KR102557170B1 - Calculation method of creeping distance of DC polymer insulator - Google Patents

Abstract

The present invention relates to a method for calculating the creepage distance of a DC polymer insulator for calculating the creepage distance by performing a creepage insulation design of the DC polymer insulator, comprising the steps of receiving modeling data of the DC polymer insulator, and based on the modeling data, the DC polymer insulator Calculating the electric field utilization factor by performing electric field analysis of the insulator, determining the shape of the test electrode based on the calculated electric field utilization factor, and calculating the creepage reference electric field of the DC polymer insulator with the determined shape of the test electrode; , Calculating the maximum creepage electric field of the DC polymer insulator based on the modeling data, and determining the creepage distance of the DC polymer insulator by comparing the creepage reference electric field and the maximum creepage electric field.

Description

Calculation method of creeping distance of DC polymer insulator}

The present invention relates to a method for calculating the creepage distance of a DC polymer insulator, and relates to a method for calculating the creepage distance of a DC polymer insulator for calculating the creepage distance by performing a creepage insulation design of the DC polymer insulator.

High-Voltage, Direct Current (HVDC) is one of the power grid systems, and is a power transmission system that transmits direct current in large quantities in contrast to the existing grid using alternating current. High-voltage direct current transmission converts the AC power produced by power plants into direct current, transmits it to where it is needed, then converts it into alternating current and supplies it to consumers, and can significantly reduce power loss compared to general AC transmission.

Currently, the voltage used in the power system is DC voltage, and new research and development of DC power devices should be performed, but research and development of DC power devices is considerably insufficient. The creepage design technology of AC polymer insulator has been researched and developed considerably, but the research and development of DC polymer insulator is insignificant, and the insulation characteristics of AC voltage and DC voltage have a large difference. R&D was needed.

Therefore, it is possible to secure the compactness and efficiency of the insulator by performing the creepage design of the DC polymer insulator and calculating the creepage distance through the experimental jig manufacturing method and the creepage distance calculation method using the method of the present invention.

Korean Patent Publication No. 10-2010-0089145 (“Insulation breakdown strength tester”, LS Cable & System Co., Ltd., 2010.08.12.)

A technical problem to be achieved by the present invention is to solve this problem, and relates to a method for calculating the creepage distance of a DC polymer insulator for calculating the creepage distance by performing a creepage insulation design of the DC polymer insulator.

The creepage distance calculation method of a DC polymer insulator of the present invention includes the steps of receiving modeling data of a DC polymer insulator, calculating an electric field utilization factor by performing electric field analysis of the DC polymer insulator based on the modeling data, Determining a shape of a test electrode based on the calculated field utilization factor; calculating a reference electric field at the creepage surface of the DC polymer insulator based on the determined shape of the test electrode; Calculating a maximum electric field and determining a creeping distance of the DC polymer insulator by comparing the creeping reference electric field and the maximum creeping electric field.

The calculating of the electric field utilization factor may include calculating a maximum electric field strength (Emax) by performing field analysis of the modeling data, and calculating the electric field utilization factor based on the calculated maximum electric field strength.

The maximum electric field strength may be calculated by averaging maximum electric field strengths according to different materials of the DC polymer insulator at a predetermined temperature.

The field utilization rate may be calculated by substituting the average value of the maximum field strength, and the field utilization rate equation may be characterized in that it is derived by the following equation.

: 전계이용률, : 최대 전계강도의 평균 값, : 인가전압, d: 전극 간격)(

: field utilization rate, : average value of maximum electric field strength, : applied voltage, d: electrode spacing)

The step of determining the shape of the test electrode may be characterized in that an electrode diameter (R) and an electrode spacing (d) of the DC polymer insulator are determined from the calculated electric field utilization factor.

In the determining of the shape of the test electrode, the electrode diameter and the electrode spacing may be determined by substituting the maximum field strength equation and the calculated field utilization factor into the field utilization equation.

The field utilization equation for determining the electrode diameter and the electrode spacing may be derived from the following equation.

: 전계이용률, U: 인가전압, d: 전극 간격, R: 전극 직경)(

: field utilization factor, U: applied voltage, d: electrode spacing, R: electrode diameter)

The creepage reference electric field equation may be calculated using a creepage discharge result value of the DC polymer insulator derived from the designed modeling data and an average value of the maximum electric field strength.

