- Type of paper
: Paper in journal
Title: The influence of core material grade on flux distortion in
three-limb transformer core
- Authors:
- Valković, Zvonimir (51515)
Journal: Anales de fisica
Number: 1
ISSN: 0211-6251
Volume: 86
Year: 1990
Pages: from 302 to 304
Number of references: 9
Language: engleski
Summary: The influence of material grade on localized flux
distribution and harmonics level has been investigated on scale models of
three-limb core made from three different core materials (M4, M0H and ZDKH
grades). In relation to the model from the conventional M4 grade material,
both models from higher grade materials (M0H and ZDKH) have higher flux
distortion. The increase of power loss due to flux distortion has been
calculated, and the results are in good agreement with the known
differences in building factors of cores with higher and conventional grade
materials.
Keywords: Transformer core, Magnetic material, Additional losses, Experiments.
- Type of paper
: Paper in journal
Title: High order finite elements for nonlinear magnetic field
calculations
- Authors:
- Rezić, Ante (93615)
Journal: Elektrotehnika
Number: 3
ISSN: 0013-5844
Volume: 35
Year: 1992
Pages: from 109 to 119
Number of references: 7
Language: hrvatski
Summary: One group of high order finite elements is described. The
article deals with up to 12-noded, 4-sided compatible curvilinear finite
elements. Their application in nonlinear isotropic magnetic field
calculation is described. An example of field calculation in the reactor
with the holes in its iron core is presented.
Keywords: Finite elements method, Nonlinear magnetic field, Calculation.
- Type of paper
: Paper in journal
Title: Finite element method in transformer core field
calculation
- Authors:
- Rezić, Ante (93615)
Journal: Elektrotehnika
Number: 4
ISSN: 0013-5844
Volume: 35
Year: 1992
Pages: from 201 to 208
Number of references: 8
Language: hrvatski
Summary: Two-dimensional finite elements method used for one of
nonlinear and anisotropic field calculations is described. It is used for
the calculation of fluxes in transformer cores. Influence of overlap and
air gap on the flux distribution is taken in account through higher
magnetic resistance in that area.
Keywords: Finite elements method, Field calculation, Transformer core.
- Type of paper
: Paper in journal
Title: Some aspects of additional losses in step-lap joints of
transformer core
- Authors:
- Valković, Zvonimir (51515)
Journal: COMPEL
Number: 1
ISSN: 0332-1649
Volume: 11
Year: 1992
Pages: from 137 to 140
Number of references: 3
Language: engleski
Summary: Magnetic properties of step-lap joints have been
investigated experimentally on scale-models of three-phase three-leg
transformer core. The influence of core induction, number of steps and
overlapping length has been investigated.
Keywords: Transformer core, Models, Magnetic characteristics, Step-lap overlap.
- Type of paper
: Paper in journal
Title: Numerical calculation of loss distribution and magnetizing
current in 3-phase 3-limbed transformer core
- Authors:
- Rezić, Ante (93615)
Journal: Elektrotehnika
Number: 5
ISSN: 0013-5844
Volume: 35
Year: 1992
Pages: from 275 to 281
Number of references: 12
Language: hrvatski
Summary: One of 2D numerical method of loss and current calculation
in transformer cores is described. Finite element numerical method is used
in the calculation. That method is employed in an example of magnetizing
current calculation and loss distribution calculation in 3-phase 3-limbed
transformer core. In comparison with measured results, obtained on scale
model, an accuracy of 5% in loss calculation is obtained.
Keywords: Finite elements method, Numerical calculation, Loss distribution, Magnetizing current, Transformer core.
- Type of paper
: Paper in journal
Title: Additional losses in overlapping area of transformer core
- Authors:
- Rezić, Ante (93615)
- Valković, Zvonimir (51515)
Journal: COMPEL
Number: 1
ISSN: 0332-1649
Volume: 13
Year: 1994
Pages: from 101 to 104
Number of references: 7
Language: engleski
Summary: The influence of overlap length and overlapping design on
core loss and magnetizing current of single-phase two-leg transformer core
has been investigated. The investigation was performed experimentally, on
scaled models, and numerically, using 2D finite element method. Two types
of overlapping, mitred and staggered one, were investigated. It has been
observed that the influence of overlap length on core magnetic
characteristics is much higher in the case of the mitred overlap than that
of the staggered one. This difference has been explained by the reduction
of core cross section due to triangle cutout in the mitred overlap.
Keywords: Transformer core, Overlap, Magnetic characteristics, Experiments, Numerical calculation.
- Type of paper
: Paper in proceedings
Title: Magnetic phenomena in step-lap transformer core
- Authors:
- Valković, Zvonimir (51515)
Proceedings title: Energetska tehnika i aditivni izvori energije
Language: hrvatski
Place: Zagreb
Year: 1991
Pages: from 18 to 18
Meeting: III simpozij o novim tehnologijama
Held: from 10/15/91 to 10/17/91
Summary: The main aims and the first results of the investigation on
the project 2-05-239 "Magnetic phenomena in step-lap transformer core" are
explained.
