JPH0223022A - 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] [Field of Industrial Application] This invention is a one-circuit breaker. The present invention relates to a circuit breaker that can detect current and issue a warning before tripping, but does not issue unnecessary alarms.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional circuit breaker,
In the figure, 1 is an AC power source, for example, a 3-phase AC 1 power source, 2 is a load supplied with power by this AC power source 1, such as a motor, and 3 is
is a circuit breaker connected between these AC power sources 1 and loads 20. This circuit breaker 3 has three-phase parts 6a, 5b, 15C, which are connected to the AC power supply 1 via the opening/closing @ structure part 4.
A main circuit 5 consisting of a main circuit 5 and each phase conductor 5a, 5 of this main circuit 5.
b, current transformer CT a + C connected to 5C respectively
T b * CT c, a rectifier circuit 6 connected to the secondary side of these current transformers, a maximum phase selection peak value conversion circuit 7 and a maximum phase selection peak value conversion circuit 7 individually connected to the output side of this rectification circuit 6. An instantaneous circuit 9 is connected to the output side of the effective value conversion circuit 8 and the maximum phase selection and peak value conversion circuit 7, and a short time limit circuit 10 is connected to the output side of the maximum phase selection and effective value conversion circuit 8. A long time limit circuit 11, a trigger circuit 12 connected to the output sides of the time limit circuit 9, short time limit circuit 10, and long time limit circuit 11, and a trigger circuit 12 connected across the rectifier circuit 6 via this trigger circuit 12. It includes a tripping coil 13 and an overcurrent indicating LED 14 connected to a long time limit circuit 11'. Note that the circuits 7 to 11 described above are made of dedicated ICs.

FIG. 6 is the first diagram of the song shown in FIG. 5, which also shows the overcurrent string disconnection characteristics of the circuit breaker 3.

The conventional circuit interrupter 53 is constructed as described above, and its operation will be described with reference to FIGS. 5 and 6. Assume now that the opening/closing mechanism 4 of the circuit breaker 3 is closed, that is, it is not tripped, and a ft current is flowing from the AC power source 1 through the main circuit 5 to the load 2. current transformer CTa,
CTb and CTc allow a secondary current proportional to the main circuit current to flow through their secondary sides.

The rectifier circuit 6 rectifies the AC secondary current of each of the three phases. The maximum phase selection and peak value conversion circuit 7 is a
The maximum phase rectified signal is selected from among the rectified signals of each phase, and this is peak ji, f1 . tj exchange. Similarly, the maximum phase selection and effective value conversion circuit 8 selects the maximum phase source 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.
The blood flow signal, which has been converted into an effective value, is supplied to a long time circuit 11 having a long time characteristic LTD. When the main circuit current 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 1000 of the chemotactic current.
After a predetermined period of time shown in FIG. 6 according to the
14 is turned on. When the trigger circuit 12 is turned on, the trip coil 13 is rescued by the rectified output of the rectifier circuit 6, opens the opening/closing mechanism 4, and cuts off the main circuit current. Similarly, when the main circuit current becomes large and exceeds, for example, 1000% or 1700% of the rated tIL flow, the short time limit circuit 10 and the instantaneous circuit 9 respectively output outputs and cut off the main circuit current.

[The invention is about to solve the problem. J111 Conventional circuit breakers such as those described above have an overcurrent line disconnection characteristic to cut off the main circuit only when the main circuit 'ki current becomes an overcurrent state, but when the main circuit it current becomes an overcurrent state, There is no small advance warning characteristic to issue an E-warning before the situation is reached;
He received 41 points for giving unnecessary publicity and for not doing so.

The present invention was made in order to solve this problem, and it is an object of the present invention to provide a circuit breaker which has an R front path t+i characteristic and does not emit unnecessary signals.

