FLICKER: Understanding the New IEEE Recommended Practice anti flicker fuckery

FLICKER: Understanding the New IEEE Recommended Practice,

anti flicker fuckery

https://www.energy.gov/sites/prod/files/2015/05/f22/miller%2Blehman_flicker_lightfair2015.pdf


Potential flicker-induced impairments,
Neurological problems, including epileptic seizure
• Headaches, fatigue, blurred vision, eyestrain
• Migraines
• Reduced visual task performance
• Increased autistic behaviors, especially in children
• Apparent slowing or stopping of motion (stroboscopic effect)
• Distraction

1 Naomi J. Miller, FIES, FIALD May 2015 Designer/Senior Staff Scientist Pacific Northwest National Laboratory FLICKER: Understanding the New IEEE Recommended Practice LightFair 2015 – DOE SSL Program Booth 1875 Brad Lehman Department of Electrical and Computer Engineering Northeastern University Chair, IEEE Standards PAR1789 Group (LED Lighting) 2 Flicker, flutter, shimmer • Repetitive change in magnitude over time, or modulation, of the luminous flux of a light source • Light source modulation Visible, invisible, perceptible, detectable (sensation) • Sensation: External conditions are detected; neurons respond • Visible flicker = Luminous modulation is sensed and perceived • Invisible flicker = Luminous modulation is sensed, but not perceived Flicker - Terminology 2 3 Stroboscopic vs. Phantom array effects • Stroboscopic effect: Luminous flux modulation made perceptible by the motion of objects, when the observer’s eye is still • Phantom array effect: Luminous flux modulation made perceptible by the motion of the observer’s eye, when the light source is still Flicker - Terminology 3 4 • Neurological problems, including epileptic seizure • Headaches, fatigue, blurred vision, eyestrain • Migraines • Reduced visual task performance • Increased autistic behaviors, especially in children • Apparent slowing or stopping of motion (stroboscopic effect) • Distraction Potential flicker-induced impairments 4 5 • Duration of exposure (longer is worse) • Area of the retina receiving stimulation (greater is worse) • Location in visual field (central is worse because it projects to a greater area of the visual cortex, even though flicker is less noticeable) • Brightness of the flash (higher luminances are worse; scotopic luminances produce low risk, high mesopic and photopic luminances produce higher risk) • Contrast of the flash with the surround luminance (higher is worse) • Color contrast of flash (deep red is worse) What makes flicker worse 5 6 Flicker Factors Flicker factors for both Visible and Invisible Flicker • Modulation Frequency • Modulation Amplitude • DC Component • Duty Cycle 6 7 IESNA has defined two metrics for flicker: • Percent flicker – 0-100% scale – Older, but more well-known and more commonly used – Accounts for average, peak-topeak amplitude – Does not account for shape, duty cycle, frequency • Flicker index – 0-1.0 scale – Newer, but less well-known and rarely used – Accounts for average, peak-topeak amplitude, shape, duty cycle – Does not account for frequency Source: IES Lighting Handbook, 10th Edition • Percent Flicker = • Percent Flicker ≠ • Flicker Index = Flicker - Metrics A B A B x   100% 100%x A- B Average Area1 Area1+ Area 2 8 (The SUSPENSE KILLER) Here’s the equation: Max % Flicker ≤ Flicker Frequency x 0.08 Flicker – Applied Metrics 9 BK 08-94A Incandescent, Halogen, Metal Halide 9 BK 10-X-37A BK 10-21D BK 09-111D 20W Halogen MR16 35W Halogen MR16 25W Self-Ballasted (Electronic) Ceramic Metal Halide PAR38 60W A19 10 Magnetically-ballasted Electronically-ballasted 10 BK 10-X-28 BK 10-X-32 BK 10-X-33 BK 10-X-34 T12 Fluorescent Quad-Tube CFL A19 CFL Quad-Tube CFL Fluorescent 12 Flicker in early LED products (some lamps/luminaires) 12 14 S01: Vrms load = 120 (on) D22: Vrms load = 115 (max dim) D22: Vrms load = 95 D22: Vrms load = 75 D22: Vrms load = 55 D22: Vrms load = 30 (min) Effect of Dimming - LED lamp A controlled by phase-cut dimmer 14 15 S01: Vrms load = 120 (on) D22: Vrms load = 115 (max dim) D22: Vrms load = 95 D22: Vrms load = 75 D22: Vrms load = 55 D22: Vrms load = 30 (min) LED lamp B controlled by phase-cut dimmer 15 16 S01: Vrms load = 120 (on) D22: Vrms load = 115 (max dim) D22: Vrms load = 95 D22: Vrms load = 75 D22: Vrms load = 55 D22: Vrms load = 30 (min) LED downlight controlled by phase-cut dimmer Flicker typical of all tested SSL modules marketed as containing “AC LEDs” 16 18 What determines