JP6251861B1 - Transformer degradation status display device - Google Patents

Abstract

Disclosed is a transformer degradation status display device capable of continuously displaying the degradation status of a transformer for all transformers including a small capacity transformer. A method of multiplying the degree of polymerization decrease gradient at a place where the installation site temperature and the operating load factor are intermediate as a reference gradient Kc and multiplying the reference gradient Kc by a gradient correction coefficient R is used. , The gradient correction coefficient R, the installation location temperature difference Td (difference between the diagnosis transformer installation location temperature and the reference temperature) and the insulation paper temperature difference Tzs (insulation paper temperature and reference load at the diagnosis transformer operating load factor) R = 1 / EXP (−H (Td + Tzs)) based on the difference between the insulating paper temperature and the insulating paper temperature, and the insulating paper temperature difference Tzs is a slope correction coefficient R value of 0.4 to 2.5. A graph showing a state in which the degree of polymerization is decreased at an actual gradient K obtained by multiplying the reference load factor by a gradient correction coefficient R obtained by a regression equation related to the operating load factor U that falls within the range. [Selection] Figure 2

Description

  The present invention relates to a technique for displaying a deterioration state of a transformer as a decrease in average polymerization degree (hereinafter abbreviated as polymerization paper) of insulating paper (hereinafter abbreviated as insulation paper) mounted between transformer windings and the like. .

  The remaining life is estimated based on the degree of polymerization degree of the insulating paper, and the transformer is renewed before the life of the transformer is reached to prevent accidents due to deterioration.

As means for investigating the state of deterioration of the insulating paper, a known method for taking out a part of the insulating paper and measuring the degree of polymerization at the time of a transformer power outage, or a method such as the following literature 1 and literature 2 for estimating the degree of polymerization while operating Has been taken.
Japanese Patent No. 4323396 Japanese Patent No. 5387877

  A known method of taking out a part of insulating paper and measuring the degree of polymerization can only be carried out at the time of periodic inspection. Since this is not possible, the sign of an accelerated decrease in the degree of polymerization was missed, and there was a drawback that accident prevention measures such as improvement of transformer usage conditions were delayed.

  The method of Patent Document 1 that can grasp the degree of polymerization even when the transformer is operating removes the estimated thermal history of the insulating paper temperature from the load history of the diagnostic transformer, weather information, and the insulating oil temperature measured at the time of inspection. A method is employed in which the remaining life is obtained by matching with a master curve indicating the relationship between the thermal history of the insulating paper and the degree of polymerization produced from the measured value of the degree of polymerization of the transformer insulating paper.

  The method of Patent Document 2, which is another method that can grasp the degree of polymerization even when the transformer is operating, is the deterioration of CO, CO2, furfural, etc. contained in the insulating oil collected during periodic inspection of the transformer to be diagnosed. A method is used in which the degree of polymerization is estimated based on the operating environment data such as the amount of the index component, the years of operation of the transformer to be diagnosed, and the load factor, and the remaining life is obtained.

  However, the methods of Patent Document 1 and Patent Document 2 are evaluation methods for specific transformers that obtain insulation deterioration index data from insulating paper or insulating oil, and for transformers that do not obtain insulation deterioration index data. Because it is not applicable and is an intermittent evaluation method at every inspection, it will miss the sign of an accelerated decrease in the degree of polymerization when there is a sudden deterioration in transformer usage conditions after inspection, and prevent accidents. There was a drawback that it could not be implemented in a timely manner.

  The present invention has been made in view of such circumstances, and the degree of polymerization from the start of use of the transformer to the present over all transformers including small-capacity transformers in which acquisition of an insulation deterioration index is often not made. By continuously showing the state of decline, it is possible to monitor signs of decreased polymerization due to sudden changes in transformer operating conditions, and to improve transformer operating conditions in a timely manner. To do.