The creepage reference electric field equation may be derived from the following equation.

(E _SD,MAX : Creepage standard electric field, V _SD : Creepage discharge result value, E _MAX : Average value of maximum electric field strength)

The step of calculating the maximum electric field in creepage may be characterized in that the maximum electric field in creepage is calculated by simulating the modeling data.

The determining of the creepage distance of the DC polymer insulator may include determining a value of the creepage distance that satisfies a condition that the maximum electric field of creepage does not exceed the reference electric field of creepage.

The maximum electric field strength (Emax) may be characterized in that it is derived by the following equation.

(Emax: maximum electric field strength, U: applied voltage, R: radius of sphere, d: creepage distance of DC polymer insulator)

In the present invention, the stability of the DC polymer insulator can be determined by comparing the creepage maximum electric field with the creepage reference electric field.

In addition, the present invention can determine the creepage distance of the DC polymer insulator through comparison of the maximum creepage electric field and the creepage reference electric field.

In addition, the present invention can improve the efficiency by miniaturizing the DC polymer insulator by calculating the minimum value of the creepage distance of the DC polymer insulator.

1 is a flowchart of a method for calculating the creepage distance of a DC polymer insulator of the present invention.
2 is a diagram showing a sphere-to-sphere electrode structure for fabricating an experimental electrode.
3 is a diagram showing the maximum creepage electric field strength according to the DC polymer material and temperature.
4 is a graph showing analysis results after performing DC electric field analysis for each material and temperature of a DC polymer insulator.
5 is a diagram illustrating a test electrode determined based on the calculated field utilization factor.
6 is a diagram showing a DC polymer insulator and a maximum creepage DC electric field calculated through DC electric field analysis.

Advantages and features of the present invention and methods for achieving them will become clear with reference to the detailed description of the following embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments make the disclosure of the present invention complete and those skilled in the art in the art to which the present invention belongs It is provided to fully inform the person of the scope of the invention, and the invention is defined only by the claims. Like reference numerals designate like elements throughout the specification.

The present invention is a technology for calculating the creepage distance of a DC polymer insulator through electric field analysis. The creepage reference electric field of the DC polymer insulator is calculated, and the creepage reference electric field and the maximum creepage electric field of the DC polymer insulator are compared to determine the stability of the DC polymer insulator. can be evaluated and the creepage distance can be calculated.

The present invention can calculate the creepage distance that satisfies the condition that the maximum creepage electric field of the DC polymer insulator does not exceed the creepage reference electric field, and from this, calculate the minimum value of the creepage distance so that the DC polymer insulator can be manufactured. It can be manufactured down to size.

Hereinafter, a method for calculating the creepage distance of the DC polymer insulator of the present invention will be described in detail with reference to FIGS. 1 to 6 .

1 is a flow chart of a method for calculating the creepage distance of a DC polymer insulator of the present invention, FIG. 2 is a diagram showing a sphere-to-sphere electrode structure for manufacturing an experimental electrode, and FIG. Figure 4 is a graph showing the analysis results after performing DC electric field analysis for each material and temperature of the DC polymer insulator, and Figure 5 is a diagram showing a test electrode determined based on the calculated field utilization factor. 6 is a drawing of a DC polymer insulator and a diagram showing the maximum creeping DC electric field calculated through DC electric field analysis.

After schematically describing the creepage distance calculation method of the DC polymer insulator of the present invention with reference to FIG. 1, it will be described in more detail with reference to FIGS. 2 to 6.

1, the creepage distance calculation method of the DC polymer insulator of the present invention includes the steps of receiving modeling data, calculating the field utilization factor, determining the shape of the test electrode, and calculating the creepage reference field. It includes the step of calculating the creepage maximum electric field, and the step of determining the creepage distance of the DC polymer insulator.

Specifically, the present invention includes the steps of receiving modeling data of a DC polymer insulator, calculating an electric field utilization factor by performing an electric field analysis of the DC polymer insulator based on the modeling data, and calculating a test electrode based on the calculated electric field utilization factor. The step of determining the shape, the step of calculating the creepage reference electric field of the DC polymer insulator with the determined shape of the test electrode, the step of calculating the maximum creepage electric field of the DC polymer insulator based on the modeling data, and the step of calculating the creepage reference electric field and the maximum creepage electric field of the DC polymer insulator and comparing the electric field to determine the creepage distance of the DC polymer insulator.

