JPS59113715A - Opposite phase protecting circuit for circuit breaker - 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] [Technical Field of the Invention] [The present invention detects when a reverse phase occurs in the main circuit connected to a three-phase AC power supply, and The present invention relates to an anti-phase protection circuit for a circuit breaker for cutting off a power source and a main circuit.

[Technical background of the invention]

Conventionally, anti-phase protection circuits for circuit breakers generally detect anti-phase using two transformers that detect the phase of the main circuit.

FIG. 1 is a block diagram showing the configuration of such a conventional anti-phase protection circuit of a circuit interrupter.

As shown in FIG. 1, a power supply 1 is a main circuit and supplies power to a load 3 via an interrupter 2. Now, connect each phase of the main circuit to R and S.
*If T, transformer 4 is connected between R-8 phases,
A transformer 5 is connected between the ST phases. One of the secondary output terminals of these transformers 4 and 5 is connected as a common terminal, and the capacitor? 6 to a voltage sensing circuit 7 and a resistor 8. Furthermore, the transformer 4
The other output terminal of the transformer 5 is connected to the other end of the resistor 8, and the other output terminal of the transformer 5 is connected to the other end of the voltage determination circuit 7.

The gate electrode of the thyristor 9 is connected to the output terminal of this voltage judgment circuit 7, and the thyristor 9 is ignited by a trigger signal (4) which is issued by determining the magnitude of the voltage input to the voltage judgment circuit 7. do. Furthermore, the other output terminal of the transformer 5 is connected to the cathode electrode of this thyristor 9, and the tripping coil 10 is connected to the anode electrode. Further, 11 is a power supply circuit that supplies power to this tripping coil.

In the anti-phase protection circuit of the conventional circuit breaker as described above, the phase order of the AC voltage application in the main circuit is changed to, for example, R-8-
In the case of T, as shown in Fig. 2, the R-8 phase-to-phase voltage v1
is the waveform of A, and the S-T phase voltage v2 is the R-8 phase voltage vl.
Waveform of B with 120° phase delay, T-R phase voltage v
3 is the S-T phase voltage v2) It becomes a waveform of C whose phase is further delayed by 120°. Therefore, the above V1 # V2 zV
3 is each v! =Eslnω1 −・−(1)v
2 = EsIn(ωt-120°) (2
)V 3 = E gh+ (ωt-240°)...
...It is expressed as (3). Here, E is the voltage peak value, ω
represents the angular frequency, and t represents the time.

Furthermore, if the number of turns is the same on both the primary and secondary sides of each of the transformers 4.5 in FIG.
Since the R-8 correlation voltage applied to the R-8 correlation voltage and the S-T interphase voltage applied to the voltage determination circuit 7 each pass through the capacitor 6, the voltage V4 + Vs (i.e., the second In the figure, the waveform shown is E. Expressing this as a formula, v4=Es1rI(ωt+90°), ・-
・−・(4) V s' = Ed+ (ωt −300
) −(5). Therefore, if v1 to v5 are expressed in a vector diagram, the relationships will be as shown in FIG. 3 (,).

Now, assuming that the impedances of the resistor 8 and the input terminal of the voltage determination circuit 7 are equal, the voltage vo input to the voltage determination circuit 2 is the R-8 phase-to-phase voltage 4 through the capacitor 6 and the T-R This is a voltage difference between ± and the phase-to-phase voltage v3.

Therefore, Vo at the time of positive phase can be expressed as 1
・・・・・・(6)Vo=Tv
3-v4. This relationship is represented by the vector diagram in FIG. 3(b). The absolute value of this *0 +V, + is 0.62E
......(7).

In this state, for example, suppose that a reverse phase occurs between the R phase and the T phase. Then, v4 on the right side of equation (6)
will just replace vs. Therefore, the voltage ``o'' applied to the voltage determination circuit 7 at this time is expressed by the following equation.

■.・=±V3−v.

2 (8) This relationship is represented by the vector diagram in FIG. 3(c). Therefore, the absolute value of vo' at this time 1ψo'1 is 1.45E
......(9).

As described above, the peak value of the voltage applied to the voltage judgment circuit 7 changes from 0.62E when the phase is positive to 1.45E when the phase is negative. Light doing phase protection.

[Problems with background technology]

In the anti-phase protection circuit of the conventional circuit breaker with the above configuration, the magnitude of the power supply voltage applied to the main circuit is 100, 200, 41
5V, etc.), the voltage peak value E also changes, so there is a problem in that the circuit constants of the voltage determination circuit 7, etc. must be changed depending on the main circuit voltage.

Additionally, since a transformer was used, special consideration was required from the viewpoint of safety, considering the magnitude of the withstand voltage. Furthermore, this type of anti-phase protection circuit is generally installed in conjunction with the overcurrent and overload protection circuit of a circuit breaker, and recently it has been widely used as a means of detecting overcurrent and overload for the main circuit voltage. For safety reasons, current transformers are increasingly being used. Therefore, there has been a strong desire to realize a circuit breaker that can be used in combination with this current transformer even in anti-phase detection.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to detect phase inversion using a current transformer, so that the circuit constant does not depend on the main circuit voltage, and this current transformer An object of the present invention is to provide an anti-phase protection circuit for a circuit breaker, which enables the combined use of a current transformer for detecting overcurrent and overload, and as a result, has greatly improved versatility and safety.