In order to achieve the above object, the method according to claim 1 is that the transformer used in Japan is designed and manufactured in accordance with a domestic standard (JEC-2200, JISC4304). Focusing on the fact that the temperature rise value of the transformer is considered to be almost the same for the insulation paper material and the operating load factor, the polymerization process that has been published in Japan has been published in Japan. Based on the view that it can be considered that the graph will be within the range of the minimum gradient path and maximum gradient path of the time-gradual decline graph group, the transformer is in the best operating condition (the temperature of the place where the transformer is installed is The degree of polymerization of the transformer is assumed to be continuously operated at the average temperature and the transformer operating load factor is the lowest load factor of the operating load factor distribution in Japan). Drop , The transformer operates continuously under the worst operating conditions (the temperature at the location where the transformer is installed is the annual average temperature in the high temperature region in Japan and the operating load factor of the transformer is the highest load factor of the operating load factor distribution in Japan) The degree of polymerization of the transformer is reduced along the maximum gradient line in the graph of the degree of polymerization aging deterioration, and the transformer is operated between the best and worst operating conditions (the temperature of the place where the transformer is installed is low). The operating load factor is continuous with the average load factor (hereinafter referred to as the reference load factor Uc) of the operating load factor distribution at a temperature intermediate between the annual average temperature in the temperature region and the annual average temperature in the high temperature region (hereinafter referred to as the reference temperature Tc). The degree of polymerization of the transformer to be operated decreases along a straight line intermediate between the minimum gradient path and the maximum gradient path, and the degree of polymerization of the transformer under diagnosis whose operating conditions change is the minimum gradient line. Polymerization with transition between maximum gradient straight lines A means for obtaining a temperature Ta at the installation location of the transformer to be diagnosed by setting a decrease region, and an installation site temperature difference between the installation site temperature Ta and the reference temperature Tc (any one of 11 to 13 ° C.) Means for calculating Td, means for obtaining the operating current I of the diagnostic transformer, means for calculating the operating load factor U from the operating current I, and increase in insulation paper at the operating load factor U of the diagnostic transformer Means for calculating an insulation paper temperature difference Tzs between the temperature Tz and the rising temperature Tzc of the insulation paper according to the reference load factor Uc (any one of 35 to 40%); The degree of polymerization of the transformer, which is assumed to be continuously operated with the temperature being the reference temperature Tc and the operation load factor being the reference load factor Uc), is the degree of polymerization at the start of transformer operation (any of 800 to 1000) 20 / year to 30 / The gradient of the degree-of-polymerization decrease line in the intermediate operating condition, which is assumed to decrease at any one of the gradients of the year, is defined as a reference gradient Kc. In the diagnostic transformer, the degree of polymerization is multiplied by the gradient correction coefficient R to the reference gradient Kc. The degree-of-polymerization transition transition determining means that is decreased at the actual gradient K, and the gradient correction coefficient R are calculated by the following formula R = 1 / exp (related to the transformer installation location temperature difference Td and the insulating paper temperature difference Tzs). -H (Td + Tzs)) (Equation 1)
(Where H is any one of 0.0693 (1 / ° C.) to 0.1155 (1 / ° C.) ), and the insulating paper temperature difference Tzs in (Expression 1) When the temperature range of the installation location temperature difference Td is 8 ° C. (−4 to + 4 ° C. centering on the reference temperature) and the range of the operating load factor U is 40% (−20 to + 20% centering on the reference load factor) Is calculated by a regression equation related to the operating load factor U such that the value of the gradient correction coefficient R is 0.4 to 2.5, and the calculated insulation paper temperature difference Tzs is substituted into the calculation formula of the gradient correction coefficient R. Means for calculating the gradient correction coefficient R; means for multiplying the reference gradient Kc by the gradient correction coefficient R calculated by calculating the reference gradient Kc with the calculated gradient correction coefficient; and the actual gradient K Calculate the degree of polymerization by time of the degree of polymerization that gradually decreases by the storage unit Means and, means for rubbing storing daily final value of another polymerization degree the time in each date on the date by polymerization degree storage unit of the storage unit, the current time earlier plurality of times to store the time for each time in a different polymerization degree storage unit (For example, as a mean value of a plurality of hourly polymerization degree decrease gradients used for calculating the hourly polymerization degree at 19:00 on the previous day, 15:00 on the previous day, and 19:00 on the previous day, prediction of future polymerization degree transition after the current time Means for calculating the gradient, means for calculating the future polymerization degree transition estimated gradient after the current time according to the calculation conditions (transformer calculation installation location temperature and calculation operation load factor) input from the input unit, and the date The polymerization degree transition from the start of use of the diagnostic transformer read from the separate polymerization degree storage unit and the hourly polymerization degree storage unit to the current time and the future polymerization degree transition after the current time after the current time along the expected gradient Expected polymerization degree transition and future degree of polymerization estimation Means for displaying the estimated polymerization degree transition after the current time along the estimated gradient in a long-term polymerization degree transition graph from the start of use of the diagnostic transformer to several tens of years, or based on the long-term polymerization degree transition graph and the current point And means for simultaneously or alternately displaying a short-term polymerization degree transition graph of several days.

