EMC’14/Tokyo
16A1-H1
Evaluation of Magnetic Field Generated by Power
Facilities in Accordance with IEC 62110
Yusuke Miyaji, Mitsuki Shimada and Yukio Mizuno
Katsuhiko Naito
Nagoya Institute of Technology
Nagoya, Japan
N. S. Co., Ltd.
Nagoya, Japan
Abstract—This paper reports results of magnetic flux density
(denoted as magnetic field hereafter) measurements under power
transmission lines and around power distribution equipment.
Measurements were carried out in accordance with IEC 62110
established in 2009, which prescribes measurement and
evaluation procedures of uniform and non-uniform magnetic
field generated by ac power systems with regard to human
exposure. The average and the maximum exposure levels of
magnetic field generated such power facilities were evaluated and
found much lower than the reference level from the ICNIRP
Guidelines.
Keywords—magnetic field; power transmission lines; padmounted transformer; switchgear; vertical cable; average and
maximum exposure levels; IEC 62110
I.
INTRODUCTION
Calculation results of power frequency magnetic field have
been reported, which are generated by power facilities such as
transmission lines [1-3], substations [4-6] and so on [7-8].
Reports of measurement results of magnetic field have also
been published [9-13]. However, there seem little papers
dealing with magnetic field near power distribution equipment
such as pad-mounted transformers, switchgears and vertical
cables, which are installed on sidewalks in urban areas.
Evaluation of magnetic field generated by such equipment is
important from the standpoint of public exposure to magnetic
fields, because people passed by them closely in some cases.
To evaluate magnetic field generated by ac power systems
with regard to human exposure, an international standard IEC
62110 [14] was established in 2009. The standard prescribes
measurement and evaluation procedures of uniform and nonuniform magnetic field.
In this paper, magnetic field generated by power facilities
was evaluated based on measurement results in accordance
with IEC 62110. Magnetic field generated by transmission
lines is considered almost uniform near the ground. On the
other hand, non-uniform magnetic field is generated by power
distribution equipment such as pad-mounted transformers,
switchgears and vertical cables.
Evaluation results are also discussed by comparing the
average and the maximum exposure levels with the reference
levels from the ICNIRP Guidelines [15].
Copyright 2014 IEICE
II.
OUTLINE OF IEC 62110
A. Introduction
This standard specifies fundamental procedures for
measurement of electric and magnetic fields, and, with regard
to human exposure, in order to obtain a field value that
corresponds to a spatial average over the entire human body.
The standard is applied to measurement of fields generated
by AC power systems in areas accessible by the public. It
establishes a common measurement procedure to evaluate the
exposure levels of the human body to electric and magnetic
fields among the general public. It is not applicable to
occupational exposure.
The values obtained in accordance with this standard are
for use to determine whether the fields comply with exposure
limits by comparing them with the field limits for general
public exposure such as the reference levels from the ICNIRP
Guidelines [15], MPE from the IEEE [16] or national
regulations. If the values obtained are higher than the reference
level or MPE, it does not necessarily mean that the basic
restriction is exceeded, in which case other methods must be
used to ensure that the basic restriction is not exceeded.
B. Fundamental Measurement Procedures
Three different measurement procedures are specified in
the standard depending on field characteristics; single-, threeand five-point measurements.
1) Single-point measurement: Where the field is considered
to be uniform, the field level at the position of interest should
be measured at 1.0 m above the ground or the floor in the
building.
2) Three-point measurement: Where the field is considered
to be non-uniform, the field levels at the position of interest
should be measured at three heights, 0.5 m, 1.0 m and 1.5 m
above the ground or the floor in a building.
Beside power equipment or in a building, measurement
should be performed at a horizontal distance of 0.2 m from its
surface, boundary or a wall as shown in Fig. 1 (a). In situations
where the equipment has a height less than 1.5 m, the threepoint measurement must be performed at equidistant heights
with the highest being at the same height as the top of the
equipment as shown in Fig.1 (b).
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EMC’14/Tokyo
16A1-H1
Measuring points
0.2m
0.2m
0.5m
H
0.5m
H/3
H
H/3
0.5m
1.0 m or
top height
H/3
H ≥ 1.5 m
H < 1.5 m
(a)
(b)
Top
surface
0.2 m
Fig. 2. Procedure to obtain the maximum exposure level beside power
equipment.
Fig. 1. Three-point measurement beside power equipment [14].
3) Five-point measurement: Where there are sources of field
below the ground or the floor and there is a reasonable
possibility that a person is likely to lie down above it, fivepoint measurement should be performed as follows.
The field level should be scanned at a height of 0.2 m
above the ground or the floor to find the value and the position
of the maximum field. The value and the position of the second
maximum field should be scanned on a circle with a radius of
0.5 m centered on the maximum position. Another
measurement should be made at the point that is symmetric to
the second maximum. A further two measurements should be
made, along the line perpendicular to the line passing the
former three measurement points, at distances of 0.5 m on
either side of the position of the maximum.
measurement should be performed. When the position of the
maximum field within the area of interest is already known, the
three-point measurement should be performed at that position.