[Summary of the invention]

In order to achieve the above object, the present invention uses a current transformer as a means for detecting anti-phase in the main circuit, and half-wave rectifies and waveforms the two phase currents of the main circuit detected by the current transformer. A means is provided for obtaining a digital pulse and outputting an anti-phase detection signal when the state of one of these digital pulses at the time of rising or falling is different from the state of the other one at the time of positive phase. It is characterized by anti-reciprocal protection.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6.

Figure 4 is a circuit diagram showing the configuration of the anti-phase protection circuit of the circuit breaker according to this embodiment. In FIG. 4, the same parts as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

In FIG. 4, 12a to 12c are current transformers that detect the current flowing in each phase, and 13a to 13b are current transformers 12a to 1.
Current transformers 12a, 12b are connected to full-wave rectify the alternating current from 2c, RlS, and T-phase currents. The winding end of each detection coil of the current transformers 12h, 12b, 12c is connected to the anode of the rectifier 13d and the cathode of the rectifier 13h. . In addition, the rectifier 13h
The cathode of ~13d is connected to the power supply circuit 15 via the resistor 14.
The other end of the power supply circuit 15 is commonly connected to the anodes of the rectifiers 13e to 13h.

On the other hand, for the two current transformers 12a and 12b, the winding start of the detection coil is located close to the other rectifiers 16a and 16a.
The R and S currents detected by the current transformers 12a and 12b are half-wave rectified. Furthermore, the cathode of the rectifier 16a is connected to the resistor 1.
7a to the data input terminal of the D-type flip-flop 18 (hereinafter referred to as the "flip-flop" terminal), and the cathode of the rectifier 16b is connected to the D-type flip-flop 0 through a resistor 17b.
Each terminal is connected to 18 clock input terminals (hereinafter referred to as CK terminals). Further, the set input terminal (hereinafter referred to as S terminal) of this D-type flip-flop 180 is an output terminal of a set circuit 19 that outputs a set signal at the moment when the power supply voltage of the power supply circuit +≧carp 15 shifts to a steady state. is connected, and the inverting output terminal (hereinafter referred to as an alternating terminal) of the D-type flip Flora f18 is connected to the dart electrode of the thyristor 9.

In the anti-phase protection circuit of the circuit breaker configured as described above, if the phase order of the main circuit is R-8-T, current transformer 12g+12b.

Each output current waveform of 12c is F in FIG.

The currents shown in F, G, and I( are passed through a full-wave rectifier circuit such as rectifiers 13a to 13h in FIG. 4, and have the waveform of I in FIG. 5. Furthermore, a power supply circuit 1 consisting of a Zener diode etc. is connected via a resistor 14.
Added to 5.

As a result, the terminal voltage of the power supply circuit 15 has a constant voltage waveform shown by J in FIG. The above is the current transformers 12a to 12c.
This is the process of converting the alternating current obtained by the method into a constant voltage power source.

On the other hand, the alternating currents output from the current transformers 12 a r 12 b are each hand-rectified by the rectifiers 16 a * 16 b, resulting in waveforms shown at K and L in FIG. 5. To these waveforms, the voltages indicated by L are applied to the anodes of the rectifiers 20a and 20b via resistors 178 and 17b, respectively, and the voltage difference exceeding the power supply voltage of the wire circuit 15 is clipped, so that the voltages indicated by L are applied to the anodes of the rectifiers 20a and 20b, respectively. The result will be the square wave shown.

Furthermore, these waveforms M and N are input to the D terminal and cK terminal of the D-type clip flop 18 at the subsequent stage, respectively.

FIG. 6 is a waveform diagram for explaining the operation of the above-described clip-flop 18. Note that the same parts as in FIG. 5 are given the same reference numerals and detailed explanations will be omitted.

The above-mentioned Rig Frog 15) has a function of storing the state of the signal applied to the D terminal at the rising edge of the signal input to the jHcK terminal.

Therefore, the waveforms M and N obtained in the above process are respectively D
When applied to the CK terminal and the CK terminal, the output terminal of the D-type clip flop 18 (hereinafter referred to as the Q terminal) has the waveform shown in FIG. Here, the level holding time t of waveform P is the time from when the circuit breaker is turned on until the first rising edge is applied to the CK terminal of the above-mentioned flop/flop 18, and is a maximum of 20 m5ec (when the power supply frequency is 50 Hz].

Therefore, the set circuit 19 in FIG. 4 applies an O level voltage to the S terminal of the above-mentioned flip-flop 18 until the power supply voltage of the power supply circuit 15 shifts to a steady state. As a result, the above t can be set to 0.

