Environment Impact Assessment For Jiangxi Shangrao Sanqingshan Airport Beijing Guohuantiandi Environmental Technology Development Center. Ltd. Oct. 2012 Content

Impact Analysis of electromagnetic radiation

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4.8 Impact Analysis of electromagnetic radiation

4.8.1 Impact Analysis of electromagnetic radiation of 110kV Maozao Line relocation and modification project

1. Impact forecast and evaluation of power frequency electromagnetic field and radio interference environment of transmission line

The 110kV Maozao Line relocation and modification project is modified from original #8 double circuit branching pipe rod on the side of Maojialing Substation to framework of Zaotou 110kV Substation. Voltage class is 110kV. Wire type is LGJ-240/30 steel-cored aluminum strand, earth wire type is JLB20A-80 aluminum clad steel strand, optical cable model is OPGW-2S1/24B1 and cable type is YJLW03-1×the new 630mm2-64/110. The length of overhead line is 10.32km, length of cable path is 2300m, and the whole line is erected in single circuit.

Theoretical calculation: According to Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998), the evaluation adopts method recommended by International Conferences of Large Power Grids by the 36.01 Working Group and the method recommended by GB15707-1995 Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines to calculate the power frequency electromagnetic field intensity and radio interference level of the space under high-voltage transmission line.

(1) Theoretical calculation mode

(i) Calculation of power frequency electric field intensity

Equivalent charge on high-voltage transmission line is line charge, because the radius r of high-voltage transmission line is far less than erection height, the location of equivalent charge can be considered at the geometric center of transmission line.

The transmission line is infinitely long and parallel to the ground, and the ground can be regarded as good conductor; use the mirror image method to calculate equivalent charge on transmission line. The following matrix equation can be written:

Formula (1)

In which: -single-row matrix of voltage to ground of each conductor;

-single-row matrix of equivalent charge of each conductor;

-n order matrix composed by potential coefficient of each conductor (n is number of conductors).

matrix can be determined by voltage and phase of transmission line; take 1.05 times the rated voltage as the calculation voltage from the perspective of environmental protection.

matrix is obtained by principle of mirror image. Potential coefficient

is calculated according to the formula below:

Formula (2)

In which: -air dielectric coefficient, ;

-distance from No.i conductor to No.j conductor;

-distance from mirror image conductor of No.i conductor to No.j conductor;

-height of No.i conductor from ground;

-conductor radius;

. Formula (3)

In which: -bundle conductor radius;

-number of partial conductor;

-partial conductor radius.

According to matrix and matrix, use formula (1) to obtain matrix.

When the equivalent charge amount of each conductor in unit length is obtained, electric field strength of any point in space can be obtained according to the principle of superposition, electric field componentandat (x, y) point can be expressed as:
Formula (4)

Formula (5)

In which: -coordinate of conductor I (I=1, 2, …, n);

-number of conductors;

-respectively the distance from conductor I and its mirror image to the calculation point.

Total electric field intensity of any point in space is:

Formula (6)

(ii) Calculation of power frequency magnetic field intensity

It is forecast from power frequency magnetic field intensity that according to recommendation of International Conferences of Large Power Grids by the 36.01 Working Group, calculate the contributions of single conductor of high-voltage transmission line to power frequency magnetic field intensity of ambient space:

Formula (7)

In which: I-current value in Conductor I;

h-vertical distance from conductor to forecast point;

L-horizontal distance between conductor and forecast point.

For the three-phase circuit, horizontal and vertical components of magnetic field intensity formed by different phases must separately consider the current phase according to vector composition of phases.

(iii) Calculation of radio interference field intensity

The calculation of radio interference field intensity is subject to basic formula recommended by Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

Intensity of radio interference from AC high voltage overhead power transmission lines at 0.5MHz:

Formula (8)

In which: -value of radio interference field intensity, dB (µV/m);

-conductor radius, cm;

-straight-line distance from interfered point to conductor, m;

-maximum potential gradient of conductor surface, kV/m.

In which:

In which: R-circle diameter passing center of partial conductor, cm;

n-number of partial conductor;

d-diameter of partial conductor, cm;

g-average surface potential gradient of conductor, .

