1Standards and Calibration Laboratory, SCL

Evaluation of Flicker Severity in Standards and Calibration

Laboratory (SCL)

Speaker: Chung Yin, PoonStandards and Calibration Laboratory (SCL)The Government of the Hong Kong Special

Administrative Region

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Learning Objectives

• To introduce the meaning of flickers in power line

• To describe a method for calibrating flicker source and flickermeter

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Introduction

• Flicker is the change in brightness of a lamp due to rapid fluctuations in the voltage of the power supply

• Cause disturbance to human visual perception system

• Voltage change characteristic at the terminals of the equipment under test, such as microwave ovens, washing machines

• All types of voltage fluctuations may be assessed by direct measurement using a flickermeter

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Introduction

Source: Figure B.1, IEC 61000-4-15-2010 Flickermeter - Functional and design specifications

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Evaluation of flicker parameters

• Flickermeter (Functional and design specification in IEC 61000-4-15)

• Flicker source (Limits of voltage changes produced by an equipment in IEC 61000-3-3)

• SCL developed a system to evaluate the accuracy of flicker source and flicker measurement functions of flickermeter

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Operating Principle• Flicker waveform is modeled as an amplitude

modulated (AM) signal in power line (120 V / 230 V)

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Operating Principle

• Relative voltage change / Voltage fluctuation

• Vupper: Amplitudes of upper sideband

• Vlower: Amplitude of lower sideband

• Vcarrier: Amplitude of the carrier

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Calibration of flicker source - Setup

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Resistive voltage divider

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Calibration of flicker source - Setup

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Calibration of flicker source

• Voltages of lower sideband (Vlower), carrier (Vcarrier) and upper sideband (Vupper) in dB are measured by signal analyzer

• Accuracy of the voltage fluctuation of standard flicker source can be determined

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Calibration of flickermeter

• Flickermeters under test are calibrated by direct comparison with the standard flicker source

• Calibration in terms of voltage fluctuation and modulating frequency

• Instantaneous flicker sensation (Pinst) will be compared against the theoretical values as illustrated in IEC 61000-4-15

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Calibration of flickermeter - Setup

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What to be measured?

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Measurement uncertainties

• Depends on– Amplitude accuracy of signal analyzer– Performance of standard flicker source– Calibration setup

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Maximum uncertainty of voltage fluctuation measurement

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Measurement uncertainties

• Flicker source: Measurement uncertainty < 0.03% at 95% confidence level

• Flickermeter: Measurement uncertainty < 0.3% for determination of flicker severities at 95% confidence level

• Type testing of Class F1 flickermeters according to IEC 61000-4-15– Tolerance of 8% in Pinst for sinusoidal voltage changes

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Ratio between the specifications of standard flicker source and maximum measurement uncertainty (TUR)

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Thank you