Electromagnetic Stirrer
This steel company is producing Alloy and Special Steels since 1966 and has kept pace with the developments by quickly adopting newer technologies to meet the requirements of the day and has always remained in the forefront as quality steel producer in the country. YASKAWA G7 drive -300kW is supplied for Mould electromagnetic stirrer (M-EMS) application which is used in continuous casting mills for production of alloy steels and special graded steels.
The total automation system solutions are provided and executed along with VIPA (PLC)
What is EMS
Electromagnetic stirring (EMS) is the process by which a high level of stirring efficiency can
be achieved through interaction between the magnetic field from the static induction coil and
the electrically conducting metal bath. The chemical composition, solidification conditions
and the nature of the liquid steel flow in the mould affects the surface quality and the inner
structure of the cast product. Mould electromagnetic stirring (M-EMS) technique promotes
the formation of an equalized crystallise zone in the strand. It causes the refinement of the
solidification structure, improvement in the quality of the surface, sub surface and the inner
structure of the cast product.
In the previous systems they had the provision for the producing only one kind of the graded
steel and there were also trying to upgrade the existing systems such that they have
flexibility in production of different types of graded steels.
Solution & Benefits
YASKAWA G7 3-level control low voltage drive was best suitable for this application to meet
the requirements and also for the total automation of the process we have integrated the
VIPA-PLC-HMI to the system. Unlike conventional drives, the G7 creates a variable output
by switching in 3-level control method to approach the sine wave output voltage. It provides
the solution to problems like motor insulation damage to surge voltage, and electrolytic
Corrosion of motor bearings due to shaft voltage.
By controlling the required output frequency and the current to be delivered to the coils form
the G7 drives through HMI which was installed near EMS coil (approx. 35mts) we are able
to stir the hot metal mould in the M-EMS coils to achieve the required grading of the steel.
Results
Yaskawa provided the solution for continuous casting mill section and now started taking
production for iron billets, with different grades steel and they are able to produce clean steel
to their customers. The total system provided runs with smooth operation along with
increase in the productivity and quality of the product.
Company management was happy with the robustness, quality of drives and also project
execution which was carried out.
G7 drive with 3-level control method was first
general purpose drive to use 3-level control
method, to approach sinewave output voltage.
It provides the solution to problem like motor
insulation damage to surge voltage, electrolytic
corrosion of bearing due to shaft voltage and
also inbuilt 12 pulse input convertor
configuration for harmonic reduction.
