Compatibility Part 4: Economic benefits of compatibility testing of LED lighting devices and systems

March 17, 2011
Most lighting manufacturers fail to realize that making an upfront investment in avoiding product failures always proves to be more economical than trying to figure out how to fix it later, explains PHILIP KEEBLER in the latest article in his series on compatibility.


This article is the Fourth part of an ongoing series on the compatibility of LED lighting products – see Related Stories.


Manufacturers simply cannot afford to use their first customer sites as test beds. Product demonstrations at customer sites are intended to demonstrate the expected performance, functions, and benefits of a new product – not determine whether or nor the product will fail in its own electrical environment. This is especially true for electronic lighting products.

Customers have grown to think of lighting products as rather simple devices – one installs a new product, flips a switch, and the lights come on. Customers realize that lighting products are becoming electronic, more modernized and sophisticated, and should provide more functions and benefits, especially in our energy-conscious times. However, customers don’t want to be bothered with having to determine why a product failed early. Product failures are meant for the development and testing laboratories. EPRI frequently tells the manufacturers it works with that “Failures should occur in the lab, not on the customer floor.”

Sending messages to new users of LED lighting

If a manufacturer of an LED lighting product does not fully address compatibility and reliability in efforts to avoid product failures, then the occurrence of a product failure at a customer site sends a number of unintended messages to the customer. These messages are:

  • Something was overlooked in the design: The customer might be thinking that the product “works” (lights up) but that the design is not complete. Customers expect designers to take care of all the details of design including avoidance of failure.
  • The product is defective: The word “defective” is frequently used when products experience early failure. The customer might suspect that the product is defective.
  • The product was not manufactured correctly: Customers realize that electronic products must be assembled; but, how are they assembled – by machine or by hand? The customer might be thinking that there is a missing part or that a part was put in backwards, or that something was not soldered or wired correctly.
  • I have purchased a product that has placed me in a high risk position: Sometimes customers really take early product failure very seriously – and they should. The first impression says a lot. After that first early failure, the customer will always be thinking: “Is this going to happen again?” Manufacturers should do every reasonable thing they can do to prevent early failures from occurring.
  • Can I really count on LED lighting to be reliable? Customers don’t have a lot of experience with LED lighting – it’s the new kid on the block. In fact, some customers don’t even have first-hand experience with compact fluorescent lamps (CFLs). If a customer has had a bad experience with early CFL failures, then they will immediately think of those experiences when early LED product failure occurs. Not knowing much about LED lighting already places customers in an uneasy position. Then, when an early failure occurs, they immediately start to have reservations about the reliability of LED lighting products. So, the lighting industry should avoid allowing customers to experience early LED product failures. Manufacturers should also learn from CFL failures and recall the damage caused by CFL failures.
  • Was the product ever tested? Most customers realize that products are supposed to be thoroughly tested before they enter the marketplace. The majority of customers have experienced a product recall. When an LED product failure occurs, the customer wonders if that product was ever tested and if it was tested thoroughly. If the product was tested, then why is an early failure occurring? Was something overlooked during test planning? Did failures occur during testing that were not properly addressed?
  • How am I going to be sure that this problem doesn’t happen next time? That first impression is extremely important. No customer wants to wonder about having early product failures every time a new LED product is installed. If a customer experiences an early LED product failure, then that customer will be more inclined to purchase an LED product manufactured by another company. Customers want to be sure that they don’t have a negative experience the next time.
  • Word of mouth: One of the best forms of communication is “word of mouth.” If a customer experiences an early product failure, then one can rest assured that some of their friends are going to hear about it. Imagine how far a story about tens or even hundreds of early LED product failures will travel? When “word of mouth” occurs, LED product manufacturers want it to be a positive word about the good experiences that occurred in a customer’s environment – not about failures.
Make a small investment upfront, or pay later

When LED product failures occur, one can rest assured that the manufacturer will hear about them. The economics of having to go back and fix a product problem after production are not deemed favorable by anyone’s upper management. Imagine having to open up a sealed box containing an electronic product to change one resistor, running the factory tests again, and then sealing the box back up for shipment. This is an expensive and burdensome process! In most cases, the same holes on a circuit board could be used. However, the cost of enduring such a change is astronomical.