Keywords: Transformer, Core, Step-lap overlap, Core loss.
- Type of paper
: Paper in proceedings
Title: Additional losses in overlapping area of transformer core
- Authors:
- Rezić, Ante (93615)
- Valković, Zvonimir (51515)
Proceedings title: ISEF'93
Language: engleski
Place: Warsaw, Poland (PL)
Year: 1993
Pages: from 127 to 130
Meeting: International symposium on electromagnetic fields in electrical engineering
Held: from 09/16/93 to 09/18/93
Summary: The influence of overlap length and overlapping design on
core loss and magnetizing current of single-phase two-leg transformer core
has been investigated. The investigation was performed experimentally, on
scaled models, and numerically, using 2D finite element method. Two types
of overlapping, mitred and staggered one, were investigated. It has been
observed that the influence of overlap length on core magnetic
characteristic is much higher in the case of the mitred overlap than that
of the staggered one. This difference has been explained by the reduction
of core cross section due to the triangle cutout in the mitred overlap.
Keywords: Transformer core, Overlap, Magnetic characteristics, Experiments, Numerical calculation.
- Type of paper
: Paper in proceedings
Title: Presentation of anisotropic and hysteretic magnetic
properties of grain-oriented transformer sheet
- Authors:
- Rezić, Ante (93615)
Proceedings title: Zbornik radova 40. jubilarni godišnji skup KoREMA
Language: hrvatski
Place: Zagreb
Year: 1995
ISBN/ISSN: 953-6037-08-4
Pages: from 202 to 206
Meeting: 40. jubilarni godišnji skup KoREMA
Held: from 04/19/95 to 04/21/95
Summary: A method of presentation of non-linearity between magnetic
field density B and magnetic field strength H in materials having very
steep magnetization curve, like grain-oriented transformer sheets has been
worked out in detail. A method of presentation of anisotropic and
hysteretic properties of these materials is described, too. Having these
presentations, necessary magnetic property data can be included in
numerical computation of magnetic field, as in the case of finite element
numerical method. Calculated results of the magnetic property presentations
are compared with accessible data of measurement, and good agreement
between them has been found.
Keywords: Magnetizing curve, Approximation methods, Non-linearity, Anisotropy, Hysteresis.
- Type of paper
: Paper in proceedings
Title: Calculation of flux distribution in transformer core
taking hysteresis into account
- Authors:
- Rezić, Ante (93615)
- Valković, Zvonimir (51515)
Proceedings title: ISEF'95
Language: engleski
Place: Warsaw, Poland (PL)
Year: 1995
Meeting: International symposium on electromagnetic fields in electrical engineering
Held: from 09/25/95 to 09/27/95
Summary: Calculation of flux distribution in three-phase three-limb
transformer core has been made using 2D finite element method. The
calculation has been performed with and without taking into account
hysteresis of magnetic material. Anisotropy of magnetic material has
modeled through the so-called elliptic permeability model. Comparison of
results of calculation and results of measurement has been performed for a
scale model of transformer core. An agreement better than 3% has been
obtained, for calculated and measured results of third harmonics and of
flux distortion factor when hysteresis has been taken into account. The
CPU-time was 6-10 times longer when hysteresis has been included into
calculation.
Keywords: Transformer core, Magnetic flux distribution, Numerical calculation, Hysteresis.
- Type of paper
: Summary in proceedings
Title: IMPROVEMENT OF TRANSFORMER CORE MAGNETIC PROPERTIES USING
STEP-LAP DESIGN
- Authors:
- Valković, Zvonimir (51515)
- Rezić, Ante (93615)
Proceedings title: SOFT MAGNETIC MATERIAL 10 - ABSTRACTS BOOKLET
Language: engleski
Place: Dresden, Germany
Year: 1991
Pages: from 147 to 147
Meeting: Soft Magnetic Materials Conference
Held: from 09/11/91 to 09/13/91
Summary: Improvement of core magnetic properties using the step-lap
joint design was investigated on scale-models of a three-phase three-limb
core. The reduction of the core loss and the magnetizing current obtained
with the step-lap design is 2-4.4% and 31-37%, respectively.
Keywords: Transformer, Magnetic core, Step-lap design, Models, Magnetic characteristics.
- Type of paper
: Summary in proceedings
Title: EFFECT OF ELECTRICAL STEEL GRADE ON TRANSFORMER CORE
AUDIBLE NOISE
- Authors:
- Valković, Zvonimir (51515)
- Editors
- Bertotti, G.
Proceedings title: SOFT MAGNETIC MATERIALS CONFERENCE - ABSTRACTS
Language: engleski
Place: Venezia, Italy
Year: 1993
Pages: from S6-24 to S6-24
Meeting: Soft Magnetic Materials Conference
Held: from 09/29/93 to 10/01/93
Summary: The effect of different material grade on the noise level
of a single-phase dry-type transformer model was experimentally
investigated. The models with MOH and ZDKH material have roughly the same
noise, while the model with M4 grade has up to 7.5 dB higher noise.
