KR101140478B1 - Apparatus and method for testing varistor - Google Patents

Abstract

The present invention relates to a varistor testing apparatus and method.
A varistor testing apparatus according to the present invention includes: a signal generating unit for generating a signal for a varistor test; A power amplifier for generating an output voltage capable of level adjustment by amplifying the power of the signal output from the signal generator and applying the output voltage to one end of the varistor to be tested; A leakage current sensing unit connected to the other end of the test target varistor to sense a leakage current flowing through the test target varistor; And an operation display unit for indicating that the leakage current is detected.

Description

[0001] Apparatus and method for testing varistor [0002]

The present invention relates to a varistor test apparatus and method, and more particularly, to a varistor test apparatus and method for detecting a deterioration of a varistor used in a railway vehicle control circuit or the like in advance

A varistor is an abbreviation of 'variable resistor' and is a nonlinear semiconductor resistance element whose resistance value is changed by the voltage applied across both ends. In other words, the varistor has a characteristic that the resistance value changes according to the voltage applied to the varistor. For example, the varistor exists as an insulator until the breakdown voltage is reached, and then changes to a conductor when the breakdown voltage is reached . Due to such characteristics, the varistor is mainly used to protect the internal electric / electronic circuit system from the external surge voltage or the like.

On the other hand, in this regard, railroad vehicles are one of the fields where varistors are widely used. Modern railway vehicles, due to the rapid development of advanced technology, have been equipped with numerous mechanical devices as well as a large number of electric, electronic and information communication devices. In addition, many varistors are used to protect these electric, electronic, . For example, in the case of a chopper railway vehicle, it is necessary for the protection of general electronic devices, protection of semiconductor devices (diodes, transistors, thyristors), protection of communication devices, measurement and control devices, 25,000 varistors are in production.

However, as the varistors deteriorate over time, the dielectric strength of the varistors is gradually lowered, and accordingly, the varistors are more susceptible to the same writing as in the past. In particular, in the case of a railway vehicle, unlike a general case in which a varistor is replaced when an arbitrary varistor fails, there is a possibility that a large-scale accident that the railway vehicle is stopped due to the failure of the varistor may occur, It is very important to replace beforehand to minimize the disturbance.

However, in the conventional case, there was no specific standard for judging whether the varistor was bad or not to replace the old varistor. Therefore, when the varistors were to be replaced at the time of maintenance of the heavy water line of the railway car, cracks, etc., or by detecting smell of burning smell due to deterioration, the obsolete varistors were selected and replaced.

Accordingly, there is a desperate need for a concrete standard for judging whether a varistor mounted on a railroad car is good or for making it easier to inspect the varistor.

It is an object of the present invention to provide a dedicated test apparatus and method for a varistor which is a typical surge voltage absorbing element that protects an electric and electronic circuit system from intrusion of a surge voltage, .

It is another object of the present invention to provide a varistor testing apparatus and method that can provide a specific criterion for judging whether a varistor used in a railway vehicle is judged, and can easily test the varistor.

For this purpose, a varistor testing apparatus according to an aspect of the present invention includes: a signal generating unit for generating a signal for testing a varistor; amplifying power of a signal output from the signal generating unit to generate an output voltage capable of level adjustment; A power amplifier for applying the output voltage to one end of the varistor to be tested; a leakage current detector connected to the other end of the varistor to be tested for detecting a leakage current flowing through the varistor under test; And an operation display unit for displaying the operation display unit.

In another aspect of the present invention, there is provided a varistor testing method comprising the steps of: a) generating a signal for a varistor test, b) generating an output voltage capable of level adjustment by amplifying power of the generated signal, c) The method comprising the steps of: applying a voltage to one end of a varistor to be tested; d) detecting a leakage current flowing from the other end of the varistor to be tested; and e) indicating that the leakage current is detected.

According to the present invention, it is possible to stably protect the electric / electronic circuit system from intrusion of a surge voltage by previously detecting and replacing a faulty varistor used in a control circuit or the like of a railway vehicle through a test apparatus I have.

In addition, according to the present invention, it is possible to prevent homogeneous faults by establishing the durability of the varistors used in railway vehicles and establishing test standards, and by improving the efficiency of maintenance due to the use of dedicated test apparatus, Thereby contributing to the improvement of passenger service.

1 is a configuration diagram of a varistor testing apparatus according to an embodiment of the present invention.
2 is a circuit diagram of a varistor testing apparatus according to an embodiment of the present invention.
3 is a flowchart of a varistor testing method according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unnecessarily obscure.

