JPH0255518A - Circuit breaker - Google Patents

Abstract

PURPOSE:To obtain a circuit breaker having a preliminary-alarm characteristic and an anti-time-limit characteristic by detecting main circuit current before it gets to the long time-limit region in the overcurrent tripping characteristics, and by generating a preliminary-alarm signal based on the operating time of the circuit breaker. CONSTITUTION:When the current flowing to a main circuit 5 gets to e.g., 70% of the rated current, a preliminary-alarm issuing current detection circuit 30 detects a preliminary-alarm issuing current portion PAL-GC, a value of a DC signal converted in an effective value from a maximum phase selection and effective value conversion circuit 8. A preliminary-alarm anti-time-limit characteristic circuit 31 issues a preliminary-alarm signal after the specified time in accordance with the current detected by the preliminary-alarm issuing current detection circuit 30 and the anti-time-limit characteristic PAL-AT based on the operating time of a circuit breaker 3A and supplies it to a preliminary-alarm output circuit 21. As a result, it excites a relay coil 24 to close a normally open contact 24a, while a control power source 23 energizes a buzzer 26 to ring and turns ON a preliminary-alarm operation displaying LED 25.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention provides a circuit breaker, especially before an overcurrent flows through its main circuit and the opening/closing mechanism is required. This invention relates to a circuit breaker that can detect current before it reaches a long time limit and issue a warning in advance.

[Prior Art] Fig. 3 is a block diagram of a conventional circuit/disconnector disclosed in Japanese Patent Application No. 63-168.994, with a partial circuit diagram not shown. A three-phase AC power source, 2 a load supplied with power by this AC power source 1, and 3 a circuit breaker connected between these AC power sources and the load 2. This circuit disconnector 3 has three-phase conductors 511, 51], 5(!) connected to the AC power supply 1 via the switching mechanism section 4.
A main circuit 5 consisting of a main circuit 5 and each phase conductor 5a, 5 of this main circuit 5.
b, 5c, respectively connected to current transformers CTa, CTb,
CTc, a rectifier circuit 6 connected to the secondary side of these current transformers, a maximum phase selection and peak value conversion circuit 7 and a maximum phase selection and effective value conversion circuit connected individually to the output side of this rectification circuit 6. circuit 8, and an instantaneous circuit 9 and a short time limit circuit 10 individually connected to the output side of the maximum phase selection/peak value conversion circuit 7.
, a long time limit circuit 11 connected to the output side of the maximum phase selection and effective value conversion circuit 8, and 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.
A tripping coil 13 is connected between both ends of the rectifier circuit 6 via the trigger circuit 12, and an overcurrent indicating LED 14 is connected to the long time limit circuit 11. In addition,
The above-mentioned circuits 7 to 1] are made with dedicated ICs.

The circuit breaker 3 is further connected to the output side of the maximum phase selection/effective value conversion circuit 8, and detects the main circuit current before reaching the long time region in the overcurrent tripping characteristic and issues a warning in advance. an advance warning circuit 20 having advance warning characteristics for causing
an advance warning output circuit 21 connected to the output side of this advance warning circuit 20 and operated by the advance warning signal;
For example, a control power supply 23 of AC 100 pol 1 or more is connected to the input side of the advance warning output circuit 21 via a voltage drop unit, for example, a transformer 22, and is connected to the output side of the advance warning output circuit 21 and excited by the output thereof. The relay coil 24 and its normally open contact 24a, and the relay coil 24
An alarm generating means, for example, an LED 25 for displaying advance alarm operation, which is connected in parallel with the advance alarm output circuit 21 and is lit by the output of the advance alarm output circuit 21, and a control power supply 2 via a normally open contact 24a.
Another alarm generating means connected between both ends of the alarm 3 includes a buzzer 26.

FIG. 4 is a curve diagram showing the overcurrent tripping characteristics and advance warning characteristics of the circuit breaker 3 shown in FIG. The overcurrent trip characteristic A is, for example, 100% to 1000% of the rated current.
% long time range LTD, 1000% to 1700% short time range STD, and 1700% or more instantaneous range L
Consists of N5T. In addition, advance warning characteristic B is such that the main circuit current exceeds, for example, 70% of the rated current or the long time period LTD
Pre-warning characteristic PAI- to issue a warning before the
Consists of.

The conventional circuit breaker 3 is constructed in a double series, and its operation will be explained with reference to FIGS. 3 and 4.

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 CT a
, CTl), CTc allows a secondary current proportional to the main circuit current to flow through its secondary side. The rectifier circuit 6 rectifies the AC secondary current of each of the three phases. The maximum sum selection/peak value conversion circuit 7 selects the maximum rectified signal of the rectified signals of each of the three phases 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 region I NST and short time region ST of the overcurrent trip characteristics shown in Fig. 4, respectively.
The direct current signal supplied to the instantaneous circuit 9 and the short time limit circuit 10 having the characteristics of
Long time circuit 11 with characteristics D and advance warning characteristics P
The signal is supplied to an advance warning circuit 20 having an AL.

When the current flowing through the main circuit 5 exceeds, for example, 70% of the rated current, the advance warning circuit 20 outputs the value of the DC signal converted into the effective value from the maximum phase selection/effective value conversion circuit 8, that is, the advance warning characteristic shown in FIG. A pre-warning signal is supplied to the pre-warning output circuit 21 after a certain period of time, for example 40 seconds, depending on the PAL.

Then, this 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 also turns on the advance warning operation display LED 25. Turn it on.

