WO2020017693A1 - Apparatus for automatically determining failure type of transformer - Google Patents

Abstract

The present invention relates to an apparatus for automatically determining a failure type of a transformer, the apparatus comprising: a measurement unit including a plurality of probes (first and second probes) which are in contact with a plurality of terminals (primary terminal and secondary terminal) of a transformer (TR), respectively, and removing or penetrating an oxide film formed in each of the terminals to come into contact with the lower layer of the oxide film and be connected to same; and a control unit which measures primary and secondary wire wound resistances, a turn ratio, and an insulation resistance of the transformer by means of the measurement unit, self-diagnoses, through a self-diagnosis, whether wrong wire connection, an error of a device itself, or internal circuit abnormality occurs, and stores and temperature-corrects a result of the self-diagnosis and a result of the measurement so as to synthetically determine the state of the transformer on the basis of the measured values and thus output a result of the determination through a report or a display screen.

Description

Automatic Type of Failure Identification of Transformer

The present invention relates to a device for automatically determining a failure type of a transformer, and more particularly, in order to accurately analyze the cause of a failure of a transformer, by using a probe for removing an oxide film on the surface of a transformer terminal, a winding resistance, The present invention relates to a device for automatically determining a failure type of a transformer, which measures a turn ratio and an insulation resistance, and makes it possible to accurately determine a state of a transformer using the measured values.

According to the latest statistics, about 980,000 units of distribution transformers have been installed and operated as of December 2017, and according to the statistics of the last five years, 9,000 units, or about 1% of the installed quantity, are increasing every year. In addition, the number of faults is about 5.76%, about 6,000 units are generated every year, accounting for about 67% of the number of transformers increasing every year.

As a result of an accurate failure analysis on the cause of the transformer failure (corrosion), about 38% of the requested transformers have been removed from normal products due to failure determination and error.

The reason why the normal product (i.e., normal transformer) is mistaken for failure is not caused by the transformer itself, but by external factors (e.g. temporary overcurrent due to short circuit on the load side, external contact, under rated protection device fuse, etc.). Occurs when the COS (Cut Out Switch), which is a protective device of the transformer, is simply opened (Off), which is caused by the failure of the measuring device to determine whether the transformer has failed, inadequate terminal connection of the measuring device, etc. The main reason is the error of the device or the lack of function of the existing measuring device.

A summary of the cause of the misidentification of a normal product as described above is shown in Table 1 below.

division	Specific reason
Diagnostic (rater)	* Insufficient background knowledge of transformer * Insufficient understanding of various diagnostic equipments * Insufficient knowledge of accurate status determination of measured values of diagnostic equipment * Subjective judgment about long-term requirements and changes in measured values during measurement (winding resistance)
existing measuring equipment (Measuring device)	* No change in transformer material and structure * Expensive variety of equipment required for proper judgment * No correction function for environmental factors (temperature, humidity) for measured values * Some types of failure (turn-off short circuit, etc.) TLC 1 1 Transformer Last Check: The only check device used in the transformer field)
measurement environment	* Insufficient background knowledge on transformer structure * Inaccurate measurement due to different winding resistance by transformer capacity * Inaccurate resistance measurement due to transformer terminal corrosion (oxide film)
How to measure	* Various measurement methods and judgment criteria by transformer status diagnosis (device) * Different measurement methods and positions by transformer measurement elements

Conventional equipment used for the diagnosis or inspection of transformer is TLC (Transformer Last Check, a measuring device used in the field of transformers), which simply determines whether the transformer winding is disconnected and insulation resistance to determine the transformer status.

Therefore, due to the inaccuracy of TLC in the field, TLC and other equipment (or measuring devices and measuring equipments) are used repeatedly.In terms of diagnosis or inspection of such transformers, technical limitations of conventionally used equipment (or measuring equipment and measuring equipment) Table 2 is summarized below.

division

Technical limitations

TLC

Winding short circuit and disconnection whether measured Poor-under-test transformer measurement target-measuring satiety terminal changes accompanying-winding resistance measurable (Tr capacity per winding resistance phase-to-Turn paragraph measurable winding ratio measurements member-disconnection (open) or short-circuit of the winding ( short) only check-changing number of turns by winding portion breakdown unknown - teonseon or interlayer short circuit when the transformer is determined as a normal road, O poor also insulation resistance (1kV DC) poor-temperature calibration measurement reliability oxide reduced bushing clamped to member Measurement error when forming film-Extremely long periods of use in outdoor

Table 3 summarizes the functional limitations of conventional measuring equipment (eg TLC).

division	Limitations (Problems) of Conventional Devices
Dedicated Equipment	Winding disconnection equipment (function extremely limited)
Measurement element	① Winding break or short circuit ② Insulation resistance (No temperature compensation)
Measure Probe	General alligator clip (no oxidation pick removal)
State judgment method	Subjective judgment by person (requires background knowledge of composition)
Self-diagnosis	none
Other key features	Individual probe connection for each measuring element

As described above, if a normal transformer is misidentified as a bad transformer, the cause of dismantling can be classified into three types.