III.
EXPERIMENTAL
A. Measurement under Ttransmission Lines
A magnetic flux density meter with three coils (EMDEX II,
Enertech Consultants) was used. Resultant magnetic field in
root mean square was obtained.
In cases where a person is not likely to lie on the ground or
the floor, the three-point measurement shall be used.
Magnetic field was measured at 1 meter above the ground
following the single-point measurement procedure in seven
countries. Nominal voltages of transmission lines were 500-,
400-, 275-, 220- and 115-kV. Measurement was carried out at
every 1 meter along a path perpendicular to transmission lines
at the lowest clearance to draw magnetic field profile, from
which the maximum exposure level was obtained.
C. Average and Maximum Exposure Levels
The average exposure level corresponds to a spatial average
of field over the entire human body to which the individual is
exposed to. It is defined as shown in Table 1 depending on
measurement procedures described above.
B. Measurement around Distribution Facilities
A magnetic flux density meter (Model 3470, HIOKI E. E.
Corporation) was used. The senor consists of three concentric
coils and resultant magnetic flux density in root mean square
can be obtained.
TABLE I.
Measurement
Procedure
Magnetic field measurements were carried out five times in
different month of a year around six pad mounted transformers
(6,600V/105-210V), six switchgears (6,600V) and five vertical
cables (6,600V), which are installed on sidewalks in urban
areas and accessible by the public.
AVERAGE EXPOSURE LEVEL
Definition of Average Exposure Level
single-point
measured field value
three-point
arithmetic mean of the three field values
five point
arithmetic mean of the largest three field values
The maximum exposure level is defined as the maximum of
the average exposure levels over the area of interest.
Beside power equipment, the maximum exposure level is
obtained as follows: The magnetic field should be measured at
a height of 1.0 m above the ground, around equipment at a
horizontal distance of 0.2 m from its surface, at appropriate
intervals as shown in Fig. 2. In situations where the equipment
has a height less than 1.5 m, the field level should be scanned
at the top height of the equipment instead of 1.0 m. At the
position where the maximum field level is found, a three-point
Copyright 2014 IEICE
Since the height of any equipment was less than 1.5 m,
magnetic field was scanned at its top height and at a horizontal
distance of 0.2 m from its surface facing to pedestrian passage.
After finding the position of the maximum magnetic field, the
average exposure level was obtained by following the threepoint measurement procedure.
Then, magnetic field was scanned at its top height around
equipment at a horizontal distance of 0.2 m from its surface at
appropriate intervals. After finding the position of the
maximum field, the maximum exposure level was obtained by
performing the three-point measurement at the position.
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EMC’14/Tokyo
RESULTS AND DISCUSSION
A. Under Trasmission Lines
Fig. 3 shows an example of magnetic field profile measured
at 1 m above the ground along a path perpendicular to 500 kV
transmission lines at the lowest clearance. From this figure, the
maximum exposure level of 2.02 μT can be obtained.
The maximum exposure levels of magnetic field under nine
transmission lines are summarized in Fig. 4, where filled and
unfilled bars indicate 60 Hz and 50 Hz in grid frequency,
respectively. The maximum exposure level is less than 11 μT,
which is much lower than the reference level of 200 μT from
the ICNIRP Guidelines.
B. Around Distribution Facilities
The average and the maximum exposure levels of magnetic
field generated by six pad-mounted transformers are shown Fig.
5 (a) and (b), respectively. Fig. 6 (a) and (b) shows the average
and the maximum exposure levels of magnetic field generated
by six switchgears, respectively. Vertical cables generate the
maximum exposure level of magnetic fields shown in Fig. 7.
The average and the maximum exposure levels of magnetic
field are much lower than the ICNIRP reference level of 200
μT for any distribution equipment.
2.5
Magnetic field (μT)
2.0
a
b
c
1.5
18
Average exposure level (μT)
IV.
16A1-H1
16
14
12
10
8
6
4
2
0
1.0
1
2
3
4
5
6
5
6
(a) Average exposure levels
0.5
18
-25 -20 -15 -10 -5
0
5
10
15
20
25
30
Maximum exposure level (μT)
0.0
35
Distance (m)
Fig. 3. Magnetic field profile along a path perpendicular to 500 kV
transmission lines at the lowest clearlance.
10
14
12
10
8
6
4
2
0
8
1
2
3
4
(b) Maximum exposure levels
6
Fig. 5. Average and Maximum exposure levels of magnetic field generated
by pad-mounted transformers.
4
3.0
2
0
Average exposure level (μT)
Maximum
level(μT)
[μT]
Maximumexposure
exposure level
12
16
500 500 500 500 400 400 275 220 115
Nominal voltage (kV)
Fig. 4. Maximum exposure levels of magnetic field generated by
transmission lines.