flicker in LED sources? • LED flicker and dimming performance depends on the LED driver • Dimmers and other electronics can induce or increase flicker 18 Products more likely to flicker: • AC LEDs • DC LEDs with simple/inexpensive drivers (e.g., inadequate capacitors) • Integral lamp LEDs on some electronic transformers • LEDs dimmed with phase cut dimmers (triac, e.g.) • LEDs with Pulse Width Modulation (PWM) drivers 19 • Flicker waveforms not available from cut sheets yet • See the product in person, with the same driver/transformer/dimming setting of final installation • Try a flicker wheel or a spinning top • Sometimes a digital camera picks up flicker • Wave your fingers in the light or scan your eyes side to side; look for phantom array effect • Can’t we get a reliable metric??? How can you tell if a product flickers? 19 No flicker Flicker 20 • IEEE PAR1789 committee formed in 2008 to research issue, evaluate risk of flicker from SSL, and develop recommended practice. (Brad Lehman, chair.) • Developed Risk Assessment procedure and published document in 2012. IEEE PAR1789 Recommended Practice PROBABILITY Very Low Low Medium High Very High Mild Harmful Severe Catastrophic SEVERITY 21 Methodology for developing recommendations • Plotted data from multiple studies based on risk level, probability of exposure, and severity of exposure • Characterized data reliability (from opinion to solid data) • Plotted % Flicker (modulation) and frequency for no effect level (green) and low risk level (yellow). • Lehman and Wilkins authored article, “Designing to Mitigate the Effects of Flicker in LED Lighting” – IEEE Power Electronics Magazine, Sep 2014 • IEEE PAR1789 committee Recommended Practice written, debated, reviewed, and documented. Recently passed by committee and IEEE Board. Likely to be published in June 2015. IEEE PAR1789 Recommended Practice 22 • June 2015 Expected Publication • 1 st Ballot September 2014 • Final Ballot (passed) January 2015 Recommended Practice • January 2012 Internal Hazard Analysis Report • January 2010 • Publicly available on IEEE PAR1789 website Report on Biological Effects of Flicker •Nov. 2008 • ~50 members: industry, academics, and labs • Observers: NEMA, CIE, IEC, EnergyStar, OSHA IEEE PAR1789 formed Timeline – IEEE PAR1789 IEEE Recommended Practice 23 • Test to determine the flicker frequency in Hz of the SSL product (it must be ≥100 Hz) • Test to determine the % Flicker of the SSL product • Multiply the frequency by 0.08 and round up to the nearest whole number to get the max Allowable % Flicker • If % Flicker of the SSL product is LOWER than the Allowable Flicker, then the product is acceptable for all but the most unusually sensitive individuals. • If frequency is difficult to determine, % Flicker shall not exceed 10%. How to apply IEEE PAR1789 Recommended Practice Example: At 120 Hz frequency, max allowable % flicker is 10%. At 1250 Hz or higher, 100% flicker is allowed. 24 Utilities and energy efficiency organizations • Require flicker documentation for EE programs Manufacturers: • Be proactive now. Test for flicker. Test over dimming range. (Flicker meters are coming out of the woodwork!) • Demand drivers that produce less flicker, or higher frequency • Avoid PWM dimming unless combined with other techniques • Publish flicker waveforms and flicker metrics Specifiers • Avoid products more likely to produce flicker • See products in person. Learn to test for flicker. • Specify products where • Flicker Freq ≥ 100 Hz • % Flicker ≤ Flicker Freq x 0.08 (normal populations), or • % Flicker ≤ Flicker Freq x 0.0333 (special populations) Managing Risk: Recommendations 24 25 Offices Classrooms Industrial spaces General lighting Hospitals/clinics Task lighting Application - Where Flicker Matters 25 26 TV studios/videoconferencing (Anywhere video cameras are used) Where Flicker Matters 26 27 Accent lighting on artwork? Roadways/parking lots Sports and industrial lighting on 3-phase electrical system Where flicker is less important Very low intensity holiday lighting? 27 28 (Just please avoid the epilepsy frequencies and use for very short duration) Warning lights Discotheques Where flicker might be an advantage 28 29 Resources (and thanks for listening!) DOE CALiPER Report 20.2 29 DOE Flicker Fact Sheet In July, Google “IEEE PAR1789 Recommended Practice for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers” Naomi . Miller @ PNNL . gov Lehman @ ece . Neu . edu