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Transcript of 1 Standards and Calibration Laboratory, SCL Evaluation of Flicker Severity in Standards and...
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