  According to the method of the present invention, over the entire transformer used in Japan, the degree of polymerization is accelerated by sudden deterioration of the use conditions by continuously showing the degree of polymerization degree deterioration from the start of use of the transformer to the present. It is possible to constantly evaluate the degree of polymerization reduction and the quality of transformer operating conditions without overlooking the state of degradation, and improve transformer operating conditions in a timely manner to prevent accidents caused by transformer deterioration. it can.

  It is a graph which shows the fall area | region and reference | standard gradient of the polymerization degree in this invention.   4 is a graph showing a long-term polymerization degree transition of the transformer deterioration display device according to the present invention.   It is a short-term polymerization degree transition display graph of the transformer deterioration display apparatus by this invention.   3 is a long-term and short-term polymerization degree transition composite display graph of the transformer deterioration display device according to the present invention.   It is a block diagram which shows the structure of the transformer degradation display apparatus by the Example of this invention.   It is a flowchart which shows the process of the transformer degradation display apparatus by the Example of this invention.   It is a graph which shows the relationship between the operation years described in JEM1463, and an average degree of polymerization.   It is a graph which shows the relationship between the number of years of operation and average polymerization degree which are described in transformer manufacturer technical data description.   This is a survey table of transformer load factor according to type of industry published by the Japan Electrical Manufacturers' Association.

  Hereinafter, the best mode for carrying out selection of a transformer according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a graph showing a transition region and a reference gradient of the degree of polymerization according to the present invention, based on FIGS. In FIG. 7, the straight line 1a indicates the minimum gradient in the degree-of-polymerization transition graph (the degree of polymerization at the start of operation is 900 and the rate of decrease is 12.5 / year). The straight line 1b is the straight line on the lower limit side of the degree of polymerization shown in FIG. 8 showing the maximum gradient in the degree-of-polymerization transition graph (the degree of polymerization at the start of operation is 900, and the decrease gradient is 50 / year). 1c is an intermediate straight line between the minimum gradient straight line 1a and the maximum gradient straight line 1b (the polymerization degree at the start of operation is 900, and the decreasing gradient is the reference gradient K (25 / year)).

  Regarding the range of transformer installation temperature Ta, the minimum temperature is 8 ° C in the Hokkaido region and the maximum temperature is 16 ° C in the Kyushu region based on the annual average temperature for the past 40 years based on the data published by the Japan Meteorological Agency. For the range, the standard deviation value σ calculated by quoting 290 load factors described as per day in the industry survey table of transformer load factors shown in FIG. 9 and assuming that the load factor distribution is a normal distribution is σ. From the average value of 37.3%, the minimum load factor is 19.5% (37.3-2σ) and the maximum load factor is 55.2% (37.3 + 2σ).

H in (Formula 1), which is the calculation formula of the gradient correction coefficient R, is based on the Arrhenius half law regarding the thermal degradation of the insulator, and in the case of the 0.0693-6 ° C. half law in the case of the 10 ° C. half law. Of 0.18 and half-rule of 8 ° C, which is considered to be highly compatible with Class A insulating materials (Example: Kanto Electrical Safety Association Research Report Summary Version-Insulation in private electrical works) Degradation Statistics and Preventive Maintenance-Chapter 4, Organizing Degradation Mechanisms-Degradation Factors for Insulating Materials-Thermal Degradation, H = 0.08664 adopted in the case of January 2010) Gradient correction coefficient R = 1 / exp ( -0.08664 (Td + Tzs)) (Equation 3)
Has been applied.