1 is a block diagram of a varistor testing apparatus according to an embodiment of the present invention. 2 is a circuit diagram of a varistor testing apparatus according to an embodiment of the present invention.

1, a varistor testing apparatus 100 according to an exemplary embodiment of the present invention includes a signal generating unit 110, a power amplifying unit 120, a leakage current detecting unit 130, an operation display unit 140, .

In detail, the signal generator 110 generates a basic signal (sine wave, pulse, etc.) used for testing the varistor. 2, the signal generator 110 according to the present invention is implemented as a sinusoidal oscillation circuit using two OP AMPs (Operational Amplifiers) (LM 358). However, the signal generating unit 110 may be implemented in various forms other than that illustrated in FIG. 2, and may also be implemented to generate pulses in addition to sine waves. On the other hand, in the circuit of FIG. 2, the sinusoidal signal generated by using two OP AMPs is input to the power amplifier 120 through the resistor R8.

The power amplifying unit 120 amplifies the power of the signal output from the signal generating unit 110 to generate an output voltage capable of adjusting the level, and applies the generated output voltage to one end of the varistor. To this end, the power amplifier 120 according to the preferred embodiment of the present invention may be configured as a level controller, a push-pull amplifier, a transformer, etc., So that the output voltage of the varistor can be applied to the varistor.

Referring to FIG. 2, the level adjuster R7 adjusts the magnitude of the signal output from the signal generator 110, and the output signal is input to the OP AMP (LM 386). Here, the adjustment of the level adjuster R7 is performed by the user, and as a result, the output voltage applied to the test target varistor 200 is adjusted. On the other hand, the output of the OP AMP (LM386) is input to the push-pull amplifiers Q1 and Q2 composed of two transistors, and the push-pull amplifiers Q1 and Q2 amplify the signal output from the level adjuster R7. The signals output from the push-pull amplifiers Q1 and Q2 are input to the transformer T1 and the transformer T1 boosts the voltage of the signal output from the push-pull amplifiers Q1 and Q2, 200). For reference, the transformer T1 serves as an isolator and also serves to increase electrical efficiency through impedance matching.

The leakage current sensing unit 130 is connected to the other end of the test subject varistor 200 to sense a leakage current flowing through the test subject varistor 200. Referring to FIG. 2, if the varistor is operated as a conductor due to the voltage applied to the test target varistor 200, a current flows through the varistor 200 to be tested. Then, Amplifies the current sensed at the other end of the varistor 200 using the transistor Q3, and transmits the amplified current to the operation display unit 140. [

Then, the operation display unit 140 displays the detection result of the leakage current sensed by the leakage current sensing unit 130. 2, the operation display unit 140 is configured to display a result of leakage current detection using a light emitting diode (LED) and a meter. However, in addition to the illustrated embodiment, the operation display unit 140 may be implemented in a variety of analog and / Of course.

Also, the operation display unit 140 may be implemented so as to intuitively determine whether the varistor is good or bad, taking into account the voltage applied to the test target varistor 200 (i.e., the output voltage of the power amplifier) and the magnitude of the leakage current have. For example, in the case of a railway vehicle in Korea, a DC 100 V power source is mainly used. On the basis of this, a judgment criterion of the varistor can be set as shown in Table 1 below.

[Table 1] Varistor Judgment Criteria

Therefore, when the user performs the test while gradually increasing the voltage applied to the varistor 200, the operation display unit 140 turns on the red LED when the leakage current of a predetermined value or more is detected when the voltage applied to the varistor is 350 V or less and when a leakage current of a predetermined value or more is sensed at 350V to 400V, the yellow LED is turned on to indicate that the LED is in a usable state. If a leakage current of 400V to 440V is detected, To indicate that it is in the highest performance state.

Hereinafter, a varistor testing method according to the present invention will be described with reference to FIG. For example, the method of testing a varistor according to the present invention can be performed by, for example, the above-described varistor testing apparatus. Accordingly, the specific procedure or operation principle of the varistor testing method can be referred to the description of the varistor testing apparatus Will be briefly described below.

3 is a flowchart of a varistor testing method according to an embodiment of the present invention.

Referring to FIG. 3, first, in step S310, the signal generator 110 generates a basic signal (sine wave, pulse, etc.) used for testing a varistor. The generated signal is input to the power amplifying unit 120.