First, due to the environmental characteristics in which the transformer is used, it is exposed to the outside for a long time due to primary and secondary terminal corrosion, that is, an increase in contact resistance due to the formation of an oxide film (see FIG. 1) (which is almost changed to an insulator level by the oxide film). Measurement error is one cause. Therefore, in order to prevent measurement errors caused by the oxide film, there is a need for a probe for automatically removing the oxide film. FIG. 1 is an exemplary view showing photographs taken of primary and secondary terminals in which an oxide film is formed in a general transformer.

Next, when inspecting the transformer, a number of factors, that is, winding resistance, number of turns, and insulation resistance, should be measured, and comprehensive judgments should be made using these measured values. Is another cause. Therefore, there is a need for an apparatus for performing objective judgment using the measured values collectively.

In addition, because a variety of different equipment (ie, measuring device, measuring equipment) is used, different judgment criteria for each equipment is applied, or measurement error due to the failure of any one of the equipment itself is another cause. Therefore, there is a need for a device that can measure and synthesize all the measured values of a transformer (hereinafter, simply referred to as TR, Transformer) at one device at one time.

Background art of the present invention is disclosed in Republic of Korea Patent Publication No. 10-2015-0037267 (2015.04.08. Published, externally operated tap-changing transformer and a failure diagnosis method using the same).

According to an aspect of the present invention, the present invention was created to solve the above problems, using a probe (Probe) to remove the oxide film on the surface of the transformer terminal for accurate failure analysis of the cause of the transformer failure Accordingly, an object of the present invention is to provide a device for automatically determining a failure type of a transformer, which measures winding resistance, turn ratio, and insulation resistance, and accurately determines a state of a transformer using the measured values.

An apparatus for automatically identifying a failure type of a transformer according to an aspect of the present invention includes a plurality of probes (first and second probes) contacting a plurality of terminals (primary and secondary terminals) of a transformer TR, A measuring unit which removes or penetrates the oxide film formed on each terminal and contacts and is connected to the lower layer of the oxide film; And measuring the primary and secondary winding resistance, the winding ratio, and the insulation resistance in the transformer through the measuring unit, and self-diagnosing faulty wiring, equipment error, internal circuit abnormality, and the like through the self-diagnosis. And a control unit for storing the result and the measured result and correcting the temperature, and comprehensively determining the state of the transformer based on the measured values and outputting the result through a report or a display screen.

In the present invention, the probe, using a crocodile clip-type head portion bite the clamp terminal of the transformer, the user holding the handle rotates from side to side, each terminal using a portion formed to protrude sharply like teeth formed on the crocodile clip-type head It is characterized in that it is formed to remove the oxide film on the surface.

In the present invention, when the user pushes the lever of the probe while the user pushes it into the clamp terminal of the transformer, the film removal tip formed at the inlet side of the head removes the oxide film of the clamp terminal, and in this state, When placed, the probe is formed to be in contact with the portion from which the oxide film has been removed.

In the present invention, the control unit, when the power of the automatic failure type determination device of the transformer is turned on, performs a self-diagnosis and calibration, and if the abnormality as a result of the self-diagnosis and calibration, and outputs an alarm to the user , If it is normal, it displays normal to the user, and if the user selects the automatic mode according to the usage environment among the automatic or manual check mode, it executes the automatic mode to automatically measure the status measurement value of the transformer to automatically determine whether there is a failure. When the user selects the manual mode, the user may receive an instruction of a measurement operation on the state measurement value and determine whether there is a failure based on the corresponding measurement value.

In the present invention, when the automatic mode is executed, the controller selects the transformer capacity, measures the winding resistance according to the capacity of the transformer, then measures the winding ratio and the insulation resistance, and displays the measured values on the display screen. And analyzing the measured values at the same time to determine whether the winding resistance measurement value is in the set normal range, whether the number of turns ratio measurement value is in the set normal range, and whether the insulation resistance is in the set normal range or not. It is characterized by displaying on the display screen.

