JP2002140974A - Circuit breaker and circuit breaking system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To count number of opening and closing times considering contact ablation due to applied current of the circuit breaker, and to alarm and indicate a service life of an opening/closing part when the count reaches a defined num ber. SOLUTION: Number M of opening and closing times until now is read out (41), the present contact output state (ON or OFF) is detected and the state is set as a previous value S1 (42), the present contact output state is detected at a predetermined interval and the state is set as a present value S2 (43). When the previous value is different from the present value (44) and it is contact OFF (break) (51), the number is corrected by a break current (52 and 53) and is counted (54). When the contact is not OFF but ON (51), the number is counted (45), and, when the counted number M reaches the defined number N (46), an alarm is outputted (47). When the number is smaller than the defined number, the present value S2 is set to the previous value S1 (48), and the operation is repeated from the step 43 until the counted number reaches the defined number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker and a circuit breaker system for detecting and protecting an electric circuit by detecting electric current in the electric circuit. When such a state as the opening / closing life occurs, this state is detected.

[0002]

2. Description of the Related Art FIG.
FIG. 8 is a block diagram of a conventional circuit breaker with an opening / closing number display device shown in Japanese Unexamined Patent Application Publication No. H11-209, and FIG. In the figure, 102 is a wiring circuit, 101 is a switching contact, 104 is a thermal trip element, 1
Reference numeral 05 denotes an electromagnetic counter, and reference numeral 106 denotes a visual display unit of the electromagnetic counter 105.

The operation will be described. When the load current flowing through the wiring circuit 102 exceeds the specified current and the current supply time reaches the specified time, the thermal type tripping element 104 operates to open the switching contact 101. The operation of the open / close contact 101 is mechanically detected and output as a contact, and the contact signal is input to the electromagnetic counter 105 to count the number of open / close operations and display it on the visual display unit 106.

[0004]

In the above system, the electromagnetic counter 105 is installed on the circuit breaker.
It was necessary to periodically go to the place where the circuit breaker was installed, visually check and record the number of times of opening and closing, and determine whether the life of the circuit breaker had been reached. In addition, the switching life is affected by the wear of the switching contacts due to the current at the time of interruption.However, in the above method, the current value at the time of interruption is unknown, so that the state of consumption of the contacts cannot be determined, and there is a problem that an accurate life cannot be determined. Was.
Further, when the switching life suddenly came to an end due to welding or the like due to excessive current, this could not be detected.

The present invention has been made to solve the above-described problem, and has as its object to provide a circuit breaker that predicts the switching life according to the number of times the circuit breaker is opened and closed. Further, the present invention provides a circuit breaker that corrects the number of times of opening and closing according to a current value at the time of opening to predict an accurate switching life. Further, there is provided a circuit breaker capable of detecting when the switching life is suddenly reached due to contact welding or the like, and a circuit breaker system for preventing an accident using the circuit breaker.

[0006]

According to a first aspect of the present invention, there is provided a circuit breaker for opening and closing a switching contact according to a current flowing through an electric circuit to be interrupted to open and close the electric circuit. , A counting means for counting and accumulating the number of times of opening and closing or the number of times of opening and closing of the on-off contact, and a notifying means for notifying according to the accumulated number of times.

(2) A circuit breaker according to a second aspect of the present invention is a circuit breaker that opens and closes an open / close contact by driving an open / close contact according to a current flowing through an electric circuit to be interrupted.
Means for counting the number of times of opening and closing of the on / off contact, correcting the number of times of opening in accordance with the magnitude of current at the time of the opening operation, and counting the number of times of closing of the on / off contact; The number of opening and closing times is added by adding the corrected number of opening times to the number of opening and closing times, and a means for accumulating the number of opening and closing times and a notifying means for notifying according to the magnitude of the accumulated number of times are provided.

(3) A circuit breaker according to a third aspect of the present invention is a circuit breaker which opens and closes the electric circuit by driving an open / close contact in response to a current flowing through an electric circuit to be interrupted.
Means for counting the number of times of opening and closing of the on / off contact, correcting and accumulating the number of times of opening in accordance with the magnitude of current at the time of the opening operation of the on / off contact, and reporting in accordance with the magnitude of the accumulated number of times. It is provided with a notifying means.

(4) A circuit breaker according to a fourth aspect of the present invention is the circuit breaker according to any one of the first to third aspects, wherein a communication interface for transmitting the cumulative number of times of switching, a notification output, and the like, and a circuit. An indicator for displaying the output of the communication interface is provided near the circuit breaker housing.