Keywords: Transformer, Magnetic core, Noise, Models.
- Type of paper
: Summary in proceedings
Title: INVESTIGATION OF CORE NOISE LEVEL ON A DRY-TYPE
TRANSFORMER MODEL
- Authors:
- Valković, Zvonimir (51515)
- Editors
- Lachowicz, H. K.
Proceedings title: SOFT MAGNETIC MATERIALS CONFERENCE - ABSTRACTS
Language: engleski
Place: Krakow, Poland
Year: 1995
Pages: from 92 to 92
Meeting: Soft Magnetic Materials Conference
Held: from 09/12/95 to 09/14/95
Summary: The influence of over-lap length in core joints and of
quality of core stacking on noise level was investigated on a single-phase
dry-type transformer model. Increasing the over-lap length from 4 to 28 mm,
the noise level has increased 3.4 - 7.1 dB. The variation of the measured
noise levels was correlated with the variation of the measured magnetizing
currents.
Keywords: Transformer, Magnetic core, Step-lap design, Noise, Models.
- Type of paper
: Mentorship
Title: ADDITIONAL LOSSES IN THREE-PHASE TRANSFORMER CORE
Faculty: Viša tehnička škola Zagrebačko
Mentor: VALKOVIĆ ZVONIMIR
Date of defense: 09/22/94
Number of pages: 34
Author: Bardač Krešimir
Degree level: D.A.
- Type of paper
: Mentorship
Title: THE MODEL FOR TRANSFORMER NOISE INVESTIGATION
Faculty: Viša tehnička škola Zagrebačko
Mentor: VALKOVIĆ ZVONIMIR
Date of defense: 02/21/95
Number of pages: 41
Author: Bobić Goran
Degree level: D.A.
- Type of paper
: Survey/Study
Title: INVESTIGATION OF THE INFLUENCE OF LAMINATION JOINT DESIGN
ON CORE MAGNETIC CHARACTERISTICS
- Authors:
- Valković, Zvonimir (51515)
- Rezić, Ante (93615)
- Ilić-Roller, Dinka (134506)
Ordering party: KONČAR - Institut za elektrotehniku
Institution depot: KONČAR - Institut za elektrotehniku
Year: 1992
Number of pages: 16
Language: hrvatski
Summary: The influence of joint overlapping on transformer core
magnetic characteristics was invesigated on a model of single-phase
transformer core. The investigation was performed experimentally on
scale-models and numerically using 2D finite element method.
Keywords: Transformer, Magnetic core, Magnetic characteristics.
- Type of paper
: Survey/Study
Title: INVESTIGATION AND DEVELOPMENT OF STEP-LAP CORES
- Authors:
- Rezić, Ante (93615)
Ordering party: KONČAR - Institut za elektrotehniku
Institution depot: KONČAR - Institut za elektrotehniku
Year: 1994
Number of pages: 37
Language: hrvatski
Summary: Magnetic characteristics of three-phase step-lap
transformer cores were analized. Method of core loss and magnetizing
current calculation was developed, both for conventional and superoriented
magnetic material. Calculated and measured data were compared. Technical
and economical comparison of step-lap and conventional core is given.
Keywords: Transformer, Magnetic core, Core loss, Magnetizing current.
- Type of paper
: Survey/Study
Title: MEASUREMENT AND ANALYSIS OF DRY-TYPE TRANSFORMER NOISE
- Authors:
- Valković, Zvonimir (51515)
Ordering party: KONČAR - Distributivni i specijalni transformatori
Institution depot: KONČAR - Distributivni i specijalni transformatori
Year: 1994
Number of pages: 13
Language: hrvatski
Summary: Method for calculation of dry-type transformer noise was
developed. Results of calculation are in good agreement with measurements.
Keywords: Transformer, Noise, Calculation.
- Type of paper
: Survey/Study
Title: MAGNETIC CHARACTERISTICS OF ELECTRICAL STEEL AND STEP-LAP
CORES OF POWER TRANSFORMER
- Authors:
- Rezić, Ante (93615)
Ordering party: KONČAR - Energetski transformatori
Institution depot: KONČAR - Energetski transformatori
Year: 1995
Number of pages: 25
Language: hrvatski
Summary: A new method of magnetic characteristics calculation of
three-limb and five-limb step-lap transformers core was developed. The
results of the calculation are in good agreement with results of the
measurements.
Keywords: Transformer, Magnetic core, Magnetic characteristics, Calculation.
- Type of paper
: Invited lecture
Title: TRANSFORMER CORES - SOME RECENT RESEARCH TOPICS
Institution: THIRTEEN ANNUAL CONFERENCE ON PROPERTIES AND APPLICATIONS OF MAGNETIC MATERIALS
Year: 1994