In the present invention, the control unit, since the resistance value varies depending on the winding length when measuring the winding resistance of the transformer, by using the following equation 1 to determine whether the winding resistance is normalized,

(Equation 1)

ε: change rate (%), M _n : measured value of nth winding resistance

If the change rate (ε) is less than or equal to the set value or equipment error, it is determined that the winding resistance has been normalized stably, and if the change rate (ε) is greater than the set value or equipment error, it is determined that an error. do.

In the present invention, the controller initializes the operating power source and the set measurement variable, turns on the primary side measurement operating power source and the secondary side measurement operating power source for measuring the winding ratio, and then measures and outputs the AC output value and the AC input value. Calculate the winding ratio using the measured value, and apply the AC input power to the primary winding and measure the voltage output to the secondary side when the winding ratio is measured, using the following Equation 2 and Equation 3 below. It is characterized by calculating the.

(Equation 2)

(Equation 3)

Where N is the number of turns, V is the voltage, and I is the current

In the present invention, the control unit stores the calculated winding ratio in the storage unit when the calculated winding ratio is within a specified error range, and ends or restarts the measurement when the calculated winding ratio is out of the error range. .

In the present invention, the control unit, to measure the insulation resistance, turn on the operating power of the measuring circuit unit, generates and applies a DC 1kV power supply (HV), measures the current temperature, and flows through the main insulation of the transformer Calculate the insulation resistance value by measuring the leakage current (leakage_current), but apply “Insulation Resistance * (1+ (1 / (234.5 + Temperature) * (Temperature-25.0))” to compensate for the insulation resistance. It characterized in that to perform.

In the present invention, the controller checks whether the insulation resistance value for performing the temperature compensation maintains a value within a preset error range for a predetermined time, and as a result of the check, the insulation resistance value for performing the temperature compensation is When the value within the preset error range is maintained for a predetermined time, the insulation resistance value for performing the temperature compensation is stored in a storage unit, and the insulation resistance value for performing the temperature compensation is a value within the preset error range for a predetermined time. If it is not maintained, the check process is repeated for a specified loop time, and if the insulation resistance value for which the temperature compensation is performed after the specified loop time does not maintain a value within a preset error range, it is treated as an error. do.

In the present invention, the control unit, in order to determine the final state of the transformer by using the measured value, and determines the state for the winding resistance measurement value, the winding ratio measurement value, and the insulation resistance measurement value, one of the measured values If it is bad, the transformer is finally determined to be in a bad state, and if all of the measured values are normal, the transformer is finally determined to be in a normal state.

According to an aspect of the present invention, the present invention measures the winding resistance, turn ratio, and insulation resistance by using a probe (Probe) to remove the oxide film on the surface of the transformer terminal for accurate failure analysis of the cause of the transformer failure Then, the measured values can be used to accurately determine the state of the transformer.

1 is an exemplary view showing a picture of the primary and secondary terminals in which the oxide film is formed in a typical transformer.

Figure 2 is an exemplary view showing a schematic configuration of a failure type automatic determination device of a transformer according to an embodiment of the present invention.

FIG. 3 is an exemplary view showing a photograph of the shapes of a plurality of probes in FIG. 2. FIG.

4 is an exemplary view showing a probe having a rotatable tooth in FIG. 2.

FIG. 5 is an exemplary view shown to describe a schematic operation of a controller in FIG. 2.

FIG. 6 is a flowchart illustrating an operation for diagnosing a transformer of the control unit in FIG. 2. FIG.

7 is a flowchart for explaining a method of executing an automatic mode in FIG. 6.

FIG. 8 is a flowchart illustrating a method of selecting winding resistance for each capacity of a transformer in FIG. 7.

FIG. 9 is a flowchart for explaining a method of executing a passive mode in FIG. 6.

FIG. 10 is a flowchart for schematically explaining a method of measuring winding resistance in FIG. 7.

FIG. 11 is a flowchart for explaining a more specific method of determining winding resistance in FIG. 10.

FIG. 12 is a flowchart for explaining a turn ratio measurement method in FIG. 7. FIG.

FIG. 13 is a flowchart for explaining a method for measuring insulation resistance in FIG.

FIG. 14 is a flowchart for describing a method of comprehensively determining a state of a transformer using measured values in FIG. 7. FIG.