(2) Calculation parameters

See Table 11-1-1 for main erection parameters of the line (with the tower type No. 1B-ZM11 (single-circuit) as the theoretical calculation object):

Table 11-1-1 Table for theoretical calculation parameters

Item

Parameter

Voltage class

110kV

Erection method

Single-circuit line erection

Tower type

1B-ZM11

Suspension method

Single-circuit triangle arrangement

Phase sequence arrangement

ABC

Wire type

LGJ-240/30 model steel-cored aluminum strand

Gross sectional area of conductor

275.96mm²

Outer diameter of conductor

21.6mm

Max. operating current of line

290A

Distance of bottom conductor from ground

7.0m (The minimum design height crossing the resident plot by maximum sag)

6.0m (The minimum design height crossing the non-resident plot by maximum sag)

Calculation range

(i) Power frequency electric field, magnetic field: horizontal direction: from center 0m, both sides 50m, spacing 1m.

Vertical direction: ground 1.5m

(ii) Radio interference: horizontal direction: side conductor 0m, both sides 64m, spacing 1m.

Vertical direction: ground 2m

(3) Forecast result

The evaluation forecasts the power frequency electric field intensity and power frequency magnetic field intensity generated at 1.5m from the ground at the maximum slag as well as the radio interference level at the 2m from the ground with the frequency of 0.5MHz as for the project 110kV single-circuit transmission line. See Table 11-1-2 and Table 11-1-3 for specific forecast result.

Table 11-1-2 Theoretical calculation result of power frequency electric field intensity and magnetic field intensity of 110kV single-circuit triangle arrangement line

Horizontal projection distance from line center (m)	Crossing resident plot, 7m from Bottom conductor to ground		Crossing non-resident plot, 6m from Bottom conductor to ground
Horizontal projection distance from line center (m)	Electric field aggregative quantity at 1.5m from ground (kV/m)	Magnetic field aggregative quantity at 1.5m from ground (μT)	Electric field aggregative quantity at 1.5m from ground (kV/m)	Magnetic field aggregative quantity at 1.5m from ground (μT)
0	1.765	3.772	2.063	9.368
1	2.039	8.616	2.477	10.267
2	2.243	8.996	2.795	10.929
3	2.332	9.114	2.927	11.142
4	2.292	8.939	2.836	10.826
5	2.141	8.516	2.570	10.100
6	1.922	7.941	2.221	9.178
7	1.679	7.308	1.866	8.238
8	1.442	6.684	1.546	7.374
9	1.227	6.104	1.276	6.616
10	1.041	5.582	1.055	5.966
15	0.480	3.772	0.450	3.885
20	0.255	2.791	0.231	2.836
25	0.153	2.202	0.137	2.224
30	0.100	1.813	0.089	1.826
35	0.070	1.540	0.062	1.548
40	0.052	1.337	0.046	1.342
45	0.040	1.181	0.035	1.185
50	0.031	1.058	0.028	1.060

As shown in Table 11-1-2, at the line height of 6.0m from the ground (the minimum design height crossing the non-resident plot by maximum sag) and 7.0m from the ground (the minimum design height crossing the resident plot by maximum sag), maximum values of theoretical calculation electric field intensity exist at ±3m from the line center, 2.927kV/m and 2.332kV/m respectively. After that, the electric field intensity rapidly declines with the increase in line central distance; it declines to 0.231kV/m and 0.255kV/m respectively at 20m from line center, and declines to 0.028kV/m and 0.031kV/m respectively at 50m from line center, which is less than evaluation standard of 4kV/m and compliant with requirement of evaluation standard data of power frequency electric field intensity of 4kV/m of Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998).

At the line height of 6.0m from the ground (the minimum design height crossing the non-resident plot by maximum sag) and 7.0m from the ground (the minimum design height crossing the resident plot by maximum sag), maximum values of theoretical calculation magnetic field intensity exist at ±3m from the line center, 11.142μT and 9.114μT respectively. The magnetic field intensity declines with the increase in line center distance, the theoretical calculation data are less than evaluation standard of 100μT.