According to the present invention, modeling data of a DC polymer insulator may be input and electric field analysis may be performed on a drawing of a DC polymer insulator included in the modeling data. The maximum field strength equation (E _max ), the average value of the maximum field strength, the field utilization factor (η) equation, and the field utilization factor value may be calculated by performing electric field analysis of the modeling data. After that, the shape of the test electrode can be determined, and the shape of the test electrode can be determined by deriving the electrode diameter and the electrode spacing by substituting the maximum field strength equation into the calculated field utilization equation. The creepage reference electric field is calculated using the diameter and distance of the test electrode, and the creepage distance can be calculated by determining the stability of the DC polymer insulator by comparing the creepage reference electric field and the maximum creepage electric field. In particular, the DC polymer insulator can be manufactured by minimizing the creepage distance by determining the creepage distance value that satisfies the condition that the maximum creepage electric field does not exceed the creepage reference electric field and determining the minimum creepage distance among them.

Hereinafter, it will be described in more detail with reference to FIGS. 2 to 6 .

2 is a diagram showing a sphere-to-sphere electrode structure for fabricating an experimental electrode.

Referring to FIG. 2 , before performing electric field analysis, DC polymer modeling data may be input (S210). The input DC polymer modeling data may be as shown in FIG. 2, and after receiving the DC polymer modeling data, the field utilization factor of the sphere-to-sphere electrode structure of the input modeling data may be calculated (S220).

In the step of calculating the field utilization factor (S220), the field utilization factor may be calculated by performing field analysis of the DC polymer insulator based on the input modeling data. In addition, electric field analysis of the modeling data may be performed to calculate maximum electric field strength, and field utilization may be calculated based on the calculated maximum electric field strength.

Prior to calculating the field utilization factor, field analysis may be performed to calculate the maximum field strength, and the field utilization factor may be calculated based on the calculated maximum field strength. The field utilization factor can be calculated by comparing the maximum creepage field strength. The field utilization factor can be calculated by deriving the maximum field strength equation by performing field analysis using the sphere-to-sphere electrode structure of the modeling data, and substituting the average value of the maximum field strength into the field utilization factor equation.

Prior to calculating the electric field utilization factor, an electric field analysis is performed through Equations 1 to 7 to be described later to derive Equation 8 representing the maximum electric field strength equation (S220).

If there is a point charge at the center of the sphere electrode in the input modeling data of FIG. 2, the potential of the surface of the conductor sphere may be equipotential. Conductor point charge Q _{0 (} ) is at the center of the left sphere and there is no virtual zero potential surface with the right sphere, the metal conductor surface, which is the surface of the left sphere, becomes an equipotential surface.

However, if the point charge -Q ₀ is located at the center of the sphere on the right, the electric field distribution becomes symmetric with respect to the imaginary plane P, but because of this, the surface potential of the imaginary sphere does not become equipotential. Actually, since the sphere is a conductor, the surface of the sphere becomes equipotential, but in the calculation considering only the position of the point charge, the surface of the sphere does not become an equipotential surface.

Therefore, as a complementary method, the sphere surface should be made equipotential, and the potential of the sphere surface can be improved if there is an additional image charge +Q ₁ in the sphere electrode a little away from the center of the left sphere.

The image charge of +Q ₁ may be as shown in Equation 1.

Through Equation 1, the image charge is As it is separated from the center by a distance of , the surface of the left sphere becomes an equipotential surface and corresponds to an actual conductor sphere, but to balance the charges, the charge of -Q ₁ must also exist symmetrically on the right sphere, and due to this, the equipotential surface of both spheres is again misaligned with the surface of the conductor sphere.

Correction for this may be as shown in Equation 2.

Through Equation 2, the image charge is Charges that are separated from the center by a distance of

The process of Equations 1 and 2 can be repeated to make the surface of the metal conductor sphere an equipotential surface, and the electric field on the surface of the sphere, which is the highest electric field derived through the repetitive process, can be as follows.

If Equation 3 is rearranged into a point charge Q _n , it can be obtained as follows.

If Equation 4 is rearranged as a distance x _n from the center of the sphere, it can be obtained as follows.

