JPH0223023A - Circuitbreaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a circuit breaker, especially the current K before the switching mechanism is tripped due to an overcurrent flowing in its main circuit, and the current before the overcurrent fLK is reached. The present invention relates to a circuit breaker that can detect and issue a warning in advance of tripping, and can also prevent an LED for indicating advance warning operation from being erroneously lit at that time.

[Conventional technology]

Figure 5 is a block diagram showing a conventional circuit breaker.
In the figure, 1 is an AC power source, for example, a three-phase AC power source; 2 is a load, such as a motor, supplied with power by this AC power source IK; and 3 is a circuit breaker connected between the AC power source 1 and the load 20. This circuit breaker 3 includes a main circuit 5 consisting of three groove bodies 5a, 5b, and 5c connected to an AC power source 1 via a switching mechanism part 4, and each phase conductor 5a, 5b of this main circuit 5.
, 5c are connected to current transformers CTa, CTb, C, respectively.
Tc and a distorted current circuit 6 connected to the secondary side of these current transformers.
The maximum phase selection fish peak value change * circuit 7 and the maximum phase selection moat effective value conversion circuit 8 and the maximum phase selection and peak type conversion circuit 7 are connected individually to the output side of the flash flow circuit 6. Momentary circuit 9 and short-time circuit 10 connected individually on the output side
and a long time limit circuit 11 connected to the output side of the maximum phase selection and effective value conversion circuit 8, and these instantaneous circuits 9 and short time limit circuits 10.
and a trigger circuit 12 connected to the output 11tllK of the long time limit circuit 11, a tripping coil 13 connected between both ends of the rectifier circuit 6 via this trigger circuit 12, and an overcurrent indicator connected to the long time limit circuit 11. It is equipped with an LED 14 for use. Note that the circuits 7 to 11 described above are made of dedicated ICs.

FIG. 6 is a curve diagram showing the overcurrent tripping characteristics of the circuit breaker 3 shown in FIG.

The conventional circuit breaker 3 is constructed as described above, and its operation will be explained with reference to FIGS. 5 and 6. Assume now that the switching mechanism section 4 of the circuit breaker 3 is closed, that is, it is not tripped, and current is flowing from the AC power source 1 through the main circuit 5 to the load 2. Current transformer CTa,C
Tb and CTc are 2 which is proportional to the main circuit current on the secondary side.
Next, apply the current.

The rectifier circuit 6 rectifies the alternating current of each of the three phases and the secondary M current.

The thickest phase selection and peak value conversion circuit 7 selects the largest phase rectified signal among the three-phase direct current signals from the rectifier circuit 6 and converts it to a peak value. Similarly, the maximum phase selection and effective value conversion circuit S selects the maximum phase rectified signal and converts it into an effective value.

The peak value-converted DC signal has the instantaneous characteristic lN5T and short-time characteristic STD among the overcurrent bow removal characteristics shown in Fig. 6, respectively.
is supplied to the instantaneous circuit 9 and the short time limit circuit 10 having the effective value ! The converted DC signal is supplied to a long time delay circuit 11 having a long time delay characteristic LTD. When the current in the main circuit exceeds, for example, 125% of the rated current, the long time limit circuit 11 changes the value of the DC signal converted to an effective value, for example, from 125% to 100% of the rated current.
After a predetermined time shown in FIG. 6, an output is output in response to 0%, and the trigger circuit 12 is turned on, and the excessive 'fI! t. Turn on the flow display LED 14. When the trigger circuit 12 is turned on, the trip coil 13 is excited by the rectified output of the rectifier circuit 6, opens the opening/closing mechanism section 4, and cuts off the flow in the main circuit 11t. Similarly, when the main circuit itt current becomes large and exceeds, for example, 1000% or 1700% of the rated current, the short time limit circuit 10 and instantaneous circuit 9 output outputs to cut off the main circuit current.

[Problem to be solved by the invention]

The conventional circuit breaker described above has an overcurrent tripping characteristic that only cuts off the main circuit when the main circuit current reaches an overcurrent state. There was a problem that there was no pre-warning feature for issuing a warning just before the warning occurred, and it was not possible to prevent the erroneous lighting of the pre-warning operation display LED.

The present invention has been made to solve these problems, and an object of the present invention is to provide a circuit breaker that has advance warning characteristics and can also prevent erroneous lighting of an LED for indicating advance warning operation.

[Means to solve the problem]

The circuit breaker according to the present invention includes an advance warning circuit having advance warning characteristics for detecting a current before an overcurrent and issuing a warning in advance, and a prior warning signal from this advance warning circuit. A skewer advance warning output circuit to be operated, a relay coil excited by the output of the advance pipe output circuit, and an advance warning operation display LED connected in parallel with the relay coil and lit by the output; A capacitor connected in parallel with this advance warning operation display LED is provided.

[For pestle]

In this invention, when the pre-trt axis circuit having the pre-alarm characteristic detects the main circuit 1 flow before an overcurrent occurs, it generates the pre-source stock (f1), and operates according to the pre-t↑ report signal. The relay coil is excited by the output of the advance warning output circuit, which in turn sounds the buzzer and lights up the advance warning operation display LED.Furthermore, the capacitor connected in parallel with the advance warning operation display LED is Reduce the voltage generated in the relay coil.

