1 Standards and Calibration Laboratory, SCL Evaluation of Flicker Severity in Standards and Calibration Laboratory (SCL) Speaker: Chung Yin, Poon Standards and Calibration Laboratory (SCL) The Government of the Hong Kong Special Administrative Region

2 Standards and Calibration Laboratory, SCL Learning Objectives To introduce the meaning of flickers in power line To describe a method for calibrating flicker source and flickermeter

3 Standards and Calibration Laboratory, SCL 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

4 Standards and Calibration Laboratory, SCL Introduction Source: Figure B.1, IEC Flickermeter - Functional and design specifications

5 Standards and Calibration Laboratory, SCL Evaluation of flicker parameters Flickermeter (Functional and design specification in IEC ) Flicker source (Limits of voltage changes produced by an equipment in IEC ) SCL developed a system to evaluate the accuracy of flicker source and flicker measurement functions of flickermeter

6 Standards and Calibration Laboratory, SCL Operating Principle Flicker waveform is modeled as an amplitude modulated (AM) signal in power line (120 V / 230 V)

7 Standards and Calibration Laboratory, SCL Operating Principle Relative voltage change / Voltage fluctuation V upper : Amplitudes of upper sideband V lower : Amplitude of lower sideband V carrier : Amplitude of the carrier

8 Standards and Calibration Laboratory, SCL Calibration of flicker source - Setup

9 Standards and Calibration Laboratory, SCL Resistive voltage divider

10 Standards and Calibration Laboratory, SCL Calibration of flicker source - Setup

11 Standards and Calibration Laboratory, SCL Calibration of flicker source Voltages of lower sideband ( V lower ), carrier ( V carrier ) and upper sideband ( V upper ) in dB are measured by signal analyzer Accuracy of the voltage fluctuation of standard flicker source can be determined

12 Standards and Calibration Laboratory, SCL 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 ( P inst ) will be compared against the theoretical values as illustrated in IEC

13 Standards and Calibration Laboratory, SCL Calibration of flickermeter - Setup

14 Standards and Calibration Laboratory, SCL What to be measured?

15 Standards and Calibration Laboratory, SCL Measurement uncertainties Depends on – Amplitude accuracy of signal analyzer – Performance of standard flicker source – Calibration setup

16 Standards and Calibration Laboratory, SCL Maximum uncertainty of voltage fluctuation measurement

17 Standards and Calibration Laboratory, SCL 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 – Tolerance of 8% in P inst for sinusoidal voltage changes

18 Standards and Calibration Laboratory, SCL Ratio between the specifications of standard flicker source and maximum measurement uncertainty (TUR)

19 Standards and Calibration Laboratory, SCL Thank you