15 is an exemplary view showing a field measurement method and a measurement result screen using a failure type automatic determination device of a transformer according to the present embodiment.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of a failure type automatic determination device of a transformer according to the present invention.

In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary depending on the intention or convention of a user or an operator. Therefore, the definitions of these terms should be made based on the contents throughout the specification.

Figure 2 is an exemplary view showing a schematic configuration of a failure type automatic determination device of a transformer according to an embodiment of the present invention.

As shown in FIG. 2, the apparatus for automatically determining a failure type of a transformer according to the present embodiment includes a measuring unit 100, a control unit 200, an output unit 300, and a storage unit 400.

The measurement unit 100 includes a plurality of probes (first and second probes) 110 and 120 contacting a plurality of terminals (eg, primary terminals and secondary terminals) of the transformer TR, The oxide film formed on the terminals (eg, primary and secondary terminals) is removed or drilled through and contacted and fixed (connected) to the bottom of the oxide layer.

In this case, terminals (eg, primary terminals and secondary terminals) to which the plurality of probes (first and second probes) 110 and 120 are in contact and fixed (connected), respectively, are not necessarily fixed and may be interchanged with each other. Pay attention to

FIG. 3 is an exemplary view showing photographs photographing shapes of a plurality of probes in FIG. 2. 3 (a) is an exemplary view showing a first probe 110 connected to the primary terminal of the transformer TR, Figure 3 (b) is a second terminal connected to the secondary terminal of the transformer (TR) 2 is an exemplary view showing the probe 120.

As described above, the clamp terminal used for the transformer TR typically uses a bronze casting of KS D 6024 or a forging anti-static material of KS D 5101. Therefore, an oxide film is formed on the surface of the terminal when exposed to the external environment for a long time. The oxide film is an insulating component, and forms a high resistance between the terminal and the measurement probe to display a value higher than the prescribed winding resistance, which causes a diagnostic error of the transformer as if the winding was disconnected.

Therefore, the measurement unit 100 is made to penetrate or remove the oxide layer and to contact the lower portion of the oxide layer in order to prevent the error caused by the oxide layer.

Referring to FIG. 3A, the first probe 110 bites a clamp terminal of a transformer using an alligator clip type head, and a user who grabs a handle rotates left and right, so that teeth formed on the alligator clip type head (like teeth). Sharply protruded and interlocked portions) to remove (or pierce) the oxide film on the surface of the terminal.

Referring to FIG. 3 (b), the second probe 120 has a pointed probe 123 installed inside the head, and secures the clamp with a spring therein so that the user holding the handle rotates left and right. The probe 123 removes (or drills) the oxide film on the surface of the terminal like a tooth. More specifically, when the user pushes the lever 122 of the second probe 120 and pushes it into the clamp terminal of the transformer, the film removing tip 121 formed at the inlet side of the head removes the oxide film of the clamp terminal. In this state, when the lever 122 is released, the contact terminal (that is, the probe) 123 may be in contact with the portion where the oxide film is removed.

At this time, the measurement unit 100, as shown in Figure 4, may include a probe in the form that can penetrate the oxide layer by rotating the handle to protrude teeth. 4 is an exemplary view showing a probe having a rotatable tooth in FIG. 2.

On the other hand, the essential elements to be checked before and after the installation of the transformer are the primary and secondary winding resistance, the number of turns, and the insulation resistance measurement to check the main insulation performance of the transformer. The most commonly used measuring element is winding resistance. However, the resistance varies because the windings vary in length and thickness, depending on the capacity of the transformer. In addition, as the material of the winding is changed from copper to aluminum, the failure pattern is also changed. For example, the winding resistance corresponding to the partial insulation breakdown is measured, but the turn ratio is sometimes changed due to the short circuit between turns or between layers. Therefore, the condition of the transformer should not be determined using only one measurement of the winding resistance.

Accordingly, the control unit 200 applies an algorithm for measuring and determining each of the essential inspection elements and finally combining the results to increase the reliability of the transformer inspection.

FIG. 5 is an exemplary view shown to describe a schematic operation of the controller in FIG. 2.

