JP5456582B2 - Transformer soundness diagnosis method, soundness diagnosis device, and soundness diagnosis program - Google Patents

Description

  The present invention relates to a transformer health diagnostic method, a health diagnostic device, and a health diagnostic program. More specifically, the present invention relates to a technique suitable for use in determining the presence or absence of a rare short in a transformer.

  In response to demands for cost reduction in maintenance and management of power distribution facilities and industrial waste reduction for the formation of a recycling-oriented society, reuse of pole transformers for power distribution has been carried out. In Non-Patent Document 1, as criteria for determining the reuse of transformer windings, (1) presence or absence of abnormalities such as burnout or winding contamination, (2) presence or absence of conduction (disconnection), or quality of insulation resistance, (3) If there are two or more winding repair histories, three items of necessity of rewinding are introduced. A similar test may be performed when a fuse blows due to lightning.

  However, in the above test, it is impossible to detect rare shorts or winding misalignments that are problematic as an abnormality of the pole transformer. Moreover, it is desirable that the diagnosis of the soundness of the pole transformer can be performed without opening and closing the top cover of the pole transformer in order to reduce labor and to prevent moisture from being mixed into the pole transformer. Note that the layer of the winding wound around the iron core of the transformer is called a layer, and a state where the layers are short-circuited is called a rare short or an interlayer short circuit.

  As a conventional method for determining the presence or absence of a rare short in a distribution pole transformer, for example, an alternating voltage having a different frequency is sequentially applied to the windings of the transformer, and the exciting current of the transformer with respect to the alternating voltage having a different frequency is used. A first-order differentiation is performed on the approximate curve of the measured excitation current value. When the differential value is positive, it is determined that there is no short circuit, and when the differential value is negative, it is determined that there is a short circuit (Patent Document 1). ).

  Further, there is a frequency response analysis (FRA) as a method for diagnosing abnormality of a transformer winding. In frequency response analysis, a sinusoidal electrical signal (eg, voltage) is input and the amplitude of the output signal (eg, current) is measured while changing the frequency from several tens [Hz] to several [MHz]. (For example, impedance) is obtained. The transfer function shows resonance by electrical constants such as leakage inductance, ground capacitance, and interwinding capacitance. If there is an abnormality in the transformer winding, these electrical constants change and the transfer function (specifically, For example, the resonance frequency) changes. In the frequency response analysis, the abnormality of the transformer winding is diagnosed by the presence or absence of the change compared with the transfer function measured when the transformer is in a healthy state.

JP2009-14528

IEEJ Technical Report No. 1164: Trends and Issues in Life Cycle Management of Distribution Equipment, 2009

  However, the method for determining the presence or absence of rare short in Patent Document 1 requires a device for measuring current by sweeping the frequency over a wide range of 300 to 2000 [Hz] and at several hundred points (hundreds of frequencies). There is a problem that measurement is required and cost and much labor and time are required. In particular, since a large number of distribution pole transformers are installed, the rare short presence determination method of Patent Document 1 cannot be said to be highly versatile when targeting distribution pole transformers.

  Further, the frequency response analysis also needs to be performed by changing the frequency from several tens [Hz] to several [MHz], which is costly and takes much time and effort. In fact, frequency response analysis is applied exclusively to transformers larger than the distribution / transformation class, and there is no application example to distribution pole transformers with a very large number of installations.

  Accordingly, the present invention provides a method for diagnosing transformer health, which is capable of determining the presence or absence of a short-circuit in a short time with little effort without opening and closing the top cover of the transformer and using only a general-purpose device. An object is to provide a device and a health diagnosis program.

  The present inventor, while examining the transformer soundness evaluation method that can be carried out with only a general-purpose device in a small amount of time and in a short time without opening and closing the upper lid of the transformer, a specific point of the pole transformer It has been found that the presence or absence of a rare short can be determined by measuring the transfer function of only the frequency. A test for verifying the validity of this technical idea unique to the present invention (hereinafter referred to as a verification test) will be described below.

ただし、ｊ：虚数単位，
ω：角周波数 をそれぞれ表す。 In principle, the transfer function measured in the frequency response analysis can be arbitrarily selected from winding impedance, admittance, voltage ratio, and the like. In the verification test, as shown in FIG. 3, the input voltage Vin (jω) injected into the winding and the output voltage Vout (jω) based on the 50Ω impedance are measured, and the transfer function H ( jω). In FIG. 3, reference numeral 1 denotes a pole transformer, reference numeral 2A denotes a primary winding, reference numeral 2B denotes a secondary winding, and reference numeral 5 denotes a measuring device.

