Limitation of voltage fluctuations and flicker in low-voltage power supply systems

The purpose of the test is to measure the amplitude of voltage variations that may cause flicker in lighting devices due to voltage fluctuations resulting from load variations on the grid.

Specifically, typical equipment generating fluctuations includes cyclically operating equipment, those with thermostats that switch loads on and off, energy regulators, and voltage fluctuations occurring during motor start-ups, component activations, etc. Although lighting devices are primarily affected by these causes, leading to flickering, flicker measurement also applies to lighting devices because the static number of devices that can be switched on and off simultaneously is significant.

Flicker measurement involves determining various parameters, from those strictly related to network fluctuation to static parameters.

In the case of measuring the effect of switching on, statistical parameters are not considered, but only the relative variation, maximum over time (dc%, dmax%, and dt%) will be evaluated. In the case of cyclic operation of the device under test, it is important to determine the static parameters PST and PLT.

limiti fluttuazione

The test requires:

  • Dedicated power source with adjustable voltage and frequency
  • Analyzer compliant with the requirements of IEC 61000-4-15
  • Reference impedance
  • Data acquisition and processing software

As with harmonics, the applicable standards depend on the maximum current absorbed and the intended use of the device under test:

EN 61000-3-3
Electromagnetic Compatibility (EMC) - Part 3-3: Limitation of voltage changes, voltage fluctuations, and flicker in low-voltage power supply systems for equipment with rated current <= 16 A per phase and not subject to connection conditions.

EN 61000-3-11
Electromagnetic Compatibility (EMC) - Part 3-12: Limitation of voltage changes, voltage fluctuations, and flicker in low-voltage power supply systems for equipment with rated current <= 75 A per phase and subject to connection conditions.