As shown in FIG. 5, the probes 110 and 120 having an oxide film removing function formed on the clamp terminals of the transformer are connected to four clamp terminals of the transformer, respectively (S111), and the controller 200 is connected to the transformer. Measure essential elements (e.g. primary and secondary winding resistance, turns ratio, insulation resistance, etc.) necessary for diagnosing the condition of the sensor, and also make the self-diagnosis (or self-diagnosis) function to generate incorrect wiring, equipment self error, internal Diagnosing the presence or absence of a circuit error by itself (S112). In addition, the control unit 200 records and corrects the measured result (measured value) and makes a comprehensive determination based on the measured values, and stores the result of the determination in the storage unit 400 (S113). ). In addition, the controller 200 may create, store, and output the stored information as described above in a form desired by the user (S114).

Hereinafter, more specific operations of the controller 200 will be described.

FIG. 6 is a flowchart illustrating an operation for diagnosing a transformer of the controller in FIG. 2.

As shown in FIG. 6, when the power of the equipment (that is, the automatic device for determining the failure type of the transformer) according to the present embodiment is turned on (S121), the controller 200 starts an algorithm (S122) and self-diagnoses (Self). Check) and calibration (S123).

As a result of the self-diagnosis and calibration, if it is abnormal (abnormal of S123), an alarm is output to the user (S125), and if it is normal (normal of S123), a normal indication is displayed to the user (S124).

After that, it is configured to select the automatic or manual check mode, when the user selects the automatic mode according to the use environment (S126 automatic), the control unit 200 sets the automatic mode (S129) and the corresponding automatic mode It executes (S130). On the other hand, if the user selects the manual mode (S126 manual), the controller 200 sets the manual mode (S127) and executes the corresponding manual mode (S128).

FIG. 7 is a flowchart for describing a method of executing an automatic mode in FIG. 6, and FIG. 8 is a flowchart for explaining a method for selecting winding resistance for each capacity of a transformer in FIG. 7. 6 is a flowchart for describing a method of executing a manual mode in FIG. 6.

Referring to FIG. 7, when the automatic mode is executed, the controller 200 selects a transformer capacity (S141).

Here, the capacity selection of the transformer is a function commonly applied to the automatic mode and the manual mode, and the transformer capacity selection is because the normal range of the resistance of the primary winding is determined as shown in Table 4 below.

Accordingly, the control unit 200 measures the winding resistance (that is, the primary winding resistance) according to the capacity of the transformer (S142), measures the number of turns (S143), and also measures the insulation resistance (S144). Measurement values are displayed (S145), and the measurement data are analyzed (S146).

That is, the controller 200 compares and analyzes whether the primary winding resistance measurement value is within a normal range (see Table 4). Similarly, the controller 200 analyzes the number of turns ratio and the insulation resistance measurement value to indicate whether it is defective or normal (S147 and S148), and stores the data in the storage unit 400 (S149).

Capacity (kVA)	10	20	30	50	75	100	160
Primary winding resistance (Ω)	130-160	60-80	35-45	15-25	10-15	5-10	Undefined

Referring to FIG. 8, in order to select a winding resistance for each transformer capacity, the controller 200 or the user selects a corresponding capacity if the first capacity (for example, 20 KVA) is determined according to an automatic or manual mode. (S162), if the second dose (for example, 30 KVA) (YES in S162), select the corresponding dose (S164), if the third dose (for example 50KVA) (YES in S165), select the corresponding dose (S166), If the fourth dose (eg, 75 KVA) (YES in S167), select the corresponding dose (S168), and if the fifth dose (eg, 100 KVA) (YES in S169), select the corresponding dose (S170), and the sixth dose ( Example: 160KVA) (YES in S171) select the corresponding capacity (S172).

Referring to FIG. 9, when the manual mode is executed, the user selects a transformer capacity through a user interface (not shown) (S151). After that, the user instructs to measure the winding resistance (S152), measures the number of turns (S153), and measures the insulation resistance (S154) to display the measured values (S155). In fact, the manual mode may be referred to as a mode for instructing a measurement operation.

The winding resistance measurement method is described below.

For reference, the winding of the transformer is divided into primary and secondary, and the secondary winding has a small resistance (0.1Ω) and is very easy to measure because of the wide conductor cross-section and the short line leg. However, since the primary winding has a small cross-sectional area and a very long positive value, the resistance value fluctuates momentarily when the measurement is made, and the resistance value is stabilized only after a predetermined time elapses, so that the true value can be known.

FIG. 10 is a flowchart for schematically describing a winding resistance measuring method in FIG. 7, and FIG. 11 is a flowchart for explaining a more specific winding resistance determination algorithm (method) in FIG. 10.

As shown in FIG. 10, the controller 200 measures the primary winding resistance and the secondary winding resistance of the transformer (S211 and S212) and calculates winding resistance values thereof (S213).