The insulation paper temperature difference Tzs in the above (Formula 1) to (Formula 3) is calculated by the following regression formula shown in (Formula 4) or (Formula 5), etc., the temperature Ta at the transformer installation location and the transformer operating load factor. This is an example of satisfying the condition that the range of the gradient correction coefficient R is 0.4 to 2.5 in the adopted range of U.
Tzs = A (U ^x −Uc ^x) (Expression 4)
(However, A is any one of 20 (° C.) to 50 (° C.) , and ^x is any one of 1 to 3)
Tzs = C (α + U ² (1−α)) − D · U ^y −C (α + Uc ² (1−α)) − D · Uc ^y (Equation 5)
(However, C is any one of 30 (° C.) to 70 (° C.) , α is 0.25 for a silicon steel core transformer, 0.05 for an amorphous iron core transformer, and D is a silicon steel core. In the case of a transformer, one of 10 (° C) to 30 (° C) , in the case of an amorphous iron core transformer, one of 30 (° C) to 70 (° C) , ^y is 2 to 4)
In ^{Example, Tzs = 23 (U 1.23 -Uc} 1,23) which range of slope correction coefficient R becomes 0.5 to 2 ... (6)
Has been adopted.

FIG. 2 is a graph showing a long-term display of the deterioration state of the transformer according to the present invention. A solid line 21 indicates a transition of the polymerization degree from the start of use of the diagnostic transformer to the current time. ₂
Jh ₂ = Jh ₁ −Δh (Expression 7)
(However, Jh ₁ is the degree of polymerization by hour one hour before the current time, Δh is the degree of polymerization degree reduction from one hour before to the current time shown in (Equation 8) described later (polymerization degree reduction gradient per hour))
Δh = Kcj × R (Equation 8)
(However, Kcj is a reference gradient per hour shown in (Equation 9) described later)
Kcj = 25/8760 = 0.005854 (formula 9)
Periodic degree of polymerization of due date polymerization degree, which is the final daily value of the calculated hourly degree of polymerization (for example , due date degree of polymerization on the last day of each month, degree of degree of polymerization on the last day of each month, etc.) ).

Dashed line 22, Ky was an average of a plurality of 1 hour per degree of polymerization reduction gradient in the polymerization degree predicted transition indicates a degree of polymerization reduction expected gradient Ky multiple times by the degree of polymerization reduction expected gradient Ky the current time after = (Kr ₁ + Kr ₂ + Kr ₃ + Kr ₄ ) / 4 (Equation 10)
(Where Kr ₁ is the gradient of decrease in polymerization degree per hour used for calculating the degree of polymerization by hour at the current time, Kr ₂ is the gradient of decrease in polymerization degree per hour used for calculation of the degree of polymerization by hour at 19:00 the previous day, Kr ₃ Is the lowering degree of polymerization degree per hour used to calculate the degree of polymerization by hour at 5 o'clock the previous day , and Kr ₄ is the lowering degree of polymerization degree per hour used to calculate the degree of hourly degree of polymerization at 19:00 the day before)
It is said.

A two-dot chain line 23 is a transition of the polymerization degree trial calculation under the trial calculation conditions (trial calculation installation location temperature difference Tdt, trial load factor Ut), and the trial slope correction coefficient Rt is Rt = 1 / exp (−0.08664 (Tdt + Tzst). (Equation 11)
(However, Tzst is the insulation paper temperature difference under the trial calculation condition shown in (Formula 12) described later)
Tzst = 23 (Ut ^1.23 -Uc ^1.23 ) (12)
And calculated as the estimated polymerization degree transition after the current time by the calculated gradient Kt obtained by multiplying the calculated gradient correction coefficient Rt by the reference gradient K.