Where j: imaginary unit,
ω: represents angular frequency.

  In this verification test, measurement (hereinafter referred to as short-circuit measurement) in the state where the winding on the side not being measured is short-circuited with respect to each of the primary winding 2A and the secondary winding 2B and measurement is not performed. Measurement is performed with nothing connected between the winding terminals (hereinafter referred to as open measurement).

  First, FIG. 4 shows an example of a transfer function of a normal (that is, healthy) pole transformer by measurement under the above-described conditions. The transfer function shown in FIG. 4 (a) is for a pole transformer with a rated capacity of 10 [kVA], and the transfer function shown in FIG. 4 (b) is for a pole transformer with a rated capacity of 50 [kVA]. Is.

The following is confirmed from the results shown in FIG.
i) Opening measurement of primary winding (solid line in the figure)
When the frequency becomes higher than the commercial frequency, the transfer function gradually decreases.
ii) Short circuit measurement of the primary winding (dotted line in the figure)
When the frequency becomes higher than the commercial frequency, the transfer function gradually decreases.
The first resonance frequency is higher than in open measurement.
The resonance having the lowest frequency is called the first resonance, and the frequency at that time is called the first resonance frequency.
iii) Opening measurement of secondary winding (dashed line in the figure)
The first resonance frequency is several hundreds [Hz], specifically 200 to 300 [Hz].
Note that the frequency band in which the value of the transfer function is increasing or decreasing as the occurrence of the first resonance is referred to as the first resonance frequency band.
A relatively large resonance different from the first resonance appears at several hundreds [kHz].
iv) Secondary coil short circuit measurement (two-dot chain line in the figure)
At a frequency of several tens [kHz] or less, the transfer function is almost 0 [dB].

  Next, the transfer function is measured after simulating a rare short with the same pole transformer as above. Here, the winding structure of the pole transformer used in this verification test is shown in FIG.

  The rare of the primary winding 2 </ b> A is wound on each of the left and right sides of the iron core 4, for a total of 24. The number of turns of each rare is 150 times for each of the left and right rares closest to the tap board 3, and all other rares are 234 times.

  In addition, the rare of the secondary winding 2B is wound on each of the left and right sides of the iron core 4, and the total number is four. Each rare has 21 turns. The rare of the secondary winding 2B has a structure in which the left rare of the iron core 4 is connected to the right rare and the right rare is connected to the left rare.

Then, pull out the upper winding of each rare, connect it above the oil level of the pole transformer, and provide terminals (H _L2,3 ^{+ to} H _L12 ⁺ , H _L2,3 ^{− to} H _L12 ⁻ ) to make a short circuit To simulate a rare short.

The measurement result of the transfer function when the primary winding rare is short-circuited is shown in FIG. The following is confirmed from the results shown in FIG.
i) Resonance observed in the vicinity of several hundreds [Hz] in the normal state is not an open measurement of the secondary winding.
In other words, the transfer function in the frequency band of several hundreds [Hz] is 0 [dB].
ii) Resonance that was not normal appears in the vicinity of 10 kHz in the open measurement of the secondary winding.

  When a rare short occurs, a closed loop surrounding the iron core is created. This is equivalent to the fact that what was a two-winding transformer becomes a three-winding transformer and the windings are short-circuited. At this time, even if the secondary winding is in an open state, the characteristics of the iron core are ignored as in the short-circuit measurement. It is the first resonance of several hundreds [Hz] that represents the characteristics of the iron core, which disappears.

  Note that the resonance that appears in the vicinity of 10 [kHz] due to the rare short is considered to be due to the primary side leakage inductance and the interwinding capacitance. The calculated value of the resonance frequency of the pole transformer in this verification test is 10.8 [kHz], which almost coincides with the transfer function measurement result. In addition, another measurement (open measurement) is performed to measure the transfer function of the secondary winding while gradually increasing the rare number of the primary winding to be short-circuited. The resonance frequency shifts to the higher frequency side when the number of short-circuiting rares increases. It was also confirmed that This is because as the number of shorted rares increases, the leakage inductance contributing to this resonance decreases.

  In addition, the transfer function is measured after short-circuiting adjacent turns near the lead portion of the primary winding of the transformer. The short circuit between turns is regarded as the case where the degree of the short circuit is the smallest. In the present invention, the short circuit is included in the rare short circuit that can be determined by the transformer health diagnosis method of the present invention as one of the abnormality of the transformer. In the case of a pole transformer, it is considered that a short circuit between turns is not likely to occur in practice.

