Lights that flicker experience what is known as power fluctuations. It causes a flicker effect that is barely noticeable or strobe-like. When a person is exposed to flickering lights for an extended period of time, it can have a significant impact on their health, and concentration levels and reduce their recovery times. However, flickering lights can also affect the lighting system’s performance.
As such, it’s imperative to know what steps to take to ensure the LED lighting in your home or business is free of flickers.
What Causes Lights to Flicker?
When there is a fluctuation in a light source’s output, the light will flicker. The flickering results from the light switching turning off and on because of the changes in the power voltage magnitude (alternate current). The Hertz (Hz) measurement provides an idea of how noticeable the flickering will be. The majority of people can see flickering below 50 to 70Hz, but studies show some individuals are especially sensitive to flickering and can see frequencies of more than 100Hz.
And, for some individuals, it is their subconscious that picks up the higher frequencies.
Flickering can happen to every lighting type – fluorescent, halogen, incandescent, and LED. Seeing this flickering isn’t as easy in less energy-efficient lights. That’s because the filament keeps its heat (thermal persistence) and will continue to work even when it is experiencing fluctuations.
Thermal persistence does not occur with LED lights, meaning the light stops working immediately when the power supply is turned off. So, should an LED be connected to a 50Hz AC supply, it will shut off 50 times a second, which the human eye can detect.
Fixing the issue is as easy as installing a fully-capable control system or LED driver to regulate the main power supply’s frequency. The key is finding the equipment necessary to handle the requirements of the system’s environment and main power requirements. By doing so, you can pretty much eliminate the flickering altogether.
What Kind of Effects Can Flickering Cause?
A light flicker can have little to no effect on some people, while others can have a tremendous impact on their health. For those with increased sensitivity, it can lead to the following problems:
- Eye strain
- Inability to concentrate
- Lethargy
Many people are susceptible to light frequency changes, which can lead to headaches and migraines. People with epilepsy may even suffer seizures from the constant flickering.
It’s not uncommon for light flickering to produce a stroboscopic effect. This effect means moving objects look as if they are slowing down. This effect is acceptable at a nightclub but can have devastating consequences in a work environment, especially industrial environments with moving parts.
The lighting industry has ensured that LED lighting is the industry’s standard for energy efficiency. Still, many designers have failed to understand the impacts flickering can have in places like factories, offices, or retail.
According to research, an increase in a flicker’s kilohertz range means people are less likely to see it. Therefore, it’s imperative to attain a frequency level best for the lighting system you have installed.
How Flickering Can Affect LED Lights
There is no persistence with LEDs, so the light output frequency is time to the power source’s output waveform. A run-of-the-mill LED driver has an output frequency that’s boosted two times more than input frequency (50Hz input voltage equates to 100Hz output frequency). While most people will be unable to see the flickering, they will still experience the side effects of prolonged exposure – headaches, eye strains, and lethargy.
Flickering can happen when there is a pulse with modulation, which is a common method of dimming. Pulse with modulation can regulate the LED’s power input, making the flickering noticeable unless there is some regulation of the PWM frequency.
A well-designed LED driver can potentially boost the output to thousands of hertz, making it impossible for the human eye to see. To ensure this, the LED driver must be installed near the LED light, which isn’t always possible in a typical lighting system. However, it’s often delegated to professional situations like television and film shoots.
LED Driver and Control System Designs
If you want an LED light free of flickering, a capacitor should be installed to the driver output to offset the ripple. The drawback is that it can decrease the system’s reliability and lifespan. (Low-quality capacitors are notoriously known to affect systems.)
It’s also essential to use drivers that have two-stage power factor correction that can regulate three things – noise, ripple, and output frequency.
No matter what method is chosen, it’s important to find and install a high-quality LED driver that reduces the output ripple current fluctuations. It’s why lighting designers need to work closely with LED driver manufacturers and suppliers to come up with a solution that will work in the setting the design will be installed.
How to Ensure You Get Flicker-Free Products
There are several things that lighting professionals can do that will help decrease the possibility of flickering in their products. For example, steer clear of AC-LED-advertised products. The low price, coupled with no driver and a simple circuit design, can generate a 40% flicker rate with full output. Dimmer levels can cause an even higher flicker percentage.
You want to make sure the supplier understands flickering and how the driver can affect it.
There are two things to be mindful of to ensure the best possible outcome:
- Strike a balance between performance and price
- Light quality should be ideal regardless of where it’s being installed