The above is an explanation of the operation of the D-type clip-flop 18 in positive phase. That is, during the positive phase, a voltage at the θ level is always output from the mutual terminals, so the thyristor 9 in FIG. 4 maintains the cut-off state.

On the other hand, in the anti-phase protection circuit with the above configuration, for example, now S
Suppose that an antiphase occurs between the phase and the T phase.

In this case, the waveforms G and H in FIG. 5 are interchanged, and the phase of the current flowing in the S phase is delayed by exactly 120°. Therefore, C of the above-mentioned flip-flop 18
A voltage having a waveform indicated by U in FIG. 6 is applied to the K terminal. As a result, since the state of the D terminal at the rising edge of the waveform U (that is, the state of the waveform M) is O level, the output from the Q terminal becomes V, and the output from the Q terminal becomes the waveform shown by W. . Therefore, the output from this terminal is applied to the dart electrode of the thyristor 9, and the main circuit is cut off by making the thyristor 9 conductive.

In the anti-phase protection circuit of the circuit breaker according to the present embodiment as described above, the current phase of the main circuit is changed between the current transformers 12a to 12.
c, the circuit constants do not depend on the magnitude of the main circuit voltage. Furthermore, since the anti-phase detection method uses a digital circuit to directly detect the phase, the detection accuracy is greatly improved compared to the conventional method.

In the above embodiment, the operation when the S phase and the T phase in FIG.
It goes without saying that exactly the same operation is performed when an antiphase occurs.

In addition, in the above-described flop/flop 18, the state of the signal applied to the D terminal at the rising edge of the signal input to the CK terminal is maintained, but the state of the signal applied to the D terminal at the falling edge of the signal input to the CK terminal is maintained. It goes without saying that antiphase detection can be performed in exactly the same manner using a flop that maintains the state of . In this case, waveforms N and M shown in FIG. 6 may be applied to the CK and D terminals, respectively.

Further, in the above embodiment, the thyristor 9 is used as an output latch circuit for pulling the main circuit, but in this embodiment, the output from the mutual terminals of the D-type clip flop 18 remains in its output state during the anti-phase period. Therefore, instead of using the thyristor 9 as described above, an element such as a transistor may be used instead.

Furthermore, as mentioned above, the outputs from the mutual terminals of the D-type flip-flop 18 at the time of anti-phase cannot be maintained at the power supply voltage level of the power supply circuit 16, by providing an operation delay circuit at the next stage. Compared to conventional methods, it is possible to significantly improve the accuracy of delay time. Furthermore, by adding digital circuits such as oscillators and counters, the above accuracy can be further improved.

〔Effect of the invention〕

As described above, according to the present invention, since a current transformer is used for anti-phase detection, the circuit constant of the anti-phase protection circuit does not depend on the magnitude of the main circuit voltage. It can be used in combination with a current transformer for overcurrent and overload detection. Therefore, it is possible to provide an anti-phase protection circuit for a circuit breaker with greatly improved versatility and safety.

In addition, since a digital circuit is used to directly check the change in the phase as the anti-phase discrimination means, the accuracy of anti-phase discrimination is greatly improved. can be provided.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams for explaining a conventional anti-phase protection circuit for a circuit interrupter. Fig. 1 is a block diagram showing an anti-phase protection circuit for a circuit interrupter. FIG. 4 is a block diagram showing the configuration of the out-of-phase protection circuit of the circuit breaker, and FIG. 5 is a diagram showing an example of determining the output and voltage of the transformer in FIG. FIG. 6 is a waveform chart showing the full-wave rectification, single-wave rectification, and waveform shaping process of the output current. FIG. 6 is a waveform chart showing the operating state of the D-type flip flop shown in FIG. 1...Power supply, 2...Main circuit breaker, 3...Load, 4.5...Transformer, 6...Capacitor, 7...
Voltage judgment circuit, 8, 14, 17a, 17b
...-Resistor, 9... Thyristor, 10... Tripping coil, 11.15... Power supply circuit, 12a-1
2 (! # 13a~1 3 h jl 6
a s 1 6 b s 2 0 a
p20b... Rectifier, )8... D-type frizzo flop, 19... Set circuit. Applicant's agent Patent attorney Suzue Takehiko 1st WJ Figure 2 Figure 3rI! j (a) (b) (c) Figure 4 Figure 5 -→-1

Claims (2)

[Claims] (1) At least two current transformers installed in the main circuit to detect two different phase currents in the main circuit, and half-wave rectification and waveform shaping of the alternating current obtained by these current transformers. A means for converting into a digital pulse, and a state of the second digital pulse at the time of rising or falling of the first digital pulse by means of the antiphase of the main circuit of the at least two digital pulses obtained by this means. An anti-phase protection circuit for a circuit breaker, comprising means for outputting an anti-phase detection signal when the state differs from the normal phase state. (2) The circuit according to claim 1, wherein the current transformer is a means for detecting overload and short-circuit conditions so as to cut off the main circuit when the main circuit is overloaded and short-circuited. Breaker anti-phase protection circuit.