At this time, the capacitance C between the two spheres may be equal to Equation 7 according to Gauss' law.

If the actual distance S between the two spheres is greater than the radius R of the spheres (S>R), the maximum field strength expression of E(R) can be expressed as Equation 8.

In this way, an electric field analysis may be performed (S220) on the sphere-to-sphere electrode structure of the input modeling data through Equations 1 to 7, and through this, the maximum electric field strength equation (Equation 8) may be derived.

After deriving the maximum electric field strength expression (Emax), the electric field utilization factor (η) may be calculated (S220) through comparison of the maximum creepage electric field strength.

Figure 3 shows the result of creeping electric field analysis according to the polymer material and temperature, and Fig. 4 shows the creeping electric field strength according to the polymer material and temperature.

Referring to FIG. 3 , an average value of the maximum electric field strength may be calculated by comparing the maximum creepage electric field strength according to the material and temperature of the DC polymer insulator. The maximum electric field strength is a value calculated by averaging the maximum electric field strengths according to different materials of the DC polymer insulator at a predetermined temperature, and can be calculated after comparing the maximum creepage electric field strength.

When comparing the maximum creepage field strength, it can be compared according to the material and temperature of different DC polymers. In this specification, creepage electric field strength according to a predetermined polymer material and temperature was compared. In this specification, the electric field strengths according to temperatures of 293K, 313K, 333K, and 353K and different polymer materials A, B, C, and D were compared, and the results thereof can be shown in FIG. 4 and Table 1.

Emax[kV/mm] A B C D 293K 5.14 5.12 4.56 4.97 313K 8.05 8.09 7.77 7.04 333K 9.26 10.48 9.88 9.75 353K 12.70 12.70 12.20 11.88

As shown in FIG. 4 and Table 1, the maximum electric field strength may vary depending on the material and temperature of the DC polymer. However, there is no significant difference in the maximum electric field for each material, and since the difference appears depending on the temperature, it can be seen that the temperature affects. It can be seen that the maximum field strength increases as the temperature rises, unlike the vertical field. At this time, in the case of a high-voltage direct current transmission (HVDC) converter valve, since insulation is performed in a space where temperature and humidity are controlled, called a converter valve hall, the temperature does not change significantly from room temperature during normal operation.

)을 산출(S220)할 수 있다.Therefore, using the maximum field strength at 293K, the field utilization rate (

) can be calculated (S220).

The maximum field strength at 293 K is not significantly different for different polymer materials. Thus, the maximum field strength calculated the average maximum electric field strength at 293K and selected it as 4.95kV/mm.

The maximum electric field strength in this specification means an average value calculated by averaging the maximum electric field strengths of different materials of DC polymer insulators at a predetermined temperature. In addition, the predetermined temperature in this specification means 293K. However, the predetermined temperature is 293K because insulation is performed in a space where temperature and humidity are controlled during normal operation of the HDVC converter valve, and the temperature does not change significantly from room temperature. , and is not limited to 293K.

The field utilization factor expression may be the same as Equation 9.

( : field utilization rate, : average value of maximum electric field strength, : Applied voltage, : electrode spacing)

applied voltage and the electrode spacing d of the DC polymer insulator can be substituted with a predetermined value, and accordingly the applied voltage At 50 kV, Equation 10 can be calculated by substituting 500 mm for the electrode spacing d of the DC polymer insulator into Equation 9, which is the field utilization factor expression.

The field utilization factor can be calculated by substituting the average value of the maximum field strength into the field utilization factor equation.

값 0.02를 산출(S220)할 수 있다.applied voltage A value of 50 kV and a creepage distance of DC polymer insulator d value of 500 mm, and a maximum electric field strength As a result of substituting the value of 4.95 kV/mm into Equation 9, which is the field utilization rate, the field utilization rate

A value of 0.02 may be calculated (S220).

That is, the field utilization factor can be calculated by substituting the average value of the maximum field strength derived based on the creepage field analysis result according to the material and temperature of the DC polymer into the field utilization equation.

