Total Harmonic Distortion in LED Lighting

The switch to LED lighting offers tremendous benefits – energy savings, longer lifespans, and improved light quality. However, there’s one technical aspect to consider: Total Harmonic Distortion (THD).


What is Total Harmonic Distortion?

Imagine a perfect electrical current waveform as a smooth sine wave. Electrical devices often introduce “harmonics,” additional current components at multiples of the main frequency (usually 60 Hz in the US). These harmonics distort the original sine wave, creating total harmonic distortion. Total harmonic distortion is expressed as a percentage. In this post, we’ll explain why lower percentages are beneficial when considering an LED conversion in your facility.

LEDs themselves don’t generate significant THD. However, the power supplies (drivers) that convert AC power to DC power for the LEDs can. Low-quality drivers might introduce higher THD. So, it’s important to understand the LED system in its entirety.


Why THD Matters


Energy Efficiency. Some may think that as long as you’re switching out higher consumption lighting for an LED, you’ll be efficient. Well, distorted current can lead to higher energy consumption and negate some of the energy-saving benefits of LEDs. It’s important to have LED fixtures with lower THD so the electrical current is closer to a pure sinusoidal wave, which improves energy efficiency.   

Heat Generation. Higher harmonic distortion means the system is working harder to produce what it is expected to produce. This increases heat generation in the electrical wiring and components, increasing the risk of overheating and shortening the lifespan of the fixture and other connected devices.

Power Quality. High THD can disrupt power quality for other equipment in the facility. As power quality of the facility decreases, the electrical system will have less stable voltage and current, which affects the overall performance of the electrical system and other devices.

Interference. High THD can cause electromagnetic interference (EMI) and other disruptions in nearby electronic devices. Lower THD reduces the risk of interference and makes the LED fixtures more compatible with other equipment.

Reliability. Lower THD can improve the reliability of the LED fixtures and other devices on the same electrical system. This can reduce maintenance costs and increase the overall lifespan of the equipment.

It’s important to consider THD in your LED upgrade, especially in manufacturing plants where processes can be easily affected by power quality and harmonics. Many manufacturers only advertise the life of their LED chips but do not consider the system as a whole. By understanding THD and making informed choices, you can ensure your LED lighting upgrade delivers optimal benefits without compromising the performance and efficiency of your entire electrical system.