  FIG. 7 shows the measurement result of the transfer function when the primary winding turns are short-circuited. From the results shown in FIG. 7, it is confirmed that the transfer function of the secondary winding / opening measurement (the one-dot chain line in the figure) is about −5 [dB] in the case of a short circuit between turns. This value is large compared to the transfer function of a normal pole transformer.

  From the results of the above verification test, it is possible to determine the presence or absence of short-to-turn or rare short based on the transfer function of the first resonance frequency band, and transfer function of only one specific frequency of the pole transformer The validity of the technical idea peculiar to the present invention for determining the presence or absence of a rare short (including a short circuit between turns) is confirmed by measuring. Although this verification test targets distribution pole transformers, the knowledge gained from this verification test is that it is possible to determine the presence or absence of short-to-turn shorts or rare shorts in the transformer. This technical idea can be applied to other types of transformers.

  Moreover, from the result of the verification test, it is confirmed that the first resonance frequency band of the distribution pole transformer is about 200 to 300 [Hz], and a rare short (including a short circuit between turns) occurs. The transfer function is confirmed to be about −5 [dB] or more.

The present invention is based on the above-mentioned knowledge. Specifically, the method for diagnosing the transformer health according to claim 1 is characterized in that either the primary winding or the secondary winding of the transformer is wound. With the wire open, measure the transfer function of the other winding at a specific frequency in the frequency band where the first resonance of the healthy transformer appears, and the value of the transfer function at the specific frequency is a predetermined threshold In the following cases, it is determined that no short circuit between turns of the one winding or a rare short has occurred, and if the value of the transfer function at a specific frequency is larger than a predetermined threshold, the one winding It is determined that a short circuit between turns or a short circuit has occurred .

The transformer health diagnostic device according to claim 2 is a transformer in a healthy state measured with one of the primary and secondary windings of the transformer open. Storage means in which the value of the transfer function of the other winding at a specific frequency in the frequency band in which the first resonance appears is recorded, means for reading the value of the transfer function at a specific frequency from the storage means, If the value of the transfer function at a frequency is less than or equal to a predetermined threshold value, it is determined that no short circuit between turns of the one winding or a rare short has occurred, and the value of the transfer function at a specific frequency is determined in advance. Means for determining that a short circuit between turns of the one winding or a rare short has occurred .

According to a third aspect of the present invention, there is provided a soundness diagnosis program for a transformer, which is measured in a state where one of the primary winding and the secondary winding of the transformer is opened. A computer having access to the storage means storing the transfer function database in which the value of the transfer function of the other winding at a specific frequency in the frequency band where the first resonance appears is stored in the transfer function database. A process of reading a transfer function value at a frequency, and if the transfer function value at a specific frequency is equal to or less than a predetermined threshold value, it is determined that a short circuit between turns or a rare short has not occurred in the one winding. If the value of the transfer function at a specific frequency is greater than a predetermined threshold, it is determined that a short circuit between turns of the one winding or a rare short has occurred. It is as to carry out the process and that.

  Therefore, according to the soundness diagnosis method, soundness diagnosis apparatus, and soundness diagnosis program for these transformers, it is determined whether or not there is a short circuit between turns of the winding or a rare short circuit based on the value of the transfer function at a specific frequency. Therefore, the presence or absence of a rare short is determined without taking the effort of sweeping the frequency over a certain range and without opening and closing the upper lid of the transformer.

  According to the transformer soundness diagnosis method, soundness diagnosis apparatus, and soundness diagnosis program of the present invention, it is possible to determine the presence or absence of a rare short circuit without taking the trouble of sweeping the frequency over a certain range. Therefore, it is possible to improve the versatility of the soundness diagnosis technique by reducing the labor and the measurement time by using only the general-purpose device. In the case of performing measurement by sweeping the frequency in the low frequency band, the measurement time is generally long. However, according to the present invention, this is not necessary, so that the measurement time can be greatly reduced as compared with the conventional method. It becomes possible.

  In addition, according to the transformer health diagnosis method, the health diagnosis device, and the health diagnosis program of the present invention, it is possible to determine the presence or absence of a rare short without opening and closing the top cover of the transformer. Diagnosis avoids impairing the soundness of the pole transformer, thereby improving versatility. In particular, the installation location of the pole transformer is usually outdoors, but according to the present invention, the upper lid is not opened and closed, so there is no need to pay attention to the maintenance of the internal state of the pole transformer, and the field applicability is greatly increased. It becomes possible to improve.

