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Tim Patel
Tim Patel
1/26/2015 11:39:49 AM
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Re: impacting so much of urban modernization these days.
Hi Scott,

Most of the failed components are passives and semiconductor components (e.g., bridge rectifier diodes).  These would be in unprotected luminaire designs -- i.e., those without overvoltage protection provided in the driver or those without SPDs installed.  MOV-based SPDs normally do not reach their end-of-life or go offline within the expected lifetime of the luminaire unless they were subjected to an abnormally high number of surges.

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Scott Elder
Scott Elder
1/26/2015 11:31:56 AM
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Re: impacting so much of urban modernization these days.
Thanks Tim.

"Many of these failures are attributed to power line issues such as surges, low power quality, temporary overvoltages, etc."

So do the SPDs and MOV-type elements set the actual (read: in the field) lifetimes for off-line LED products?  In other words, if you were to order the list of failed elements, LEDs would not be at the top, but what would be the top two?  Passives, SPD, MOVs,... ?

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Tim Patel
Tim Patel
1/26/2015 9:55:50 AM
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Re: impacting so much of urban modernization these days.
Hi Scott,

You certainly raise a good point about the robustness of traditional lighting technologies (e.g., HPS) when it comes to dealing with power quality or transient issues on the power line.

Cities like Seattle and Las Vegas have had success in retrofitting street lighting over the last few years.  However, some studies performed by various LED lighting consortiums show that power supply / driver component failures is the most prominent source of failure in an LED luminaire.  Many of these failures are attributed to power line issues such as surges, low power quality, temporary overvoltages, etc.

In some regions of the world, power quality is a major concern, and LED lighting designers are having to design added protection into drivers or luminaires (from a systems level) to mitigate the effects of these issues.  Although the cost of adding this protection may appear to detract from the overall benefit of retrofitting existing lighting, over the expected longer period of lifetime for LED luminaires, the cost is still expected to be recovered.

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Scott Elder
Scott Elder
1/25/2015 6:23:42 PM
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Re: impacting so much of urban modernization these days.
Hi Tim,

I've been studying the problem of retrofitting street lighting (i.e. high pressure sodium) with LED systems.  While the lifetime and efficiency benefits of LEDs can't be argued, I wonder about the cost benefits when power line issues are added into the problem.  It seems the inductive ballasts and relative simplicity of existing technologies (HPS) solve these issues quite well.  Certainly the robustness of HPS has been substantially tested over the past several decades.  Can you share your experience with this issue in regards to cities that have adopted LED street lighting?  What are their experiences with power line robustness?

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uchiha
uchiha
1/8/2015 12:22:49 AM
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Artist
Re: capital investment
 @sunitaT0 : Yes of course your argument is correct. It'll increase the profit but the problem is how far it is possible?

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SunitaT0
SunitaT0
12/31/2014 4:11:47 AM
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Master
Re: capital investment
@uchiha: I think if LED's are coupled with smart lighting solutions then the energy efficiency and the cost to benefit ratio graph would increase substantially towards profit. I've seen LED's being used in street lighting and they give a far clearer road view and much more energy savings than traditional CFLs or high watt light bulbs.

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Tim Patel
Tim Patel
12/30/2014 2:00:11 PM
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Re: impacting so much of urban modernization these days.
@nasimson:

Great questions!

There are various approaches for including circuit protection into LED lighting.  All are dependent on the specific application and intended environment for the LED lighting. 

For example, indoor LED bulbs and lights typically are not subjected to the same levels of transient overcurrents and overvoltages as those installed in outdoor locations, so the level of protection required is normally not as high.  Typically, fast-acting fuses with low nominal operating currents are used in indoor LED lighting.  Where overvoltage protection is needed, semiconductor-based components like TVS diodes can provide an adequate level of overvoltage protection with fast response time.

On the other hand, for outdoor LED lighting applications, a higher level of overvoltage and overcurrent protection is needed.  This is due to the occurrence of surges on AC power lines originating from lightning strikes, utility power factor correction, load switching, and other events.  For some outdoor LED lighting or even indoor industrial LED lighting installations, high-reliability in the lighting system is required, and thus more robust circuit protection, such as high-energy withstand surge protection modules and surge-resistant fuses, would be needed.

The benefit of most overvoltage protective devices is that they typically draw very little leakage or "quiescent" current, and therefore there is very little loss in efficiency.  Overcurrent protective devices, on the other hand, do normally dissipate some finite amount of power during normal operation.  However, the benefit in terms of protecting against disastrous short-circuit or overload conditions (which could potentially lead to explosions and/or fire) is most often worth the small cost to add such protection into circuits.

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nasimson
nasimson
12/30/2014 1:27:11 PM
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Master
Re: impacting so much of urban modernization these days.
@Tim:

> Are there any particular topics that you would like to discuss?

An interesting learning can be around what are different approaches around circuit protection with special reference to LED lights? And whats their efficacy and cost to benefit ratio?

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uchiha
uchiha
12/30/2014 12:34:30 AM
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Artist
Re: capital investment
Yes.. Maybe you are correct.no need to worry about that.

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fasmicro
fasmicro
12/29/2014 5:08:33 PM
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Master
Re: capital investment
>> Interest in LED lighting is at an all-time high as industrial facilities increasingly zero in on energy efficiency, sustainability and cost containment as key metrics for capital investment decisions. 

The fear is that let not the drop in crude oil price depress this interest in sustainability and efficiency. If the prices of gas goes very low, the cost analysis may not necessarily favor extra money for efficiency. Why worry if gas is very low that we can waste it!

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