Table 11-1-3 Value of radio interference level of 110 kV single-circuit line theoretical calculation

Horizontal projection distance from line center(m)	6.0m	7.0m	Horizontal projection distance from line center(m)	6.0m	7.0m
Horizontal projection distance from line center(m)	Value of radio interference at 2m from ground (0.5MHz) dB (μV/m)		Horizontal projection distance from line center(m)	Value of radio interference at 2m from ground (0.5MHz) dB (μV/m)
0	33.16	30.45	24	12.10	11.51
1	34.73	31.57	26	10.84	10.27
2	35.83	32.30	28	9.69	9.13
4	35.66	32.19	30	8.61	8.07
6	32.82	30.20	32	7.61	7.08
8	29.27	27.42	34	6.68	6.15
10	25.99	24.62	36	5.79	5.28
12	23.14	22.06	38	4.98	4.46
14	20.68	19.78	40	4.18	3.68
16	18.55	17.75	45	2.39	1.90
18	16.66	15.95	50	0.79	0.31
20	14.98	14.32	55	-	-
22	13.47	12.85	60	-	-
23*	12.77	12.16	64	-	-

Note: 23* is 20m from side conductor;

*Radio interference level in the table refers to the conditions at the frequency of 0.5MHz.

As shown in Table 11-1-3, radio interference values at minimum line height of 6.0m and 7.0m from the ground as for the conductor projection of 20m with line bottom at height of 2.0m from the ground of 110 kV single-circuit triangle arrangement overhead line at frequency of 0.5MHz are 12.77dB (μV/m) and 12.16dB (μV/m) respectively, which satisfy the limit requirement of 46dB (μV/m) for 110kV in fine days of Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

Calculated according to the theory, in case that newly built relocation and modification project adopts single-circuit line erection, it is necessary to ensure at the line height of 6.0m from the ground (the minimum design height crossing the non-resident plot by maximum sag) and 7.0m from the ground (the minimum design height crossing the resident plot by maximum sag), the line operating theory calculation can satisfy evaluation standard of power frequency electric field intensity of 4000V/m and power frequency magnetic field intensity of 0.1mT of Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998) with the minimum height satisfied. At the same time, the line operating theory calculation can satisfy the requirement at 20m from the transmission line for voltage class of 110kV and radio interference limit value≤46dB (μV/m) at the frequency of 0.5MHz in the fine days regulated in Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

2. Lines by comparison measurement

Carry out electromagnetic field environment impact forecast and evaluation of the 110kV overhead line of the project with the comparison object of 220kV Ferry Substation-110V Yinkeng Substation 110kV line project of Yudu County.

(1) Feasibility of comparison

See Table 11-1-4 for main indicator comparison between comparison line and evaluation line.

Table 11-1-4 Comparison table of main technical indicators of comparison line

Technical indicators	Comparison line	Evaluation line
Name of line	220kV Ferry Substation-110V Yinkeng Substation 110kV line project	Single-circuit overhead line of project
Voltage class	110kV	110kV
Wire type	LGJ-300/40	LGJ-240/30
Conductor arrangement method	Triangle arrangement	Triangle arrangement
Erection height of Bottom conductor from the ground	12.5m	/

(2) Monitoring section and point

Power frequency electric field and power frequency magnetic field: 110kV line attenuation section takes ground projection point of the conductor center at maximum slag as the measurement origin, and carries out monitoring of attenuation section along the vertical line direction. The measurement takes the side conductor projection as the starting point with the monitoring point spacing of 5m, and extends to 50m beyond the ground projection of side conductor.

Radio interference: Vertical 110kV line takes the side conductor projection as the starting point with the monitoring point spacing of 2ⁿm, and extends to 64m to carry out multi-frequency measurement at 20m of measurement path.

(3) See Table 11-1-5 and Table 11-1-6 for monitoring results.

