JPH0443823Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a lightning arrester inspection device, and particularly to an improvement that allows easy switching when inspecting a plurality of items.

<Prior Art> A lightning arrester is inserted into the ground wire or wiring of an electronic meter to limit the lightning surge voltage generated by a lightning strike to a voltage below which does not damage the meter. A varistor is used as the discharge element of this lightning arrester, but since the varistor deteriorates due to surge voltage, it is necessary to inspect the state of deterioration.

There are the following two items for this inspection.

Leakage current should be small. This is to confirm that there is no adverse effect on the operation of the protected equipment during normal operation.

The discharge starting voltage must be a predetermined value. This is to confirm whether the discharge element has deteriorated and to ensure operation in the event of a lightning strike.

Lightning arrester inspection equipment measures the above two items by switching between them. For this switching, a rotary switch is used, for example, and a circuit necessary for the inspection is connected to each contact of the rotary switch.

<Problem that the invention aims to solve> However, the specifications of baristas vary and are not unified. Therefore, methods have been taken to prepare test circuits for each specification, or to switch settings using a relay via a logic circuit, but it is complicated to connect the switches for each specification. There was also the problem that switching was time consuming.

The present invention has solved these problems, and aims to provide a lightning arrester inspection device that allows easy switching of inspection items in response to varistors with different specifications.

<Means for Solving the Problems> FIG. 1 is a configuration block diagram illustrating the present invention that achieves the above object. This device is a lightning arrester 10
The purpose of this test is to inspect the deterioration of varistors used in varistors, and has the following configuration.

The test designating means 20 designates at least a leakage current test or a discharge voltage test of the varistor. The leakage current testing circuit 31 applies a predetermined voltage to the varistor and measures the leakage current flowing through the varistor. The discharge voltage test circuit 32 measures the discharge start voltage of the varistor. The contact is leakage current test circuit 3
1 or on a line connecting the discharge voltage test circuit 32 and the lightning arrester 10. switching circuit 40
turns this contact on and off. Memory control means 50
stores the on/off state of the contact according to the leakage current test or discharge voltage test, controls the switching circuit 40 in accordance with the test designated by the test designation means 20, and operates the leakage current test circuit 31 or the discharge voltage test circuit. The connection state between the lightning arrester 32 and the lightning arrester 10 is controlled to the stored state.

<Function> Each component of the present invention has the following function. The memory control means stores the on/off state of the contact that realizes the connection state between the test circuit and the lightning arrester corresponding to the leakage current test and the discharge voltage test, and switches the switching circuit according to the test item designated by the test designation means. Control. This connects the leakage current test circuit, discharge voltage test circuit, and lightning arrester to perform the necessary tests.

<Example> The present invention will be explained below using the drawings.

FIG. 2 is a circuit diagram showing a specific configuration of the present invention. In the figure, a varistor 12 is housed in a lightning arrester 10. The tracks 71 and 72 are the varistors 12
The line 73 is another line used for inspecting the lightning arrester 10.

Switches 21 and 22 are test designation circuits that input the type of test, and encoders 23 and 24 are circuits that generate address signals corresponding to switches 21 and 22, and are connected to bus 80.

The test circuit 33 is a circuit that tests the leakage current of the varistor 12, and since the standard values of applied voltage and leakage current differ depending on the type of varistor, it is preferable to prepare several types of applied voltages. For example, 4~
30V for a 20mA current signal, 8V for a thermocouple, 8V for a resistance thermometer, 100V for a power supply, etc.
Preferably, a circuit is provided to compare whether the leakage current exceeds the standard value. For example above,
5μA for current signals, 2μA for thermocouples, 2μA for resistance temperature detectors, 1μA for power supplies, etc. The test circuit 34 is a circuit that measures the discharge starting voltage of the varistor 12, and since the standard value of the discharge starting voltage differs depending on the type of varistor, it is preferable to prepare several types of applied voltages. For example, if the discharge start voltage is defined as the applied voltage that causes a current of 1 mA to flow through a varistor, then it is 40 V for a 4 to 20 mA current signal, 22 V for a thermocouple, 22 V for a resistance temperature detector, and 22 V for a power supply.
270V etc. The test circuit 35 is a circuit that tests the operation of the lightning arrester 10 when connected to an electronic meter protected by the lightning arrester 10.

