furnace transformers and reactors design and features - Tamini

INTRODUCTION AND OPTIONS
ELECTRIC ARC FURNACE TRANSFORMERS AC TECHNOLOGY
Aiming to improve the efficiency and quality of the
melting process the iron and steel and
electrometallurgical engineers and the arc furnace
manufacturers have become more and more
attentive to any improvement directed to satisfy their
demand for:
maximum stability of the arc during the different
stages of the whole melting process
reduction of electric disturbances (flicker) on the
power supply network during melting process
productivity increase
reduction of electrode consumption
optimization of the cost of electric arc furnace
equipment and of its operating costs.
Conscious that proper design and adequate
production technology of the furnace transformers are
fundamental for a high efficiency of the plant
operation, Tamini is continuously devoting a
prominent attention to the developments in the arc
furnace conception and to the updating of the
melting process requirements.
Tamini has consequently always been in close contact
with the arc furnace manufacturers and operators, in
order to adapt the design and the characteristics of
the furnace transformers to the most advanced
technologies. In particular, the operation with long
arcs has demanded:
much higher secondary voltage (up to 1500 V
and over, at highest tap)
installation of series reactors, in order to increase
the total reactance of the system
universal adoption of on-load tap-changer for the
secondary voltage regulation
adoption of on-load tap-changers for the
reactors.
The result of these technologies , together with a
greater use of chemical energy (burners, lances) and
the installation of ladle furnaces, has been a dramatic
reduction of electrode and energy consumption.
The increase of the productivity is very high.
Recent years have also seen the development of DC
electric arc furnaces which have proved to be in
some cases an interesting alternative to the more
popular AC furnaces.
Tamini technology for AC and DC furnace
transformers is illustrated in the relevant paragraphs.
3. Two 93.5 MVA 30/0.9-0.5 kV AC-EAF transformers for Indonesia
TRANSFORMERS AND SERIES
REACTORS FOR AC FURNACES
The typical electric diagram of a modern AC arc
furnace is shown here aside.
This diagram does not show the complete auxiliary,
control and protection equipment normally
associated with the arc furnace plant and which is
selected taking into account the main parameters of
the installation (characteristics of the feeding
4. A 123 MVA AC-EAF transformer for France coupled with the saturable reactor see fig. 7
network, requirements of the supply utility, type of
instrumentation and automation etc.)
During the design of the electric system Tamini gives
all necessary assistance to the system engineer, in
order to co-ordinate the various parameters of the
auxiliary equipment. While designing the furnace
transformers and series reactors, the possibility of
abnormal loads and overvoltages foreseen by the
system engineer is carefully considered.
AC EAF Basic Diagram
High Current Connection
A.C. Furnace
Step-down Transformer
Reactor
Furnace Transformer
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