THE CLIENT
A leading Italian paper manufacturing group.
THE NEED
In paper-making processes, numerous non-linear electrical loads coexist. These devices draw non-sinusoidal currents that propagate through the internal network, causing a significant increase in current total harmonic distortion (THD I).
Typical effects of harmonic distortion include overheating, nuisance tripping of protective devices, mechanical vibrations, increased losses and malfunctions of control systems.
Effective mitigation in plant LV switchboards requires a combined approach: automatic power factor correction to keep cosφ within an optimal range, and detuned reactors to decouple capacitors from the dominant harmonics.
OUR SOLUTION
Main technical data required by the customer and included in the supply:
- Model: Multimatic FV35V (detuned power factor correction bank, top of the range).
- Operating voltage (Ue): 400 V
- Capacitor bank rated voltage (Un): 550 V
- Frequency: 50 Hz.
- Tuning frequency: fD = 135 Hz (factor N = 2.7).
- Harmonic tolerance: THD-Ir% = 100%
- Harmonic tolerance: THD-Vr% ≤ 25% (suitable for operation even on networks with high voltage distortion).
- Plant target: reduce busbar THD-V down to ≤ 8% (design target value; depends on the harmonic spectrum and network impedance).
- Installed power: 640 kvar at 400 V.
Construction features and equipment included in the supply:
- Degree of protection: IP4X; bottom cable entry; dimensions 1830x675x2360 mm.
- Controller: 8BGA (automatic step control) with built-in disconnector and MCP5 accessory; auxiliary voltage 110 V.
- Short-circuit withstand current: 25 kA / 0.3 s.
Technical note: tuning at 135 Hz decouples the capacitors from low-order harmonics (especially the 5th and 7th), prevents resonance phenomena and limits the harmonic current that would flow into the bank, stabilizing the power factor even with numerous VFDs and highly dynamic loads.