JP3756716B2 - AA neutral wire phase loss circuit breaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an AA neutral wire phase loss protection circuit breaker having a function of interrupting a circuit and protecting a load against a high voltage generated when a neutral wire of a single phase 3-wire line is lost. In particular, it relates to countermeasures for high frequency noise.
[0002]
[Prior art]
In recent years, with the widespread use of single-phase three-wire distribution circuits, circuit breakers with AA neutral wire phase loss protection function that protects connected devices from abnormal voltage due to phase loss of the neutral wire are widely used.
As shown in the circuit diagram of FIG. 3, such a conventional AA neutral line breaker with phase loss protection is provided between the voltage lines L1 and L2 and the neutral line N (hereinafter referred to as L1-N and The voltage between the L2 and N2 is rectified by the diodes D1 and D2, divided by the two resistors R1 and R2, and the voltage applied to the resistor R2 is monitored between a and c of the abnormal voltage detection circuit 6, When a phase failure of the neutral line N occurs and an overvoltage is applied between L1 and N2 or between L2 and N, the voltage applied to both ends of the resistor R2 rises. When the voltage exceeds a certain level, an abnormal voltage is detected. An ON signal of the thyristor 9 is output from the terminal b of the circuit to turn on the thyristor 9, and the trip coil 3 is excited to cause the contact 4 to be tripped.
[0003]
[Problems to be solved by the invention]
On the other hand, a load device uses a number of circuits that easily generate high-frequency noise, such as inverter control and fuzzy control, as its control method, and such a circuit between L1-N or L2-N of the phase loss protection circuit. When high frequency noise is applied, the pulsed high voltage generated by the noise may be judged as an overvoltage due to phase loss, and an unnecessary operation may be performed. There is a tendency for unnecessary operation of the protective circuit breaker of the stranded wire phase to increase.
[0004]
Therefore, in view of the above problems, an object of the present invention is to provide an AA neutral wire phase loss protection circuit breaker that operates with an overvoltage due to an open phase and does not operate with a high frequency noise.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is provided with an AA that includes a phase loss detection circuit that shuts off the main circuit and protects the circuit when the neutral line of the single-phase three-wire circuit is lost. Neutral wire phase loss protection circuit breaker, wherein the phase loss detection circuit detects a line voltage and an abnormal voltage generated by a phase failure of the neutral wire in response to voltage information of the voltage detection circuit. And an abnormal voltage monitoring circuit that detects and outputs a cutoff signal of the main circuit, and a ferrite core bead is interposed in the voltage detection circuit.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an example of an AA neutral wire phase loss protection circuit breaker according to the present invention. The main circuit 2 is provided with a contact 4 that is opened by the operation of a trip coil 3 and detects a leakage. A current transformer 5 is provided, and an abnormal voltage monitoring circuit 6 detects leakage and abnormal voltage.
[0007]
The phase loss detection circuit is an IC (integrated circuit) abnormal voltage monitoring circuit 6, rectifies the voltage between L1-N and between L2-N by diodes D1, D2, and divides the voltage by resistors R1, R2. When the voltage across the resistor R2 is connected to the voltage detection circuit 7 connected between a and c of the abnormal voltage monitoring circuit 6 and a phase failure of the neutral line N occurs, between L1 and N2 or between L2 and N Overvoltage is applied to both ends of the resistor R2, and when the voltage exceeds a certain level, the abnormal voltage monitoring circuit 6 determines that the phase is out of phase and turns on the thyristor 9 from the b terminal. The thyristor 9 is turned on, the trip coil 3 is excited and activated, and the contact 4 is pulled off.
[0008]
As shown in the figure, a ferrite core bead 10 is attached to a voltage detection line having a resistance R1. This ferrite core bead 10 exhibits a low resistance value for a low frequency such as a commercial frequency, but a large resistance value for a high frequency. By mounting, the ferrite core bead 10 has an overvoltage due to an open phase at both ends of the resistor R2. Appears normally, but high-frequency noise appears greatly attenuated. Therefore, the abnormal voltage monitoring circuit 6 can be a normal phase detection circuit that operates normally when an overvoltage occurs due to a phase loss and does not easily operate when high frequency noise occurs.
Thus, by providing the ferrite core beads, unnecessary operations due to high frequency noise can be reduced. In addition, the conventional phase loss detection circuit has a simple configuration in which a ferrite core bead is attached to the voltage detection circuit, and it does not take time.
[0009]
FIG. 2 is a circuit diagram showing another embodiment of the present invention. The power supply circuit of the abnormal voltage monitoring circuit 6 is different from that of the above embodiment, and a diode bridge 11 is provided for full-wave rectification. Also in this case, by attaching the ferrite core bead 10 to the voltage detection circuit provided with the resistor R1 in the same manner as in the above embodiment, the overvoltage due to the open phase appears as usual at both ends of the resistor R2, but the high frequency noise is greatly attenuated. As a result, unnecessary operations due to high frequency noise can be reduced.
[0010]
【The invention's effect】
As described above in detail, according to the first aspect of the present invention, the overvoltage is generated by the occurrence of an overvoltage due to an open phase, but the overvoltage due to the high-frequency noise is not interrupted. Disappears. In addition, since only the ferrite core beads are attached to the voltage detection circuit of the conventional phase loss detection circuit, no labor is required.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an AA neutral wire phase loss protective circuit breaker showing an example of an embodiment of the present invention.
FIG. 2 is a circuit diagram of an AA neutral wire phase loss protection circuit breaker showing another embodiment of the present invention.
FIG. 3 is a circuit diagram of a conventional AA neutral wire phase loss protection circuit breaker.
[Explanation of symbols]
2 .... Main circuit, 3 .... trip coil, 4 .... contact, 5 .... current transformer, 6 .... abnormal voltage monitoring circuit, 7 .... voltage detection circuit, 10 .... ferrite core beads.

Claims (1)

AA neutral line phase loss protection circuit breaker equipped with a phase loss detection circuit that shuts off the main circuit and protects the circuit when the neutral phase of the single phase three-wire circuit is lost.
An abnormality in which the phase loss detection circuit detects a line voltage and detects an abnormal voltage generated due to a phase failure of a neutral line upon receiving voltage information of the voltage detection circuit and outputs a cutoff signal of the main circuit And a voltage monitoring circuit, wherein a ferrite core bead is interposed in the voltage detection circuit.

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