Active Harmonic Filter Sizing: What Happens When You Get It Wrong Learn how harmonic current, load cycles, topology, temperature, and SVG/AHF selection affect THDi performance. Consider a textile mill with dozens of VFD-driven spinning frames. A 100 A active harmonic filter (AHF) is installed, but THDi at the PCC falls only from 28% to 19%. The unit is operating normally; it is simply too s...
The Hidden Costs of Incorrect Active Harmonic Filter Sizing Got a call last month from a panel builder in Malaysia. His customer — a textile mill running 47 VFD-driven spinning frames — had commissioned a 100A AHF three months earlier. THDi at the PCC dropped from 28% to 19%. Not terrible, but nowhere near what the spec promised. The supplier insisted the unit was working. It wa...
How Regenerative Loads Affect Industrial Power Quality Regenerative loads are common in modern industrial systems. They appear when a motor changes from consuming power to returning power. This often happens during braking, lowering, deceleration, or rapid speed changes. Cranes, hoists, elevators, rolling mills, centrifuges, test benches, and conveyor systems can all create regenerative loads. The...