Now, imagine having to recall 10,000 LED products because of an unexpected failure that occurred on the power line that damaged the LED driver. Regardless of the type of failure, something will have to be changed for the upcoming production runs. In many cases, that change will require a tool change which adds thousands of dollars to the design.

The manufacturer that experienced this large number of failures might say, “Much of the focus during product development was placed on making sure all of the components of the product could be fitted together during the manufacturing process. Much time was also spent on selecting the proper LED array and checking to make sure that there were no thermal issues. The LED driver was recommended through another engineer at another LED lighting company. We didn’t give too much thought to what might happen to the driver if an electrical disturbance occurred. I was told that it had been tested for safety and that it had LM-79 and LM-80 certification when used in another product.”

What most manufacturers fail to realize is that making an upfront investment in avoiding product failures always proves to be more economical than trying to figure out how to fix it later. Any experienced product engineer should already know this. However, many product engineers for LED products might not know enough about compatibility and reliability (and power quality) and how to use well-defined tests to measure how compatible and reliable their products are before they sign off for final production.

Knowing how an LED product will perform in just a few critical areas is simply not enough. An LED product engineer must know about performance related to illumination of the LEDs, thermal management of the array and driver, and most importantly, what can occur outside of the LED product that will influence its behavior and ability to operate in the electrical environment where it must live.

Product engineers have hindsight 20/20 vision when product failures occur. They frequently go back and think about the issues they are comfortable with, such as component temperatures, trace spacings on circuit boards, and circuit performance issues associated with power supplies, control, and signal management. An engineer might not think too much about what can happen on the power line and how this might influence the circuitry on the front end of the driver. After all, the driver is simply a special power supply that converts AC to DC in the form of regulated DC on the output that is suitable for driving LEDs.

An engineer might ask the questions: What if I knew more about the problems that can occur on the power line? What can happen to the line voltage that might cause an early failure to occur? What are the types of disturbances that can occur on the line voltage? How would one rank their severity? Are those disturbances all destructive in nature or are some non-destructive and only present upsets and malfunctions for LED products?

The electrical environment where an LED product must live includes the customer facility. However, the customer facility must endure not only what comes from the utility but also what disturbances might be generated by the company next door. Regardless of the origin of potentially harmful disturbances, they will make it to the input of an LED product. An investment in testing LED products will allow product engineers to determine what is needed in product designs to minimize the influence that these disturbances can have on LED products. Without this knowledge, product development budgets should include hundreds of thousands of dollars in engineering development and design and product replacement costs, not to mention the cost of failure analysis and testing after-the-fact, to deal with early product failures.

Product warranties for any electronic product should be written very carefully in today’s electrical environment. Manufacturers of electronic fluorescent lighting products wrote their first warranties with knowledge gained from providing magnetic products for so many years. These manufacturers had no knowledge of what to expect when their customers bought their electronic products and connected them to building power systems. Thousands and thousands of ballast failures occurred. Manufacturers didn’t know where to turn, not only to identify the cause of the failures but also to determine how to stop them.

Utilities who offered rebates and incentives for using the new high-efficiency fluorescent products turned to EPRI to help them answer the questions. EPRI’s knowledge of the interactions between the power system and electronic products was invaluable in determining the cause of failure and how to revise ballast designs to significantly reduce failures. Utilities wanted to be sure that ballast manufacturers received this knowledge first hand so they could revise their ballast designs, enabling them to produce products with improved performance that would not experience early failure in their intended electrical environments.

Manufacturers soon learned the value of investing in compatibility and reliability testing for electronic fluorescent products. Instead of spending millions of dollars honoring product warranties, product replacement costs, re-engineering time, and changes to manufacturing, manufacturers realized they should be investing only thousands of dollars in compatibility and reliability testing. To most manufacturers, this math was a no-brainer.