JP3995756B2 - Earth leakage protection relay with buzzer - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a leakage protection relay that is incorporated in household electrical appliances and industrial electrical equipment to prevent electric shock and protect the leakage of the equipment, and further emits a buzzer sound to notify the leakage status.
[0002]
[Prior art]
As shown in FIG. 5, a conventional buzzer alarm type earth leakage protection relay is composed of a relay with a main circuit contact having a c-contact structure, and in the absence of leakage, the voltage on the power supply side is supplied to the load side to prevent leakage. In the detected state, the power supply side voltage is supplied directly to the buzzer (the load side is cut off) to obtain a buzzer sound. However, although the buzzer sound is high, a relay with a c-contact structure is required and the outer shape is large. Cost was high.
[0003]
[Problems and objects to be solved by the invention]
An object of the present invention is to provide a leakage protection relay with a buzzer that has a small outer shape, is inexpensive, and can generate a necessary buzzer volume.
[0004]
[Means for Solving the Problems]
A leakage protection relay with a buzzer provided on the electric circuit so that the exterior is covered with a resin case and the load circuit is shut off at the same time when a leak occurs, and the relay contact for cutting off the load circuit is driven. The relay coil, the buzzer, and the SCR to be connected in series, one end of the relay coil is connected to the primary side of the relay contact of the first phase in the electric circuit, and the cathode side of the SCR is connected to the cathode side of the SCR Connected to the primary side of the relay contact of the second phase in the electric circuit, the buzzer power source is obtained from the electric circuit, and output from a zero-phase current transformer provided in the electric circuit generated by electric leakage When the leakage current in the electric circuit exceeds a certain level, the trigger signal from the amplification unit that outputs the trigger signal enters the gate of the SCR. When the SCR is triggered, the circuit board is configured such that the buzzer connected in series with the relay coil is energized together with the relay coil, and the buzzer sounds at the same time as the relay coil shuts off the load circuit. A cylindrical resonance tube molded with resin integrally with the case is provided inside the case so as to surround the buzzer provided on the circuit board. Provided a leakage protection relay with a buzzer characterized in that by providing a hole, a resonance chamber is constituted by the circuit board, the resonance cylinder, and the small hole, and the volume of the buzzer is increased. Thus, while using a small buzzer, the volume can be increased by the resonance cylinder or the resonance box with the resin case as a part. Both it is possible to use a relay of a simple b contact structure of the structure there is no need to use a relay of c-contact structure for driving the buzzer, generally small, it can be constructed at low cost.

