JPS63107415A - Leakage relay - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an earth leakage relay that detects and notifies leakage current in a main electric circuit.

[Prior art and its problems]

Earth leakage relays detect leakage current in the main electrical circuit.

When this leakage current exceeds a predetermined value, it is activated to notify this by means such as sounding a buzzer or lighting an indicator lamp. A conventional example of such an earth leakage relay is shown in FIG. In FIG. 3, a zero-phase current transformer 2 as an earth leakage detection means is inserted into the main electric circuit 1, and the secondary coil of this zero-phase current transformer 2 is connected to an output circuit 4 via an amplifier 3. A relay 5 is connected to operate the output of the output circuit 4. A buzzer (not shown) is connected to the contact 5a of the relay 5.
A notification device such as an indicator lamp is connected. 6 is a test switch for passing a test current corresponding to the leakage current through the zero-phase current transformer 2, and 7 is a reset switch for resetting the output circuit 4. This earth leakage relay has a built-in rectifier circuit and is driven by a power supply circuit 8 connected to an AC power supply 9.

When a leakage occurs in the main electric circuit 1, a voltage is induced in the secondary coil of the zero-phase current transformer 2, this voltage is amplified by the amplifier 3, and the output operates the relay 5.

When the relay 5 operates, it switches the contact 5a, so that a buzzer connected to the contact 5a sounds or an indicator lamp lights up to notify the user of a current leakage. This earth leakage relay can be reset by closing the reset switch 7 after the earth leakage in the main electric circuit 1 is removed. Further, during a test such as maintenance, the earth leakage relay can be tested by closing the test switch 6 and passing a test current through the zero-phase current transformer 2.

This earth leakage relay has a simple configuration and works reliably, but it is unclear how much leakage current is constantly flowing through the main electrical circuit, and how large the leakage current is when the earth leakage relay operates. There was a drawback.

[Purpose of the invention]

An object of the present invention is to provide an earth leakage relay having a device for indicating the magnitude of leakage current.

[Key points of the invention]

The gist of the present invention is to provide an earth leakage relay that detects and notifies a leakage current in a main electric circuit by means of an earth leakage detection means, and includes a digital display means for displaying the magnitude of the leakage current in the main electric circuit based on the output of the earth leakage detection means. Alternatively, an analog display means is provided, and by displaying the current value based on the output of the earth leakage detection means, it is possible to display the earth leakage current at each time.

[Example of invention]

An embodiment of the present invention is shown in the block diagram of FIG.

Figure 2 shows an earth leakage relay assembled into a unit.

Here, the same parts as in FIG. 3 are given the same reference numerals. In FIG. 1, a zero-phase current transformer 2. Amplifier 3. Output circuit 4.
Relay 5 with contacts 5a. The test switch 6 and the reset switch 7 are the same as those in the prior art, and are driven by a power supply circuit 8 that rectifies the AC power source 9 as in the conventional one.

However, this earth leakage relay differs greatly from the conventional one in that it is equipped with a digital display means 10. This digital display means 10 is a means for amplifying the voltage induced in the secondary coil of the zero-phase current transformer 2 with an amplifier 11 and displaying this output digitally. A Φ converter 12 converts it into a digital quantity, and a microcomputer 13 that processes the output of the converter 12 and has a built-in liquid crystal driver 13a. It includes a liquid crystal display 14 and is connected in this order.

This earth leakage relay has an appearance as shown in FIG. 2 and is used by being connected to the secondary coil of a zero-phase current transformer. In FIG. 2, an amplifier 3, an output circuit 4. Relay 5. Amplifier 11
．． Microcomputer 13. The power supply circuit 8 and the like are housed in a case 15. Further, the liquid crystal display 14 is arranged on the front of the case 15.

Lined up next to it, reset switch 7, test switch 6
are arranged for easy operation. A terminal plate 16 is provided on the rear upper surface of the case 15, and a terminal for connecting the secondary coil of the zero-phase current transformer 2 and a contact 5a of the relay 5 are connected to a buzzer.
Terminals for connecting to display lamps, etc., and original terminals are provided.

Since the operation of the relay 5 due to the leakage current of this earth leakage relay is exactly the same as that of the conventional one already mentioned, this explanation will be omitted, and the operation of the digital display means 10 will be described.
When the main electric circuit IK leakage current flows, a voltage is induced in the secondary coil of the zero-phase current transformer 2.

This voltage is amplified by an amplifier 11 and inputted to an NΦ converter 12, where it is converted into a digital signal. The output converted into a digital signal is processed by the microcomputer 13 and applied to the liquid crystal display 14 via the liquid crystal driver 13a for display.

Note that analog display means may be provided instead of this digital display means. In this case, the voltage induced in the secondary coil of the zero-phase current transformer may be amplified with an amplifier, rectified, and read as a leakage current scale with a voltmeter or the like.

〔Effect of the invention〕

As described above, according to the present invention, in addition to operating a relay using the output of a zero-phase current transformer inserted into the main electric circuit, notification is made using a buzzer, an indicator lamp, etc.

A digital display means or an analog display means is provided to display the current value based on the output of the zero-phase current transformer as the earth leakage detection means, and the leakage current flowing in the main electric circuit is displayed. The leakage current in the electric circuit can be monitored, and when the earth leakage relay is activated, the degree of occurrence of the earth leakage can be determined by reading the leakage current value.

[Brief explanation of the drawing]

1 and 2 each show an embodiment of an earth leakage relay according to the present invention, and FIG. 1 is a block diagram. FIG. 2 is a perspective view showing the overall appearance of Units)K. FIG. 3 is a block diagram showing an example of a conventional earth leakage relay. 1... Main electric circuit, 2... Zero-phase current transformer, 10...
Digital display means. Figure 1 1 et al. 21st! 1

Claims (1)

[Claims] 1) An earth leakage relay that detects and notifies a leakage current in the main electric circuit by a leakage detection means, which includes a digital display means or an analog display means that displays the magnitude of the leakage current in the main electric circuit based on the output of the earth leakage detection means. An earth leakage relay characterized by the following: