JP4100065B2 - Circuit breaker with advance warning - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to setting of an alarm pickup value of a circuit breaker with a pre-alarm.
[0002]
[Prior art]
FIG. 3 is a block diagram of a conventional electronic circuit breaker with a pre-alarm disclosed in, for example, Japanese Patent Application Laid-Open No. 4-218229. In the figure, 1 is a wiring circuit, 2 is a switching contact, 3 is a current transformer for detecting a load current flowing through the wiring circuit 1, and 4 is a current detection circuit provided on the secondary side of the current transformer 3, The circuit 4a, the burden circuit 4b, and the maximum phase selection circuit 4c are configured. Reference numeral 5 denotes an A / D conversion circuit that converts the analog output of the current detection circuit 4 into a digital signal, and reference numeral 6 denotes a control unit that includes a microcomputer, which is based on the A / D converted load current and a rated current described later. A comparison is made with the anti-time characteristic and the pre-alarm pickup set value that are set.
Reference numeral 7 denotes a trip circuit, which opens and closes the switching contact 2 in response to a command from the control unit 6 to cut off the load current of the wiring circuit 1. Reference numeral 8 denotes a characteristic setting unit, which includes a circuit breaker tripping characteristic of the control unit 6, a setting of a rated current value, a dip switch for setting a current pickup value of a prior alarm, and the like. Reference numeral 9 denotes a memory means for storing the circuit breaker tripping characteristic value set by the characteristic setting unit 8 and the pickup current value of the prior alarm. Reference numeral 10 denotes a pre-alarm output circuit, which drives an alarm device such as LED lighting or contact output in accordance with pre-alarm pickup set value over-information from the control unit 6.
[0003]
The circuit breaker does not perform a breaking operation below its rated current (energization allowable current), and has a counter-time characteristic that shortens the time until the breaking operation at a ratio of the rated current over. The circuit breaker does not shut off when the rated current over-energized state continues for a short time, but when a new load current is applied to the energized state, the breaking operation is unexpectedly performed. In an electronic device such as a personal computer, the unexpected shut-off operation causes inconvenience such as loss of memory contents, so that a pre-alarm that knows in advance that the load current exceeds the rated current has been provided. The pre-alarm is used for checking the load current abnormality by appropriately setting the pre-alarm pickup current value.
The prior alarm informs the electric device user that the load current is close to the set rated current (preliminary alarm pickup current value), and prompts the user to turn off the power to unnecessary devices, thereby preventing the circuit breaker from being shut off unexpectedly. Is.
[0004]
[Problems to be solved by the invention]
A conventional circuit breaker with a pre-alarm estimates the load current specified in the specifications of the connected load equipment and sets a slightly larger current value considering the margin to the load current value. Therefore, it is different from the actual load current, and there are many cases where it is not appropriate as the selection setting of the pre-alarm pickup current value for monitoring the abnormality of the load current. The pre-alarm pickup current value is generally set to be equal to or lower than the rated current of the circuit breaker, and it is necessary to call attention to the fact that the pickup current value exceeds the rated current.
[0005]
The present invention has been made to solve the problems as described above, the pre-alarm pickup current value the user has been properly selected in the conventional, is set as the reference current performance of the circuit breaker Accordingly, an object of the present invention is to provide a circuit breaker with a pre-alarm that can perform an appropriate pre-alarm issue by reducing the difference between the actual load current and the pre-alarm pickup current value.
[0006]
[Means for Solving the Problems]
The circuit breaker with a pre-alarm according to the present invention measures a pre-alarm means for giving an alarm when the energizing current exceeds a preset current value equal to or lower than a preset rated current value, and a moving average current value of the actual energizing current. The maximum current measuring means for storing the maximum value is provided, and the pickup current value is changed to a value obtained by adding a margin to the maximum value of the moving average current value by an externally applied signal.
[0007]
And the above-mentioned thing is provided with the timer means which generate | occur | produces the provision signal from the outside at a predetermined interval.
[0008]
In addition, when the changed pickup current value exceeds the rated current value of the circuit breaker, the changed pickup current value is set to a new rated current value, and an alarm different from the prior alarm is output.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a block diagram of a circuit breaker with a prior warning showing Embodiment 1 of the present invention, and FIG. 2 is a flowchart for explaining the operation of the circuit breaker with a prior warning of the present invention.
In the figure, reference numerals 1 to 10 are the same as those of the above-described conventional apparatus, and thus description thereof is omitted. Reference numeral 11 denotes a maximum current measurement unit, which measures the load current of the wiring circuit 1 subjected to sampling A / D conversion output from the A / D conversion circuit 5 to obtain a moving average current value, and stores and holds the maximum current value. . A timer means 12 outputs a time signal at predetermined intervals (for example, one day, one week, one month).
Reference numeral 13 denotes a pick-up current value changing unit, which is measured by the maximum current measuring unit 11 in the interval with respect to a pre-alarm pick-up current value set manually by the characteristic setting unit 8 or a pick-up current value previously calculated and set. A new pickup current value is calculated and set from the result and stored in the memory means 9. Reference numeral 14 denotes a rated current abnormality alarm output circuit.
[0010]
Next, operation | movement of the circuit breaker with a prior warning of this invention is demonstrated with the flowchart of FIG.
First, the factory default value of the circuit breaker or the rated current value and pre-alarm pickup current value of the circuit breaker manually set by the user from the characteristic setting unit 8 are captured (step 201). Manual setting of the rated current value and the pre-alarm pickup current value at the circuit breaker is made by selecting a selection button (not shown) for selecting whether or not to change to the pickup current value change mode provided in the characteristic setting unit 8. The value or default value is used as it is or whether it is changed in accordance with the actual load current.
