JPH04218229A - Circuit breaker - Google Patents

Abstract

PURPOSE:To facilitate coordination of the rated breaking of a circuit breaker with an advance. CONSTITUTION:A circuit breaker is equipped with a control circuit 2 having a current-to-operating-time characteristic lower than that of a tripping means 1, and an alarm device 3 is actuated by an output signal of that control circuit 2 and also equipped with a characteristic value changing means 4 to change the current-to-operating-time characteristic of the control circuit 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to circuit breakers.

0002

2. Description of the Related Art A circuit breaker is provided with a tripping means having a current vs. operating time characteristic of a rated current, and is configured to trip when the current in the electrical circuit has elapsed over a corresponding period of time.

0003

SUMMARY OF THE INVENTION This type of circuit breaker requires changes in rated current as the load increases, and advance warning has become necessary to avoid widespread power outages. However, there was a problem in that the setting of advance warning and rated current levels was complicated, and the setting of protection coordination was complicated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a circuit breaker that can easily coordinate interrupting based on rated current and advance warning.

[0005]

Means for Solving the Problems The present invention provides a tripping means having a first current versus operating time characteristic and a second current versus operating time characteristic lower than the first current versus operating time characteristic. a control circuit that outputs an output signal when the current in the electric circuit passes a corresponding time; an alarm device that operates according to the output signal of the control circuit; and a characteristic that changes the second current versus operating time characteristic. and a value changing means.

[0006]

[Operation] According to the structure of the present invention, when the overcurrent in the electric circuit passes a time corresponding to the first current vs. operation time characteristic, the tripping means performs a tripping operation, but before that, the tripping means performs a tripping operation. Since the time characteristic is lower than the first current versus operating time characteristic, an alarm is output. Therefore, if the first current versus operating time characteristic is set to the maximum rated current characteristic of the circuit breaker, and the second current versus operating time characteristic is set to a rated current characteristic smaller than the maximum rated current, then in the event of an overcurrent, In addition to being able to trip reliably and protect the electrical circuit, an alarm output can be used to notify you of an increase in load or the need to change the rated current before a trip occurs, and an alarm output can be used to disconnect unnecessary loads. It is also possible to control the Moreover, since the characteristic value of the second current vs. operating time characteristic can be changed by the characteristic value changing means, it is easy to give advance warning, and it is easy to obtain coordination between cutoff of rated current and advance warning.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained with reference to FIGS. 1 to 3. That is, this circuit breaker has a tripping means 1, a control circuit 2, an alarm device 3, and a characteristic value changing means 4. The tripping means 1 has a first current versus operating time characteristic. In the embodiment, it is composed of a current detection circuit 5, a rated current control circuit 6, a tripping circuit 7, and a contact tripping mechanism section 8. The current detection circuit 5 detects the current in the electric line 9, and as shown in FIG. 2, it includes a current transformer 10, a full-wave rectifier circuit 11 for full-wave rectifying the output of the current transformer 10,
A burden circuit 12 that converts full-wave rectification into voltage, and a burden circuit 1
It consists of an A/D conversion circuit 13 that A/D converts the output of 2. Further, the rated current control circuit 6 is configured such that the current detected by the current detection circuit 5 has a first current vs. operating time characteristic Q1 shown in FIG.
That is, it outputs an output signal when the operating time according to the trip characteristic has elapsed, and has the same configuration as the control circuit 2 shown in FIG. 2. That is, it has a count value determination device 14 that converts the digital value of the A/D conversion circuit 13 into a count value corresponding to the inverse time limit operation characteristic, and when the fault current increases, the count value is increased to a predetermined value. The time it takes to count up to 1 is shortened, and the fault current and operating time can have inverse time characteristics. The counting device 15 counts the count value determined by the count value determining device 14. Further, the determination device 16 compares the total count value of the counting device 15 with a predetermined determination value, and outputs an output signal to the tripping circuit 7 when the total count value exceeds the determination value. The tripping circuit 7 performs a tripping operation based on the output signal of the rated current control circuit 6, trips the contact tripping mechanism section 8, and opens the contact section.

As shown in FIG. 3, the control circuit 2 has a second current vs. operating time characteristic Q2 lower than the first current vs. operating time characteristic Q1, and the current in the electric line 9 passes the corresponding time. Outputs an output signal when In the embodiment, a count value determination device 14 that limits a count value depending on the magnitude of the current detected by the current detection circuit 5, and a count device 1
5 and a determination device 16, which are the same as those described for the rated current control circuit 6.