에 도출된 0.02를 대입하고, 값에 수학식 8의 최대 전계강도 값을 대입하여 도출하면 수학식 11과 같을 수 있다. DC 폴리머 애자의 전극 직경 및 전극 간격은 전계이용률 식에 최대 전계강도 식과 산출된 전계이용률을 대입하여 결정 가능할 수 있다. 전극 직경 및 전극 간격을 결정하는 전계이용률 식은 하기의 수학식 11로 도출될 수 있다. Field utilization value in the field utilization equation of Equation 9

Substituting 0.02 derived from If the value is derived by substituting the maximum electric field strength value in Equation 8, Equation 11 may be obtained. The electrode diameter and electrode spacing of the DC polymer insulator may be determined by substituting the maximum field strength equation and the calculated field utilization factor into the field utilization factor equation. The field utilization factor equation for determining the electrode diameter and the electrode spacing can be derived as Equation 11 below.

As a result of analyzing Equation 11, it is possible to calculate the electrode diameter R and the electrode spacing d, and it can be seen that the electrode diameter R is 0.2d (d: electrode spacing).

Based on the analysis result, the diameter of the electrode is selected to be 0.2 times the electrode spacing, and the shape of the test electrode having the same field utilization value can be determined (S230). The electrode diameter R and the electrode spacing d can be determined from the calculated field utilization factor.

5 is a diagram illustrating a test electrode determined based on the calculated field utilization factor.

In this specification, as shown in FIG. 5, when determining the shape of the test electrode, the diameter of the electrode is determined by 0.2 times the electrode spacing to form four electrodes having the same field utilization value to determine the shape of the test electrode (S230 ) as an example.

In FIG. 5, by selecting the diameter of the electrode as 0.2 times the electrode spacing, when the electrode diameter R is 5 mm, 7.5 mm, 10 mm, and 12.5 mm, the electrode spacing d is 25 mm, 37.5 mm, 50 mm, and 62.5 mm, respectively. Can be designed.

Meanwhile, the electrode spacing d means a spacing gap between a pair of electrodes.

As shown in FIG. 5, the creepage reference electric field of the DC polymer insulator may be calculated using the creepage dielectric breakdown test electrode designed through electric field analysis (S240).

The creepage reference electric field can be calculated using the DC polymer creep discharge result value derived through the determined test electrode and the average value of the maximum electric field strength derived through the DC polymer electric field analysis.

The creepage reference electric field equation can be calculated using the average value of the creepage discharge result value and the maximum electric field strength of the DC polymer insulator derived from the designed modeling data, and may be as shown in Equation 12 below.

(E _SD,MAX : Creepage standard electric field, V _SD : Creepage discharge result value, E _MAX : Average value of maximum electric field strength)

In Equation 12, E _SD,MAX represents the DC polymer creepage reference electric field. In addition, V _SD represents the DC polymer creep discharge result value derived through the designed experimental jig, and E _MAX represents the average value of the maximum electric field strength of the DC polymer insulator derived through DC polymer electric field analysis.

serial number Φ10
d=25mm Φ15
d=37.5mm Φ20
d=50mm Φ25
d-62.5mm 8.40 9.07 11.45 12.44 average 10.34

Table 2 shows the DC polymer creeping dielectric breakdown voltage derived through the designed electrode, and Equation 13 can be obtained by substituting the DC electric field analysis result value and the DC creeping dielectric breakdown voltage value.

According to Equation 13, the DC creepage reference electric field value E _SD,MAX can be calculated (S240) as 51.18 kV/mm by multiplying the V _SD value of 10.34 and the E _MAX value of 4.95 (S240), and when calculating the creepage distance of the DC polymer insulator, it is about 51 kV A reference electric field of /mm can be applied.

After calculating the creepage reference electric field (S240), the maximum electric field of the DC polymer insulator may be calculated (S250) to determine the creepage distance of the DC polymer insulator (S260).

6 is a drawing showing a DC polymer insulator and a maximum creepage electric field calculated through electric field analysis.

6 is a view of a DC polymer insulator. The DC polymer insulator shown in the figure shows an applied voltage of 50 kV and an electrode spacing of 500 mm. The maximum creepage electric field can be calculated by simulating the modeling data.

As a result of performing DC electric field analysis by simulating the modeling data of the DC polymer insulator of FIG. 6, the maximum creepage electric field E _MAX,S is calculated as 10 kV/mm (S250).

After calculating the creepage maximum electric field (S250), the creepage distance of the DC polymer insulator may be determined (S260).

