JP3034056U - Earth leakage detector - Google Patents

Abstract

(57) [Abstract] (Correction) [Problem] To obtain an earth leakage detector having a built-in overtemperature prevention function. SOLUTION: 1 is a zero-phase current transformer for detecting a leakage current, and 2 is an exciting coil 3 by a leakage detection signal from a zero-phase current transformer 1.
A drive circuit for supplying an exciting current to the device, 4 an electric circuit opening / closing mechanism portion driven by the exciting coil 3, 5 a test switch for detecting a leakage and confirming an electric circuit interruption, 6 a power receiving plug for obtaining a commercial power source, 7 supplies the power. Zero-phase current transformer 1
The current that flows in the two electric circuits that penetrate the
It has a phase difference of 0 degree. When there is no occurrence of leakage, the currents flowing through each are the same, so the magnetic fluxes generated by each other cancel each other out, and no output is generated in the zero-phase current transformer 1.
Should a leakage occur, an output will be generated in the zero-phase current transformer 1 due to the difference in current flowing in the two electric paths. Due to this output, the drive circuit 2 causes an exciting current to flow through the exciting coil 3 to open the electric path opening / closing mechanism section 4 and disconnect the electric path.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention relates to a leakage detector for detecting an leakage current and immediately interrupting a circuit to prevent an accident due to the leakage.

[0002]

[Prior art]

 FIG. 5 is a block diagram showing a conventional leakage detector. In the figure, 1 is a zero-phase current transformer for detecting leakage current, 2 is a drive circuit for flowing an exciting current to the exciting coil 3 in response to the leakage detection signal from the zero-phase current transformer 1, and 4 is an exciting coil. An electric circuit opening / closing mechanism driven by 3, 5 is a test switch for detecting electric leakage and confirming electric circuit interruption, 6 is a power receiving plug for obtaining commercial power, and 7 is an outlet metal fitting for supplying the electric power.

Next, the operation of the conventional leakage detector will be described. The electric currents flowing through the two electric paths penetrating the zero-phase current transformer 1 have a phase difference of 180 degrees. If there is no occurrence of leakage, the currents flowing through each are the same, so the magnetic fluxes generated by each other cancel each other out, and no output is generated in the zero-phase current transformer 1. Should a leakage occur, the zero-phase current transformer 1 will output due to the difference in the currents flowing through the two circuits. With this output, the drive circuit 2 causes an exciting current to flow through the exciting coil 3 to open the circuit opening / closing mechanism 4 and disconnect the circuit.

The test button 5 is provided, and by operating the test button 5, a current is caused to flow through the zero-phase current transformer 1 to simulate the electric leakage, so that the circuit can be surely cut off. It is something to confirm.

[0005]

[Problems to be solved by the device]

 The conventional leak detector is configured as described above, and has only a leak detection function and a circuit cutoff function.

Therefore, for example, a water temperature control device for an ornamental fish tank comprising a heater for increasing the water temperature, a water temperature sensor for detecting the water temperature, and a control circuit for controlling the heater heating operation by the signal is used as a conventional leak detector. When connected to and used in, it can detect electric leakage and shut off the circuit, but it does not have the function to detect abnormal heating of the heater or the circuit shutoff. For example, when the water tank falls or is destroyed due to a disaster such as an earthquake or a sudden accident, or the heater is exposed from the water due to carelessness and the heater control by the water temperature sensor is lost, the heater is heated and a fire occurs. There was a risk of a secondary disaster.

The present invention is intended to provide a safer earth leakage detector by providing a function of immediately cutting off the electric path even in the case of a sudden accident as described above.

[0008]

[Means for Solving the Problems]

 In the leakage detector according to the present invention, one electric circuit is branched, and a temperature switch that opens and closes according to temperature change is connected between the electric circuit taken out through the zero-phase current transformer and the other electric circuit. The temperature switch is closely attached and fixed to a heater connected to a temperature controller which is supplied with power from a leakage detector.

Instead of the temperature switch, a float switch that opens and closes due to buoyancy in the liquid is fixed to the heater connected to the temperature controller.

[0010]

[Action]

 According to the leakage detector thus configured, since the temperature switch is closely fixed to the heater, if the heater is exposed from the water for some reason and is heated, the temperature switch operates the leakage detector, Cut off the electric circuit and prevent heater heating.

Further, when the float switch is attached to the heater, the heater is exposed from the water so that the float switch operates the leakage detector to shut off the electric path and prevent the heater from being heated.