2.5
2.0
1.5
1.0
0.5
0.0
1
2
3
4
(a) Average exposure levels
Copyright 2014 IEICE
623
5
6
EMC’14/Tokyo
16A1-H1
[1]
Maximum exposure level (μT)
3.5
3.0
[2]
2.5
2.0
[3]
1.5
1.0
[4]
0.5
0.0
1
2
3
4
5
6
[5]
(b) Maximum exposure levels
Fig. 6. Average and maximum exposure levels of magnetic field generated
by switchgeras.
[6]
Maximum exposure level (μT)
4.0
[7]
3.5
3.0
2.5
[8]
2.0
1.5
[9]
1.0
0.5
[10]
0.0
1
2
3
4
5
[11]
Fig. 7. Maximum exposure levels of magnetic field generated by vertical
cables.
V.
[12]
CONCLUSIONS
The average and the maximum exposure levels of magnetic
field generated by transmission lines and power distribution
equipment installed on sidewalks were evaluated in accordance
with IEC 62110. They are much smaller than the reference
levels from the ICNIRP Guidelines.
Further measurements is planned to collect much data. A
method will be discussed to estimate the average and the
maximum exposure levels in the basis of current flowing into
power distribution equipment.
[13]
[14]
[15]
[16]
REFERENCES
Copyright 2014 IEICE
624
K. Isaka, N. Hayashi, Y. Yokoi and M. Okamoto, “Characteristics of
ground-level electric and magnetic fields generated by ac power
transmission lines”, International Symposium on Electromagnetic
Compatibility, Vol. 2, pp. 511-514, 1989.
A. E. Tzinevrakis, D. K. Tsanakas and E. I. Mimos, “Analytical
calculation of the electric field produced by single-circuit power lines”,
IEEE Trans. on Power Delivery, Vol. 23, No. 3, pp. 1495-1505, 2009.
G. Mazzani, “The role played by current phase shift on magnetic field
established by ac double-circuit overhead transmission lines - Part I:
Static analysis”, IEEE Trans. on Power Delivery, Vol.32, No.2, pp. 939948, 2006.
N. Hayashi, K. Isaka, H. Kume and Y. Yokoi, “Power frequency
magnetic field in a 187/66-kV electric power substation”, International
Symposium on Electromagnetic Compatibility, vol. 2, pp. 505-510,
1989.
N. Goto, Y. Uga, K. Kato, M. Shimizu, A. Yoshida, H. Okubo,
“Investigation of magnetic field environment based on line current
condition in 77kV substation”, Trans. of IEE Japan, Vol. 121-B, No. 7,
pp. 874-880, 2001 (in Japanese).
J. Lago, L. Skurcak, P. Bojda, M. Savcak, “Application of the
mathematical modeling on EHV substation’s electric and magnetic
fields at limit operating conditions”, CIGRE EMF-ELF, pp. 309-319,
Paris, 2011.
Qingmin Li and Joseph D. Yan, “Computational investigation of the
magnetic-field distribution in a 145-kV/40-kA rotary-arc circuit
breaker”, IEEE. Trans. on Power delivery, Vol. 21, No. 1, pp. 135-141,
2006.
B.W. Jaekel, “General description and assessment concept for magnetic
field distributions caused by switchgear installation”, IEEE Trans. on
Power Delivery, Vol. 22, No. 1, pp. 167-177, 2007.
I. Magne, F. Audran, E. Mayaudon, D. Clement, and F. Deschamps,
“50Hz electric and magnetic field measurements in high voltage
substations,” CIGRE EMF-ELF, Sarajevo, Paper 20, 2009.
D. Clement, F. Deschamps, I. Magne, and M. Burceanu, “Interlaboratory 50 Hz EMF measurement,” presented at the BioEM, Davos,
Switzerland, P-194, 2009.
K. Tanaka, Y. Mizuno, K. Naito, “Measurement of power frequency
electric and magnetic fields near power facilities in several countries”,
IEEE Trans. on Power Delivery, Vol. 26, No. 3, pp. 1508-1513, 2011.
S. Nuic, M. Veledar, E. Aganovic, Z. Bajamovic, S. Carsimanovcic, M.
Ljevak, “Electromagnetic fields and safety distances in the environment
of 400 kV overhead lines”, CIGRE EMF-ELF, pp. 89-94, Paris, 2011.
L. Zhao, W. Gui-fang, J. Gio, J. Lu, “Measurement and analysis of
electromagnetic environments of 1000kV UHV AC transmission project
in China”, CIGRE EMF-ELF, pp. 125-135, Paris, 2011.
IEC 62110, “Electric and magnetic field levels generated by AC power
systems - Measurement procedures with regard to public exposure”,
2009.
ICNIRP, “Guidelines for limiting exposure to time-varying electric and
magnetic fields (1 Hz to 100 kHz), Health Physics, Vol. 99, No. 6, pp.
818-836, 2010.
IEEE Std C95.6, “IEEE standard for safety levels with respect to human
exposure to electromagnetic fields, 0-3 kHz”, 2002.