[0011]
The gist of the present invention is to change according to the actual load current, and this pickup current value change mode will be described (step 202). In the initial energization of the circuit breaker, even if the pickup current value change mode is selected, the default value or the rated current value and the pre-alarm pickup current value manually set by the user are used. The moving average value of the effective value of the load current of the wiring electric circuit 1 obtained by sampling the A / D conversion of the energization current of the circuit breaker by the maximum current measuring unit 11 is calculated (step 203).
Then, the updated maximum current value Imax of the average current value of the measurement time series is recorded in the memory means 9 (step 204).
[0012]
At this time, the characteristic setting unit 8 is provided with setting means so that the moving average target period can be arbitrarily set between 1 and 15 minutes depending on the nature of the load. The moving average is used to eliminate the influence of a temporary peak current such as the starting current of the motor.
The moving average current value can be obtained by simply dividing the sample current value sum by the sampling number n for each moving average target period, discarding the old sample current value of the moving average target period, and calculating the latest sample current value. A method of calculating a moving average while adding, or a weighted moving average method (exponential smoothing method) may be used as long as the influence of a temporary peak can be eliminated.
[0013]
Pre-alarm pick-up current in response to a change command based on a pressing signal of a manual change button provided in the characteristic setting unit 8 or an interval signal after a certain period of time (for example, 1 day, 1 week, 1 month) measured by the timer means 12 A new pickup current value based on the maximum current value Imax recorded within the predetermined period (corresponding to the “changed pickup current value” in claim 2, hereinafter referred to as a new pickup current value) Ip (Step 205). The new pickup current value Ip is normally set to a value obtained by adding a margin (5 to 10%) to the maximum current value Imax (step 206). At this time, if the new pickup current value Ip is less than or equal to the rated current value Ik of the circuit breaker, the next pickup current value is used as it is (steps 208 and 211).
[0014]
Changing the setting of the new pick-up current value manually is complicated to make the pick-up current value follow the fluctuation of the load current that changes depending on the season and time zone, but the interval signal by the timer means 12 is changed every fixed period. Since the pickup current value is updated, the trouble can be solved.
[0015]
In addition, when the new pickup current value Ip exceeds the rated current value Ik, the user sets the pickup current value to the rated current value and confirms that the new pickup current value Ip to be set from the actual conducting current is greater than or equal to the rated current value. Outputs an alarm different from the prior alarm that informs the user. For example, if the pre-alarm is a continuous sound or the LED is continuously lit, the intermittent sound or tone color is changed and the LED flashes when the new pickup current value Ip exceeds the rated current value Ik (steps 207 to 211).
[0016]
In this way, the user is notified by an alarm different from the prior alarm that the rated current value was changed to the pickup current value instead of the current value that was originally set as the pickup current value, and the energization current became close to the rated current. In some cases, it may be necessary to increase the rated capacity of the circuit breaker.
[0017]
In general, an electronic circuit breaker is adopted as such a circuit breaker with a prior alarm. In the electronic circuit breaker, the rated current in several steps below it can be selected and set for the maximum current carrying capacity (rated frame capacity). For example, when the rated frame capacity is 225 A, the rated current can be selected and set in five stages of 125 A, 150 A, 175 A, 200 A, and 225 A.
Now, if the rated current is set to 200 A and an alarm is issued when the pickup current value exceeds 200 A, the user manually sets the rated current to 225 A from the characteristic setting unit 8. This manual change of the rated current can be automatically changed by the electronic circuit breaker, but it is for the purpose of realizing that the rated current has been changed.
[0018]
Then, that the alarm comes is intended to notify that the daily use current is approaching the rated current of the circuit breaker, for example when the 225A rated current of the circuit breaker described above is the rated frame capacity, the same Since the circuit breaker cannot be changed to the rated current any more, it is suggested to replace the circuit breaker with an increased rated frame capacity.
[0019]
【The invention's effect】
As described above, according to the present invention, the circuit breaker with a pre-alarm detects the maximum moving average value of the actual load current, and sets the new pre-alarm pick-up current value based on the actual load current. Current abnormality can be monitored more appropriately.
[0020]
Also, if the new pick-up current value exceeds the rated current value of the circuit breaker, an alarm different from the pre-alarm is issued, the energizing current is close to the rated current, and in some cases the rated capacity of the circuit breaker is increased. Can be necessary.
[Brief description of the drawings]
FIG. 1 is a block diagram of a circuit breaker with a prior alarm according to the present invention.
FIG. 2 is an operation flowchart of the circuit breaker with a prior alarm according to the present invention.
FIG. 3 is a block diagram of a conventional electronic circuit breaker with a pre-alarm.
[Explanation of symbols]
2 switching contacts, 3 current transformer, 4 current detection circuit,
5 A / D conversion circuit, 6 control unit, 7 trip circuit,
8 characteristic setting section, 9 memory means, 10 advance alarm output circuit,
11 maximum current measuring unit, 12 timer means,
13 Pickup current value changing section,
14 Rated current abnormality alarm output circuit.

Claims (2)

In the circuit breaker with a pre-alarm that issues an alarm when the energization current exceeds the pickup current value below the preset rated current value,
Maximum current measurement means that measures the moving average current value of the actual energization current and stores the maximum value is stored, and the pickup current value is added to the maximum value of the moving average current value by an external signal. A circuit breaker with a pre-alarm, characterized in that it includes a timer means for generating the given signal at a predetermined interval . When the changed pickup current value exceeds the rated current value of the circuit breaker, the changed pickup current value is changed to a new rated current value, and an alarm different from the prior alarm is output. The circuit breaker with prior warning according to claim 1 .

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