JP2016100267A - Leak current detector for leakage circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leak current detecting circuit of an improved leak circuit breaker which is arranged so that electric power economization and the reduction in power consumption can be achieved by reducing an amount of power consumed by the leak detecting circuit while retaining an anti-leakage protective function of a leakage circuit breaker.SOLUTION: A detector which is installed in a leak circuit breaker and serves to detect a leak current ranging from AC current to DC current comprises: a magnetic core 2 surrounding a main circuit conductor 1 of the leak circuit breaker; an exciting coil 3 wound around the magnetic core 2; an oscillation circuit 4 which generates a magnetic excitation current of rectangular waves supplied to the exciting coil 3; a detecting circuit 5 which detects a measurement signal of a leak current passing through the main circuit conductor 1 from the change in an output signal of the oscillation circuit 4; and a power source circuit 6 which drives the oscillation circuit 4 and the detecting circuit 5. The detector further comprises power source intermittent control means which turns the driving power source ON/OFF with a short cycle. The intermittent control means includes a switching element 7 connected to an output side of the power source circuit, and a control circuit 8 which controls the switching element 7 in intermittent ON/OFF, and sets the power source intermittent cycle on the basis of operation specifications of the leak circuit breaker.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a leakage current detection device for a leakage breaker that is mounted on a leakage breaker and detects a leakage generated in a distribution path.

  Recently, Type B is equipped with a protection function that can handle leakage currents in all areas from AC to DC as an earth leakage breaker applied to various distribution systems such as photovoltaic power generation systems and uninterruptible power supply systems in addition to AC commercial power supplies. Development of products for earth leakage circuit breakers conforming to (IEC standards) is underway.

  Also, a leakage current detection device using a fluxgate magnetic sensor is known as a leakage current detection device applied to the Type B leakage breaker. As an example, a magnetic core that surrounds the main circuit conductor of the earth leakage breaker, an exciting coil wound around the magnetic core, an oscillation circuit that generates a rectangular wave exciting current supplied to the exciting coil, and a change in the output signal of the oscillation circuit A fluxgate type leakage current detection device (see Patent Document 1) comprising a detection circuit for detecting a leakage current measurement signal of direct current and alternating current components flowing in the main circuit conductor, and a distribution system equipped with this leakage current detection device There is known an earth leakage circuit breaker (Patent Document 2) in which an earth leakage protection from a pure direct current to a high frequency current is performed.

  The circuit configuration and operation of the leakage current detection device and the leakage breaker disclosed in Patent Document 1 and Patent Document 2 are described in detail in each patent document.

JP 2012-2723 A JP 2013-38047 A

  By the way, the said leakage current detection apparatus (patent documents 1, 2) mounted in the earth-leakage circuit breaker has the subject as follows. That is, in the leakage detection device of Patent Documents 1 and 2 that uses the above-described fluxgate-type magnetic sensor to detect and protect leakage that occurs unexpectedly in the distribution system to be protected, supply it to the excitation coil of the magnetic core. When the distribution system is energized with respect to the oscillation circuit that generates the exciting current and the detection circuit, the drive power supply (the control for circuit drive that is mounted on the earth leakage breaker and the interphase voltage of the main circuit conductor is rectified to DC Power supply) is continuously supplied to detect leakage that occurs unexpectedly in the distribution system.

  For this reason, compared with the leakage detection method that does not require power supply during normal times when no leakage occurs, such as ZCT (Zero Phase Current Transformer) applied to the conventional AC leakage breaker (Type A (IEC standard)) As a result, the power consumption required for driving the leakage detection circuit increases.

  In this regard, the inventors have calculated that a flux gate compared to a detection circuit in which a normal ZCT is installed to detect a leakage occurring in the distribution system (AC) from the secondary side output. In the detection method adopting the type of leakage detection device, the current consumption of the leakage detection device including the amount of excitation current supplied to the excitation coil of the magnetic core increases by an order of magnitude and the power consumption increases up to about 10 times. Moreover, considering that the number of earth leakage breakers installed in large-scale photovoltaic power generation facilities and the like will increase, the amount of power consumed by the earth leakage breakers in the facility will increase considerably. Therefore, it is desired to save electricity by keeping the power leakage supplied to the leakage detection circuit as low as possible while maintaining a predetermined leakage protection function for each leakage breaker.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce the amount of power consumed by the leakage detection circuit while maintaining the leakage protection function of the leakage breaker so that power saving and power saving can be achieved. Another object of the present invention is to provide a leakage current detection circuit for a leakage breaker improved.

In order to achieve the above object, according to the present invention, a leakage current detection device for detecting a leakage current in all regions from an alternating current to a direct current generated in a distribution system by being mounted on the leakage breaker is a main circuit of the leakage breaker. A magnetic core surrounding the conductor, an exciting coil wound around the magnetic core, an oscillation circuit for generating an exciting current of a rectangular wave to be supplied to the exciting coil, and a leakage current flowing in the main circuit conductor from a change in the output signal of the oscillation circuit In the detection circuit that detects the measurement signal, and the oscillation circuit and the power supply circuit that drives the detection circuit,
Power supply intermittent control means for turning ON / OFF the drive power supply of the oscillation circuit and the detection circuit in a short cycle is provided.

  The power supply interruption control means comprises a switching element connected to the output side of the power supply circuit and a control circuit for intermittently turning on / off the switching element, and the power interruption period is a leakage breaker. It is set corresponding to the operation specifications of (Claim 2).

  According to the leakage detection device having the above configuration, the drive power is continuously supplied to the oscillation circuit and the detection circuit that generate the excitation current supplied to the excitation coil of the magnetic core in the leakage detection device whenever the distribution system is energized. Compared to the conventional method, the amount of power consumed by the oscillation circuit and the detection circuit can be reduced to save power and save power.