It is a flowchart explaining an example of embodiment of the soundness diagnostic method of the transformer of this invention. It is a functional block diagram of the transformer health diagnostic device when the transformer health diagnostic method of the present embodiment is implemented using a program. It is a figure explaining the transfer function measuring method. It is a figure which shows the transfer function of the normal pole transformer of a verification test. It is a figure explaining the winding structure of the pole transformer of a verification test. It is a figure which shows the transfer function of the pole transformer which simulated the rare short of a verification test. It is a figure which shows the transfer function of the pole transformer which simulated the short circuit between turns of a verification test.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 and 2 show an example of embodiments of a transformer health diagnosis method, a health diagnosis device, and a health diagnosis program according to the present invention. As shown in FIG. 1, the method for diagnosing the health of a transformer according to the present invention includes a transformer in a healthy state in which either one of the primary winding and the secondary winding of the transformer is opened. The transfer function of the other winding at a specific frequency in the frequency band in which the first resonance appears is measured (S1), and the short-circuit between turns of the one winding or a rare short is based on the value of the transfer function at the specific frequency The soundness of the transformer is determined based on the presence or absence of (S2).

  In addition, the transformer health diagnosis apparatus according to the present invention is the first transformer of a healthy state measured with one of the primary and secondary windings of the transformer open. Storage means (16) in which the value of the transfer function of the other winding at a specific frequency in a frequency band where one resonance appears is recorded, and means for reading the value of the transfer function at a specific frequency from the storage means (16) (11a) and means (11b) for determining the soundness of the transformer based on the presence or absence of a short circuit between turns of the one winding or a rare short based on the value of the transfer function at a specific frequency. .

  The transformer health diagnostic method and the transformer health diagnostic device described above can also be realized by executing the transformer health diagnostic program of the present invention on a computer. The transformer health diagnosis program according to the present invention is the first resonance of a transformer in a healthy state measured with one of the primary and secondary windings of the transformer open. A transfer function at a specific frequency is transferred from the transfer function database to a computer accessible to a storage function storing a transfer function database in which the transfer function value of the other winding at a specific frequency in the frequency band where the And a process of judging the soundness of the transformer based on the presence or absence of a short circuit between turns of the one winding or a rare short based on the value of the transfer function at a specific frequency. ing.

  In the present embodiment, a case where a transformer health diagnosis program is executed on a computer will be described as an example.

  FIG. 2 shows an overall configuration of a computer 10 (that is, a transformer health diagnostic device 10; hereinafter simply referred to as a health diagnostic device 10) for executing the transformer health diagnostic program 17. The soundness diagnosis apparatus 10 includes a control unit 11, a storage unit 12, an input unit 13, a display unit 14, and a memory 15, and is connected to each other by a signal line such as a bus. The health diagnostic apparatus 10 is connected to a data server 16 through a signal line such as a bus, and signals such as data and control commands are transmitted and received (that is, input / output) through the signal line.

  The control unit 11 performs operations related to overall control of the soundness diagnosis device 10 and diagnosis of soundness of the transformer by the soundness diagnosis program 17 of the transformer stored in the storage unit 12. Arithmetic processing unit). The storage unit 12 is a device that can store at least data and programs, and is, for example, a hard disk. The memory 15 serves as a memory space that is a work area when the control unit 11 executes various controls and calculations, and is, for example, a RAM (abbreviation of Random Access Memory).

  The input unit 13 is an interface for giving at least an operator's command to the control unit 11, and is, for example, a keyboard.

  The display unit 14 performs drawing / display of characters, graphics, and the like under the control of the control unit 11 and is, for example, a display.

  Then, by executing the transformer health diagnosis program 17, the control unit 11 of the health diagnosis apparatus 10, which is a computer accessible to the data server 16, transmits the transfer function at a specific frequency from the transfer function database 18. Based on the transfer function data reading unit 11a that performs the process of reading the value and the transfer function value at a specific frequency, the soundness of the transformer is determined based on the presence or absence of a short-circuit between turns or a rare short of the one winding. A soundness determination unit 11b that performs processing is configured.

  In the present embodiment, the first resonance of the healthy transformer measured by the data server 16 with one of the primary and secondary windings of the transformer open. It functions as a storage means for storing a transfer function database in which the values of the transfer functions of the other winding at a specific frequency in the frequency band in which is stored.

