JP2804868B2 - Circuit breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker,
More particularly, the present invention relates to a circuit breaker for stabilizing the operation of an integrating circuit for reproducing a waveform of a current signal for circuit interruption determination detected from an AC electric circuit.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing the entire structure of a conventional circuit breaker. In the figure, U, V, W, and N denote each phase of an AC power supply (not shown), 1 denotes a main circuit as an AC electric circuit composed of phase conductors connecting each phase and a load, and 3 denotes a trip coil as a tripping electromagnetic device. When the magnetism is excited, the breaking contact 2 is opened via the breaking mechanism 4 and when the magnetism is demagnetized, the breaking contact 2 is closed. 5 is a current transformer having each phase conductor of the main circuit 1 as a primary winding, 6 is a rectifier circuit which is connected to the current transformer 5 and converts AC to DC of the main circuit 1, and 7 is connected to the rectifier circuit 6. A power supply circuit for supplying necessary voltages to various circuits to be described later;
Is an electronic switch connected in series with the trip coil 3 between both ends of the power supply circuit 7.

Reference numeral 9 denotes an air-core coil as a current detection coil electromagnetically coupled to each phase conductor of the main circuit 1, which detects a load current by the magnetic flux of each phase conductor and generates an induced voltage at both ends of the coil. An overcurrent signal regeneration circuit 10 is connected to both ends of the air-core coil 9 and reproduces the generated induced voltage into a current signal. A rectification signal circuit 11 rectifies the current signal reproduced by the overcurrent signal regeneration circuit 10. , 12
B is a maximum phase selection circuit that selects the maximum phase rectification signal among the rectification signals of each phase connected to each other on the output side of the rectification signal circuit 11, and 13 and 14 are maximum phase selection circuits 12A and 12
A peak value conversion circuit and an effective value conversion circuit for converting the rectified signal selected by B into a peak value and an effective value, respectively.

A trip 15 occurs when the rectified signal from the maximum phase selection circuit 12 exceeds a predetermined instantaneous trip characteristic.
Instantaneous trip circuit that outputs a signal to the electronic switch 8
Reference numeral 6 denotes a short time trip circuit for outputting a trip signal to the electronic switch 8 when the peak-converted rectified signal from the peak value conversion circuit 13 exceeds a predetermined short time trip characteristic. Since other circuits are not directly related to the present invention, the description thereof is omitted here.

FIG. 6 is a circuit diagram showing a detailed configuration of the overcurrent signal reproducing circuit 10. As shown in FIG. In the figure, reference numerals 10A to 10D denote operational amplifiers constituting an integrating circuit, respectively, and reproduce the original overcurrent waveform by integrating the induced voltage detected by the air-core coil 9 in the form of a differential signal. 10A1 and 10A2 are input resistors for inputting an overcurrent signal from the air-core coil 9 to the operational amplifier 10A, and 10A3 and 10A4 are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier 10A to form a time constant circuit of an integrating circuit. It is a feedback resistor and an integration capacitor. In the other operational amplifiers 10B to 10D, similar resistors and capacitors are connected to form an integrating circuit.

Next, the operation of the conventional circuit breaker will be described focusing on the operation of the overcurrent signal regeneration circuit 10. When a load current flows through each phase conductor constituting the main circuit 1, a magnetic field is generated in the phase conductor. When the air-core coil 9 electromagnetically coupled to the phase conductor detects the magnetic field by electromagnetic induction, an induced voltage having a waveform obtained by differentiating the load current waveform is generated at both ends of the air-core coil 9.

An induced voltage generated at both ends of the air core 9 is applied to the operational amplifier 10A through input resistors 10A1 and 10A2, for example.
, The operational amplifier 10A becomes the integrating capacitor 10
A4, since the integration circuit is configured together with the input resistor 10A3, the input induced voltage is converted to the original load current waveform, that is, sin.
The load current waveform forming the curve is differentiated and the phase is advanced.
When the induced voltage waveform forms an s-curve, the induced voltage waveform is integrated and reproduced as a sin curve, and is output as a current signal to the rectified signal circuit 11 at the subsequent stage. The rectified signal circuit 11 performs full-wave rectification on the input current signal, and outputs the current signal to the peak value conversion circuit 13 through the maximum phase selection circuit 12A to obtain the peak value of the load current.

[0008]

A conventional circuit breaker is:
As described above, the power supply voltages of all the circuits including the overcurrent signal regeneration circuit are supplied from the power supply circuit based on the load current. Therefore, in the overcurrent signal regeneration circuit, if the operational amplifier captures the current signal from the air-core coil in a state where the power supply voltage does not rise to a certain voltage value, the current signal is not completely integrated but is output as an inaccurate current signal and is output in the subsequent stage. There is a problem that the above circuit malfunctions.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to make the operation of the circuit effective after detecting that the power supply voltage of the circuit has risen to a constant value. The purpose is to obtain a vessel.