Table 11-1-5 Monitoring data of power frequency electric field and power frequency magnetic field environment of 110k line of 220kV Ferry Substation-110V Yinkeng Substation

No.	Distance from monitoring point to starting point(m) 47#-48#	power frequency electric field intensity (V/m)	power frequency magnetic field intensity (μT)
1	Projection from central conductor at 0m	687.5	1.215
2	Projection from central conductor at 5m	754.3	1.086
3	Projection from central conductor at 10m	565.6	0.812
4	Projection from central conductor at 15m	383.1	0.598
5	Projection from central conductor at 20m	169.4	0.336
6	Projection from central conductor at 25m	91.24	0.212
7	Projection from central conductor at 30m	69.39	0.152
8	Projection from central conductor at 35m	43.12	0.103
9	Projection from central conductor at 40m	36.14	0.087
10	Projection from central conductor at 45m	28.64	0.066
11	Projection from central conductor at 50m	25.73	0.059

It can be seen from Table 11-1-5 that power frequency electric field intensity measured at the height of 1.5m from the ground near the comparison 110kV line project is 25.73-687.5V/m and magnetic field intensity is 0.059-1.215μT, which are less than the limit requirement of 4kV/m and 0.1mT in Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998).

Table 11-1-6 Monitoring data of radio interference of 110kV line project of 220kV Ferry Substation-110V Yinkeng Substation

Measurement point	Distance from monitoring point to starting point	Frequency (MHz)	Quasipeak dB(μV/m)
220kV Ferry Substation-110V Yinkeng Substation 110kV line project	Projection from central conductor at 0m	0.5	40.46
	Projection from central conductor at 1m	0.5	40.17
	Projection from central conductor at 2m	0.5	39.24
	Projection from central conductor at 4m	0.5	40.89
	Projection from central conductor at 8m	0.5	38.62
	Projection from central conductor at 16m	0.5	37.48
	Projection from central conductor at 20m	0.15	45.36
		0.25	41.21
		0.5	37.17
		1.0	40.68
		1.5	71.23
		3.0	40.83
		6.0	43.87
		10	46.31
		15	44.51
		30	38.69
	Projection from central conductor at 32m	0.5	36.41
	Projection from central conductor at 64m	0.5	36.13

It can be seen from Table 11-1-6 that the radio interference at frequency of 0.5MHz of the comparison 110kV line project is 36.13-40.89dB (μV/m), which satisfies the limit requirement of 46dB (μV/m) of 110kV in fine day conditions of Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

It is known through theoretical calculation and comparison, when the conductor is LGJ-240/30 model steel-cored aluminum strand frame to mainly erect the tower type of No. 1B-ZM11 (single-circuit), under the premise that the erection height of conductor satisfies the regulations of Technical Code for Designing 110-500kV Overhead Transmission Line (at height of 6.0m from the ground for the conductor (the minimum design height crossing the non-resident plot by maximum sag) and at height of 7.0m from the ground for the conductor (the minimum design height crossing the resident plot by maximum sag)), the influence of power frequency electric field intensity, power frequency magnetic field intensity and radio interference generated during operation in 110kV single-circuit line formed after the project line is established and put into operation on electromagnetic radiation of the environment are less than standard limits of power frequency electric magnetism of 4kV/m and power frequency magnetic field of 0.1mT regulated in Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998) and national standard value of radio interference of 46dB (V/m) at the frequency of 0.5MHz in fine day conditions regulated in Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

According to path design diagram of the line and the field inspection of project surroundings, the villages nearest the sensitive points surrounding the line are Gaojiashan and Gaojiashan Village. It can be known through monitoring data of theoretical calculation and comparison that power frequency electric field intensity and power frequency magnetic field intensity generated during operation of the line rapidly decline with the increase in horizontal distance from side conductor, and the maximum values of power frequency electric field intensity and power frequency magnetic field intensity monitored of comparison project at 10m from side conductor are respectively 0.5656kV/m and 0.812 (μT). It can be known that the influence on electromagnetic radiation of sensitive points along the line after the transmission and transformation project is established and put into operation are less than standard limit of power frequency electric magnetism of 4kV/m and power frequency magnetic field of 0.1mT regulated in Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998).

4.8.2 Impact analysis of electromagnetic radiation of 110kV WangZao Line relocation and modification project of Sanqingshan Airport

1. Impact forecast and evaluation of power frequency electromagnetic field and radio interference environment of transmission line

(1) Theoretical calculation mode

Same as 110kV Maozao Line relocation and modification project.