[0012]

Embodiment 1 FIG. 1 is an embodiment in which the present invention is used in a water temperature regulator for an ornamental fish tank. In the figure, 1 to 7 are the same as those explained in the conventional device. Reference numeral 8 is a temperature regulator for the ornamental fish tank, and the regulator-side power receiving plug 9 is connected to the outlet metal fitting 7 of the leakage detector. The heater 10 connected to the ornamental fish tank temperature controller 8 and the water temperature sensor 11 are installed in the water tank 12 at positions facing each other. Reference numeral 13 denotes a temperature switch that closes when the operating temperature is exceeded, which is closely fixed to the heater 10 and connected to the contact terminal of the test switch 5 of the earth leakage detector.

With the above-mentioned configuration, the heater 10 is exposed from the water, and the temperature control by the water temperature sensor 11 and the temperature controller 8 for the aquarium fish tank is lost due to a sudden accident or carelessness. When heated, the temperature switch 13 fixed to the heater 10 is heated to close the circuit.

When the temperature switch 13 is closed, a current flows through the zero-phase current transformer 1, so that a leakage detection operation is performed and the drive circuit 2 drives the exciting coil 3. As a result, the electric line opening / closing mechanism 4 operates to open the electric line, and the power supply to the ornamental fish tank temperature regulator 8 can be immediately cut off to prevent the heater 10 from overheating.

[0015]

Second Embodiment FIG. 2 is an embodiment in which the temperature switch 13 of the first embodiment is replaced with a float switch 14 that opens and closes by buoyancy in liquid. A float switch 14 that is closed when the buoyancy stops working is fixedly attached to the heater 10.

When the heater 10 is exposed from the water, the float switch 14 fixedly attached to the heater 10 is also exposed from the water, so that the buoyancy is lost and the float switch 14 performs the closing operation. With this circuit closing operation, the electric leakage detection operation of the first embodiment will be performed, and the power supply to the temperature regulator 8 for the ornamental fish tank can be immediately shut off, and the temperature of the heater 10 can be prevented from rising excessively.

[0017]

Third Embodiment Although the temperature switch and the float switch are used independently in the above embodiment, the same effect can be obtained even if the temperature switch and the float switch are connected in parallel and fixed to the heater 10 at the same time. In addition, it is possible to obtain a more reliable heater temperature rise prevention effect.

[0018]

Fourth Embodiment FIG. 3 shows an embodiment in which one terminal of the temperature switch 13 is connected to one electric path via the zero-phase current transformer 1 and the other terminal is connected to the other electric path. Needless to say, the same effect can be obtained by using a float switch instead of the temperature switch 13 or using a parallel connection of both.

[0019]

Fifth Embodiment FIG. 4 shows an embodiment of the present invention in a temperature controller for an ornamental fish tank which has a leakage detector built therein.

In the above-described embodiment, the case of using the temperature controller for the ornamental fish tank has been described, but it goes without saying that it can be used for other liquid temperature controllers and objects other than liquids.

[0021]

[Effect of the invention]

 Since the present invention is configured as described above, it is not necessary to add a new circuit, the device is inexpensive, and a reliable effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a fourth embodiment of the present invention.

FIG. 4 is a block diagram showing a fifth embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional leakage detector.

[Explanation of symbols]

 1 Zero-Phase Current Transformer 2 Drive Circuit 3 Excitation Coil 4 Electric Circuit Opening / Closing Mechanism Section 5 Test Button 6 Power Receiving Plug 7 Outlet Metal Fitting 8 Ornamental Fish Tank Temperature Controller 9 Regulator Side Power Plug 10 Heater 11 Water Temperature Sensor 12 Water Tank 13 Temperature Switch 14 float switch

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[Procedure amendment]

[Submission date] June 15, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims for utility model registration

[Correction method] Change

[Correction contents]

[Utility model registration claims]

Claims (3)

[Utility model registration claims] 1. A zero-phase current transformer for detecting a leakage current, a leakage detection section composed of an electronic circuit, an opening / closing mechanism section for interrupting an electric path by a signal from the leakage detection section, and a power receiving plug for obtaining a commercial power source. And a leakage detector equipped with an outlet fitting for supplying the power source, at least one of the electric paths is branched, and between the electric path taken out through the zero-phase current transformer and the other electric path. A leak detector consisting of a temperature switch that opens and closes depending on the temperature. 2. The earth leakage detector, wherein in the earth leakage detector, a float switch that opens and closes due to buoyancy of liquid is connected instead of the temperature switch. 3. The earth leakage detector, wherein in the earth leakage detector, at least one electric path is branched, and a terminal taken out through a zero-phase current transformer and a terminal connected to the other electric path are provided.