Article
Luminaires manufactured with LEDs (light emitting diodes) are quickly 
becoming the preferred form of lighting in both commercial and 
industrial lighting. Even residential lighting is moving toward that 
option.<br><br>For example, LED fixtures and bulbs illuminate about 95% of my own home, including outdoor flood lighting.

When Your LED Engine Dies, Fix It

Steve Maurer, IME
Luminaires manufactured with LEDs (light emitting diodes) are quickly becoming the preferred form of lighting in both commercial and industrial lighting. Even residential lighting is moving toward that option.

For example, LED fixtures and bulbs illuminate about 95% of my own home, including outdoor flood lighting.

The U.S. Department of Energy stated in their 2016 Energy Savings Forecast of Solid-State Lighting in General Illumination Applications report, that approximately 36% of existing commercial buildings will use LED lighting by 2020.

I wouldn't doubt it's actually way more than that by now.

So, what's an LED engine?

The engine is comprised of two basic parts: the LED module and the LED driver. In most cases, the luminaire houses these two components.

The driver is the power source for the module and converts higher voltage alternating current into the low-voltage direct current that, well, drives the LED modules. Besides the voltage conversion, the driver also maintains the voltage and current levels in the LED circuit at specific rated levels.
The LED driver may look like a fluorescent ballast, but internally, it's quite a bit different.

Not all drivers are created equal
Additionally, there are two types of drivers—constant current and constant voltage—with each type serving a different purpose. They are not interchangeable; therefore, the replacement driver must match the one being replaced.

Constant current drivers provide a constant current to the LED circuit within a specific voltage range. These drivers, when part of a new fixture, are "tuned" at the manufacturer to provide the proper power and also to adjust the light level of the fixture.

Constant current drivers are used in quite a few applications: outdoor lighting, general indoor lighting, specialty, and architectural lighting.

The label will spec out the output voltage range, such as 2-42VDC, and give the specific output current or current range.

If a constant current driver needs replacing, it must be replaced with a similar driver and tuned properly. This can be done at the end-user's location, following the manufacturer's instructions.
Constant voltage drivers, often used in signage, will provide a specific output voltage. Typically, it will be either 12VDC or 24VDC.

Replacing an LED Driver
Again, remember that a constant current LED driver cannot be replaced by a constant voltage LED driver. So, that's the first consideration when choosing a replacement.

Secondly, determine the type of luminaire being repaired. This may have some effect on the size and physical configuration of the driver.

Next, determine the driver output requirements. Three specifications to look for are:

  • Current (mA) – equivalent to the specified current or up to 10% less than the rating. Lower than that can cause a visually detectable difference in the lighting level when compare to surrounding fixtures.
  • Maximum power (W) – this refers to the available amount of watts, and is not necessarily what is used by the LED modules. It should be equivalent or slightly higher.
  • Output voltage (V) – this refers to the output range of the LED driver and may be listed as a specified voltage or a range.

One other consideration is lighting control requirements. Many drivers are equipped with a 0-10VDC dimming terminals for control. In most cases, this driver can be used with or without a dimming circuit.

Finally, here are some best practices for maintaining the driver's health and longevity. This comes from a paper about LED strategies, written by Universal Lighting Technologies:

  • Make sure the right LED Driver type is selected to support the chosen LED type. Constant Current and Constant Voltage drivers are not interchangeable.
  • Match the LED load to be less than the maximum Output Voltage and Power of the driver.
  • Mount the driver away from heat sources and where it can shed heat. Additionally, make sure not to exceed the ambient temperature range or the maximum case temperature specified for the driver.
  • Use the driver in its specified environment. For example, if it’s not rated for outdoor use or damp spaces, select a different driver.

LED lighting may not last forever, but it's longevity and reduced power consumption make it the favorite type of illumination for many industrial and commercial applications.
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