(5) A circuit breaker according to a fifth aspect of the present invention is a circuit breaker which opens and closes the electric circuit by driving an open / close contact in accordance with a current flowing through an electric circuit to be interrupted.
There is provided means for detecting an open / closed state of the on / off contact after the output of the cutoff signal, and determining whether or not the on / off contact is in a non-open state in accordance with the detected on / off state.

(6) According to a sixth aspect of the present invention, there is provided a circuit breaker according to the fifth aspect, and power supply to an input side electric circuit of the circuit breaker when the circuit breaker determines that the circuit breaker is not opened. And means for shutting off.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram of an overcurrent detection device for an electronic circuit breaker according to Embodiment 1 of the present invention. FIG. 2 is a flowchart of the opening / closing frequency integration and alarm processing. In FIG. 1, reference numeral 1 denotes a wiring circuit (a single-phase example is shown, but a multi-phase circuit may be used); 2, a switching contact; 3, a current transformer that detects a current flowing through the wiring circuit 1;
Reference numeral 4 denotes a current detection circuit, a rectifier circuit 4a for converting a secondary output of the current transformer 3 into a DC voltage signal, and an instantaneous trip of the rectified current value to the trip circuit 13, and smoothing of the rectified current to obtain a voltage. Circuit 4b as an output signal of the first circuit and a waveform conversion circuit 4c for obtaining the effective value of the output signal of the burden circuit 4b
Consists of

Reference numeral 5 denotes an A / D conversion circuit for converting the analog output of the current detection circuit 4 into a digital signal, and reference numeral 6 denotes a control unit which outputs a cutoff signal by an operation described later, and includes a microcomputer. Reference numeral 7 denotes an output circuit that outputs a signal for opening the switching contact 2 in response to a cutoff signal from the control unit 6. Reference numeral 8 denotes an electromagnetic device for converting a signal from the output circuit 7 into a mechanical signal, for example, an electromagnetic coil. A setting unit 9 sets an overcurrent tripping characteristic and sets a threshold value of the number of times of opening and closing, which is a basis of an alarm output.

Reference numeral 10 denotes an open / close detection device that detects an open / closed state (on / off state) in conjunction with the open / close contact 2 and outputs a contact to the control unit 6. For example, a movable contact having an opening / closing contact 2 (preferably, a holder formed of an insulator holding the movable contact, an opening / closing mechanism for opening / closing the movable contact, or a trip bar for applying a trip trigger to the opening / closing mechanism ) Is a microswitch or an electromagnetic coil linked to the opening / closing operation of (1). Reference numeral 11 denotes a non-volatile memory that stores the number of times of opening and closing calculated by the control unit 6, for example, an EEPROM.

Reference numeral 13 denotes an instantaneous trip circuit which outputs a cutoff signal to the output circuit 7 when the current value detected in the wiring circuit 1 exceeds a predetermined value. In the case of a multi-pole circuit breaker, a cutoff signal is output when the largest one of the peak values of each phase exceeds a predetermined value. Reference numeral 20 denotes a circuit breaker main body.

Here, the operation characteristics of the circuit breaker according to the first embodiment will be described. The operation characteristics are the same as the operation of a general electronic circuit breaker, that is, the operation (time period) characteristics are predetermined. The characteristic is that the cutoff operation is performed in a shorter time as the current flowing through the wiring circuit 1 is larger. In the case of the first embodiment, when a very large current such as a short-circuit current flows, the instantaneous tripping circuit 13 performs a breaking operation, and when a large current flows such that the instantaneous tripping circuit 13 does not operate, the control unit 6 detects that the continuation time has passed a predetermined time, and performs a shut-off operation. The operation characteristics of the control unit 6 include a short time limit characteristic and a long time limit characteristic from the relationship between the magnitude of the current and the duration thereof.

Reference numeral 31 denotes a display unit, which displays a load current value, the number of times of switching, and an alarm according to a signal from the control circuit 6. 3
Reference numeral 2 denotes a communication interface (communication I / F), which transmits a processing result of the control unit 6 via a communication line. Reference numeral 30 denotes an external unit, which accommodates the display unit 31 and the communication interface 32 and is attached near the circuit breaker main body 20 or a main body housing (not shown).

Next, the operation will be described. The current flowing through the wiring circuit 2 is detected by the current transformer 3, the level is converted by the current detection circuit 4, input to the A / D conversion circuit 5, and converted into a digital signal. This value is squared by the control unit 6 to calculate an effective value. When the effective value exceeds a predetermined value, the internal timer starts counting, and after a predetermined time elapses, the control section 6 outputs a signal to the output circuit 7, and the output causes the electromagnetic device 8 to operate.

