63
EMF ESTIMATION IN SWITCHGEARS AT THE KURGAN POWER
SUBSTATIONS NEAR CABLE LINES 6(10) kV
A.
I.
S
IDOROV
,
R
USSIA
,
A.
V.
K
ORZHOV
,
R
USSIA
,
O.
M.
M
ALYSHEVA
,
R
USSIA
South Ural State University, e-mail: olgusiy@mail.ru
Electromagnetic field (EMF) is one of the adverse
operational factors, influencing to maintenance
personnel [1]. The EMF measuring operations at
11 Kurgan substations 110/6(10) kV and 35/6 kV were
carried out in switchgears 6(10) kV such types as K-37,
K-12, K-27, K-47, K-59. More than 2000 measurements
were carried out during the work.
The current standard (SanPiN 2.2.4.1191-03)
prescribes to perform estimation of EMF (50 Hz) at
industrial conditions separately by electric field intensity
(E, kV/m), magnetic field intensity (H, A/m) or magnetic
induction (B, uT) [2]. The measuring operation should be
performed at height of 0,5; 1,5 and 1,8 m above the floor
level and at a distance of 0,5 m from the equipment and
walls of building. But maintenance personnel can come to
the equipment at a distance closer than 0,5 m, so, we
think, that this fact should be considered during measuring
operation.
All analyzed cubicle switchboards should be
divided by their design by two types: 1) switchgears,
where cells with electrical equipment are located close to
the wall of building and 2) switchgears, where there is a
passage between cells and the wall of building.
The switchgears of the second type are more
interesting for the research, because of the conducting
parts of electric installations are located at the back of
cells. Measurements in such switchgears were carried
out at passages between cells and walls of buildings at
height of 0,5; 1,5 and 1,8 m at the next points: near
switchgear cells and at distance of 0,5 m.
During electromagnetic environment analysis the
exclusive focus is directed to the electric and magnetic
fields of industrial frequency because field intensity is
maximum at 50 Hz. In reality, the current, flowing in an
electric installation, has a number of harmonic
components [3]. That's why besides measurements of
EMF at 50 Hz we also identified the frequency content
of electric (fig. 1) and magnetic fields. The
measurements were carried out by device "EFA-300
Narda", which has measurement error 3-8% [4].
The values of electric field intensity are located in
the range 0,7 V/m - 107,8 V/m, in other words these
values don't exceed the maximum permissible level
(5 kV/m [2]). The values of magnetic induction in
switchgears of the first type also don't exceed the
maximum permissible level [2] for 8 hours working day.
Excess of the maximum permissible level of magnetic
induction was observed near cells of transformer
bushings and cable lines with great loads for switchgears
of the second type. The maximum magnetic induction
was observed near transformer bushing cell and was
equal 852 uT (H=678 A/m) at I
max
=1400 A.
Fig. 1. The frequency content of electric field.
So during the EMF analysis in switchgears
6(10) kV the main attention should be paid to magnetic
component of EMF. It is necessary:
1) to consider the overall impact of magnetic field
at 50 Hz and its frequency content;
2) to take into account design of substations,
switchboard cells types, character of maintenance
personnel work at operation of switchgears;
3) to pay main attention to transformer bushing
cells, cable lines with great loads cells and conducting
parts without metal enclosures;
4) to carry out measurements near windows on the
back of switchboard cells.
Information about the authors
A. I. Sidorov is a doctor of engineering science,
professor; A. V. Korzhov is a candidate of engineering
science, associate professor; O. M. Malysheva is a
postgraduate student.
References
1. Korzhov, A.V. Theoretical and experimental
study of the levels of electromagnetic fields near power
cables 6-10 kV / A.V. Korzhov, A.I. Sidorov / EMC
Technology. - 2009.- № 1. - P. 46-53.
2. Electromagnetic fields in production conditions:
SanPiN 2.2.4.1191-03. - Moscow: Russian Ministry of
Health, 2003.- 37 p.
3. Sidorov, A.I. Electromagnetic fields near high
voltage electrical installations: Monograph /
A.I. Sidorov, I.S. Okrainskaya. - Chelyabinsk: SUSU,
2008. – 204 p.
4. Portable analyzer EFA-200, EFA-300: 5 Hz to
32 kHz. For isotropic measurements of magnetic and
electric fields. - Http://www.emftest.ru/files/EFA-
300_DS_RU.pdf