The calculation of the winding resistance value can be set by the user, and the average value is obtained by measuring the unit of measurement in ms.

At this time, the resistance value varies depending on the winding length when measuring the winding resistance, and converges when a predetermined time (for example, 20 seconds) has elapsed (S215).

Therefore, the controller 200 waits for a predetermined time to elapse (NO in S214, and repeats S215), and then calculates a winding resistance determination algorithm (method) shown in Equation 1 below to calculate the measurement reference value of the resistance. By applying, it is determined whether the winding resistance is normalized (S214).

ε: change rate (%), M _n : measured value of nth winding resistance

Equation 1 is a formula for obtaining a convergence value when measuring winding resistance, and calculating a rate of change of the measured value to recognize the final winding resistance measurement value.

The winding resistance measurement value determined as described above is stored in the storage unit 400 (S216).

At this time, if the cancel button is input by the user during the measurement of the winding resistance (S217), the measurement operation is terminated (or restarted).

Referring to FIG. 11, in the process of determining whether the winding resistance is normalized (S214), if the change rate ε calculated through Equation 1 is less than or equal to a user-set value or equipment error (Example of S214a) After determining that the winding resistance is stably normalized, the winding resistance measurement value is stored in the storage unit 400 (S216) and then terminated. The change rate ε is greater than the set value or the equipment error (that is, the error range). If large (NO in S214a), error processing is terminated (S214b).

FIG. 12 is a flowchart for explaining a turn ratio measurement method in FIG. 7.

Referring to FIG. 12, the controller 200 initializes an operating power source and set measurement variables (S241 and S242). In addition, the controller 200 turns on the primary side measurement operation power and the secondary side operation power (S243, S244). In addition, the controller 200 measures and calculates an AC output value and an AC input value (S245 and S246). In addition, the control unit 200 calculates the winding ratio using the measured values of the S245 and S246 (S247).

If the calculated winding ratio is within the error range (Yes of S248), the calculated winding ratio is stored in the storage unit 400 and then terminated (or restarted) (S249), and if the calculated winding ratio is outside the error range ( NO at S248) Exit (or restart) immediately. In this case, although not shown, an alarm may be output.

For reference, the distribution ratio (transformation ratio) of distribution class transformers used in Korean distribution lines is defined in KS C 4306 (2011) as shown in Table 5 below.

Item	Tolerance
Transformer ratio	+1/200 of the specified transformer

Tolerance here means the allowable difference between the specified value and the test result.

For reference, the method of calculating the number of turns ratio (or winding ratio) in step S247 will be described in more detail. When measuring the number of turns ratio, an AC input power is applied to the primary winding and the voltage output to the secondary side is measured. Calculate the number of turns through and Equation 3.

Equation 2 below is a general formula for calculating the transformer turn ratio, and Equation 3 is a turn ratio measurement formula.

Where N is the number of turns, V is the voltage, and I is the current

Accordingly, the calculated number of turns is compared with the value set in Table 5 (permissible difference), and the test is completed after the determination of the normal existence and the calculated value.

Hereinafter, a method of measuring insulation resistance will be described.

For reference, the insulation resistance is calculated by measuring the leakage current with DC 1kV applied in order to check the insulation performance of the main insulation inside the transformer, that is, insulation paper and oil. However, since the existing insulation resistance measuring instrument did not have a probe or a temperature correction circuit to remove the oxide film, the measurement value was inaccurate, making it difficult to determine the correct state of the transformer.

FIG. 13 is a flowchart illustrating a method of measuring insulation resistance in FIG. 7, and as shown in FIG. 13, in this embodiment, a temperature correction function may be added to accurately determine a state of a transformer.

As shown in FIG. 13, the control unit 200 turns on the operating power of the measurement circuit unit (not shown) to measure the insulation resistance (S261), and generates and applies a DC 1kV power source (HV) (S262 and S263). ).

At this time, the temperature is measured to compensate for the insulation resistance (S264), and the insulation resistance value is calculated by measuring the leakage current (leakage_current) flowing through the main insulation of the transformer (S265).

In addition, the controller 200 performs temperature compensation on the insulation resistance calculated in step S265 (S266).

Here, as the temperature compensation (temperature correction) of the insulation resistance, “insulation resistance * (1+ (1 / (234.5 + temperature) * (temperature-25.0))”) may be applied. The equation for temperature compensation can be calculated through repeated experiments and simulations.