  In carrying out the present invention, first, the transfer function of the transformer is measured (S1). When there are a plurality of transformers to be diagnosed, the process of S1 is performed for each transformer to be diagnosed. Further, when there are a plurality of times of soundness evaluation, the process of S1 is performed for each evaluation time.

  In the present invention, with one of the primary winding and the secondary winding of the transformer being opened, the other at a specific frequency in the frequency band in which the first resonance of the healthy transformer appears. The winding transfer function is measured. Hereinafter, in this embodiment, the case of determining the soundness of the primary winding of the transformer will be described, and therefore, the transfer function of the secondary winding is measured with the primary winding of the transformer open. Is done.

  The measurement of the transfer function is performed, for example, by a method conventionally used in frequency response analysis performed on a transformer. On the other hand, since it is necessary to sweep the frequency in the conventional frequency response analysis, it is necessary to use a measuring device having a frequency sweep function (see FIG. 3). A measuring device that performs measurements at the required frequency is sufficient. For example, a measuring device including an oscillator (for example, 300 Hz), an amplifier, a 50Ω resistor, and a voltmeter (in other words, a measuring device conventionally used in frequency response analysis that does not have a frequency sweep function. For example, as shown in FIG. Using the measuring device 5 having no frequency sweep function), the input voltage Vin (jω) injected into the secondary winding 2B of the pole transformer 1 and the output voltage Vout (jω) based on the 50Ω impedance are obtained. This is done by measuring and obtaining the transfer function H (jω) defined by Equation 1.

  Here, in the present invention, a transfer function at a specific frequency is measured. And in this invention, it is preferable to measure the transfer function in the frequency of the specific one point in the frequency band in which the 1st resonance of the transfer function of a transformer at the time of a healthy state appears. In the present invention, as the frequency for measuring the transfer function, in the case of a pole transformer, the frequency band in which the first resonance of the secondary winding / opening measurement appears is specifically about 200 to 300 [Hz], for example. Therefore, it is conceivable to measure the transfer function at a specific frequency in the range. However, the present invention is not limited to this, and any frequency band where the first resonance of the transfer function of the transformer to be diagnosed appears. Other frequencies may be used. In the case of the same type of transformer, the transfer functions are the same, and therefore the frequency bands in which resonance occurs are the same.

  When the frequency to measure the transfer function is uniquely determined, and there is an existing measurement result of the transfer function at the transformer of the same type as the transformer to be diagnosed (but healthy), use the measurement result The measurement frequency may be determined, or the frequency of the first resonance may be calculated based on the design specification of the transformer to be diagnosed, and the measurement frequency may be determined using the calculation result. When diagnosing a plurality of transformers of the same type, the measurement frequency may be determined using the result of measuring the transfer function of one healthy transformer. Note that the measurement frequency may not coincide with the frequency of the first resonance as long as it is within the range of the first resonance frequency band.

  In addition, when measuring the transfer function of a healthy transformer in advance and determining the measurement frequency, for example, in the healthy transformer, the frequency is gradually decreased from the first resonance frequency, and the value of the transfer function is resonant. The frequency f1 that is equal to or higher than the frequency band threshold value and the frequency f2 that is gradually increased from the first resonance frequency and the transfer function value is equal to or higher than the resonance frequency band threshold value are measured. It is conceivable that the frequency within is the measurement frequency. Here, the resonance frequency band threshold is a value of the transfer function for determining that the value of the transfer function is increasing or decreasing as the first resonance occurs, and is a value smaller than a soundness determination threshold described later (specifically Is set to, for example, twice the soundness determination threshold.

  In this embodiment, the value of the transfer function at a specific frequency is stored in the data server 16 as the transfer function database 18. When there are a plurality of transformers to be diagnosed, the transfer function data is stored in the data server 16 as the transfer function database 18 after being associated with information (for example, ID) for identifying each transformer. Further, when there are a plurality of time points for soundness evaluation, the transfer function data is stored in the data server 16 as the transfer function database 18 after being associated with the information at the time of measurement.

  Subsequently, the soundness of the transformer is determined using the transfer function data prepared by the process of S1 (S2). When there are a plurality of transformers to be diagnosed, the process of S2 is performed for each transformer to be diagnosed. Further, when there are a plurality of times of soundness evaluation, the process of S2 is performed for each evaluation time.

  Specifically, the soundness determination unit 11 b of the control unit 11 reads the value of the transfer function of the transformer from the transfer function database 18.