(2) Calculation parameters

See Table 11-2-1 for main erection parameters of the line (with the tower type No. 1B-ZM11 (single-circuit) as the theoretical calculation object):

Table 11-2-1 Table for theoretical calculation parameters

Item	Parameter
Voltage class	110kV
Erection method	Single-circuit line erection
Tower type	1B-ZM11
Suspension method	Single-circuit triangle arrangement
Phase sequence arrangement	ABC
Wire type	LGJ-240/30 model steel-cored aluminum strand
Gross sectional area of conductor	275.96mm²
Outer diameter of conductor	21.6mm
Max. operating current of line	290A
Distance of bottom conductor from ground	7.0m(the minimum design height crossing the resident plot by maximum sag)
Distance of bottom conductor from ground	6.0m(the minimum design height crossing the non-resident plot by maximum sag)
Calculation range	(i) Power frequency electric field, magnetic field: horizontal direction: from center 0m, both sides 50m, spacing 1m. Vertical direction: ground 1.5m (ii) Radio interference: horizontal direction: side conductor 0m, both sides 64m, spacing 1m. Vertical direction: ground 2m

(3) Forecast result

Table 11-2-2 Theoretical calculation result of power frequency electric field intensity and magnetic field intensity of 110kV single-circuit triangle arrangement line

Horizontal projection distance from line center (m)	Crossing resident plot, 7m from Bottom conductor to ground		Crossing non-resident plot, 6m from Bottom conductor to ground
Horizontal projection distance from line center (m)	Electric field aggregative quantity at 1.5m from ground (kV/m)	Magnetic field aggregative quantity at 1.5m from ground (μT)	Electric field aggregative quantity at 1.5m from ground (kV/m)	Magnetic field aggregative quantity at 1.5m from ground (μT)
0	1.765	3.772	2.063	9.368
1	2.039	8.616	2.477	10.267
2	2.243	8.996	2.795	10.929
3	2.332	9.114	2.927	11.142
4	2.292	8.939	2.836	10.826
5	2.141	8.516	2.570	10.100
6	1.922	7.941	2.221	9.178
7	1.679	7.308	1.866	8.238
8	1.442	6.684	1.546	7.374
9	1.227	6.104	1.276	6.616
10	1.041	5.582	1.055	5.966
15	0.480	3.772	0.450	3.885
20	0.255	2.791	0.231	2.836
25	0.153	2.202	0.137	2.224
30	0.100	1.813	0.089	1.826
35	0.070	1.540	0.062	1.548
40	0.052	1.337	0.046	1.342
45	0.040	1.181	0.035	1.185
50	0.031	1.058	0.028	1.060

As shown in Table 11-2-2, at the line height of 6.0m from the ground (the minimum design height crossing the non-resident plot by maximum sag) and 7.0m from the ground (the minimum design height crossing the resident plot by maximum sag), maximum values of theoretical calculation electric field intensity exist at ±3m from the line center, 2.927kV/m and 2.332kV/m respectively. After that, the electric field intensity rapidly declines with the increase in line central distance; it declines to 0.231kV/m and 0.255kV/m respectively at 20m from line center, and declines to 0.028kV/m and 0.031kV/m respectively at 50m from line center, which is less than evaluation standard of 4kV/m and compliant with requirement of evaluation standard data of power frequency electric field intensity of 4kV/m of Technical Regulations on Environmental Impact Assessment of Electromagnetic Radiation Produced by 500 KV Ultrahigh Voltage Transmission and Transfer Power Engineering (HJ/T24-1998). The maximum values of theoretical calculation magnetic field intensity exist at ±3m from the line center, 11.142μT and 9.114μT respectively. The magnetic field intensity declines with the increase in line center distance, the theoretical calculation data are less than evaluation standard of 100μT.