As described above, it is checked whether the insulation resistance value, which has been subjected to temperature compensation, maintains a value within a preset error range (eg, 50 Kohm) for a predetermined time (eg, 3 seconds) (S267).

As a result of the check (S267), if the insulation resistance value performing the temperature compensation maintains a value within a preset error range (for example, 50Kohm) for a predetermined time (for example, 3 seconds) (YES in S267), the control unit ( 200 stores the insulation resistance value of the temperature compensation in the storage unit 400 (S268).

However, if the insulation resistance value performing the temperature compensation does not maintain a value within a preset error range (eg 50 Kohm) for a predetermined time (eg 3 seconds) (No in S267), the designated loop time (eg 10 seconds). ) Repeats the steps S264 to S267 (S269), and the insulation resistance value for which the temperature compensation is performed does not maintain a value within a preset error range (for example, 50 Kohm) even after the specified loop time (for example, 10 seconds). If not (NO in S267), an error process is performed and it ends immediately (S270). In this case, although not shown in the drawing, an alarm may be output during error processing.

Hereinafter, a method of comprehensively determining a state of a transformer using the measured value will be described.

FIG. 14 is a flowchart for describing a method of comprehensively determining a state of a transformer using measured values in FIG. 7.

As shown in FIG. 14, the control unit 200 measures winding resistance (S311), and loads the measured value stored in the storage unit 400 (S312). The resistance (that is, primary winding resistance) is compared (S313) and the resultant value is output (S314).

In addition, the controller 200 measures the number of turns (S315), loads the measured value stored in the storage unit 400 (S316), and compares the user set value or the KS standard (S317) with the result value. It outputs (S318).

In addition, the control unit 200 measures the insulation resistance (S319), loads the measured value stored in the storage unit 400 (S320), and compares the user set value or the KS standard (S321) as a result. The value is output (S322).

In addition, the control unit 200 compares the state (eg, normal, abnormal) of the three result values (S323), and writes the final determination result as a report (S324) or outputs through the display screen (S325) ).

For example, the final judgment is that if any one of the three measured values is bad, the final judgment is normal when all are normal (see FIG. 15C).

15 is an exemplary view showing a field measurement method and a measurement result screen using a failure type automatic determination device of a transformer according to the present embodiment. As shown in FIG. Based on the measurement elements (winding resistance, winding ratio, and insulation resistance), the state of the transformer can be determined and self-diagnosis can be performed.

As described above, in order to accurately determine the state of the transformer, the probes 110 and 120 for removing the oxide film formed on the surface of the transformer and the measurement of the winding resistance, the winding ratio, and the insulation resistance, which are essential measurement elements, are performed at the same time. . The reason for this is that in the prior art, it is often judged that the normal is wrong due to the high resistance caused by the oxide film, or when it is measured only one value, the other value is overlooked and the error is normal. In addition, existing equipment simply displays measured values, which can lead to human error that the user subjectively judges without the background knowledge of the transformer.

However, this embodiment has the effect of making the objective and accurate transformer state determination by eliminating the subjective judgment intervention of the user based on all measurement elements (winding resistance, winding ratio, and insulation resistance) when the transformer is diagnosed.

The present invention has been described above with reference to the embodiments illustrated in the drawings, but this is merely exemplary, and various modifications and equivalent other embodiments are possible from those skilled in the art. I will understand the point. Therefore, the technical protection scope of the present invention will be defined by the claims below.

Claims (11)

1. And a plurality of probes (first and second probes) in contact with a plurality of terminals (primary terminal and secondary terminal) of the transformer TR, and remove or drill through the oxide film formed on each terminal. A measuring unit in contact with and connected to the lower layer of the; And

   Measure the primary and secondary winding resistance, winding ratio, and insulation resistance in the transformer through the measuring unit, and self-diagnose faults, equipment errors, internal circuits, etc. through self-diagnosis. And a control unit for storing the measured result and correcting the temperature, and determining the state of the transformer based on the measured values and outputting the result through a report or a display screen. Discrimination device.
2. The method of claim 1, wherein the probe,

   The clamp terminal of the transformer is used to bite the clamp terminal of the transformer using a crocodile clip-type head, and the user holding the handle rotates from side to side to remove the oxide film on the surface of each terminal by using a portion formed to protrude and engage like a tooth formed in the clip of the crocodile-type head. Automatic type failure detection device characterized in that the transformer.
3. The method of claim 1, wherein the probe,

   When the user pushes the lever of the probe and pushes it into the clamp terminal of the transformer, the descaling tip formed at the inlet of the head removes the oxide film of the clamp terminal. Failure type automatic identification device of a transformer, characterized in that formed in contact with the part.
4. The method of claim 1, wherein the control unit,

   When the power supply of the transformer failure automatic discrimination device is turned on, self-diagnosis and calibration are performed.