The current flowing through the wiring circuit 2 is
The current detected by the current detection circuit 4 and rectified by the current detection circuit 4 is input to the instantaneous trip circuit 13, and when the input value exceeds a predetermined value, a signal is output to the output circuit 7. It operates to open and close the on-off contact 2, and the wiring circuit 1 interrupts the load current.

At this time, the open / close detection device 10 also operates in conjunction with the open / close contact 2 to output a signal. This output is input to the control unit 6 to count the number of times of opening and closing. The EEPROM 11 stores the number of times of opening and closing up to now, and displays a cumulative number of times of opening and closing obtained by adding the stored value and the counted number of times to the display unit 3.
Displayed at 1. Further, the threshold value set by the setting unit 9 is compared with the cumulative number of times of opening and closing.
An alarm is output to the display unit 31 to indicate that the number has exceeded the specified number. The number of times of opening and closing and the alarm are transmitted to a host device (not shown) via the communication interface 32.

The details of the number accumulation operation will be described with reference to the flowchart of FIG. The process of calculating the effective value of the current and the tripping operation are performed separately from the process of FIG. 2, but the description is omitted because it has no direct relation to the present invention. (1) When the control unit 6 starts operating, the EEPROM 11
Is read and stored in the memory of the microcomputer (step 4).
1). (2) Next, the state of the contact output (ON,
OFF state) is detected and stored in the memory as the previous contact state value S1 (step 42).

(3) Next, the opening / closing detection device 10
Is read and stored in the memory as the current contact state value S2 (step 43). (4) The previous contact state value S1 and the current contact state value S2 are compared, and if the state changes (from ON to OFF or from OFF to ON), it is determined that the opening / closing operation has been performed, and the number M of opening / closing operations is incremented by +1 ( Steps 44 and 45).

(5) Next, this value is compared with the threshold value N for alarm judgment set by the setting unit 9, and if it is not less than N, an alarm is output (steps 46 and 47). (6) The current value S2 of the contact state is stored as the previous value S1 of the contact state every time irrespective of the presence or absence of a state change (step 4).
8).

Although not shown in FIG. 2, the control unit 6
Is terminated by power failure or the like, the number of times M is
It is stored in the PROM 11. In the flow of FIG.
Although the example in which the contact output of the opening / closing detection device 10 is read at regular time intervals and the number of times of opening / closing is counted has been described, control is performed every time the state of the contact output of the opening / closing detection device 10 changes (on-off or off-on). The number may be input to the unit 6 and the control unit 6 may increment (or decrement) the number of times by one.

As described above, according to the first embodiment,
Confirmation of the number of times of switching and alarms can be easily performed at the place where the circuit breaker is installed, and the labor for equipment maintenance can be saved. In addition, remote and centralized monitoring can be performed via the communication interface 32, and the labor for equipment maintenance can be further reduced.

Embodiment 2 FIG. In the first embodiment, the number of times is accumulated only in the open / close state and the determination of the alarm is performed. However, the switching life depends on the consumption of the contact due to the flowing current, but the first embodiment does not consider this consumption. Therefore, only an approximate life determination can be made. In the second embodiment, a more accurate life determination is performed by detecting a conduction current at the time of opening (interruption) and reflecting contact wear due to the conduction current in the number of times of opening and closing (to the number of times of opening and closing corrected by current). is there.

A block diagram of a circuit breaker according to a second embodiment of the present invention is the same as that of the first embodiment shown in FIG. 1, except that the number of times of opening and closing is corrected inside the control unit 6 according to the magnitude of the current. Includes accounting. This correction processing is set and stored in advance in a form of a look-up table or a formula in a ROM serving as a storage means attached to the control unit 6.

Next, an example of the correction processing formula will be described. FIG. 3 is an example of a characteristic showing the relationship between the life of the number of times of switching and the energizing current (preferably the effective value). In this case, assuming that the life of the number of times of switching when no current is applied is A and the life of switching when the current is I is B, B = A−kI ² − (1) (k is the separation time And the coefficient obtained from the contact material). Therefore, in order to calculate how many times the one opening operation with the energizing current I corresponds to the number of opening operations when no current is supplied, the number of times after correction is C, and the following (2) It looks like an expression. C = A / B = A / (A-kI ² )-(2)

The details of the operation including the correction processing will be described with reference to the flowchart of FIG. (1) Steps 41 to 48 are the same as described in the first embodiment. (2) In the second embodiment, when a change in the state of the open / close detection device 10 is determined, the open / close contact is turned off after the change.
That is, did the opening operation occur? Or, the open / close contact is OF
Instead of F, it is determined whether an ON operation, that is, a closing operation has been performed (step 51).

