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Doc# E151701 13-1
13: EN50160/IEC61000-4-15 Flicker
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13: EN 50160/IEC 61000-4-15 Flicker
13.1: Overview
Flicker is the sensation experienced by the human visual system when subjected to
changes in the illumination intensity of light sources. The primary effects of Flicker are
headaches and irritability; sometimes Flicker can trigger epileptic fits.
IEC 61000-4-15 and former IEC868 describe the methods used to determine Flicker
severity. Since this phenomenon is strictly related to the sensitivity and reaction of
individuals, it can only be studied on a statistical basis, by setting up suitable experi-
ments among people.
13.2: Theory of Operation
Flicker can be caused by voltage variations which, in turn, are caused by variable
loads, such as arc furnaces, laser printers and microwave ovens. In order to model
the eye brain change, which is a complex physiological process, the signal from the
power network has to be processed while conforming with Figure 13.1, shown on
page 13-4.
• Block 1 consists of scaling circuitry and an automatic gain control function that nor-
malizes input Voltages to Blocks 2, 3 and 4. For the specified 50 Hz operation, the
Voltage standard is 230 V RMS.
• Block 2 recovers the Voltage fluctuation by squaring the input Voltage scaled to the
reference level. This simulates the behavior of a lamp.
• Block 3 is composed of a cascade of two filters and a measuring range selector. In
this implementation, a log classifier covers the full scale in use so the gain selection
is automatic and not shown here. The first filter eliminates the DC component and
the double mains frequency components of the demodulated output. The configura-
tion consists of a .05 Hz Low High Pass filter and a 6 Pole Butterworth Low Pass
filter located at 35 Hz. The second filter is a weighting filter that simulates the
response of the human visual system to sinusoidal Voltage fluctuations of a coiled
filament, gas-filled lamp (60 W - 230 V). The filter implementation of this function
is as specified in IEC 61000-4-15.
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