〔Example〕

FIG. 1 is a block diagram showing a partial circuit diagram of an embodiment of the present invention, and in the figure, numerals 1, 2.4 to 14 are exactly the same as those shown in FIG. Circuit breaker 3 of this invention
8 is further connected to the output side of the maximum phase selection and effective value conversion circuit 8, and has an advance warning characteristic for detecting the main circuit current before reaching overcurrent #: and issuing a warning in advance. An alarm circuit 20, an advance alarm output circuit 21 connected to the output side of the advance alarm circuit 20 and operated by the advance alarm signal, and a voltage drop section, for example, a transformer 22, connected to the power supply side of the advance alarm output circuit 21. For example, a control power source 23 of AC fi 10 G volts is connected to the relay coil 24 and its normally open contact 24 which is excited by the output of the advance warning output circuit 21 on the output side of the advance warning output circuit 21.
a, an advance warning operation display LED 25 connected in parallel with the IJL/- coil 24 and lit by the output of the advance warning output circuit 21, and connected between both ends of the control power supply 23 via a normally open contact 24a. It includes a buzzer 26 and a capacitor 27 that is connected in parallel with the advance warning operation display LED 25 and reduces the voltage induced in the relay coil 24 by the magnetic flux generated by the main circuit current.

FIG. 2 is a curve diagram showing the overcurrent tripping characteristics and advance warning characteristics of the circuit breaker 3A of the present invention;
The figure is a waveform diagram showing the voltage across the LED.

In the circuit breaker 3A of the present invention shown in FIG.
When the current flowing through the main circuit w65 exceeds, for example, 70% of the rated current, the advance warning circuit 20 detects the value of the DC signal converted into the effective value from the maximum phase selection/effective value conversion circuit 8, that is, the second
An advance warning signal is supplied to the advance warning output circuit 21 after a predetermined time according to the advance warning characteristic PAL shown in the figure. Then, the advance warning output circuit 21 excites the relay coil 24 to close its normally open contact 24a, and the control power supply 23 energizes the buzzer 26 to sound it and lights up the advance warning operation LED 25. let

However, if the capacitor 27 is not provided, even if the main circuit current is large but the advance warning output circuit 21 has not outputted yet, a voltage will be induced in the relay coil 24 by the magnetic flux generated by the main circuit current, and this induced voltage is 4
The pre-warning LED 25Kl:I is applied and the voltage across it exceeds the lighting level TOL of, for example, 16V, as shown in Figure 3 (4), so the pre-warning LED 2
5 lights up incorrectly.

However, when the capacitor 27 is provided, this capacitor 27 suppresses the induced voltage, so the voltage across the LED becomes
As shown in Figure (B), the maximum level does not reach, for example, 1.3VKl, so it does not exceed the lighting level, and the L for advance warning operation
ED25 does not light up accidentally.

Although the main circuit current is large, it is still early warning output circuit 2.
If the capacitor 27 is not provided when the output is not output, the LED 25 for advance warning operation will be activated as shown in Figure 4.
It is natural that the light will turn on incorrectly.

Even if a diode (not shown) is connected to the relay coil 24 and the storage column after providing the capacitor 27, the result shown in FIG. 4 (B
As in 1), the advance warning operation LED 25 may be erroneously lit. In such a case, capacitor 27
If a diode (not shown) is connected in anti-parallel to the LED for advanced warning operation after providing a not light.

〔Effect of the invention〕

As described in detail above, the present invention provides an advance warning circuit having advance warning characteristics for detecting current before it reaches an overcurrent and issuing a warning in advance, and an advance warning signal from this advance warning circuit. an advance warning output circuit operated by the advance warning output circuit; a relay coil excited by the power of this advance warning output circuit; an LED for displaying advance warning operation connected in parallel with this relay coil and lit by the output; Since it is equipped with an LED for indicating alarm operation and a capacitor connected in parallel, it is possible to issue an alarm and notify the operator before the opening/closing mechanism of the single-circuit breaker is disconnected due to overcurrent flowing in the main circuit. If possible, it will also be effective in preventing erroneous lighting of the advance warning operation display LED during busy periods.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a partial circuit diagram of an embodiment of the invention, Fig. 2 is a curve diagram showing the characteristics of the circuit breaker of the invention, and Figs. 3 and 4 are explanations of the operation of the invention. 5 is a block diagram showing a conventional circuit breaker, and FIG. 6 is a curve diagram showing the characteristics of a conventional circuit breaker. In the figure, 1 is an AC power supply, 2 is a load, 3A is a circuit breaker, 4 is a switching mechanism, 5 is a main circuit, 9 is an instantaneous circuit, 1
0 is a short time limit circuit, 11 is a long time limit circuit, 13 is a tripping coil, 20 is an advance warning circuit, 21 is an advance tube shaft output circuit, 2
4 is a relay coil, 25 is an LED for advance alarm operation, 27
is a capacitor. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 2 Current 0? % of the rated current) Figure 4 Figure 6 Current, (fixed bolt: % to be sealed) Procedural amendment October 20, 1988

Claims (1)

[Claims] In a circuit disconnector having an overcurrent tripping characteristic for detecting an overcurrent flowing in a main circuit between an AC power supply and a load and disconnecting the main circuit, the current before the overcurrent occurs. an advance warning circuit having advance warning characteristics for detecting and issuing a warning in advance, an advance warning output circuit operated by a advance warning signal from this advance warning circuit, and an output of this advance warning output circuit. a relay coil excited by the relay coil, an advance warning operation display LED connected in parallel with the relay coil and lit by the output, and a capacitor connected in parallel with the advance warning operation display LED. A circuit disconnector characterized by being equipped with.