Dimming lamps can be extremely beneficial to a project. In order to comply with the energy code, lights need to have the ability to dim in response to daylight if the fixtures fall within a daylight zone. Occupants can have more controllability, which can make the space more comfortable, flexible and functional.
There are multiple types of dimming including forward phase or TRIAC, reverse phase or electronic low voltage and 0-10V dimming, which are some of the most common types. Phase cut dimming is the most widely installed dimming type in the US.
LEDs are inherently dimmable. LEDs have a nonlinear current-voltage relationship; the output is not directly related to the voltage across it. A small change in voltage can have a large change in current, causing the fixture to not dim as smoothly as you would want.
In order for an LED fixture to dim, it must have a dimming driver. The driver and dimmer must be compatible with each other. In new applications, as long as both are specified to be compatible it should work relatively seamlessly. However, not every driver is created equally so it is important to understand the limitations of your fixture. For example, it may only dim to 10% 20% or it does not dim linearly. The driver determines the dimming performance.
In retrofit applications, this is where some of the biggest dimming issues occur. When upgrading a facility to LEDs it is important to know that a quality fixture is needed if you want to have good results. A lower quality fixture may result in flickering, not dimming at all, audible noise and possibly other issues. The fixture might claim that it is dimmable, but that does not guarantee it will be functional with your existing dimming system. There are no standards to ensure dimmability performance, so that leaves the possibility of a lot of variation of functionality. 0-10V dimming is one of the preferred dimming types with LED. Since it has a separate control wire from the power it tends to have fewer complications.