  The chain lines 1d and 1e are the life level polymerization degree and the dangerous level polymerization degree shown in JEM 1463, and are used for the quality evaluation of the transformer operating condition with respect to the expected polymerization degree transition and the estimated polymerization degree transition.

When considering the influence on insulation paper temperature due to heating by direct sunlight during the day and radiation to the atmosphere at night when the transformer to be diagnosed is installed outdoors, the insulation paper temperature influence Tr by radiation is set to 1. Regression equation Tr = θ (sin (0.1309H) −0.636) (model 11) modeled so that the daily average is zero.
(However, θ is the fluctuation range (one of 0 to 8 ° C) per day of the influence of the insulating paper receiving and radiating temperature due to radiation, and H is the time (1 to 24))
R = 1 / exp (−0.08664 (Td + Tzs + Tr)) (Equation 12)
Is a gradient correction coefficient obtained by adding the insulating paper temperature influence Tr due to radiation to the insulating paper temperature difference due to the installation location temperature difference and the transformer operating current.

In order to reduce the temperature at the transformer installation location, when the outside air is ventilated to the transformer, the temperature difference Tg between the temperature at the installation location of the transformer and the outside air temperature and the wind speed V ( Regression equation Tk = Tg · ln (V) /2.7 (Equation 13) related to the wind velocity V) when there is a continuous air flow sufficient to cool the entire transformer
(However, the unit of wind speed V is m / V)
R = 1 / exp (−0.08664 (Td + Ts + Tr + Tk)) (Equation 13)
Is a gradient correction coefficient obtained by adding the insulating paper temperature influence Tk due to forced ventilation to the installation place temperature difference, the insulation paper temperature difference due to the transformer operating current, and the temperature influence due to radiation.

  When displaying the deterioration of a transformer that is already in operation from the middle of operation, the operation history from the start of operation to the current time (operating period, average operating period temperature of the diagnostic transformer installation location, average operating period of the diagnostic transformer Load degree) is used to calculate the hourly polymerization degree at the current time, and thereafter, the process enters the process flow of storage in the hourly polymerization degree storage unit and the next hourly polymerization degree calculation in FIG.

  For the transformer to be diagnosed, the degree of polymerization according to another life diagnosis method and the degree of polymerization reviewed by overcurrent current flow are shown.If the value is judged to be appropriate, the current degree of polymerization is reviewed and the degree of polymerization is After the replacement, the processing flow of the storage in the hourly polymerization degree storage unit and the next hourly polymerization degree calculation in FIG. 6 is entered.

FIG. 3 is a short-term display graph of the transformer deterioration state according to the present invention. The solid line 21y represents the hourly polymerization degree Jh ₂ shown in (Expression 7) up to the current time, and the polymerization degree expected transition is a broken line 22t. The estimated transition of the polymerization degree is indicated by a two-dot chain line 23t.

  FIG. 4 is a graph that combines and displays FIG. 2 and FIG. This makes it easy to recognize the future predicted value of the degree of polymerization. In FIG. 4, FIG. 3 is displayed as a whole and FIG. 2 is displayed in a reduced size. However, FIG. 2 may be displayed as a whole and FIG. 3 may be displayed in a reduced size, or FIG. 2 and FIG. May be displayed.

FIG. 5 is a block diagram showing the configuration of the transformer deterioration display device according to the embodiment of the present invention. The data collecting unit 51 collects the transformer installation site temperature and the operation current, and the operation current effective value calculation is omitted. A load factor calculation unit 52U that calculates an operation load factor via the unit, an arithmetic processing unit 52 having an hourly polymerization degree calculation unit 52a and a future polymerization degree calculation unit 52b, an hourly polymerization degree storage unit 53a, and a daily polymerization A storage unit 53 having a degree storage unit 53a, a graph creation processing unit 54 that creates a degree of polymerization history graph, a display unit 55 that displays a degree of polymerization history graph, and the rated current and trial calculation conditions of the transformer to be diagnosed are given. It comprises a setting unit 56 and a control unit 57 that provides a date and time.