The maximum creepage electric field of the DC polymer insulator derived from the drawing of FIG. 6 was 10 kV/mm, which was about 19.6% lower than the DC polymer creepage reference electric field of 51 kV/mm. Since the maximum creepage electric field of the DC polymer insulator was derived lower than the reference electric field value without exceeding the reference electric field value, it can be confirmed that the numerical value is stable. The maximum creepage electric field of the DC polymer insulator of FIG. 6 is lower than the value of the creepage reference electric field, so that the creepage length of the DC polymer insulator can be reduced more than 500 mm. When the maximum creepage electric field of the actually used insulator drawing calculated by simulating the DC polymer insulator in use is smaller than the creepage reference electric field value, the creepage distance value satisfying the condition that the maximum creepage electric field does not exceed the creepage reference electric field is determined (S260) can do.

In particular, the present invention can determine the minimum creepage distance by calculating the smallest creepage distance value under the condition that the maximum creepage electric field does not exceed the creepage reference electric field, and can minimize the size of the DC polymer insulator by applying the smallest minimum creepage distance value. can According to the present invention, the DC polymer insulator can be manufactured smaller and more compact by further reducing the creepage distance of the DC polymer insulator.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains know that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. You will understand. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (12)

Receiving modeling data of the DC polymer insulator;
Calculating an electric field utilization factor by performing electric field analysis of the DC polymer insulator based on the modeling data;
determining a shape of a test electrode based on the calculated field utilization factor;
Calculating a creepage reference electric field of the DC polymer insulator with the determined shape of the test electrode;
Calculating a maximum electric field across the surface of the DC polymer insulator based on the modeling data; and
determining a creepage distance of the DC polymer insulator by comparing the creepage reference electric field with the maximum creepage electric field;
Including,
In the step of calculating the field utilization factor,
The electric field analysis of the modeling data is performed to calculate the maximum electric field strength (Emax), and the electric field utilization factor is calculated based on the calculated maximum electric field strength,
The maximum electric field strength is an average value of the maximum electric field strength according to different materials of the DC polymer insulator at a predetermined temperature How to calculate the creepage distance of the DC polymer insulator. delete delete According to claim 1,
The creepage distance calculation method of the DC polymer insulator, characterized in that the electric field utilization factor is derived by the following formula.

(

: field utilization rate, : average value of maximum electric field strength, : applied voltage, d: electrode spacing) According to claim 4,
The step of determining the shape of the test electrode,
The creepage distance calculation method of the DC polymer insulator, characterized in that for determining the electrode diameter (R) and the electrode spacing (d) of the DC polymer insulator from the calculated field utilization factor. According to claim 5,
The step of determining the shape of the test electrode,
A creepage distance calculation method of a DC polymer insulator capable of determining the electrode diameter and the electrode spacing by substituting the maximum field strength equation and the calculated field utilization factor into the field utilization factor equation. According to claim 6,
The method for calculating the creepage distance of a DC polymer insulator, characterized in that the field utilization factor equation for determining the electrode diameter and the electrode spacing is derived by the following equation.

(

: field utilization factor, U: applied voltage, d: electrode spacing, R: electrode diameter) According to claim 4,
The creepage distance calculation method of the DC polymer insulator, characterized in that the equation of the creepage reference electric field is calculated using the average value of the maximum electric field strength and the creepage discharge result value of the DC polymer insulator derived from the designed modeling data. According to claim 8,
The creepage distance calculation method of the DC polymer insulator, characterized in that the equation of the creepage reference electric field is derived by the following equation.

(E _SD,MAX: creepage reference electric field, V _SD : creepage discharge result value, E _MAX : average value of maximum electric field strength) According to claim 1,
The step of calculating the creepage maximum electric field,
Creepage distance calculation method of a DC polymer insulator, characterized in that for calculating the creepage maximum electric field by simulating the modeling data. According to claim 1,
Determining the creepage distance of the DC polymer insulator,
The creepage distance calculation method of the DC polymer insulator, characterized in that for determining the creepage distance value satisfying the condition that the creepage maximum electric field does not exceed the creepage reference electric field. According to claim 1,
The creepage distance calculation method of the DC polymer insulator, characterized in that the maximum electric field strength (Emax) is derived by the following formula.

(Emax: maximum electric field strength, U: applied voltage, R: radius of sphere, d: creepage distance of DC polymer insulator)