A ladle furnace is composed by a three-electrode electric system, operating AC mode; working into a three-phase electrical circuit, usually placed on the vertices of an equilateral triangle in around the furnace.
Our automation system comprise functions covering the electrode regulation system as well as the control of all the auxiliary elements of the furnace which is carried out by means of a software in a dedicated PLC, which is complemented by an HMI operation and display system which allows the parameterization and process monitoring of the whole facility, including:
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Control of the LF transformer HV primary circuit:
o Voltage, current measurement & counting (kWh meter / kVARh meter),
o Incoming isolator and earthing switch status,
o Vacuum Circuit breaker and disconnectors switches status,
o Protection and trip relays status: overcurrent, under-voltage,
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LF transformer, monitoring (Buchholz relay, oil liquid level, oil flow indication, status of oil circulating pump, oil to water heat exchanger status, tap changer status & control,
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Voltage and current measurements in secondary circuit, arranged in equilateral triangle to get uniform reactance in all three phases for symmetrical power input,
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Furnace water cooling, temperature & flow monitoring,
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Electrical water cooled parts, temperature & flow monitoring:
o bus bar up to Transformer-room,
o flexible LV cables,
o power conducting arms to electrodes,
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Control of main hydraulic equipment for furnace’s movements,
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Control of furnace’s movements,
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Electrode regulation & dynamic associated strategies: Control Consumption of Electrodes, by Control Power Input, by Automatic gain control kP,
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Refining profile:
o Refining cycle,
o Electric energy requirement calculation,
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Production Tracking and Level 2 interface,
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Interfaces with: oxygen lances-manipulator, sampling lances, temperature measuring equipment, Argon bubbling station, etc.,
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Status of ladle car: weight, data and position where placed,
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Sequencing & interlocking -safety logics-. Emergency operation.