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Sunday, December 06, 2009 |
It's time for the next installment in our Best Of Ask An Engineer series, where we take some of our most insightful "Ask An Engineer" questions and post their answers where anyone can find them.
Customer names have been changed to protect the innocent.
"LED Dock Lights @ ACME"
The Question
"In our pre-retrofit meeting yesterday, one question that was asked was about the 'housing' on these units. As you know, they are all yellow & fairly similar. My contact is pretty technical & understands that the housing is also a heat sink. He was curious if the housing/heat sink were all made by the same company and if the differences between the units were the LED & power supply?"
The Answer
Regarding the housing, your customer is correct that the housing is a heat sink, and that heat sinking is very important in regards to LED life. To answer the question, our die cast aluminum housing is unique, made from our own die cast tooling, and is not available from any other OEM.
There is a visually similar unit to ours on the market that goes out under several private label names. If you had them side by side on a table top, the differences would be crystal clear. Our die cast aluminum alloy housing is designed with more mass and more fin/surface area than the competing units, which is just one of the reasons why it runs substantially cooler junction temperatures and provides substantially longer life and lumen maintenance.
The prominent competing unit also has some plastic parts in the housing that reduce durability relative to ours.
Your customer is also correct that the combination of LED and driver further define performance. Drivers, chips and circuit boards will produce different performance depending on how they are used and integrated into the fixture. E.g., all drivers of the same brand and all chips of the same brand will have different performance depending on how they are populated onto the boards, how the board circuits are designed, and how they are mechanically mated to the heat sink.
Hope this helps and if we can be of further assistance, please let me know. Since your customer is fairly technical, he might appreciate the attached PDF document which addresses the issues above.
Thanks,
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Ray Pustinger
Vice President / General Manager
Precision-Paragon [P2]
 Download The PDF
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"LED-Powered Fluorescent Tube Replacements"
The Question
"I've seen several other lighting manufacturers marketing LED-tube lamps designed as a direct drop-in replacement for fluorescent lamps. Why has [P2] opted to not offer these products?"
The Answer
At Precision-Paragon [P2] we are certainly keeping a close eye on LED tube lamps as we expect they may show some promise in the next 5 years. At this time however, LED tube lamps designed to replace fluorescent fixtures do not yet hit the mark.
The Department of Energy has been evaluating these products on an on-going basis and have just released the results from Round 9 testing. Please find attached the latest Caliper summary report. Pages 11-18 outline the latest on linear replacement products with key conclusions at the end of the report.
Here are some of the key takeaways that end users should consider:
- Buyers should be wary that rewiring a troffer to bypass the ballast may jeopardize the UL certification (or other testing certification) of the troffer, requiring recertification which may be difficult to obtain.
- 4’ linear replacement lamps that have been tested do not meet the light output and efficacies seen in 4’ T8 fluorescent lamps, even when those products are tested in troffers to obtain overall luminaire performance.
- For office areas, they generally are too directed, delivering a limited 120° distribution range compared to fluorescent troffers that have a distribution range of around 150°.
There are also concerns regarding the sockets that LED tube lamps are used with and how/if they are appropriate for line voltage as opposed to the secondary voltages of ballasts. This is an industry concern as UL has not given approval or direction on this matter. For that matter, these products are not UL listed to my knowledge.
Voltage - Many of these replacement products are being designed for 120-240V. Unfortunately, this will not work with 277V applications which many end users have.
Life - Fluorescent products are continually being rated for longer and longer lifespans. Some lamp manufacturers are now rating T8 lamps at 36,000 hours, making it difficult to justify the incremental cost difference of a 50,000 hour product.
ANSI Standards - We have also seen that many of the lamp providers are not making product which meets the ANSI standards for T8 lamp lengths. Some are coming in too short and creating arcing, effectively damaging the onboard circuit board.
Cost - In addition to the freight costs, these products are typically FOB China and as such will be subject to importation duties which, for lighting products, runs about 9%. This would push the paybacks well beyond 7 years.
Risk - Even proven technologies can get a bad manufacturing batch and have some risk of failure during implementation. If an end user were to incur a mass failure with LED tube lamps, the availability of replacement units could impact their operations until replacements arrive from China. Additionally, the warranties offered on these types of products are generally of no value as they are not supported by manufacturers with strong balance sheets and the ability to immediately respond.
I think it is a great concept and may someday be ready technically. We are certainly keeping our eyes on them. However, I think they are far too risky at this point. Given the paybacks that many desire (2-3 years), the energy projects will have paid for themselves before these technologies are solid investments, both financially and technically.
I would be glad to address any additional concerns that might arise. Please let me know how we can help.
Thank you in advance.
Sincerely,
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Joe Martin
Vice President of Engineering
Precision-Lighting
Download The PDF |
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MORE RESOURCESFAQ >>We've put together a list of answers to some of the questions our engineers are most often asked. Glossary >>This is where you can translate lighting engineer talk into something more comprehensible. Technical Info >>Here we've gathered technical information with the potential to help any lighting professional with a project.
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