The contacts are provided at the connections between the lines 71 to 73 and the input/output signal lines of each inspection device, and are connected to relay 4.
1 and 42 connect the varistor 12 and the test circuit 33, and the relay 43 connects the line 73 and the test circuit 33. Relays 44 and 45 connect varistor 12 and test circuit 34, and relay 46 connects line 73 and test circuit 34. Relays 47 and 48 connect varistor 12 and test circuit 35, and
9 connects the line 73 and the inspection circuit 35.

The EPROM 51 is connected to a bus 80 and outputs data at addresses designated by the switches 21 and 22 via the bus 80, and may be an EEPROM. The relay driver 52 is a switching circuit, and drives the relays 41 to 49 on and off in accordance with 8-bit data output from the EPROM 51. In this case, it is preferable that the voltage applied to the leakage current testing circuit 33 and the discharge voltage testing circuit 34 be specified as an output depending on the type of lightning arrester 10.

Here, the data in the EPROM 51 is assumed to be 8 bits, and the relay driver 5 is
2 is provided and three relays are driven, however, the number of relays may be as large as possible. Further, although the EPROM 51 and the test circuits 33 to 35 are shown in one-to-one correspondence, it is also possible to provide EPROMs 51 corresponding to the number of bits that can drive the relays.

The operation of the device configured in this manner will be described next. First, data for connecting test circuits 33 to 35 and lines 71 to 73 is stored in EPROM 51 by switch 2.
1 and 22 are stored at the addresses determined by numbers 1 and 22.

Next, the lightning arrester 10 is connected and a leakage current test is specified. Then, the relays 41 to 43 are turned on in accordance with the data in the EPROM 51, and the varistor 12 and the test circuit 33 are connected. Perform an inspection in this state and obtain the leakage current results. Note that the relays 44 to 49 are in an initial state, that is, an off state.

Next, if you specify the discharge starting voltage test,
According to the data in the EPROM 51, the relays 41 to 43 are turned off and the connection with the test circuit 33 is released, and at the same time, the relays 44 to 46 are turned on and the connection with the test circuit 34 is established. If an inspection is performed in this state and the results are obtained, it can be determined whether the varistor 12 has deteriorated and should be replaced.

Further, if necessary, if an operation test using a combination of the lightning arrester 10 and an electronic meter is added to the test circuit, better tests can be performed.

<Effects of the invention> As explained above, the invention has the following practical effects.

Since the connection state between the lightning arrester and the test circuit according to the test item is stored in the memory control means 50, the on/off state of the contact is changed according to the type of test, making it easy to switch the test item.

Even if the type of lightning arrester 10 is changed and the connection relationship between the line and the input/output terminal is changed, this can be easily handled by rewriting the contents stored in the storage control means 50.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG. 2 is a circuit diagram showing a specific configuration of the present invention. DESCRIPTION OF SYMBOLS 1... Lightning arrester, 20... Inspection designation means (switch), 31, 32... Inspection circuit, 40... Switching circuit (relay), 50... Memory control means (EPROM).

Claims (1)

[Claims for Utility Model Registration] A device for inspecting deterioration of varistors used in lightning arresters, comprising at least inspection designating means for specifying whether to inspect leakage current or discharge voltage of the varistor, and applying a predetermined voltage to the varistor. A leakage current test circuit that measures the leakage current flowing through the varistor, a discharge voltage test circuit that measures the discharge starting voltage of the varistor, and a line that connects the leakage current test circuit or the discharge voltage test circuit to the lightning arrester. a switching circuit that turns this contact on and off, and an on/off state of the contact in response to a leakage current test or a discharge voltage test, and controls the switching circuit in response to the test designated by the test designation means. A lightning arrester inspection device comprising: memory control means for controlling a connection state between the leakage current inspection circuit or the discharge voltage inspection circuit and the lightning arrester to a stored state.