  And the soundness determination part 11b determines that the shortness (including short circuit between turns) does not occur and the soundness of the transformer is maintained when the value of the transfer function is equal to or less than the soundness determination threshold. If it is greater than the soundness determination threshold, it is determined that a short circuit has occurred and the soundness of the transformer is impaired.

  Here, the soundness determination threshold value is a value of a transfer function for determining that a short circuit (including a short circuit between turns) has occurred and the soundness of the transformer is impaired. As the soundness determination threshold in the present invention, in the case of a pole transformer, specifically, it may be set to, for example, about −5 [dB], but is not limited to this, for example, the same type device. An appropriate value based on the value of the transfer function at the time of abnormality may be used. In addition, when determining the soundness determination threshold value uniquely, it is possible to set based on the transfer function in the state which simulated the short circuit between turns. The soundness determination threshold value is defined in advance in, for example, the soundness diagnosis program 17 of the transformer.

  Then, the soundness determination unit 11b determines that the soundness of the transformer is maintained or has been damaged as a determination result in the process of S2, when necessary, for each transformer to be diagnosed and at the time of evaluation. For example, the data is displayed on the display unit 14 or stored as a diagnosis result data file in the storage unit 12 or the data server 16, for example.

  And the control part 11 complete | finishes the process of the soundness diagnosis of a transformer (END).

  According to the soundness diagnosis method, soundness diagnosis apparatus, and soundness diagnosis program of the transformer of the present invention having the above-described configuration, the presence or absence of a rare short is determined without taking the trouble of sweeping the frequency over a certain range. Therefore, it is possible to improve the versatility as a soundness diagnosis technique by reducing the labor and the measurement time by using only a general-purpose device. In addition, according to the transformer health diagnosis method, the health diagnosis device, and the health diagnosis program of the present invention, it is possible to determine the presence or absence of a rare short without opening and closing the top cover of the transformer. Diagnosis avoids impairing the soundness of the pole transformer, thereby improving versatility.

  In addition, although the above-mentioned form is an example of the suitable form of this invention, it is not limited to this, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of this invention. For example, in this embodiment, the transfer function of the secondary winding is measured in a state where the primary winding is opened as a case where the soundness of the primary winding of the transformer is determined. Conversely, the soundness of the secondary winding may be determined by measuring the transfer function of the primary winding with the secondary winding open. In this case, for example, in the case of a pole transformer, the transfer function of the frequency at a specific point in the frequency band in which the first resonance of the primary winding / opening measurement around 1 [kHz] in a healthy state appears is measured. .

  In this embodiment, the storage means for storing the transfer function data is the data server 16, but the storage unit 12 or another storage device may be used.

  Moreover, this invention is applicable not only to a pole transformer for power distribution but to various transformers having two windings.

1 Transformer 10 Transformer health diagnostic device 17 Transformer health diagnostic program

Claims (3)

Transmission of the other winding at a specific frequency in the frequency band in which the first resonance of the transformer in a healthy state appears in a state where one of the primary winding and the secondary winding of the transformer is opened. A function is measured, and when the value of the transfer function at the specific frequency is equal to or lower than a predetermined threshold, it is determined that a short circuit between turns of the one winding or a rare short has not occurred, and the specific frequency When the value of the transfer function in is larger than the predetermined threshold value, it is determined that a short circuit between turns or a short circuit has occurred in the one winding . The other winding at a specific frequency in the frequency band in which the first resonance of the healthy transformer appears, measured with one of the primary and secondary windings of the transformer open. Storage means in which the value of the transfer function of the line is recorded, means for reading the value of the transfer function at the specific frequency from the storage means, and the value of the transfer function at the specific frequency is less than a predetermined threshold value In this case, it is determined that a short circuit between turns of the one winding or a rare short has not occurred, and if the value of the transfer function at the specific frequency is larger than the predetermined threshold, the one winding And a means for determining that a short circuit between turns or a rare short has occurred . The other winding at a specific frequency in the frequency band in which the first resonance of the healthy transformer appears, measured with one of the primary and secondary windings of the transformer open. Reading a transfer function value at the specific frequency from the transfer function database to a computer accessible to storage means storing a transfer function database in which values of transfer functions of lines are stored; When the value of the transfer function at the frequency is equal to or less than a predetermined threshold, it is determined that no short circuit between turns of the one winding or a rare short has occurred, and the value of the transfer function at the specific frequency is the predetermined value. and characterized in that is greater than a defined threshold performed a process of determining a turn between short or short circuit of said one winding is occurring Transformer of health diagnostic program that.

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