JPH0223020A - Circuitbreaker - Google Patents

Abstract

PURPOSE:To prevent erroneous indication by arranging the axis of a coil to be excited by an output from a circuit for detecting current prevailing before function of an overcurrent circuitbreaker and producing an alarm in parallel with a main circuit then shielding the coil magnetically and lighting an indication lamp based on the output from the coil. CONSTITUTION:Load currents of respective phases in a main circuit 5 for feeding AC power from an AC power source 1 to a load 2 are detected through current transformers CTa-CTc and rectified. Maximum phase is selected from the output of a rectifier circuit 6 and converted into an effective value and a long time limit circuit 11 is triggered to light a LED 12. When the effective value having maximum phase exceeds over a predetermined level, a prealarm circuit 20 produces an output and energizes a prealarm output circuit 21. Consequently, exciting current flows through a magnetically shielded coil 24 having axial direction in parallel with the main circuit 5 and a contact 24a is closed to sound a buzzer 26 through a power source 23 and to light a LED 25. By such arrangement, an alarm is provided previously and erroneous lighting of the LED 25 is prevented.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is directed to a circuit breaker, especially before an overcurrent flows through its main circuit breaker and the opening/closing mechanism is tripped. This invention relates to a circuit breaker that can detect current and issue a warning in advance of tripping.

[Prior Art] Fig. 4 is a schematic diagram showing a conventional circuit breaker. In the figure, 1 is an AC power supply, for example, a three-phase AC power supply, 2 is a load supplied by this AC power supply 1, and 3 is a load supplied with these AC power supplies. This is a circuit breaker connected between an AC power source 1 and a load 2.

This circuit breaker 3 has a main circuit 5 consisting of three-phase conductors 5a, 5b, and 5c connected to an AC power source 1 via a switching mechanism part 4, and each phase conductor 5m, 5b, and 5e of this main circuit 5. The current transformers CTa, CTb, and CTc connected to each other, the rectifier circuit 6 connected to the secondary side of these current transformers, and the maximum phase selection and peak value connected individually to the output side of the rectifier circuit 6. The conversion circuit 7 and the maximum phase selection and effective value conversion circuit 8, the instantaneous circuit 9 and the short time limit circuit 10 connected individually to the output side of the maximum phase selection and peak value conversion circuit 7, and the maximum phase selection and effective value conversion circuit A long time limit circuit 11 connected to the output side of the circuit 8, a trigger circuit 12 connected to the output sides of the instantaneous circuit 9, the short time limit circuit 10, and the long time limit circuit 11, and the rectifier circuit 6 via the trigger circuit 12. A tripping coil 13 is connected between both ends of the circuit, and an overcurrent indicating LED 14 is connected to a long time limit circuit 11.

Note that the circuits 7 to 11 described above are made of dedicated ICs.

FIG. 5 is a curve diagram showing the overcurrent release characteristics of the circuit breaker 3 shown in FIG. 4.

The conventional circuit breaker 3 is constructed as described above, and its operation will be explained with reference to FIGS. 4 and 5. Assume that the switching mechanism 4 of the circuit breaker 3 is open, that is, it is not tripped, and current is flowing from the AC power supply 1 to the load 2 through the main circuit 5.
, CTb, and CTe flow a secondary current proportional to the main circuit current on their secondary side.The Ii current circuit 6 rectifies the AC secondary current of each of the three phases. The maximum phase selection/peak value conversion circuit 7 selects the maximum rectified signal from among the three-phase rectified signals from the rectifier circuit 6 and converts it to a peak value.

Similarly, the maximum phase selection/effective value conversion circuit 8 selects the maximum 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 of the overcurrent disconnection characteristics shown in Figure 5.
The direct current signal is supplied to an instantaneous circuit 9 and a short time limit circuit 10 having an effective value conversion, and is supplied to a long time limit circuit 11 having a long time limit characteristic LTD. When the main circuit current exceeds, for example, 125% of the rated current, the long time limit circuit 11 changes the effective value converted DC signal value, for example, from 125% to 1000 of the rated current.
After a predetermined period of time shown in FIG. 5 according to the
14 is turned on. 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 4, and cuts off the main circuit current. Similarly, the main circuit current increases and the rated current, e.g.
When exceeding oo% and 1700%, short time circuit 1
0, the instantaneous circuit 9 outputs and cuts off the main circuit current.

[Problems to be Solved by the Invention] Conventional circuit breakers such as those described above have overcurrent disconnection characteristics that cut off the main circuit only when the main circuit current reaches an overcurrent level. There is no advance warning feature to issue a warning just before the circuit current becomes overcurrent.
Furthermore, there is a problem in that it is not possible to prevent erroneous lighting of the advance 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 for Solving the Problems] A circuit breaker according to the present invention includes an advance warning circuit having advance warning characteristics for issuing a warning before the current flowing in the main circuit reaches an overcurrent, and this advance warning circuit. a pre-warning output circuit operated by a pre-warning signal from the pre-warning output circuit, a relay coil excited by the output of this pre-warning output circuit, a main body disposed parallel to the axis of this relay coil, and an end covering the end of the relay coil. and a pre-warning operation display LED connected in parallel with the relay coil and lit by the output.