[■, Means to solve the problem]

Is the circuit breaker according to this invention overpowered? a first comparison means that outputs an output and turns off the normally closed switch when the current of 11 of the currents reaching `rr exceeds a predetermined value; An advance warning circuit is provided, which has a capacitor that generates a voltage according to the voltage, and a second comparison means that generates an advance warning signal by outputting an output and turning on a normally open switch when this capacitor voltage continues for a predetermined time or more. It is something.

[For production]

In this invention, when the main circuit current exceeds a predetermined value before an overcurrent occurs, the first comparison means in the advance warning circuit outputs an output and turns off the normally closed switch. When the capacitor voltage continues for a predetermined period of time or more, the second comparison means outputs an output to generate a pre-warning signal. However, if the capacitor voltage does not continue for a predetermined period of time or longer, the capacitor is instantly discharged and no advance notification signal is generated.

〔Example〕

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. Circuit breaker 3 of this invention
A 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 it reaches an overcurrent and issuing a warning in advance. The circuit 20, a photocoupler 27 consisting of a light emitting diode 27a connected to the output side of the advance warning circuit 20, and a phototransistor 27b optically coupled to the light emitting diode, and an advance tube shaft circuit connected to the output side Km of the phototransistor 27b. A pre-tube shaft output circuit 21 operated by a pre-tube shaft signal from 20 and this pre-tube shaft output circuit 2
A control power supply 23 of AC 100 volts, for example, which is connected to the power supply side of 1 via a voltage drop unit, for example, a transformer 22, and a relay that is excited by the output of the advance tube shaft output circuit 21 on the output side of the advance warning output circuit 21. The coil 24 and its normally open contact 24a, the advance % axis operation display IJD 25 as a sound axis means connected in parallel with the relay coil 24 and lit by the output of the advance alarm output circuit 21, and the normally open contact 24a. A buzzer 26 as an alarm means is connected between both ends of the control power source 230 via the control power source 230.

FIG. 2 is a curve diagram showing the overcurrent 1 release characteristic and advance telegram characteristic of the circuit breaker 3A of the present invention.

In the circuit breaker 3A of the present invention shown in FIG.
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 signal shown in FIG. After a predetermined period of time according to the characteristic PAL, an advance warning signal is supplied to the advance warning output circuit 21 through the photocoupler 27tf.

Then, the advance warning output circuit 21 excites the relay coil 24 to close its normally closed contact 24a, and the control power supply 24 energizes the buzzer 26 to sound it and lights up the advance warning operation LED 25. let

Figure 3 shows the advance warning circuit 2 shown in the block diagram in Figure 1.
00 circuit diagram, and FIG. 4 shows this advance warning circuit 2.
FIG. 2 is a waveform diagram for explaining the operation of 0.

In the advance warning circuit 20 of FIG. 3, V+, 5GN
D and V- are power supply terminals, V ref is a reference voltage supply terminal for a timer comparator to be described later, VRref is a variable reference voltage supply terminal for a comparator for advance warning generation to be described later, and RMS+
is a terminal to which the DC signal converted to an effective value is supplied from the maximum phase selection/effective value conversion circuit 8 shown in FIG. 1, and is a terminal VRr.
Between ef and 5GND is a resistor R1゜potentiometer V
R and resistor R2 are connected in series. The first comparison means, that is, the advance warning generation comparator CO1 connected between the terminals V+ and V- has its non-inverting input terminal connected to the arm of the potentiometer VR and its inverting input terminal -
is connected to terminal RMS+. Terminal Vre f and 5
A resistor R3 and a capacitor C are connected in series between GND, and resistors R4 and R5 are further connected in series in parallel with this iIt column circuit. A normally closed switch Q1 is connected in parallel with the capacitor C, and a resistor R6 is also connected.

The second comparison means, that is, the timer compensator CO2 connected between the terminals V+ and V- has its non-inverting input terminal connected to the connection point of resistors R4 and R5, and its inverting input terminal - connected to the resistor R3. and the connection point of capacitor C. A photocoupler 270 and a light emitting diode 27a are connected between the terminals ``+'' and ``V-''.