Then, in step S320, the power amplifier 120 amplifies the power of the signal generated by the signal generator 110 to generate an output voltage capable of level adjustment. Specifically, the power amplifier 120 adjusts the magnitude of the signal generated by the signal generator 110 to a desired level using a level adjuster, amplifies the level adjusted signal using a push-pull amplifier, , And the voltage of the amplified signal is boosted by using a transformer.

Then, in step S330, the power amplifier 120 applies the boosted voltage (i.e., the output voltage) to one end of the varistor 200 to be tested. In this case, if the varistor is operated as a conductor due to the voltage applied to the varistor under test, current flows through the varistor under test.

Then, in step S340, the leakage current sensing unit 130 senses a leakage current flowing through the other end of the varistor 200 to be tested.

In step S350, the operation display unit 140 displays the result of sensing the leakage current in an analog and / or digital form using an LED, a meter, or the like. In this case, the operation display unit 140 can be implemented so that the varistor can be intuitively determined in consideration of the voltage applied to the test target varistor 200 (i.e., the output voltage of the power amplifier unit) and the magnitude of the leakage current For example, when a voltage applied to the varistor is 350 V or less, if a leakage current of a predetermined value or more is sensed, the red LED is turned on to indicate that the LED is in a replacement state. If a leakage current of 350 V to 400 V is detected, When the leakage current is more than a predetermined value when the voltage is 400V to 440V, the green LED is turned on to indicate the highest performance state.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It is to be understood that the embodiments are to be considered in all respects as illustrative and not restrictive.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. .

100: varistor test apparatus 110: signal generator
120: Power amplifier 130: Leakage current detector
140: Operation indicator 200: Varistor under test

Claims (11)

In a varistor testing apparatus,
A signal generator for generating a signal for a varistor test;
A power amplifier for generating an output voltage capable of level adjustment by amplifying the power of the signal output from the signal generator and applying the output voltage to one end of the varistor to be tested;
A leakage current sensing unit connected to the other end of the test target varistor to sense a leakage current flowing through the test target varistor; And
And an operation display unit for displaying the detection result of the leakage current. The power amplifier according to claim 1,
A level controller for adjusting a size of a signal output from the signal generator;
A push-pull amplifier for amplifying a signal output from the level controller; And
And a transformer for boosting a voltage of a signal output from the push-pull amplifier. 3. The method according to claim 1 or 2,
Wherein the signal generator generates a sine wave or a pulse using at least one operational amplifier (OP AMP). 3. The method according to claim 1 or 2,
Wherein the operation display unit displays the magnitude of the leakage current in at least one of analog and digital form. 3. The method according to claim 1 or 2,
Wherein the operation display unit displays a bad state when a leakage current is detected when an output voltage applied to one end of the test target varistor is 350 V or less. 3. The method according to claim 1 or 2,
The operation display unit turns on the first LED when the leakage current is detected when the output voltage applied to one end of the test target varistor is 350 V or less and the output voltage applied to one end of the test target varistor is higher than 350 V and lower than 400 V The second LED is turned on when a leakage current is detected and the third LED is turned on when a leakage current is detected when the output voltage applied to one end of the varistor under test is more than 400 V and less than 440 V Varistor testing device. As a varistor test method,
a) generating a signal for a varistor test;
b) amplifying the power of the generated signal to generate an output voltage capable of level adjustment;
c) applying the output voltage to one end of the varistor to be tested;
d) detecting a leakage current flowing from the other end of the varistor to be tested; And
and e) displaying a result of sensing the leakage current. 8. The method of claim 7, wherein step b)
b1) adjusting the magnitude of the generated signal to a predetermined level;
b2) amplifying the level-adjusted signal using a push-pull amplifier; And
b3) boosting the voltage of the amplified signal by using a transformer. 9. The method according to claim 7 or 8, wherein step e)
And the magnitude of the leakage current is displayed in at least one of analog and digital form. 9. The method according to claim 7 or 8, wherein step e)
And when the output voltage applied to one end of the test target varistor is 350 V or less, the leakage current is displayed as a bad condition when the leakage current is detected. 9. The method according to claim 7 or 8, wherein step e)
When the leakage current is detected when the output voltage applied to one end of the varistor under test is 350 V or less, the first LED is turned on, and when the output voltage applied to one end of the varistor under test is higher than 350 V and lower than 400 V, And the third LED is turned on when a leakage current is detected when the output voltage applied to one end of the varistor under test is more than 400 V and less than 440 V. [ .

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