As South African industry doubles down on automation and energy efficiency through variable frequency drives (VFDs) and similar control technologies, many engineers are discovering an invisible but costly problem: harmonic distortion.
This often-overlooked phenomenon is introduced by non-linear loads like VFDs, arc furnaces and LED lighting. Left unchecked, harmonics degrade voltage quality, overheat motors and transformers and disrupt sensitive control systems. For plants already operating near capacity, harmonics can push systems beyond safe operating thresholds, triggering nuisance tripping, equipment derating and energy penalties.
At the Grootegeluk mine, engineers saw measurable gains after introducing passive and hybrid harmonic filters tuned to the fifth order. The intervention significantly reduced voltage distortion and improved power factor above 0.96, saving the mine avoidable and significant energy and equipment costs.
But harmonics don’t just erode system performance – they increase thermal losses (2-5% of total energy use), shorten equipment lifespan by 10-15% and cause VFD and PLC faults that disrupt production.
As more facilities become self-generators or integrate renewables, power quality compliance – especially to NRS 048-2 – is becoming a non-negotiable for grid connection and operational stability.
Fortunately, the tools now exist to measure and mitigate harmonics with precision. The VECTO system, for example, analyses distortion up to the 64th order in real time, providing complete harmonic profiling across variable loads. It calculates total harmonic distortion in line with IEC 61000-4-7 and captures phasor relationships essential for effective filter design.
For engineering teams, harmonic mitigation is not a fringe topic – it’s central to maintaining efficiency, uptime and grid compatibility. Whether using line reactors, active filters or multi-pulse VFDs, effective planning begins with accurate measurement and informed specification.
Want the full technical breakdown – including mitigation return on investment, specifications and design formulas? Read the full engineering article here.
Looking for real-world insights?
Don’t miss the Power Quality Unmasked podcast – an essential listen for plant managers and engineers. Learn how harmonic distortion, caused by modern equipment like VFDs, is affecting industrial operations in mining, manufacturing and data centres. Drawing on South African case studies and expert analysis, the podcast outlines practical strategies to safeguard equipment, maintain compliance and protect operational performance.
