JP2517499B2 - Earth leakage circuit breaker - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage breaker for detecting and breaking an electric leakage by detecting an imbalance of currents in a power source line of a commercial power source or the like.

[0002]

2. Description of the Related Art An example of a conventional earth leakage breaker 10 of this type is shown in a circuit diagram in FIG. 3, in which a detection coil 11 is attached to a power supply line 20 and a bridge circuit 12 which is a full-wave rectification circuit is provided. The thyristor 14 in which the relay coil 13a of the relay 13 is connected in series to the anode 14a is connected to the output of the bridge circuit 12 on the positive side.
In this thyristor 14, the gate 14b is connected to the output of the detection circuit 15 which is connected to the detection coil 11 and is a commercially available IC for detecting electric leakage.

In the earth leakage detection circuit 10 having the above-described structure, when the power supply line 20 is unbalanced due to earth leakage, the output of the detection coil 11 causes the detection circuit 15 to respond to drive the gate 14b. Thyristor 1
4 is made conductive, and the relay coil 13a of the relay 13 connected in series to the anode 14a of the thyristor 14 is energized, and the relay 13 opens the relay contact 13b provided on the power supply line 20 from the normally closed contact NC. As a result, the power supply line 20 is shut off.
The thyristor 14 has an anode 14a and a cathode 1
A reset switch 16 is provided at both ends of 4c, and the breaking operation can be restored by turning on the reset switch 16.

Here, the conventional leakage detection circuit 10 described above is used.
Since there is usually no means for notifying the operation in the above, damage caused by delay in confirmation of the operation when the leakage detection circuit 10 is provided in, for example, a freezer or the like. Will be huge, so
The announcement of the movement has been desired.

In order to meet this demand, in the conventional earth leakage detection circuit 10, the relay 1 as shown by the broken line in FIG.
The relay contact 13b of No. 3 is provided with a normally open contact NO, and a buzzer 17 which sounds from a commercial power source is attached to this normally open contact NO to notify the operation.

[0006]

However, in the conventional leakage detection circuit 10 described above, the buzzer 15 is used.
Is a large-sized and expensive product because it is directly struck by a commercial power source. In addition, the relay 13 also needs a normally open contact NO, which causes a cost increase, resulting in miniaturization. There was a limit to cost reduction, and the solution to this point had become an issue.

[0007]

The present invention is, as a concrete means for solving the above-mentioned conventional problems, a bridge circuit whose input side is connected to a power supply line, and a positive electrode side which is connected to the output of the bridge circuit. In a thyristor in which a relay coil of a relay is connected in series, a detection circuit connected to the gate of the thyristor, and an earth leakage circuit breaker for interrupting the power supply line by the relay coil by a relay contact,
A first resistor and a diode whose positive electrode side is a resistor are connected in series between the relay coil and the thyristor, a connection point between the relay coil and the first resistor, the diode and the thyristor. A buzzer is connected between the connection points of the second resistor and a power supply to the detection circuit from the connection point of the first resistor and the diode via the third resistor. By providing an earth leakage breaker characterized by the above, it is possible to reduce the size and cost and solve the above-mentioned conventional problems.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on an embodiment shown in the drawings. In order to facilitate understanding, the same parts as those of the conventional example will be described with the same reference numerals, and the description of the overlapping parts will be partially omitted. Reference numeral 1 in FIG. 1 denotes an earth leakage breaker according to the present invention. This earth leakage breaker 1 is basically the same as the detection coil 11 which is attached to the power supply line 20 and whose output is connected to the detection circuit 15. It is composed of a bridge circuit 12 to which a power supply line 20 is connected, a relay coil 13a of a relay 13 and a thyristor 14 which are connected in series to the output of the bridge circuit 12, and a reset is made between the anode 14a and the cathode 14c of the thyristor 14. The point that the switch 16 is connected is the same as that of the conventional example.

However, according to the present invention, the first resistor 2 and the forward diode 3 are connected in series between the relay coil 13a and the thyristor 14.
The relay coil 13a, the first resistor 2, the diode 3, the thyristor 1 are connected to the output of the bridge circuit 12 from the positive side.
4 are connected in series in this order.

A second resistor 4 is provided between a connection point P between the relay coil 13a and the first resistor 2 and a connection point Q between the diode 3 and the thyristor 14. For example, an electronic buzzer 5 having a built-in transistor oscillation circuit or the like is connected, and in addition, a connection point R between the first resistor 2 and the diode 3 is connected to the detection circuit 15 via a third resistor 6. The power of is supplied.