   As a result of the self-diagnosis and calibration, if abnormal, outputs an alarm to the user, and if normal, displays the normal to the user.

   During auto or manual check mode,

   When the user selects the automatic mode according to the usage environment, the automatic mode is executed to automatically measure the state measurement of the transformer to automatically determine whether there is a failure,

   When the user selects the manual mode, the failure type automatic determination device of the transformer, characterized in that it receives the instruction of the measurement operation for the state measurement value from the user to determine whether the failure based on the corresponding measurement value.
5. The method of claim 4, wherein the control unit,

   When auto mode is activated,

   Select the transformer capacity,

   The winding resistance is measured according to the capacity of the transformer, and then the number of turns and the insulation resistance are measured, and the measured values are displayed on the display screen and analyzed at the same time.

   Displaying on the display screen whether the winding resistance measurement value is in the set normal range, whether the number of turns ratio measurement value is in the set normal range, and whether the insulation resistance is in the set normal range or not. Automatic failure type identification device of transformer.
6. The method of claim 1, wherein the control unit,

   When measuring the resistance of the transformer, the resistance value varies depending on the length of the winding, so it is determined whether the winding resistance is normalized using Equation 1 below.

   (Equation 1)

   

   ε: change rate (%), M _n : measured value of nth winding resistance

   If the change rate ε is less than or equal to the set value or the equipment error, it is determined that the winding resistance is stably normalized.

   When the change rate (ε) is greater than the set value or the equipment error, it is determined that the error is an error type automatic determination device of the transformer.
7. The method of claim 1, wherein the control unit,

   For measuring turns ratio,

   After initializing the operating power source and the set measurement variable, turning on the primary measuring operation power and the secondary measuring operating power, measuring and calculating the AC output value and the AC input value, and calculating the turns ratio using the measured values,

   When the winding ratio is measured by applying an AC input power to the primary winding and measuring the voltage output to the secondary side, the automatic failure type determination device of the transformer, characterized in that the winding ratio is calculated using the following equations (2) and (3) .

   (Equation 2)

   

   (Equation 3)

   

   Where N is the number of turns, V is the voltage, and I is the current
8. The method of claim 7, wherein the control unit,

   If the calculated winding ratio is within a specified error range, the calculated winding ratio is stored in a storage unit,

   When the calculated turns ratio is out of the error range, the failure type automatic determination device of the transformer, characterized in that for terminating or restarting the measurement.
9. The method of claim 1, wherein the control unit,

   For measuring insulation resistance,

   Turn on the operating power of the measuring circuit, generate and apply DC 1kV power (HV),

   Measure the current temperature,

   The insulation resistance value is calculated by measuring the leakage current (leakage_current) flowing through the main insulation of the transformer.

   A device for automatically identifying a failure type of a transformer, characterized by performing temperature compensation for the insulation resistance by applying “insulation resistance * (1+ (1 / (234.5 + temperature) * (temperature-25.0))”.
10. The method of claim 9, wherein the control unit,

    It is checked whether the insulation resistance value that has performed the temperature compensation maintains a value within a preset error range for a predetermined time period,

    As a result of the check, if the insulation resistance value for which the temperature compensation is performed maintains a value within a preset error range for a predetermined time, the insulation resistance value for performing the temperature compensation is stored in a storage unit.

    If the insulation resistance value for which the temperature compensation is performed does not maintain a value within a preset error range for a predetermined time, the checking process is repeated for a specified loop time, and the insulation resistance for which the temperature compensation is performed even after the designated loop time If the value does not maintain a value within a predetermined error range, the failure type automatic determination device of a transformer, characterized in that the processing as an error.
11. The method of claim 1, wherein the control unit,

    To determine the final state of the transformer using the measured values,

    Determine the state of the winding resistance measurement value, winding ratio measurement value, and insulation resistance measurement value,

    If any one of the measured values is bad, the transformer finally determines that it is bad.

    If all of the measured values are normal, the transformer automatically determines the failure type of the transformer, characterized in that the final determination to the normal state.

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