JPH0630521A - Earth leakage relay - Google Patents

Abstract

PURPOSE:To obtain a highly reliable earth leakage relay by preventing erroneous lighting of earth leakage indicating lamp attended with application of surge voltage onto a power supply section. CONSTITUTION:The earth leakage relay comprises an earth leakage detecting section 3, a switching element 7 subjected to conduction control based on an earth leakage detection signal, a relay section 5 connected in series with the switching element 7 and fed with exciting power from a power supply section 1 upon the conduction of the switching element 7 to deliver a control output, and an earth leakage indicating section 2b connected in parallel with the relay section 5 and the power supply section 1 while in series with the switching element 7 and fed with power from the power supply section 1 upon conduction of the switching element 7 to indicate earth leakage. Furthermore, a rectifying element 8 is connected between the relay section 5 and the switching element 7 in forward direction therewith and further connected with power supply path for the earth leakage indicating section 2b in the direction for blocking conduction of the earth leakage indicating section 2b at the time of nonconduction of the switching element 7 thus preventing erroneous lighting of the earth leakage indicating section 2b upon application of surge voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage relay for detecting an earth leakage current, and more particularly to a technique for preventing erroneous lighting of a display unit for displaying earth leakage.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional indicator light circuit portion of an earth leakage relay of this type, in which an indicator light circuit portion of a two-circuit detecting leakage relay of a single-phase circuit and a three-phase circuit is constructed. In FIG. 2, 1 is a power supply unit, 2 is a display unit, 2a is a power supply display unit, 2b and 2b 'are leakage display units, 3 and 3'is a detection unit for sending a detection signal when a leakage is detected, 4 is a test unit, 5,5 '
Is a relay section, 6 is a reset section, 7 and 7'are switching elements, and 9 is a transistor.

Next, the operation will be described. When a ground fault occurs, the switching element 7 or 7'is turned on by the detection signal from the detection section 3 or 3 ', so that the power supply section 1-relay section 5 or 5'-switching element 7 or 7'-ground A current flows through the coil to the coil of the relay section 5 or 5 '. The relay operates and a contact (not shown) is switched to perform a control operation, and the relay section 5 or 5'is connected in parallel to the power source section 1 and to the switching element 7 or 7 '. The leakage indicator lamps 2b or 2b 'connected in series are lit up to indicate that the leakage indicator lamp 2b or 2b' has operated due to the leakage.

[0004]

Since the indicator lamp circuit of the conventional earth leakage relay is constructed as described above, the power supply unit 1
When a surge voltage is applied to the
When a surge voltage equal to or higher than the Zener voltage of the Zener diode ZD connected to the base of the leakage current flows through the base of the transistor 9, the leakage current is generated.
Since it flows through b or 2b ', there is a problem that the earth leakage indicator lamp 2b or 2b' is erroneously turned on.

The present invention has been made in order to solve the above problems, and prevents an erroneous lighting of the earth leakage indicator lamp due to the application of a surge voltage to the power supply section to obtain a highly reliable earth leakage relay. The purpose is to

[0006]

An earth leakage relay according to the present invention includes a detecting portion for detecting an earth leakage, a switching element which is conduction-controlled on the basis of an earth leakage detection signal sent from the detecting portion, and the switching element. A leakage display unit connected between a power supply unit and displaying a leakage current, and a relay unit and a rectifying device connected in series between the switching element and the power supply unit, the rectifying element, the switching element Are connected in the forward direction, and the leakage display section is connected in a direction to prevent energization of the leakage display section.

[0007]

In the present invention, the rectifying element prevents only the erroneous lighting of the earth leakage display portion when a surge voltage is applied, without impairing the normal operation during earth leakage detection.

[0008]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a power supply unit, 2 is a display unit, 2a is a power supply display unit, 2b and 2b 'are leakage display units,
3, 3'is a detection unit, 4 is a test unit, 5, 5'is a relay unit, 6 is a reset unit, 7, 7'is a switching element unit,
Reference numerals 8 and 8'represent rectifying elements, and 9 a transistor.

Here, the rectifying elements 8 and 8'are connected in series with the switching elements 7 and 7 ', and the leakage display portions 2b and 2'.
It is inserted in the opposite direction to b'in the blocking direction, so that the leakage display section 2b,
Only erroneous lighting of 2b 'can be prevented.

That is, in the structure shown in FIG. 1, when a ground fault occurs, the switching element 7 or 7'is turned on by the detection signal from the detection unit 3 or 3 ', so that the power supply unit 1-relay unit 5 is turned on. Alternatively, a current flows to the coil of the relay section 5 or 5'through the path of 5'-switching element 7 or 7'-ground. Then, the relay operates and a contact (not shown) is switched to perform a control operation, and the relay section 5 or 5'is the power supply section 1
The leakage indicator lamp 2b or 2b 'connected in parallel with the switching element 7 or 7'and connected in series with the switching element 7 or 7'lights to indicate that the leakage indicator lamp 2b or 2b' has operated due to the leakage.

Further, even if a surge voltage is applied to the power supply unit 1, the leakage display units 2b, 2'are inserted by the rectifying elements 8, 8'inserted in the opposite directions so as to be in the blocking direction with respect to the leakage display units 2b, 2b '. No current flows through 2b ', thus preventing erroneous lighting.

[0012]

As described above, according to the present invention, the rectifying element is inserted in series with the switching element and in the direction opposite to the leakage current circuit with respect to the leakage current circuit. In addition, there is an effect that it is possible to obtain a highly reliable earth leakage relay that can prevent only the erroneous lighting of the earth leakage display portion when a surge is applied.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an indicator light circuit of an earth leakage relay according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an indicator light circuit of an earth leakage relay according to a conventional example.

[Explanation of symbols]

 1 Power Supply Section 2 Display Section 2b Leakage Display Section 2b 'Leakage Display Section 3 Detection Section 3'Detection Section 5 Relay Section 5'Relay Section 7 Switching Element 7'Switching Element 8 Rectification Element 8'Rectification Element

Claims (1)

[Claims] 1. A detection unit for detecting an electric leakage, a switching element whose conduction is controlled based on an electric leakage detection signal sent from the detection unit, and a leakage current which is connected between the switching element and a power supply unit to display the electric leakage. And a relay section and a rectifying element connected in series between the switching element and the power supply section, the rectifying element is connected in the forward direction with the switching element, and the leakage display. The part is connected to the earth leakage display part in a direction to prevent energization to the earth leakage display part.