Table 11-2-3 Value of radio interference level of 110 kV single-circuit line theoretical calculation

Horizontal projection distance from line center(m)	6.0m	7.0m	Horizontal projection distance from line center(m)	6.0m	7.0m
Horizontal projection distance from line center(m)	Value of radio interference at 2m from ground(0.5MHz) dB (μV/m)		Horizontal projection distance from line center(m)	Value of radio interference at 2m from ground(0.5MHz) dB (μV/m)
0	33.16	30.45	24	12.10	11.51
1	34.73	31.57	26	10.84	10.27
2	35.83	32.30	28	9.69	9.13
4	35.66	32.19	30	8.61	8.07
6	32.82	30.20	32	7.61	7.08
8	29.27	27.42	34	6.68	6.15
10	25.99	24.62	36	5.79	5.28
12	23.14	22.06	38	4.98	4.46
14	20.68	19.78	40	4.18	3.68
16	18.55	17.75	45	2.39	1.90
18	16.66	15.95	50	0.79	0.31
20	14.98	14.32	55	-	-
22	13.47	12.85	60	-	-
23*	12.77	12.16	64	-	-

Note: 23* is 20m from side conductor;

*Radio interference level in the table refers to the conditions at the frequency of 0.5MHz.

As shown in Table 11-2-3, radio interference values at minimum line height of 6.0m and 7.0m from the ground as for the conductor projection of 20m with line bottom at height of 2.0m from the ground of 110 kV single-circuit triangle arrangement overhead line at frequency of 0.5MHz are 12.77dB (μV/m) and 12.16dB (μV/m) respectively, which satisfy the limit requirement of 46dB (μV/m) for 110kV in fine days of Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

2. Lines by comparison measurement

(1) Monitoring section and point

(2) See Table 11-2-5 and Table 11-2-6 for monitoring results.

Table 11-2-5 Monitoring data of power frequency electric field and power frequency magnetic field environment of 110k line of 220kV Ferry Substation-110V Yinkeng Substation

No.	Distance from monitoring point to starting point (m) 47#-48#	power frequency electric field intensity (V/m)	power frequency magnetic field intensity (μT)
1	Projection from central conductor at 0m	687.5	1.215
2	Projection from central conductor at 5m	754.3	1.086
3	Projection from central conductor at 10m	565.6	0.812
4	Projection from central conductor at 15m	383.1	0.598
5	Projection from central conductor at 20m	169.4	0.336
6	Projection from central conductor at 25m	91.24	0.212
7	Projection from central conductor at 30m	69.39	0.152
8	Projection from central conductor at 35m	43.12	0.103
9	Projection from central conductor at 40m	36.14	0.087
10	Projection from central conductor at 45m	28.64	0.066
11	Projection from central conductor at 50m	25.73	0.059

Table 11-2-6 Monitoring data of 110kV line project radio interference of 220kV Ferry Substation-110V Yinkeng Substation

Monitoring point	Distance from monitoring point to starting point	Frequency (MHz)	Quasipeak dB (μV/m)
220kV Ferry Substation-110V Yinkeng Substation 110kV line	Projection from central conductor at 0m	0.5	40.46
	Projection from central conductor at 1m	0.5	40.17
	Projection from central conductor at 2m	0.5	39.24
	Projection from central conductor at 4m	0.5	40.89
	Projection from central conductor at 8m	0.5	38.62
	Projection from central conductor at 16m	0.5	37.48
	Projection from central conductor at 20m	0.15	45.36
		0.25	41.21
		0.5	37.17
		1.0	40.68
		1.5	71.23
		3.0	40.83
		6.0	43.87
		10	46.31
		15	44.51
		30	38.69
	Projection from central conductor at 32m	0.5	36.41
	Projection from central conductor at 64m	0.5	36.13

It can be seen from Table 11-2-6 that the radio interference at frequency of 0.5MHz of the comparison 110kV line project is 36.13-40.89dB (μV/m), which satisfies the limit requirement of 46dB (μV/m) of 110kV in fine day conditions of Limits of Radio Interference from AC High Voltage Overhead Power Transmission Lines (GB15707-1995).

4.8.3 Impact evaluation of electromagnetic radiation of 10kV line newly built project of Maojialing Substation to Airport

The power frequency electromagnetic field and radio interference generated by 10kV low-voltage line of the project are relatively small, which are exempted from impact evaluation of electromagnetic radiation environment. The electromagnetic environment surrounding the line is equivalent to the background value of the region, which shall not have great impact on the surrounding electromagnetic environment and sensitive points.

4.8.4 10kV line newly built project of Zaotou Substation to Airport

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