Light-emitting diodes (LEDs) have become so prominent in so short a time that new standards and specifications are emerging faster than most engineers can gain familiarity with them. Prime among those are standards involving overcurrent and overvoltage protection from such organizations as the International Electrotechnical Commission (IEC), the Institute of Electrical and Electronics Engineers (IEEE), Underwriters Laboratories (UL), and the US Department of Energy's Municipal Solid State Street Lighting Consortium (MSSSLC), among others.
Experts say that most designers have a rudimentary understanding of the technical protection requirements for LED-based systems, but often need to be schooled on the details.
"Engineers know surge immunity," Usha Patel, director of the Latin American sales and segment marketing for Littelfuse Inc., told Design News. "They know they have to protect against lightning. They know they have to protect against inductive spikes. But there are areas where they still need to be educated."
The need to know involves many factors. Without protection, overvoltages and inductive spikes can damage sensitive electronics. And lack of understanding can cost money up front.
Patel, who has been involved with a DOE task force and other organizations on the creation of the specifications, suggests engineers familiarize themselves with the following standards:
Overcurrent protection for LED bulbs.UL 8750 addresses protection against the risk of shock and fire.
Overcurrent protection for LED luminaires. Key standards addressing the issue of overcurrent at the luminaire include UL 1598 and UL 1993, as well as UL 1310 and UL 8750.
Overvoltage protection for LED bulbs. Energy Star standards based on IEEE C62.41.2-2002 deal directly with surge suppression at LED bulbs. Outside the US, IEC61000-4-5 is the surge immunity specification for LED lighting.
Overvoltage protection for LED luminaires. DOE standards based on IEEE C62.41.2-2002 deal with surge immunity requirements for outdoor LED lighting.
There are other certification companies out there, cheaper ones. So, for those who could care less about UL standards, how do their LED regulations fair? For those people/companies, LEDs are a non-regulated business. I worked for a company making a LED system for a hybrid car. I worked on the signaling system. Based on the job's requirements and client requests, the power system would get extremely hot. I didn't like it, they didn't care, no regulations guided anyone. There needs to be a free and open regulation for such products.
Once a non-profit testing company becomes a required standard, it's a racket.
I agree that UL may not be what we believe it to be or perhaps expect it to be. We want to believe it protects us the consumer. But I also wonder how effective they are able to do that with technology growing as fast as it does.
Yet it remains a standard that many companies require - which we see all the time. I think you are right on target with your post, Cabe. We should never become complacent and trust something just because its been around a long time. If enough folks "paused," maybe they would step up and meet the rigor they were known for in the past as a testing benchmark for consumer safety...
TomBee, I agree with you and have had similar experiences with UL over the years. I think competition from the other testing labs has contributed to their improved responsiveness. However, you are right, they are not afraid to charge their standard fees if they have the opportunity.
I have had dealings with UL going back to the mid 80's. At that time they were the only game in town for most standards. Customer service was poor and costs very high. The worst was receiving a report that a device under test had failed. Getting to the bottom of the problem identified a junior engineer un-trained in the require testing methodology and under-supervised by experienced mentors.
UL has made significant strides since those days. They are more response in some ways and more cost competitive in other areas. However, they continue to find subtle ways to overcharge in unnecessary services. Case in point is frequent plant inspections when there is no production and changes to the UL file for minor or trivial modifications which then cost far beyond the effort and time expended. I suggest you always get at least two additional test labs to quote on your requirements and then carefully evaluate the 'hidden cost' components before you sign any contracts. It is the total and ongoing maintenance cost which you need to evaluate - not just the initial test program.
What would be the life of an LED Lamp? Eventhough it have a long life, the associated circuit for voltage/current regulation is important. The age/durability of the light depends up on the capability of these associated circuits.
Now a day's LED lighting solutions are so common in residence / business/office. But the major problems are associated with attaching electronic regulator circuits, which can cause damage to the LED. Due to this poor regulator circuits, LED lights may get faded over months and finally totally dimmed with no output.
Some humanoid walking robots are also good at running, balancing, and coordinated movements in group settings. Several of our sports robots have won regional or worldwide acclaim in the RoboCup soccer World Cup, or FIRST Robotics competitions. Others include the world's first hockey-playing robot and a trash-talking Scrabble player.
A recent example of a major CAE revamp is MSC Apex, released last month by MSC Software Corp. In a discussion with Design News, MSC executives noted that its next-generation platform is designed to substantially reduce CAE modeling and process time, “in some cases from weeks down to hours.”
The Thames Deckway would run for eight miles close to the river’s edge, rising and falling slightly with the tidal cycle. It will generate its own energy from a series of devices that will line the pathway and use a combination of sources to make the path self-sustaining.
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