[Operation] In the present invention, when the advance warning circuit having advance warning characteristics detects the main circuit current before reaching an overcurrent, it generates the advance warning signal, and the output of the advance warning output circuit activated by this advance warning signal causes the The relay coil is energized, the buzzer is sounded, and the LE for advance warning operation display is activated.
D is also lit.

[Embodiment] FIG. 1 is a block diagram showing a partial circuit diagram of an embodiment of the present invention, and in the figure, 1.2.4 to 14 are exactly the same as those shown in FIG. 3. Circuit breaker 3 of this invention
Further, A is an advance warning circuit connected to the output side of the maximum phase selection/effective value conversion circuit 8 and having advance warning characteristics for detecting the main circuit current before reaching an overcurrent and issuing a warning in advance. 20, an advance warning output circuit 21 connected to the output side of this advance warning circuit 20 and operated by the advance warning signal, and a voltage drop unit connected to the input side of this advance warning output circuit 21 via a transformer 22. For example, the control power supply 23 of AC 100 volts, the relay coil 24 and its normally open contact 24m excited by the output of the advance warning output circuit 21, and the output of the advance warning output circuit 21 connected in parallel with the relay coil 24. As is clear from the perspective view of FIG. The main body portion 27a is arranged parallel to the axis of the relay coil 24.
and a magnetic shield 27 having an end portion 27b that covers the end of the relay coil.

FIG. 2 is a curve diagram showing overcurrent release characteristics and advance warning characteristics of the circuit breaker 3A of the present invention.

In the circuit breaker 3A of the present invention shown in No. 112I, when the current flowing through the main circuit 5 exceeds, for example, 70% of the rated current, the advance warning circuit 20 performs effective value conversion from the maximum phase selection and effective value conversion circuit 8. for a predetermined period of time, e.g.
After 0 seconds, an advance warning signal is supplied to the advance warning output circuit 21. Then, this advance warning output circuit 21 excites the relay coil 24 to open its normally open contact 24m,
The control power source 23 energizes the buzzer 26 to make it sound, and also lights up the advance warning operation display LED 25. Note that since the relay coil 24 is provided with a magnetic shield 27, the magnetic flux due to the main circuit current passes through the magnetic shield 27 and does not pass through the relay coil 24, so that no induced voltage is generated in the relay coil 24. The advance warning operation display LED 25 is not erroneously lit.

[Effects of the Invention] As described in detail above, the present invention provides an advance warning circuit having advance warning characteristics for issuing a warning before the current flowing in the main circuit reaches an overcurrent, and an advance warning output circuit operated by the advance warning signal of the prior warning output circuit, a relay coil excited by the output of this advance warning output circuit, a main body portion disposed parallel to the axis of this relay coil, and an end portion covering the end of the relay coil. and an advance warning operation display LED that is connected in parallel with the relay coil and lit by the output, so that the rM jump mechanism of the circuit breaker is protected against overcurrent flowing in the main circuit. It is possible to issue a warning to notify the operator before it is tripped, and an LED to display the "g alarm" operation in advance.
This also has the effect of preventing erroneous lighting.

4. (Brief explanation on page 21) Fig. 1 is a block diagram showing a partial circuit diagram of an embodiment of the present invention, Fig. 2 is a curve diagram showing the characteristics of the circuit breaker of this invention, and Fig. 3 is a block diagram showing a partial circuit diagram of an embodiment of the present invention. A perspective view of the magnetic shield used in this invention, FIG. 4 is a block diagram showing a conventional circuit breaker,
FIG. 5 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 an opening/closing 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 a pre-warning circuit, 21 is a pre-warning output circuit, 2
4 is a relay coil, 25 is an LF for advance warning operation display, D
, 27 is a magnetic shield, 27m is a main body portion, and 27b is an end portion.

In each figure, the same reference numerals indicate the same or corresponding parts.

child 2 figure (B) ano, --- Saibako a7b-Mizube Broomstick 5 Electric JL (2 inches above the rated current) hand Continued Supplementary Positive book October 2nd, 1986

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 the advance warning signal from this advance warning circuit, and an excitation by the output of this advance warning output circuit. a magnetic shield having a main body disposed parallel to the axis of the relay coil and an end covering the end of the relay coil; and an advance warning connected in parallel with the relay coil and lit by the output. A circuit breaker characterized by being equipped with an LED for indicating operation.