1 is a schematic circuit diagram of a leakage detection device according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described based on the example shown in FIG.

  In the schematic circuit diagram shown in FIG. 1, 1 is a main circuit conductor of the earth leakage breaker, 2 is a ring-shaped magnetic core surrounding the main circuit conductor 1, 3 is an exciting coil wound around the magnetic core 2, and the magnetic core 2 Are inserted through conductors 1a and 1b corresponding to the forward and return paths of the main circuit. The magnetic core 2 has the non-linear magnetic characteristics of a high permeability material. 4 is an oscillation circuit that generates a rectangular wave excitation current to be supplied to the excitation coil 3, and 5 is a detection circuit that detects a measurement signal of leakage current flowing through the main circuit conductor 1 from a change in the output signal of the oscillation circuit 4. Details of the oscillation circuit 4 and the detection circuit 5 are described in detail in the above-mentioned Patent Document 1.

  Reference numeral 6 denotes a power supply circuit that supplies drive power to the oscillation circuit 4 and the detection circuit 5 (for example, a control that is mounted on an earth leakage breaker and steps down the interphase voltage (AC) of the main circuit conductor 1 and rectifies it to DC. A switching element 7 (for example, a power supply) that is connected to a power supply path between the power supply circuit 6 and the oscillation circuit 4 and the detection circuit 5 as power supply intermittent control means for turning ON / OFF the output of the power supply circuit 6 in a short cycle. , MOSFET) and a control circuit (intermittent pulse generation circuit) 8 for intermittently ON / OFF control of the switching element 7 is added to constitute a leakage detecting device.

  When a leakage breaker equipped with the leakage detection device having the above circuit configuration is connected to the distribution system and energized, a current flows through the main circuit conductor 1 and the oscillation circuit 4 and the detection circuit 5 through the switching element 7 from the power supply circuit 6. Is supplied with drive power. Here, an intermittent cycle in which the switching element 7 is intermittently turned on / off by the control circuit 8 is set in advance, so that the driving power supplied to the oscillation circuit 4 and the detection circuit 5 is intermittently set by the control circuit 8. The ON / OFF control is performed in synchronization with the cycle.

  In this case, the power interruption cycle corresponds to the trip operation time specified in accordance with the selection of the earth leakage breaker (high speed type, time delay type), and the cycle shorter than the operation time (for example, the operation time If 1/2 to 1/10 and the ON / OFF duty ratio is set to 1), the power supply to the oscillation circuit 4 and the detection circuit 5 is stopped at the dead time of the drive power source at which the switching element 7 is turned off. As a result, the amount of power consumed by the oscillation circuit 4 and the detection circuit 5 is almost halved compared to the conventional leakage detection method in which the drive power supply is continuously supplied.

  Also, when selecting the earth leakage breaker to be applied to the distribution system, the operation time from the detection of the earth leakage to the trip of the circuit breaker is specified for the high speed type is 0.1 sec, and the operation time is 0.3 to 0.8 sec for the time delay type. From the above, if the intermittent period of the drive power supply for supplying power to the oscillation circuit and the detection circuit is set to 1/2 to 1/10 of the operation time as described above (ON / OFF duty ratio is 1), the distribution system Even if an accidental leakage that occurs unexpectedly occurs during the dead time of the drive power supply (drive power supply OFF), the delay of the trip operation time of the leakage breaker is negligible.

  As a result, the oscillation circuit including the normal power supply state where there is no leakage in the distribution system while ensuring the leakage protection function imposed on the leakage breaker with practically no effect on the specified operating characteristics. 4. The amount of power consumed by the detection circuit 5 can be reduced, so that the leakage breaker can save power and save power. In addition, particularly when a large number of earth leakage breakers are connected to the power supply system as in a large-scale photovoltaic power generation facility, a large power saving effect can be expected in total.

  Note that the earth leakage breaker equipped with the flux gate type earth leakage detection circuit is equipped with a microprocessor or the like for calculating the earth leakage current, comparing with the threshold value, and the like. If this is applied, the intermittent period of the drive power supply for supplying power to the oscillation circuit 4 and the detection circuit 5 can be set and adjusted based on the clock signal, so that an independent control circuit (intermittent pulse generation circuit) 8 is added. In addition, it is possible to realize power saving of the earth leakage breaker without considering the increase in current consumption associated therewith.

DESCRIPTION OF SYMBOLS 1 Main circuit conductor of earth leakage circuit breaker 2 Magnetic core 3 Excitation coil 4 Oscillation circuit 5 Detection circuit 6 Power supply circuit 7 Switching element 8 Control circuit (intermittent pulse generation circuit)

Claims (2)

A leakage current detection device for detecting leakage currents in all regions from AC to DC generated in a distribution system by being mounted on a leakage breaker, which includes a magnetic core surrounding the main circuit conductor of the leakage breaker and wound around the magnetic core Excitation circuit, an oscillation circuit that generates a rectangular wave excitation current supplied to the excitation coil, a detection circuit that detects a measurement signal of a leakage current flowing through the main circuit conductor from a change in the output signal of the oscillation circuit, and the oscillation circuit , Comprising a power supply circuit for driving the detection circuit,
An earth leakage current detecting device for an earth leakage breaker comprising a power interruption control means for turning on / off the driving power source of the oscillation circuit and the detection circuit at a short cycle.   The leakage current detecting device according to claim 1, comprising a switching element connected to the output side of the power supply circuit, and a control circuit for intermittently ON / OFF controlling the switching element. An earth leakage current detecting device for an earth leakage breaker characterized in that the power interruption cycle is set corresponding to the operation specification of the earth leakage breaker.