(3) In the case of the closing operation, the number of times of opening and closing is set to "+
1 "(step 45). (4) In the case of the opening operation, the current I at the time of opening (cutting) is obtained from the effective current value calculated from another processing routine (step 52). (5) Using this current I, the number of times of opening and closing when no current is applied is corrected by the above-described equation (2) (step 53). (6) The number of times C after this correction is added to the number of times of opening and closing M (step 54).

In FIG. 4, the number of times of opening / closing is determined by the number of times of opening and closing when the contacts are turned off and corrected by the energizing current (however, if no current is applied at the time of opening, C = 1 according to equation (2)). The number of times of opening and closing (the number of times of switching from open to closed) is added to the number of times of opening and closing, and the cumulative value of the number of times of opening and closing is obtained. However, the contact life is largely affected by wear due to arcs between contacts generated at the time of opening. Therefore, the number of openings corrected by the current at the time of opening (interruption) is used, and the contact life is calculated by the cumulative value of the number of openings. May be estimated.

As described above, according to the second embodiment,
Since the number of switching times corrected in accordance with the energizing current is added, contact consumption due to the energizing current is reflected, and a more accurate life determination of the number of opening and closing times can be performed.

Embodiment 3 The open / closed detection signal indicating the open / closed state of the circuit breaker is not normally output when an excessive current flows and the contacts are welded because the open / close contacts themselves are not opened. Therefore, there is a problem that an abnormal current flows when the contacts are welded. In the third embodiment, contact welding is determined based on a signal from the output circuit 7 and the presence or absence of a load current after the signal is output.

The block diagram of the circuit breaker according to the third embodiment of the present invention is the same as that of the first and second embodiments shown in FIG. 1, but it is determined whether or not there is an output to the output circuit 7 inside the control unit 6. Processing.

Next, details of the operation will be described with reference to the flowchart of FIG. (1) When there is an output from the output circuit 7 (Step 6
1), (2) After a certain time in consideration of the time t1 required for the opening (cutting) operation, the energizing current value I is read (step 6).
2). (3) At this time, if a current is detected (when I> 0)
It is determined that the contact is in the closed state, that is, the contact is in the contact state due to welding or the inoperative of the opening / closing mechanism (step 63), and (4) an alarm is output (step 64). By monitoring this alarm, it is possible to determine whether the contact has been welded or the switching mechanism has failed. In this way, the electronic circuit breaker can be realized without adding new components, and thus the device does not become large.

The third embodiment can be applied to circuit breakers other than electronic circuit breakers. In this case, there are means for detecting the output of the output of the output circuit (cutoff signal or trip signal) and means for detecting the current or line voltage of the wiring circuit after a predetermined time. It is only necessary to detect whether or not the contacts of the circuit breaker have been opened as desired based on the presence or absence (or magnitude) of the current flowing through the wiring circuit or the line voltage. Further, instead of processing with a digital signal, an analog circuit may be used.

Instead of detecting the current or voltage between the switching contacts, the circuit breaker having the switching detector 10 shown in FIG. 1 uses the presence or absence of the output of the switching detector 10 or the operation of the circuit detector 10. (Operation of a microswitch or the like) may be detected to detect the open / close state of the open / close contact.

As described above, according to the third embodiment,
Since it can be determined that the open / close contact is in the non-open state even if the shut-off signal is transmitted, it is possible to take measures to prevent accidents by appropriate measures such as alarming. Further, appropriate maintenance such as early replacement of the circuit breaker can be performed. Further, in the case of an electronic circuit breaker, the circuit breaker can be realized without adding new components, so that the device does not become large.

Embodiment 4 In the fourth embodiment, a process to be performed when the contacts are not opened in the third embodiment due to welding of the contacts, non-operation of the opening / closing mechanism, and the like. FIG. 6 is a block diagram of a circuit breaker system for explaining the fourth embodiment. Reference numeral 120 denotes a higher-order circuit breaker provided with a communication external unit 130, 220A,
220B and 220C are external units 230A for communication,
Lower circuit breakers provided with 230B and 230C.