  FIG. 6 is a flowchart showing the process of the transformer deterioration display device according to the present invention, and the polymerization is gradually reduced based on the collected data from the data acquisition unit 51 for acquiring the installation location temperature and the operating current of the diagnostic transformer. Through the hourly polymerization degree calculation unit 52a for calculating the degree, the calculated hourly polymerization degree is stored for each time in the hourly polymerization degree storage unit 53a, and the day-by-day polymerization degree storage unit 53b of the day value of the hourly polymerization degree. Storage by date, transfer of a plurality of polymerization degrees by time and a plurality of polymerization degrees by date from the polymerization degree storage unit 53a by date and the polymerization degree storage unit 53b by future date to the future polymerization degree calculation unit 52b, polymerization A processing flow from the degree transition graph creation processing unit 54 to the display unit 55 is shown.

  FIG. 7 is a graph showing the relationship between the number of years of operation and the average degree of polymerization described in JEM1463-1993 “Evaluation criteria for average degree of polymerization of insulating paper for transformers” in FIG. 4. The solid line on the higher degree of polymerization corresponds to the degree of polymerization under the best use conditions in the present invention.

  Fig. 8 is a graph showing the relationship between the number of years of operation and the average degree of polymerization described in the manufacturer's technical data (January 1997, Hitachi Technical Note, Transformer "Aging deterioration of oil-filled transformers"). Among the lines shown in Fig. 1, the straight line with the maximum gradient corresponds to the degree of polymerization under the worst use conditions in the present invention.

  Fig. 9 is a table of surveys by industry of transformer load factors published in Japan (April 2002, Japan Electrical Manufacturers' Association, General Energy Research Committee, Transformer Judgment Subcommittee Survey Results). The load factor 290 data described as per day is cited in the setting of the load factor range for calculating the degree of polymerization in the present invention.

Explanation of symbols

Description of symbols Ta: installation location temperature Tc of the diagnostic transformer Tc: transformer installation location reference temperature Td: transformer installation location temperature difference (diagnostic transformer installation location temperature and transformer installation location standard Temperature difference)
Tdt: Transformer installation location temperature Tz: Insulating paper temperature during operation Tzc: Insulating paper temperature at reference load factor Tzs: Insulating paper temperature during operation and insulating paper temperature at reference load factor Insulating paper temperature difference Tzst ... Insulating paper temperature difference Tr in trial calculation conditions ... Insulating paper receiving / dissipating heat temperature effect Tk due to radiationTk ... Insulating paper temperature effect θ due to forced ventilation ... Radiation-affected temperature fluctuation range H Time (1 to 24)
I: Operating current U of the transformer to be diagnosed ... Load factor Uc ... Reference load factor Ut ... Trial load factor K ... Degradation degree actual gradient Kc ... Degree of polymerization degree reference gradient KCJ · · · time per degree of polymerization reduction reference slope Ky · · · polymerization degree reduction expected gradient Kt · · · polymerization degree reduction estimated gradient R · · · gradient correction coefficient _Jh 2 · · · the current time of the polymerization degree _Jh 1 · ·・ Degree of polymerization one hour before the current time
Δh ・ ・ ・ Decrease in polymerization degree from 1 hour before to the present time (polymerization degree decrease gradient per hour)
Kr _1: Degree of decrease in polymerization degree per hour at the current time
Kr ₂ ... Degree of decrease in polymerization degree per hour at 19:00 on the previous day
Kr ₃ ... Degree of decrease in polymerization degree per hour at 5 o'clock the previous day
Kr ₄ : Degree of polymerization decrease per hour at 19:00 the day before the previous day 1a ... Minimum gradient polymerization degree decrease line 1b ... Maximum gradient polymerization degree decrease straight line 1c ... Reference gradient polymerization degree decrease straight line 1d ... Life level polymerization degree 1e shown in JEM 1463 ... Danger level polymerization degree 21 shown in JEM 1463 ... Transition degree decrease 21y until the current time 21y ... Short-term polymerization degree just before the current time Decreasing transition 22 ... Expected transition of polymerization degree after the current time 22t ... Expected short-term transition of polymerization degree after the current time 23 ... Decreasing transition degree of polymerization degree after the current time 23t ... Short-term transition of polymerization degree after current time in 50 ... Transformer degradation status display device 51 ... Data acquisition unit 52 ... Calculation processing unit 52U ... Load factor calculation unit 52a ... Degree of polymerization by time Calculation unit 52b ... Future polymerization degree calculation unit 53 ... Storage unit 53a ... Hourly polymerization degree storage unit 53b ... Due date polymerization degree storage unit 54 ... Graph creation processing unit 55 ... Display unit 56 ... Setting unit 57 ... Control unit

