Lynn D. Churchill, Ph.D.

An extensive review of the literature regarding causes for the failure of CFL and LED lighting has disclosed that the primary causes for failure are heat and electrical overstress (EOS). EOS is a term used to describe an event whereby an electronic component is operated above its absolute maximum electrical rated value. A simple related example of that is the common electrical fuse that may be rated for 5 Amps but if there is a short and a surge of more than 5 Amps occurs, the fuse will sacrifice its life to protect the electrical components being fed by that circuit. The fuse was rated for a maximum of 5 Amps and when that was exceeded, the fuse material literally melts as it has exceeded its rated capacity.

Electronic ballasts for CFL lighting contain a small circuit board with a bridge rectifier, a filter capacitor and usually two switching transistors. The incoming AC current is first rectified (converted) to DC, then converted to high frequency AC by the transistors, connected as a DC to AC inverter. The resulting high frequency is applied to the lamp tube. The image to the right is a common integrated CFL ballast.

LED drivers (also known as LED power supplies) are similar to ballasts for fluorescent lamps or transformers for low-voltage bulbs: they provide LEDs with the electricity they require to function and perform at their best. An LED driver is illustrated on the left.

LEDs require drivers for two purposes:

1. LEDs are designed to run on low voltage (12-24V), direct current electricity. An LED driver rectifies higher voltage alternating current to low voltage direct current through a switching power supply.
2. LED drivers also protect LEDs from voltage or current fluctuations. A change in voltage could cause a change in the current being supplied to the LEDs. LED light output is proportional to its current supply, and LEDs are rated to operate within a certain current range (measured in amps).

In summary, LED drivers convert higher voltage alternating current to low voltage direct current. They also keep the voltage and current flowing through an LED circuit at its rated level.

There is a common saying “that you get what you pay for.” It should come as no surprise that both ballasts and drivers are only as good as the quality of the design and components that go into them. Cheaper products have fewer and cheaper components to keep costs down. Typically that usually means that there may be more error in their actual rated ability and performance. A $10 LED will outperform a $2 LED almost every time and last longer because its components will keep things within operating specifications and produce less heat. But there is more to the story both from an internal and external perspective.

From an internal perspective, both CFL ballasts and LED drivers use input rectifiers to convert AC to DC which is in essence what we commonly call a switching power supply. Depending on the quality of the rectifier and the presence of filters, this will usually introduce harmonics into the system. These harmonics result in power that can’t be used and must be shrugged off as heat. Usually higher end ballasts and drivers are designed with considerable attention to filtering the resultant waveform to reduce harmonics. Cheaper products do not pay as much attention to filtering and produce considerable electromagnetic interference (EMI) into the electrical system. This produces heat and reduces the potential lifetime of the ballasts or drivers.

Since both CFL and LED lamps use input rectifiers that create harmonic transients, this frequently results in lower power factors (a ratio representing usable real power to unusable reactive power). Unfortunately low power factors can result in surcharges for commercial energy users. Low power factors can also result in less efficiency and increased temperatures reducing the longevity of both CFL ballasts and LED drivers.

When CFL and LED lights are turned on they put an increased demand on the electrical system known as inrush. Inrush frequently results in overamperage beyond the operating parameters and specifications of most ballasts and drivers. Operating above those parameters again creates heat as a way to shrug the excess current and will potentially damage the ballast or driver over time. The utility company also charges for inrush as a demand charge.

The internal ability of ballasts and drivers to keep things within operating parameters is also dependent on the electricity coming into them. In particular, CFL ballasts and LED drivers are susceptible to three threats:

• Overvoltage or surges
• Overamperage such as inrush
• Harmonic transients and harmonics

Depending on the quality of the design and components, a ballast or driver will have some level of internal protection to prevent operating outside the parameters of the circuit board and damaging either components or connections between components. Consistent tripping of these components to moderate overages will eventually wear them out and put the circuit board at risk.