When the lower circuit breaker 220C recognizes in step 61 to step 63 in FIG. 5 that the contact has not been opened, it outputs an alarm in step 64. At this time, the external unit 230C outputs an alarm to the monitoring server device 300. Utilizing this alarm, the server device 300 transmits the signal to the upper circuit breaker 120 of the power distribution system.
Take appropriate measures to prevent accidents, such as opening circuits. Thus, the external units 130, 230A, 230B, 230
When a C (communication interface) is provided, these processes can be executed intensively and automatically.

As described above, according to the fourth embodiment,
When the circuit breaker does not separate due to welding of contacts, the power supply to the input side electric circuit of the circuit breaker is cut off, so that accident prevention can be surely prevented.

[0042]

(1) According to the first aspect of the present invention, the cumulative value of the number of times of opening and closing is counted, and it is notified that the cumulative value reaches the specified number, so that it is possible to determine whether the contact life has expired and to facilitate the maintenance work. .

(2) According to the second or third aspect, since the current value at the time of opening is added to the number of times of opening and closing or the number of times of opening and closing, the accurate opening and closing life according to the state of contact wear can be calculated. Will be possible.

(3) According to the fourth aspect, the cumulative number of times of opening and closing, a notification output, and the like are displayed near the circuit breaker housing.
Make maintenance work easier.

(4) Further, according to the fifth aspect, the state of contact non-separation such as welding of the contact is determined, so that appropriate accident prevention measures can be taken in the case of contact non-separation.

(5) According to the sixth aspect, when it is determined that the contacts are not separated, such as when the contacts are welded, the upstream power supply is shut off, so that an early accident can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic circuit breaker showing Embodiments 1, 2, and 3 of the present invention.

FIG. 2 is a flowchart showing a process of counting the number of times of opening and closing according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of characteristics of switching life and energizing current.

FIG. 4 is a flowchart of a process of counting the number of times of opening corrected by a breaking current according to Embodiment 2 of the present invention;

FIG. 5 is a flowchart showing a process of alarming contact welding according to Embodiment 3 of the present invention.

FIG. 6 is a configuration diagram of a circuit interruption system according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram of a conventional circuit breaker with a switching frequency display device.

FIG. 8 is an external front view of a conventional circuit breaker with a switching frequency display device.

[Explanation of symbols]

1 wiring circuit, 2 switching contacts, 4
Current detection circuit, 5 A / D conversion circuit, 6
Control unit, 7 output circuit, 9 setting unit, 10 open / close detection device, 11
EEPROM, 20 circuit breaker body, 3
0 external unit, 31 display unit, 32 communication interface, 120 upper circuit breaker,
130, 230A, 230B, 230C External unit, 220A, 220B, 220C Lower circuit breaker, 300 server device.

Claims (6)

[Claims] 1. A circuit breaker that opens and closes an electric contact by driving an open / close contact in accordance with a current flowing through an electric circuit to be interrupted, and a counting means for counting and accumulating the number of times of opening and closing or the number of times of opening and closing of the open / close contact. A circuit breaker, further comprising a reporting means for reporting according to the accumulated number of times. 2. A circuit breaker that opens and closes an electric contact by driving an open / close contact in accordance with a current flowing through an electric circuit to be interrupted. Means for correcting the number of times of opening and closing according to the magnitude of the current, counting the number of times of closing of the on / off contact, adding the number of times of closing and the corrected number of times of opening to obtain the number of times of opening and closing, A circuit breaker comprising: means for accumulating the number of times; and a notifying means for notifying according to the magnitude of the number of times of accumulation. 3. A circuit breaker that opens and closes an electric circuit by driving an open / close contact in accordance with a current flowing through an electric circuit to be interrupted, counts the number of times the open / close contact is opened, and opens and closes the open / close contact. A circuit breaker comprising: means for correcting and accumulating the number of times of opening in accordance with the magnitude of current during operation; and reporting means for reporting in accordance with the magnitude of the accumulated number of times. 4. The circuit breaker according to claim 1, wherein an output of the communication interface is provided near the circuit breaker housing, and a communication interface for transmitting a cumulative number of switching operations, a notification output, and the like. A circuit breaker characterized by comprising a display that performs the following. 5. A circuit breaker that opens and closes an electric circuit by driving an open / close contact according to a current flowing through an electric circuit to be interrupted, and detects an open / close state of the open / close contact after an interruption signal is output. A circuit breaker comprising means for determining the presence or absence of a non-open state of an on / off contact in accordance with the opened / closed state. 6. A circuit comprising: the circuit breaker according to claim 5; and means for shutting off power supply to an input side electric circuit of the circuit breaker when the circuit breaker is determined to be non-open. Blocking system.