[0010]

A circuit breaker according to the present invention comprises: a current detecting coil for generating an induced voltage corresponding to a current value when detecting a current flowing through an AC circuit; An integrating circuit for integrating and reproducing a current waveform, a short-circuiting means for short-circuiting a capacitor connected between an input terminal and an output terminal of an operational amplifier constituting the integrating circuit, and detecting a rise of a power supply voltage of the operational amplifier; When the voltage value is equal to or less than a preset value, the short-circuit means
And a short-circuit control means for outputting a short-circuit release signal to the short-circuit means to enable the integration circuit when the voltage value reaches a preset value. is there.

[0011]

In the circuit breaker according to the present invention, both ends of the capacitor constituting the integrating circuit are short-circuited by the short-circuit means until the power supply voltage of the circuit rises to a certain value, and the current is interrupted.
The charging of the capacitor is stopped to stop the integration operation. If the short-circuit control means detects that the power supply voltage has risen to a certain value, the short-circuit by the short-circuit means is released and the current is discharged.
By starting the integration operation by charging the battery, the induced voltage can be integrated.

[0012]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the circuit breaker according to the present embodiment. In the drawing, the same reference numerals as those in FIG. 5 indicate the same or corresponding parts. In the figure, reference numeral 7A denotes a power supply circuit according to the present embodiment, and 101 denotes an overcurrent signal reproducing circuit according to the present embodiment. FIG. 2 shows the overcurrent signal regeneration circuit 101 shown in FIG.
FIG. 2 is a circuit diagram showing a partial configuration of the embodiment. 6, the same reference numerals as those in FIG. 6 indicate the same or corresponding parts. In FIG, Q _A to Q _C is the FET as short-circuiting means, operational amplifier 10A~10
Feedback resistors 10A3 to 10C3 and integrating capacitors 10A4 to 1 connected between the input and output terminals of C
Both ends of the parallel circuit composed of 0A4 are short-circuited or opened by an external signal.

[0013] 102 is an integral starting voltage detecting circuit as a short-circuit control unit, Q ₁ as constituent Each FETs Q _A ~
A transistor providing a gate signal to the Q _C, the collector is connected to the ground terminal GG of the power supply circuit 7A through collector resistor R _1, the emitter is connected to the negative power supply line of the power supply circuit 7A V-. Also between the base and the ground terminal GG are connected in series circuit of a resistor R ₂ and the Zener diode ZD1 to provide a constant voltage to the base, the resistance R ₃ is further connected resistor R ₂ in series with the base between the base and emitter It is connected.

That is, the Zener voltage is applied to the base by the resistors R ₂ ,
Divided voltage is given by R _3, the divided voltage transistor Q ₁ when reaching the operating voltage of the transistor Q ₁ is turned on to off operation gives negative potential to the gate of the FETs Q _A to Q _C and.

FIG. 4 is a circuit diagram showing an output section of the power supply circuit 7A. In FIG, C ₁ on one end is the positive power supply line, a capacitor whose other end is connected to the ground terminal GG, give to the positive power supply line for example + 12V when viewed from the ground terminal GG. C ₂ to one end of the negative power supply line, a capacitor whose other end is connected to the ground terminal GG, give Tatoeba 12V to the negative power supply line when viewed from the ground terminal GG. ZD2 is a Zener diode connected in parallel with the capacitor C _1, to limit the positive-side power supply at a constant voltage of + 12V.

Next, the operation of this embodiment according to the above configuration will be described. First, when a DC voltage proportional to the load current is applied from the rectifier circuit 6 to the power supply circuit 7A, the capacitors C ₁ and C ₂ provided at the output section (FIG. 4) of the power supply circuit have the configuration shown in FIG.
As shown in the power supply voltage characteristic of FIG. At this time, the capacitor C connected to the positive power line
_When the charging voltage of ₁ reaches + 12V, the Zener diode ZD2 breaks down and limits the positive power supply V + to + 12V.

[0017] However, the ripple component for regard to the negative power supply are connected in parallel a resistor R ₄ to the capacitor C _2, etc., appear variables of the power supply to the negative power supply, until the supply voltage reaches a predetermined negative voltage V- It takes time. Therefore, when the minus power supply voltage V- reaches a constant voltage (-12 V), it can be detected that the power supply voltage of the power supply circuit 7A has risen to a constant value.