Claims (1)

Means for obtaining the temperature Ta of the diagnostic transformer installation location, means for calculating an installation location temperature difference Td between the installation location temperature Ta and a reference temperature Tc (any one of 11 to 13 ° C.); Means for obtaining the operating current I of the transformer to be diagnosed, means for calculating the operating load factor U from the operating current I, the temperature rise Tz of the insulating paper at the operating load factor U of the diagnostic transformer, and the reference load factor Uc Means for calculating an insulating paper temperature difference Tzs from the rising temperature Tzc of the insulating paper (any one of 35 to 40%), and a reference use condition (the temperature at the place where the transformer is installed is the reference temperature Tc, operation) The average polymerization degree (hereinafter referred to as polymerization degree) of the insulating paper of the transformer, which is assumed to be continuously operated at a constant load rate of the reference load ratio Uc), is the polymerization degree at the start of transformer operation (800 to 1000). 20) In the transformer to be diagnosed in which the operating gradient changes, the degree of polymerization is calculated in the reference gradient Kc in relation to the operating condition. The degree-of-polymerization degree transition determining means that is decreased by the actual gradient K multiplied by the gradient correction coefficient R, and the gradient correction coefficient R is calculated in relation to the transformer installation location temperature difference Td and the insulating paper temperature difference Tzs. Means for calculating by the formula R = 1 / exp (−H (Td + Tzs)) (where H is one of 0.0693 (1 / ° C.) to 0.1155 (1 / ° C.)) , and the above formula Insulating paper temperature difference Tzs, the temperature range of the installation location temperature difference Td is 8 ° C. (−4 to + 4 ° C. centering on the reference temperature), and the range of the operating load factor U is 40% (reference load factor is In the case of -20 to + 20% in the center) Calculated value of the coefficient R is the regression equation relating to the operating load factor U such that in the range of 0.4 to 2.5, by substituting the calculated insulation paper temperature difference Tzs the calculation formula of the gradient correction factor R Means for calculating a gradient correction coefficient R; means for calculating the actual gradient K by multiplying the calculated gradient correction coefficient R by the reference gradient Kc; means for storing calculated in each time in a different polymerization degree storage unit time of the storage unit, means for storing for each date the daily final value of another polymerization degree the time deadline by polymerization degree storage unit of the storage unit, the current After the current time as an average value of a plurality of hourly polymerization degree gradients used for calculation of hourly polymerization degree at a plurality of times before the time (for example, the current time, the previous day at 19:00, the previous day at 5:00, and the previous day at 19:00) A means for calculating the expected gradient of future polymerization degree transition and input section Means for calculating a gradient of future polymerization degree transition from the current time according to the trial calculation conditions (transformer trial installation site temperature and trial operation load factor), the date-specific polymerization degree storage unit and the hourly Polymerization degree transition from the start of use of the diagnostic transformer read from the polymerization degree storage unit to the present time, future degree of polymerization degree transition after the present time, expected degree of polymerization along the expected gradient, and future degree of polymerization degree transition trial calculation Means for displaying the estimated polymerization degree transition after the current time along the gradient in the long-term polymerization degree transition graph from the start of use of the diagnosed transformer to several tens of years, or based on the long-term polymerization degree transition graph and the current point A transformer deterioration status display device comprising: means for simultaneously or alternately displaying short-term polymerization degree transition graphs for several days.

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