The client is a Piedmontese company specializing in brass hot molding for taps and fittings components, with a technology that places it among the leaders in Italy in this sector. It is a large plant, with about 7MW of installed power, and an average consumption of 4MW mostly due to ovens and presses.
The numerous presses in the plant differ in type and power, covering processes from initial brass reinforcing steel to the final formed piece. From the electrical point of view, the presses are difficult to manage because of their cyclic loading, which results in unexpected changes of the absorbed power and the relative power factor.
The presses induce in the plant great quantities of harmonic currents that can provoke heavy disturbances to the other components of the electric plant such as wires, transformers (overheating, premature ageing, mechanical damage from vibrations), electronic and measuring equipment (malfunctions and incorrect measurements), and re-phasing capacitors (thermal and mechanical damage).
The high speed of reactive power change requested by the plant makes it impossible to re-phase correctly with normal electromechanical devices (contactors) that control the re-phasing batteries insertion/disconnection in times varying by tens of seconds.
For a correct Power factor Correction (PFC) in this plant, ICAR created a solution able to surmount the problems: MULTImatic FD25/S “SPEED” blocking filters were installed for a total reactive power of 1Mvar. These units are characterized by:
- The use of “3In” oil and paper capacitors. These capacitors are extremely strong both towards stresses in current and towards thermal stresses up to 85°C
- The use of barrier reactances to prevent harmonic damage to the capacitors (the agreed frequency is 180Hz (n=3.6))
- The use of static insertion instead of contactors. The static inserters guarantee an insertion time of all panel batteries in the order of 100ms and correct re-phasing of the more “difficult” presses.
- Reduced maintenance: the absence of moving mechanical devices reduces the panel stress, resulting in much less frequent maintenance compared to systems with traditional electromechanical contactors
- Elimination of disturbances due to harmonic currents
Elimination of penalties, leading to lower cost