Customer: Skopski Leguri – Skopje

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Custom made PID controllers, driving the electrodes of an Electric Arc Furnace.

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Current through each of the electrodes = max 100000 A  (100KA)

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Electrode Voltage = max 120V

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Furnace total Power consumption = 36MW (MegaWatts) 

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The two Iron melting furnaces are 4 floors high, and are one of the biggest in the balkan area. These PID’s are made to give command to the hydraulic motors, directly driving the electrodes inward, or out of the ore being melted. The process is complex and of very unpredictable nature. The PID’s job is to control, detect and predict any “movement” towards possible overshoot, but still keep the current consumption at optimum (usually maximum possible value). Also raise an Alarm if overshoot is predicted to happen, signalling a need for human manual override. These “movements” are very hard to predict, due to the nature of the process, and mainly that is cause of direct conductivity change, which depends out of: – the type of the ore material which comes in close contact with the electrode at a given  moment, its temperature, its physical state (liquid or solid), and the plasma behavior… That’s in general.

The main controller (white in the picture) is also custom programmed. Its role is to read data from the ISKRA measuring unit (green one in the picture) then feed the data to the PID controllers, report to the SCADA software. Each second, every event and every electrical parameter is recorded in database, for further reporting.  Also visual controls and graphs are put into the SCADA software, which is made in (.NET)

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