[0005]
[Explanation of Examples]
FIG. 1 is a first embodiment of a leakage protection relay with a buzzer according to the present invention, and FIG. 2 is an embodiment of a circuit block diagram of the leakage protection relay with a buzzer according to the present invention.
[0006]
Reference numeral 1 in FIG. 2 denotes a zero-phase current transformer that uses the power lines 2 and 3 as primary conductors and detects a leakage current generated in the load circuit.
Reference numeral 4 in FIG. 2 denotes an amplifying unit that triggers the SCR 5 when the leakage current exceeds a certain value.
In FIG. 2, 6 is a buzzer, 7 is a relay coil, and a voltage is applied when the SCR is triggered to generate a buzzer sound. At the same time, the relay operates, and the relay contacts 8 and 9 interrupt the power circuit to protect the load circuit. .
[0007]
FIG. 1 illustrates the structure of a leakage protection relay having the circuit configuration described in FIG.
[0008]
Reference numeral 10 in FIG. 1 denotes a cylindrical resonance tube molded integrally with a resin case 11, which surrounds the buzzer 6 and has a circuit board 15 mounted with circuit components (not shown) shown in FIG. A resonance chamber is constituted by the small holes 12 opened in the resin case.
[0009]
In FIG. 1, the resonance cylinder is in close contact with the circuit board 15 to form a resonance chamber, but may be in close contact with the buzzer. Here, the volume of the resonance chamber and the size of the small hole are optimally determined by the oscillation frequency of the buzzer.
[0010]
In the circuit configuration shown in FIG. 2, when leakage is detected and the SCR 5 is turned on by the output of the amplifying unit 4, a voltage is applied to the relay coil 7 to open the relay contacts 8 and 9 and simultaneously shut off the power circuit. The buzzer generates a voltage when a voltage is applied. Therefore, it is not necessary to use a relay having a c-contact structure as in the conventional example of FIG. 5, and a small and inexpensive relay can be used.
[0011]
However, the current flowing through the buzzer is limited by the current flowing through the relay coil, and there is a drawback that it is difficult to obtain a current necessary for generating a sufficient volume.
[0012]
Therefore, as shown in FIG. 1, by providing a resonance chamber in the form of a buzzer in a part of the resin case, it is possible to obtain the necessary volume, and the leakage protection relay with a buzzer is small and inexpensive as a whole. To get.
[0013]
In the present invention, a small-sized, for example, piezoelectric buzzer that is driven by a small direct current can be used, so that the outer shape can be further reduced.
[0014]
FIG. 3 shows a second embodiment of the structure shown in FIG. 1, in which a partition plate 13 is inserted between the resin case 11 and the circuit board 15, and the partition plate, a part of the resin case, and a small hole 12 are provided. And the circuit board constitute a resonance chamber, which has the same effect as the first embodiment.
[0015]
FIG. 4 shows a third embodiment of the structure shown in FIG. 1, in which a resonance chamber is constituted by a resin case 11, a small hole 12, and a small substrate 16 separated from a circuit substrate 15. It has the same effect as the embodiment.
[0016]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an earth leakage protection relay with a buzzer that is smaller in outer shape, lower in cost, and sufficiently capable of obtaining a necessary volume as compared with the conventional example.
[Brief description of the drawings]
FIG. 1 is a block diagram of a leakage protection relay with a buzzer of the present invention.
FIG. 2 is a diagram of a first structural embodiment of a leakage protection relay with a buzzer according to the present invention.
FIG. 3 is a diagram of a second structural embodiment of the leakage protection relay with buzzer of the present invention.
FIG. 4 is a diagram of a third structural embodiment of the leakage protection relay with a buzzer of the present invention.
FIG. 5 is a block diagram of a conventional earth leakage protection relay with a buzzer.
[Explanation of symbols]
1 Zero Phase Current Transformer 2 Power Line 3 Power Line 4 Amplification Unit 5 SCR
6 Buzzer 7 Relay coil 8 Relay contact 9 Relay contact 10 Resonant cylinder 11 Resin case 12 Small hole 13 formed in the resin case 13 Partition plate 14
15 Circuit board 16 Small board

Claims (1)

A leakage protection relay with a buzzer provided on the electric circuit so that the exterior is covered with a resin case and the load circuit is shut off at the same time when a leak occurs, and the relay contact for cutting off the load circuit is driven. The relay coil, the buzzer, and the SCR to be connected in series, one end of the relay coil is connected to the primary side of the relay contact of the first phase in the electric circuit, and the cathode side of the SCR is connected to the cathode side of the SCR Connected to the primary side of the relay contact of the second phase in the electric circuit, the buzzer power source is obtained from the electric circuit, and output from a zero-phase current transformer provided in the electric circuit generated by electric leakage When the leakage current in the electric circuit exceeds a certain level, the trigger signal from the amplification unit that outputs the trigger signal enters the gate of the SCR. When the SCR is triggered, the circuit board is configured such that the buzzer connected in series with the relay coil is energized together with the relay coil, and the buzzer sounds at the same time as the relay coil shuts off the load circuit. A cylindrical resonance tube molded with resin integrally with the case is provided inside the case so as to surround the buzzer provided on the circuit board. An electrical leakage protection relay with a buzzer characterized in that a resonance chamber is constituted by the circuit board, the resonance cylinder, and the small hole to increase the volume of the buzzer by providing a hole.

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