The ground terminal GG and the negative power supply line of the power supply circuit 7A configured as described above are connected to the integration start voltage detection circuit 1 built in the current signal reproduction circuit 101, respectively.
02 is connected to the ground terminal GG and the negative power supply terminal V-. In this state, the breaking contact 2 is turned on, the load current is passed to the rectifier circuit 6 through the current transformer 5, and the DC voltage is supplied to the voltage circuit 7A.
, The positive and negative power supply voltages gradually rise. However, the negative power supply voltage V- requires a longer time to rise to a constant voltage than the positive power supply voltage V + as described above.

[0019] Thus, in the integration start voltage detection circuit 102, the negative power supply voltage V- is viewed from the ground potential of the ground terminal GG, down zener diode ZD1 which is connected to the base of the transistor Q ₁ is to the potential to cause breakdown Not. Therefore, the transistor Q
Potential between the resistor R ₁ connected to the collector because the _first base operating voltage is in the OFF state irrespective is transmitted at the ground potential to the gates of the FETs Q _A to Q _C.
As a result the FETs Q _A to Q _C becomes between the source and the drain is turned on in ON operation, the operational amplifiers 10A~10C
Of the parallel circuit of the feedback resistors 10A3 to 10C3 and the integrating capacitors 10A4 to 10C4
It is short-circuited by ETQ _A to Q _C. As a result, the operational amplifier does not perform the integration operation while the voltage of the power supply circuit is not established at a constant value, so that an erroneous integrated output is not output to the rectified signal circuit 11 at the subsequent stage.

However, when the negative power supply voltage V- falls to a constant voltage value, the Zener diode ZD causes a breakdown to generate a Zener voltage. This Zener voltage is divided by the ratio of the resistors R ₃ and R ₂ to a transistor Q ₁
When applied to the base and the emitter, the transistor Q ₁ is lowered to the potential between the resistor R ₁ connected to the on-operation by the collector to the negative supply voltage V-.

[0021] As a result the FETs Q _A to Q _C off operation to the source, drain becomes nonconductive, the feedback resistor provided in each operational amplifier 1OA - 1OC 10A3～
The short circuit at both ends of the parallel circuit of 10C3 and integrating capacitors 10A4 to 10C4 is released. As a result, the operational amplifier performs an integration operation after the voltage of the power supply circuit is established at a constant value, and a normal integrated output is output to the rectified signal circuit 11 at the subsequent stage.

[0022]

As described above, according to the present invention, a current detecting coil for generating an induced voltage corresponding to a current value when a current flowing through an AC circuit is detected, and a current detected by integrating the induced voltage generated in the current detecting coil. An integrating circuit for reproducing a waveform, short-circuit means for short-circuiting a capacitor connected between an input terminal and an output terminal of an operational amplifier constituting the integrating circuit, and detecting a rise of a power supply voltage of the operational amplifier, and detecting a voltage value. When the value is equal to or less than a preset value , the short-circuit means is short-circuited, and
The integration circuit is disabled, and when the voltage value reaches a preset value, a short-circuit release signal is output to the short-circuit means to output the product.
Short-circuit control means for enabling the branch circuit, and enabling the integration operation by the operational amplifier after the power supply voltage of the operational amplifier is established at a constant value, so that an erroneous integration output is not output at power-on. This has the effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a circuit breaker according to the present invention.

FIG. 2 is a circuit diagram showing a configuration of a current signal reproducing circuit according to the embodiment.

FIG. 3 is a characteristic diagram illustrating a power supply voltage rise characteristic of the power supply circuit according to the present embodiment.

FIG. 4 is a circuit diagram showing an output unit of the power supply circuit according to the embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional circuit breaker.

FIG. 6 is a circuit diagram showing a configuration of a conventional current signal reproducing circuit.

[Explanation of symbols]

1 the main circuit 9 air-core coil 10A~10C operational amplifier 102 integration start voltage detecting circuit Q _A to Q _C FET

Continuation of the front page (56) References JP-A-49-135563 (JP, A) JP-A-2-232875 (JP, A) JP-A-4-135948 (JP, A) Jpn. , U) Actually open 63-33949 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02H 3/08-3/52

Claims (1)

(57) [Claims] 1. A current detection coil for generating an induced voltage according to a current value when a current flowing in an AC circuit is detected, an integration circuit for integrating the induced voltage generated in the current detection coil to reproduce a current waveform, and an integration circuit for integrating the induced voltage. Short-circuit means for short-circuiting a capacitor connected between an input terminal and an output terminal of an operational amplifier constituting a circuit; detecting a rise of a power supply voltage of the operational amplifier; detecting a short-circuit when a voltage value is equal to or less than a preset value;
Short-circuit control means for short-circuiting the connection means and disabling the integration circuit , outputting a short-circuit release signal to the short-circuit means when the voltage value reaches a preset value, and enabling the integration circuit . A circuit breaker, characterized in that: