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Title: CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps

Abstract

This CALiPER report examines the characteristics of a subset of lamps from CALiPER Retail Lamps Study 3 in more detail. Specifically, it focuses on the dimming, power quality, and flicker characteristics of 14 LED A lamps, as controlled by four different retail-available dimmers.

Authors:
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
OSTI Identifier:
1220494
Report Number(s):
PNNL-SA-23944
7108
DOE Contract Number:
AC05-76RL01830
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
doe, caliper, ssl, solid-state, lighting, led, lamps, flicker, dimming, performance, dimmer, power quality, retail

Citation Formats

none,. CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps. United States: N. p., 2014. Web. doi:10.2172/1220494.
none,. CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps. United States. doi:10.2172/1220494.
none,. 2014. "CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps". United States. doi:10.2172/1220494. https://www.osti.gov/servlets/purl/1220494.
@article{osti_1220494,
title = {CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps},
author = {none,},
abstractNote = {This CALiPER report examines the characteristics of a subset of lamps from CALiPER Retail Lamps Study 3 in more detail. Specifically, it focuses on the dimming, power quality, and flicker characteristics of 14 LED A lamps, as controlled by four different retail-available dimmers.},
doi = {10.2172/1220494},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2014,
month =
}

Technical Report:

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  • To date, all three reports in the retail lamps series have focused on basic performance parameters, such as lumen output, efficacy, and color quality. This report goes a step further, examining the photoelectric characteristics (i.e., dimming and flicker) of a subset of lamps from CALiPER Retails Lamps Study 3. Specifically, this report focuses on the dimming, power quality, and flicker characteristics of 14 LED A lamps, as controlled by four different retail-available dimmers. The results demonstrate notable variation across the various lamps, but little variation between the four dimmers. Overall, the LED lamps: ~tended to have higher relative light outputmore » compared to the incandescent and halogen benchmark at the same dimmer output signal (RMS voltage). The lamps’ dimming curves (i.e., the relationship between control signal and relative light output) ranged from linear to very similar to the square-law curve typical of an incandescent lamp. ~generally exhibited symmetrical behavior—the same dimming curve—when measured proceeding from maximum to minimum or minimum to maximum control signal. ~mostly dimmed below 10% of full light output, with some exceptions for specific lamp and dimmer combinations ~exhibited a range of flicker characteristics, with many comparing favorably to the level typical of a magnetically-ballasted fluorescent lamp through at least a majority of the dimming range. ~ always exceeded the relative (normalized) efficacy over the dimming range of the benchmark lamps, which rapidly decline in efficacy when they are dimmed. This report generally does not attempt to rank the performance of one product compared to another, but instead focuses on the collective performance of the group versus conventional incandescent or halogen lamps, the performance of which is likely to be the baseline for a majority of consumers. Undoubtedly, some LED lamps perform better—or more similar to conventional lamps—than others. Some perform desirably for one characteristic, but not others. Consumers (and specifiers) may have a hard time distinguishing better-performing lamps from one another; at this time, physical experimentation is likely the best evaluation tool.« less
  • This report focuses on the flicker and power quality performance of the Series 20 lamps at full output and various dimmed levels. All of the Series 20 PAR38 lamps that manufacturers claimed to be dimmable (including all halogen lamps) were evaluated individually (one lamp at a time) both on a switch and under the control of a phase-cut dimmer designed for use with "all classes of bulbs." Measurements of luminous flux, flicker, and power quality were taken at 10 target dimmed settings and compared with operation on a switch. Because only a single unit of each product was evaluated onmore » a single dimmer that may or may not have been recommended by its manufacturer, this report focuses on the performance of the products relative to each other, rather than the best-case performance of each lamp or variation in performance delivered from each lamp. Despite these limitations, the results suggest that LED performance is improving, and performance trends are beginning to emerge, perhaps due in part to the identification of preferred LED driver strategies for lamp products.« less
  • The lumen depreciation and color shift of 17 different A lamps (15 LED, 1 CFL, 1 halogen) was monitored in the automated long-term test apparatus (ALTA) for more than 7,500 hours. Ten samples of each lamp model were tested, with measurements recorded on a weekly basis. The lamps were operated continuously at an ambient temperature of 45°C (-1°C). Importantly, the steady-state test conditions were not optimized for inducing catastrophic failure for any of the lamp technologies—to which thermal cycling is a strong contributor— and are not typical of normal use patterns—which usually include off periods where the lamp cools down.more » Further, the test conditions differ from those used in standardized long-term test methods (i.e., IES LM-80, IES LM-84), so the results should not be directly compared. On the other hand, the test conditions are similar to those used by ENERGY STAR (when elevated temperature testing is called for). Likewise, the conditions and assumptions used by manufacturers to generated lifetime claims may vary; the CALiPER long-term data is informative, but cannot necessarily be used to discredit manufacturer claims. The test method used for this investigation should be interpreted as one more focused on the long-term effects of elevated temperature operation, at an ambient temperature that is not uncommon in luminaires. On average, the lumen maintenance of the LED lamps monitored in the ALTA was better than benchmark lamps, but there was considerable variation from lamp model to lamp model. While three lamp models had average lumen maintenance above 99% at the end of the study period, two products had average lumen maintenance below 65%, constituting a parametric failure. These two products, along with a third, also exhibited substantial color shift, another form of parametric failure. While none of the LED lamps exhibited catastrophic failure—and all of the benchmarks did—the early degradation of performance is concerning, especially with a new technology trying to build a reputation with consumers. Beyond the observed parametric failures nearly half of the products failed to meet early-life thresholds for lumen maintenance, which were borrowed from ENERGY STAR specifications. That is, the lumen maintenance was sufficiently low at 6,000 hours that seven of the products are unlikely to have lumen maintenance above 70% at their rated lifetime (which was usually 25,000 hours). Given the methods used for this investigation—most notably continuous operation—the results should not be interpreted as indicative of a lamp’s performance in a typical environment. Likewise, these results are not directly relatable to manufacturer lifetime claims. This report is best used to understand the variation in LED product performance, compare the robustness of LED lamps and benchmark conventional lamps, and understand the characteristics of lumen and chromaticity change. A key takeaway is that the long-term performance of LED lamps can vary greatly from model to model (i.e., the technology is not homogenous), although the lamp-to-lamp consistency within a given model is relatively good. Further, operation of LED lamps in an enclosed luminaire (or otherwise in high ambient temperatures), can induce parametric failure of LEDs much earlier than their rated lifetime; manufacturer warnings about such conditions should be followed if performance degradation is unacceptable.« less
  • This CALiPER report examines lumen depreciation and color shift of 17 different A lamps in steady-state conditions (15 LED, 1 CFL, 1 halogen). The goal of this investigation was to examine the long-term performance of complete LED lamps relative to benchmark halogen and CFL lamps—in this case, A lamps emitting approximately 800 lumens operated continuously at a relatively high ambient temperature of 45°C.
  • The CALiPER program first began investigating LED lamps sold at retail stores in 2010, purchasing 33 products from eight retailers and covering six product categories. The findings revealed a fragmented marketplace, with large disparities in performance of different products, accuracy of manufacturer claims, and offerings from different retail outlets. Although there were some good products, looking back many would not be considered viable competitors to other available options, with too little lumen output, not high enough efficacy, or poor color quality. CALiPER took another look in late 2011purchasing 38 products of five different types from nine retailers and the improvementmore » was marked. Performance was up; retailer claims were more accurate; and the price per lumen and price per unit efficacy were down, although the price per product had not changed much. Nonetheless, there was still plenty of room for improvement, with the performance of LED lamps not yet reaching that of well-established classes of conventional lamps (e.g., 75 W incandescent A19 lamps). Since the second retail lamp study was published in early 2012, there has been substantial progress in all aspects of LED lamps available from retailers. To document this progress, CALiPER again purchased a sample of lamps from retail stores 46 products in total, focusing on A19, PAR30, and MR16 lamps but instead of a random sample, sought to select products to answer specific hypotheses about performance. These hypotheses focused on expanding ranges of LED equivalency, the accuracy of lifetime claims, efficacy and price trends, as well as changes to product designs. Among other results, key findings include: There are now very good LED options to compete with 60 W, 75 W, and 100 W incandescent A19 lamps, and 75 W halogen PAR30 lamps. MR16 lamps have shown less progress, but there are now acceptable alternatives to 35 W, 12 V halogen MR16 lamps and 50 W, 120 V halogen MR16 lamps for some applications. Other uses, such as in enclosed luminaires, may require more development. At the same price point, lamps purchased in 2013 tended to have higher output and slightly higher efficacy than in 2011 or 2010. Over 30% of the products purchased in 2013 exceeded the maximum efficacy measured in 2011 (71 lm/W), with the most efficacious product measured at 105 lm/W. There appears to be increasing consistency in color quality, with a vast majority of products having a CCT of 2700 K or 3000 K and a CRI between 80 and 85. There were also fewer poor performing products tested and more high-performing products available in 2013 than in previous years. The accuracy of equivalency and performance claims was better than in 2011, but remains a concern, with 43% of tested products failing to completely meet their equivalency claim and 20% of products failing to match the manufacturer’s performance data. Although progress has been substantial, on average LED lamps remain more expensive than other energy efficiency lighting technologies -- although some aspects can be superior. Although not universal to all product lines or all product types, the issue of insufficient lumen output from LED lamps is waning. Thus, manufacturers can focus on other issues, such as reducing cost, improving electrical/dimmer compatibility, eliminating flicker, or improving color quality. While these issues are not inherent to all products, they remain a concern for the broader market.« less