The existence of harmonics and transients in the electrical supply is also a common problem as those harmonics and transients are not real power and can only be shrugged as heat if not filtered out. In fact, the most common EOS event for LED and CFL lighting is the presence of transient spikes or harmonics resulting in inefficient power that results in heat internally. A solution is the Satic Power Perfect Box (PPB), a UL listed energy management system (not a capacitor bank), that is quickly and easily installed at the distribution panel. Some of its primary attributes include:

• Harmonics Filtration – Harmonics can be introduced into the electrical system in many ways including from the grid, from CFL or LED lighting, electrical motors and switching power supplies on the premise. Removing these harmonics makes the entire electrical system cleaner and more efficient. Ballast and driver failure has been shown to be directly related to exposure to harmonics and transients. Filtering harmonics and transients will increase longevity of ballasts and drivers.
• Phase Correction – Providing phase correction will increase the percentage of power that actually accomplishes real work and produce less heat in motors and devices since there is less reactive power that can be turned into heat. This is true for not only the appliances and devices on premise but also for ballasts and drivers. Less heat also means less potential thermal stress on the CFL and LED circuit boards and lower power demand.
• Voltage Regulation – Ensuring consistent and level voltage and current is desirable for any electrical system. This includes protecting from surges (even microsurges) that can quickly damage electronics to leveling demand caused by inrush. The PPB can provide this protection to not only the ballast or driver but also the entire electrical system reducing stress on the system and potential damage to lighting.
• Electromagnetic Field (EMF) Reduction – Modern electronics, CFLs and LEDs introduce harmonics into electrical systems that result in EMF. There is increasing evidence that exposure to EMF radiation may have serious health effects. Less EMF equates to a healthier environment whether it be a home or business. Third party testing has shown that the PPB reduces Total Harmonic Distortion (THD) and the related EMF radiation.
• Lower Power Consumption – It only makes sense that if the power supplied is cleaner that it will also be more efficient. That means less power is turned into heat resulting in cooler running and more efficient electrical appliances. This means a longer life for electronics, electrical appliances, motors and lighting.

In summary, providing cleaner conditioned power to CFL or LED lighting systems will extend their lifetime. It seems prudent to include a Satic Power Perfect Box with any CFL or LED lighting system to reduce replacement or repair and maintenance costs as well as to provide a healthier more efficient electrical system. 

References:

“Understanding Electrical Overstress – EOS” Industry Council on ESD Target Levels, August 2016, https://www.esda.org/assets/Uploads/documents/White-Paper-4- Understanding-Electrical-Overstress.pdf

"The Basic Principles of Electrical Overstress (EOS)” OSRAM Semi Conductor, July 2013, http://www.osramos.com/Graphics/XPic0/00091442_0.pdf/The%20Basic%20Principles%20of %20Electrical%20Overstress%20(EOS).pdf

“Compact Fluorescent Plug-In Ballast-in-a-Socket” GE Research and Development Center, January 2002, https://digital.library.unt.edu/ark:/67531/metadc881001/

“Understanding LED Drivers” 1000Bulbs.com, May 2014, https://www.1000bulbs.com/pdf/understanding-led-drivers.pdf

“Are your LEDs electrically overstressed? Part I” Yankun Fu, April 2014, http://www.edn.com/design/led/4430043/Are-your-LEDs-electricallyoverstressed--Part-I

“Are your LEDs electrically overstressed? Part III” Yankun Fu, May 2014, http://www.edn.com/design/led/4430347/Are-your-LEDs-electricallyoverstressed--Part-III

“Bioinitiative 2012: A Rationale for Biologically-based Public Exposure Standards for Electromagnetic Fields” Bioinitiative.org, December 2012, http://www.bioinitiative.org/

“The Harmful Effects of EMF” SolarGreen Blog, June 2013, http://www.solargreen.net.au/blog/the-harmfull-effects-of-emf