The main circuit current becomes even larger, e.g. 100% of the rated current.
%, the long time limit circuit 11 outputs an output after a predetermined time shown in FIG. 4 according to the value of the DC signal converted to an effective value, for example, 100% to 1000% of the rated current, and turns on the trigger circuit 12. At the same time, the overcurrent display LED 14 is turned on. When the trigger circuit 12 is turned on, the tripping coil 13 is excited by the rectified output of the rectifying circuit 6, opening the opening/closing mechanism 4 and cutting off the main circuit current. Similarly, the main circuit current becomes larger and larger, e.g. 1000% of the rated current.
%, if it exceeds 1700%, short time circuit] 0,
The instantaneous circuit 9 outputs an output and interrupts the main circuit current.

[Problems to be Solved by the Invention] The conventional circuit breaker as described above has a problem in that the advance warning operation time and therefore the generation time of the advance warning signal are fixed.

The present invention has been made to solve these problems, and an object of the present invention is to provide a circuit breaker having an advance warning characteristic of inverse timing.

[Means for Solving Problem 1] The circuit 1-B disconnector according to the present invention detects the main circuit current before reaching the long time limit region in the overcurrent tripping characteristic and issues a warning in advance. The advance warning signal is generated by the advance warning generation current detection circuit and the inverse time limit characteristic based on the current detected by the advance warning generation' upstream detection circuit and the operating time of the circuit cutter. This system is equipped with an advance warning inverse time characteristic circuit that generates the alarm.

[Function] In this invention, the advance alarm generation current detection circuit detects the current for generating the advance alarm, and the advance alarm inverse time characteristic circuit connects the detection current of the advance alarm generation current detection circuit with the current detected by the advance alarm generation current detection circuit.
Reverse time limit 1, based on the operating time of the disconnector? The relay coil is energized by the output of the advance warning output circuit activated by this advance warning signal, and
Furthermore, the buzzer is turned on and the advance warning operation display LED is also turned on.

[Embodiment] FIG. 1 is a block diagram showing a partial circuit diagram of an embodiment of the present invention.
is exactly the same as shown in FIG. The circuit breaker 3A of the present invention is connected to the output side of the maximum phase selection and effective value conversion circuit 8 instead of the advance warning circuit 20 shown in FIG. An advance alarm generation current detection circuit 30 for detecting the main circuit current before the main circuit reaches the main circuit and generating an alarm, and a circuit breaker connected to the output side of this advance alarm generation current detection circuit 30 and connected to the detected current and circuit cutoff. The pre-warning inverse time characteristic circuit 31 generates an advance warning signal with inverse time characteristic based on the operation time of the device 3A, and the output side of the advance warning inverse time characteristic circuit 31 is connected to the advance alarm output circuit 21. ing.

FIG. 2 is a curve diagram showing the overcurrent tripping characteristics and advance warning circuit of the circuit stamen/disconnector 3A of the present invention. The overcurrent tripping characteristic A is exactly the same as that shown in FIG. Advance warning anti-time characteristic portion PAL-A parallel to the alarm generation current portion PAL-GC and the anti-time characteristic portion of the long time limit LTD
Consists of T.

In this pre-warning anti-time characteristic part PAL-AT, the larger the current, the earlier the pre-warning signal will be generated in a shorter time, and conversely, the smaller the current, the longer the time will elapse, and therefore the pre-warning signal will be generated later.

In the circuit breaker 3A of the present invention shown in FIG.
When the current flowing through the main circuit 5 reaches, for example, 70% of the rated current, the advance warning generation current detection circuit 30 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 value shown in FIG. Advance warning generation current part P A L-G
Detect C. The advance warning inverse time limit characteristic circuit 31 has a reverse time limit characteristic P A I based on the current detected by the advance alarm generation current detection circuit 30 and the operating time of the circuit breaker 3A.
- Generates a pre-warning signal after a predetermined time in response to AT and supplies it to the pre-warning output port i\82].

As a result, this advance warning output circuit 21 energizes the relay coil 2/1 to close its normally open contact 24n, so that the control power supply 23 energizes the buzzer 26 to alert the user in advance. The alarm operation display LED 25 is turned on. Note that the overcurrent tripping operation is as described above with reference to FIG.

[Effects of the Invention] As described in detail above, the present invention provides an advance warning generation current that detects the main circuit current before reaching the long time limit region during the overcurrent bow removal characteristic and generates a warning in advance. a detection circuit;
In this case, since the circuit breaker is equipped with an advance alarm inverse time characteristic circuit that generates an advance alarm signal with an inverse time characteristic based on the current detected by the nif alarm generating current detection circuit and the operating time of the circuit breaker, This has the effect of providing advance warning characteristics that match the overcurrent tripping characteristics.

[Brief explanation of the drawing]

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 the present invention, and Fig. 3 is a partial circuit diagram of a conventional circuit breaker. A block diagram (not shown) is shown, and FIG. 4 is a curve diagram showing the characteristics of a conventional circuit walker. In the figure, 1 is an AC power supply, 2 is a load, 3A is a circuit disconnector, 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, 21 is a pre-warning output circuit, 25 is a pre-warning operation display LED, 26 is a buzzer, 30 is a pre-warning generation current detection circuit, 31 is a pre-warning circuit This is an alarm inverse time characteristic circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

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 source and a load and disconnecting the main circuit, the overcurrent tripping characteristic includes: An advance alarm generation current detection circuit for detecting the current before it reaches the long time limit and generating an alarm in advance, and the current detected by this advance alarm generation current detection circuit and the operating time of the circuit breaker. an advance warning inverse time characteristic circuit that generates an advance warning signal with an inverse time characteristic based on the inverse time characteristic circuit; an advance warning output circuit operated by the advance warning signal output from this advance warning inverse time characteristic circuit; 1. A circuit breaker characterized by comprising: an alarm generating means activated by the output of the output circuit.