A resistor R7 and a normally open switch Q2 are connected in series.

Next, the operation of the advance warning circuit 20 configured as described above will be explained with reference to the waveform diagram of FIG. 4. First, the variable reference voltage of the advance warning generation comparator COI, that is, the advance warning generation level, is set to a predetermined value according to the rated current.

For example, the rating 'e1. If a is 40OA, 70% of that
In the case of 200A, it is set to 2v corresponding to 140A, which is 70% of 2g0A. At time tl, when the DC signal proportional to the effective value of the current in the main circuit exceeds the half-prewarning generation level, the prewarning comparator CO1 outputs an output and closes the normally closed switch Q1.
Turn off. Therefore, the RC timer consisting of resistor R3 and capacitor C starts operating, capacitor C is gradually charged and its voltage increases little by little. However, when the above-mentioned DC signal becomes smaller than the advance alarm generation level at time t2, the advance warning generation comparator COI does not output an output, and therefore the normally closed switch Q1 becomes ON. It discharges instantaneously through the closed switch Q1, so its voltage becomes zero. When the DC signal exceeds the pre-telegram generation level at time t3 and this state continues for a predetermined period of time, e.g., 40 seconds or more, the capacitor voltage reaches the reference voltage of the timer comparator CO2, that is, e.g., 2.5 V, which corresponds to the tube shaft output operating level. Since it is exceeded at time t4, the timer comparator CO2 outputs an output and turns on the normally open switch Q2. Therefore.

Terminal ■ From + to V- Photocoupler 270 light emitting diode 2
7a, a current flows through resistor R7 and normally open switch Q2 which is turned on. That is, the advance warning circuit 20 supplies the φ advance warning signal to the advance warning output circuit 21 through the photocoupler 27.

〔Effect of the invention〕

As described above, the present invention outputs an output when the subcurrent before an overcurrent or exceeds a predetermined value and turns the normally closed switch off.
A capacitor connected in parallel with the normally closed switch to generate a voltage according to the current exceeding the predetermined value, and a capacitor that outputs an output when the capacitor voltage continues for a predetermined time or more to switch the normally open switch. Since it is equipped with a pre-tube shaft circuit having a second comparison means that generates a pre-warning signal when the In addition to being able to issue an alarm to notify the operator, an advance warning signal is not generated unless the current exceeds a predetermined value for a predetermined period of time or more, which eliminates unnecessary alarms caused by inrush current when starting the motor, etc. It also has the effect of preventing it from emitting.

[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 this invention, and Fig. 3 is an advance telegraph circuit used in this invention. 4 is a waveform diagram for explaining the operation of the advance warning circuit shown in FIG. 3, FIG. 5 is a block diagram showing a conventional circuit breaker, and FIG. 6 is a characteristic of the conventional circuit breaker. FIG. 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 circuit, 11 is a long time circuit, 13 is a tripping coil, 20 is a prior acknowledgment circuit, 21 is a prior export power circuit, C
ot is a comparator for pre-sound axis generation as a first comparison means;
Ql is a normally closed switch, C is a capacitor, CO2 is a timer comparator as a second comparing means, and Q2 is a normally open switch. In each figure, the same reference numerals indicate the same or corresponding parts. % for 1 female of Yodo Kakudori, 2nd edition) 10% for 1939 10
20th of the month

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. a first comparison means that outputs an output and turns off the normally closed switch when the current exceeds a predetermined value; a capacitor that is connected in parallel with the normally closed switch and generates a voltage according to the current that exceeds the predetermined value; and this capacitor. an advance warning circuit having a second comparison means for generating an advance warning signal by outputting an output and turning on a normally open switch when the voltage continues for a predetermined time or more; What is claimed is: 1. A circuit breaker comprising: an advance warning output circuit which is activated by the advance warning output circuit; and an alarm means which issues an alarm by the output of the advance warning output circuit.