Next, the operation and effect of the earth leakage breaker 1 of the present invention having the above-described structure will be described. First, the first resistor 2 and the diode 3 are provided between the relay coil 13a and the thyristor 14. Is connected in series, and the electronic buzzer 5 is connected between both ends thereof, that is, the connection points P and Q, so that when the leakage is detected and the thyristor 14 is turned on, it is generated in the first resistor 2. The electronic buzzer 5 sounds due to the potential difference due to the voltage drop.

Here, the diode 3 is connected in series with the first resistor 2 because the detection circuit 15 is provided in the first resistor 2 even when the thyristor 14 is in a non-conductive state. The purpose is to prevent the electronic buzzer 5 from malfunctioning due to the voltage drop caused by the flow of a small amount of current for powering the diode 3. In the non-conducting state of the thyristor 14, the diode 3 is in the reverse bias state. The current that bypasses the detection circuit 15 and flows through the electronic buzzer 5 is cut off to prevent noise.

FIG. 2 shows a second embodiment of the present invention as a main part. In this embodiment, in addition to the previous embodiment, a light emitting diode 7 is connected in series to the diode 3. When the thyristor 14 becomes conductive due to the detection of the electric leakage, in addition to the sound of the electronic buzzer 5, the light emitting diode 7 is also turned on to visually notify the occurrence of the electric leakage.

Here, in addition to the first resistor 2,
The reason why the second resistor 4 and the third resistor 6 are adopted is to correspond to the second embodiment, and when the thyristor 14 becomes conductive, an appropriate lighting current is supplied to the light emitting diode 7. If the value of the first resistor 2 is set to supply the electric current, the value may not always be an appropriate value for the operation of the electronic buzzer 5 and the detection circuit 15. Therefore, in this case The values are adjusted by adjusting the values of the second resistor 4 and the third resistor 6.

Also, in the second embodiment described above, the operation and effect of the portion other than the visual notification by the light emitting diode 7 are the same as those in the previous embodiment.
Detailed description here is omitted.

[0016]

As described above, according to the present invention, the first resistor and the diode are connected in series between the relay coil and the thyristor, and the first resistor and the diode connected in series are connected. By using an earth leakage breaker with an electronic buzzer connected to both ends of and, when the thyristor is conducting due to an electric leakage detection, the buzzer sounds by the potential difference due to the voltage drop generated in the first resistor, which enables notification. At this time, by making the buzzer sound by the potential difference generated in the first resistor, it is possible to use a small and inexpensive buzzer such as an electronic buzzer, and a normally open contact is provided for the relay contact of the relay. Without the need
As a result, this type of leakage breaker has excellent effects in downsizing and cost reduction.

Further, since the light emitting diode is connected in series to the diode connected between the relay coil and the thyristor, the operation of the earth leakage breaker can be performed even when the light emitting diode is turned on when the electric leakage is detected. It shall be possible to make announcements, and also have the effect of making the announcements even more reliable.

[Brief description of drawings]

FIG. 1 is a wiring diagram showing an embodiment of an earth leakage circuit breaker according to the present invention.

FIG. 2 is also a wiring diagram showing a main part of a second embodiment of the present invention.

FIG. 3 is a wiring diagram showing a conventional example.

[Explanation of symbols]

1 ... Leakage breaker 2 ... First resistor 3 ... Diode 4 ... Second resistor 5 ... Electronic buzzer 6 ... Third resistor 7 ... Light emitting diode 11 ... Detection coil 12 ...... Bridge circuit 13 ...... Relay 13a ...... Relay coil, 13b ...... Relay contact 14 ...... Thyristor 14a ...... Anode, 14b ...... Gate, 14c ...... Cathode 15 ...... Detection circuit 16 ...... Reset switch P, Q , R ... Connection point

Claims (1)

(57) [Claims] 1. A bridge circuit having an input side connected to a power supply line, a thyristor connected to an output of the bridge circuit and having a relay coil of a relay connected in series to a positive side, and a detection circuit connected to a gate of the thyristor. In the earth leakage circuit breaker for interrupting the power supply line by the relay coil by a relay contact, a first resistor having a positive electrode side resistor and a diode are connected in series between the relay coil and the thyristor. While connecting a buzzer via a second resistor between the connection point between the relay coil and the first resistor and the connection point between the diode and the thyristor, the first resistor and the diode A leakage breaker, characterized in that power is supplied to the detection circuit from a connection point with the third resistor via a third resistor.