[0009] The alarm device 3 is operated by the output signal of the control circuit 2. In the embodiment, the output signal of the control circuit 2 is an alarm/
The transmission circuit 18 is switched by the switching operation of the trip changeover switch 17.
The signal is input to the alarm device 3 via the alarm device 3, and the alarm device 3 operates. Furthermore, by switching the changeover switch 17, it is also possible to operate the tripping circuit 7 using the output signal of the control circuit 2. The characteristic value changing means 4 is for changing the second current vs. operating time characteristic, and in the embodiment is comprised of a judgment value determining device 18, a memory 19, and a switch means 20. That is, the larger the determination value that is the standard of the characteristic value, the longer the operation time at the same fault current, so by changing this determination value, the characteristic value of the current vs. operation time characteristic of the circuit breaker can be varied. In this case, the judgment value determination device 18 reads the setting of the switch means 20, searches for and determines the corresponding judgment value data from the table in the memory 19, and can change the judgment value by the switch means 20. Note that the judgment value determining device 18 is provided with a judgment value setting device that provides judgment value calculation data, and the judgment value determining device 18 performs calculations using the judgment value calculation data from the judgment value setting device to determine the judgment value. It's okay. Further, the determination value setting of the determination value determining device 18 may be changed by, for example, a computer by signal transmission.

According to this embodiment, when the overcurrent in the electric line 9 passes a time corresponding to the first current vs. operation time characteristic Q1, the tripping means 1 performs a tripping operation, but before that, the second current Since the operating time characteristic Q2 is lower than the first current versus operating time characteristic Q1, an alarm is output. therefore,
The first current versus operating time characteristic Q1 is set to the maximum rated current characteristic of the circuit breaker, and the second current versus operating time characteristic Q2 is set to the maximum rated current characteristic of the circuit breaker.
By setting the rated current to a characteristic that is smaller than the maximum rated current, it is possible to trip reliably in the event of overcurrent to protect the circuit, and also to be able to notify of an increase in load or change the rated current through an alarm output before tripping. In addition, it is possible to control such things as cutting off unnecessary loads by outputting an alarm. Moreover, since the characteristic value of the second current versus operating time characteristic Q2 can be changed by the characteristic value changing means 4, it is easy to give advance warning, and it is easy to obtain coordination between cutoff of rated current and advance warning.

Furthermore, by using the second current versus operating time characteristic Q2 for alarm, it is possible to obtain the same effect as having a second circuit breaker that can be monitored and controlled. Therefore, protection coordination can be made more fine-grained. Furthermore, since this embodiment is provided with a changeover switch 17, the tripping circuit 7 can be operated by the output signal of the control circuit 2 to trip the contact portion, so that the breaking rating can be easily changed. Furthermore, since the second current versus operating time characteristic Q2 can be changed through communication with the host computer, more detailed monitoring and control can be performed by changing the alarm output state.

Note that the control circuit 2 may use other means, and in this case, the second current versus operating time characteristic Q2 is changed by changing the determination level or by changing the magnitude of the signal voltage. be able to. Further, if the transmission circuit 18 is not provided, the alarm output of the control circuit 2 is outputted to a display means such as a light emitting diode, or as a contact signal or a control signal. Further, the tripping means 1 may be of a conventionally known thermal type or electromagnetic type, which detects an abnormality and performs the tripping operation.

[0013]

Effects of the Invention In the circuit breaker of the present invention, when the overcurrent in the electrical circuit passes a time corresponding to the first current vs. operation time characteristic, the tripping means performs a tripping operation, but before that, the Since the alarm is output when the operating time characteristic is lower than the first current versus operating time characteristic, it is possible to trip reliably in the event of an overcurrent to protect the electrical circuit, and the alarm is output before tripping to prevent an increase in load. It is also possible to know the necessity of changing the rated current, as well as control such as cutting off unnecessary loads with alarm output. Moreover, since the characteristic value of the second current vs. operating time characteristic can be changed by the characteristic value changing means, advance warning can be easily issued and coordination between rated current cutoff and advance warning can be easily obtained. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a partial specific circuit diagram thereof.

FIG. 3 is a current versus operating time characteristic diagram.

[Explanation of symbols]

1. Tripping means 2 Control circuit 3 Alarm device 4 Characteristic value changing means

Claims (1)

[Claims] 1. A tripping means having a first current versus operating time characteristic and a second current versus operating time characteristic lower than the first current versus operating time characteristic to which the current in the electrical circuit corresponds. A circuit comprising: a control circuit that outputs an output signal when a time elapses; an alarm device that operates based on the output signal of the control circuit; and characteristic value changing means that changes the second current versus operating time characteristic. circuit breaker.