FIG. 6 is a flowchart in the case of a mode using an automatic rating setting button similarly showing control contents.

FIG. 7 is a schematic sectional view showing a general circuit breaker.

FIG. 8 is a circuit diagram of the circuit breaker of FIG. 7;

FIG. 9 is an explanatory diagram showing a time limit characteristic of the trip device.

FIG. 10 is a circuit diagram showing a schematic configuration of a third conventional technique.

FIG. 11 is an explanatory diagram showing a time limit characteristic in a relationship between a thermal characteristic of a higher-level device and an operation characteristic of a lower-level device.

FIG. 12 is an explanatory diagram showing adjustment of an overcurrent trip current, a long time limit operation characteristic, and a short time limit operation characteristic in a time limit characteristic.

[Explanation of symbols]

1: Circuit breaker, 6, 6a to 6c: Main circuit, 7, 7a to
7c: Main circuit contact, 10: Tripping device, 8, 8a to 8
c: current transformer, 12a to 12c: rectifier circuit, 13a to 13
c: burden circuit, 14: amplifier circuit, 15: digital signal processing circuit, 16: A / D converter, 17: microcomputer, 18: alarm display section, 19: characteristic setting section, 20: power supply circuit, 30: rating Force setting section, 31: Maximum rating setting button, 32: Automatic rating setting button, 34: Force setting state display section.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Yokoyama 46-1, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Industrial Equipment Division, Hitachi, Ltd. (72) Kazuya Aihara 46, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata 1 Industrial equipment division of Hitachi, Ltd.

Claims (3)

[Claims] 1. A main circuit contact for connecting a main circuit, a trip device for opening and closing the main circuit contact, an analog signal processing unit for detecting a load current flowing in the main circuit as an analog signal, A digital signal processing unit that converts an analog signal of the above into a digital signal and controls a trip device based on the converted digital signal, and a characteristic setting unit that adjusts a rated current flowing in a main circuit and a time limit characteristic of the trip device. A circuit breaker comprising: a rating compulsory setting unit that invalidates a function of the characteristic setting unit and automatically selects a rated current and a time limit characteristic. 2. A main circuit contact for connecting a main circuit, a trip device for opening and closing the main circuit contact, an analog signal processing unit for detecting a load current flowing in the main circuit as an analog signal, and A digital signal processing unit that converts an analog signal of the above into a digital signal and controls a trip device based on the converted digital signal, and a characteristic setting unit that adjusts a rated current flowing in a main circuit and a time limit characteristic of the trip device. In the circuit breaker having the above, having a rating compulsory setting unit that invalidates the function of the characteristic setting unit and automatically selects the rated current and the time limit characteristic, and the rated compulsory setting unit is at least set in advance. Maximum rating setting means for selecting the maximum rated value provided, and automatic rating setting means for obtaining the rated current value based on the magnitude of the load current flowing in the main circuit. A circuit breaker characterized by the above. 3. A main circuit contact for connecting a main circuit, a trip device for opening and closing the main circuit contact, an analog signal processing unit for detecting a load current flowing through the main circuit as an analog signal, and A digital signal processing unit that converts the analog signal of the above into a digital signal and controls the trip device based on the converted digital signal; and a characteristic setting unit that adjusts the rated current flowing in the main circuit and the time limit characteristic of the trip device. In the circuit breaker having the above, the function of the characteristic setting section is invalidated, and a rated compulsory setting section for automatically selecting the rated current and the time limit characteristic, and a compulsory setting state display for displaying an operation state of the rated compulsory setting section. And the rated compulsory setting unit includes at least a maximum rating setting means for selecting a preset maximum rated value, and a magnitude of a load current flowing through the main circuit. Automatic rating setting means for obtaining a rated current value based on the current value, and the forced setting state display section selectively displays contents according to the maximum rating setting means and the automatic rating setting means. vessel.