For more information please read the article "What is Dali?" Many manufacturers supply LED drivers that will accept a DALI input. A DALI signal is delivered to the LED driver(s) via two wires that are in addition to the wires delivering the mains supply. DALI is the most widespread communications protocol for commercial lighting control in use today. The most common methods of controlling a driver are as follows:ĭALI (Digital Addressable Lighting Interface). In each case the driver will require a continuous supply of mains power plus a control signal to tell it what to do. There are several ways to control a driver, or instruct it what to do. The more important question for the specifier and installer is how the driver is to be instructed to make the LEDs brighter or dimmer. They are internal to the driver and have little or no effect on the end user and the quality of the dimmed light they will see. However, if a driver uses PWM or AM is generally of little interest to an installer or specifier. There are two mains ways that a driver does this - pulse width modulation (PWM) or amplitude modulation (AM) - and these are discussed below. LEDs work at low voltages on direct current.Īs a dimmer it raises and lowers the amount of electrical energy flowing out to the LEDs. This is necessary because LEDs don’t operate on mains. If desired, the driver can be the dimming type, performing the twin functions of a driver (transforming the incoming power from 230V AC to 12-24V DC) and a dimmer.Ī dimming driver performs two functions: it is both a driver and a dimmer.Īs a driver it converts the mains AC supply (typically 230V, 50Hz) to 12-24V DC. The LED driver – seen here to the left of the picture – is a separate item and is accessible to the installer. Installing a common design of commercial light fitting. This is how most dimming is achieved in commercial and industrial installations. If the driver is separate from the lighting fixture, or is accessible within it, then the best way to dim the LEDs will be by using a dimming driver. DIMMING LEDS WHICH HAVE A SEPARATE DRIVER So, to answer the very general question “Can LEDs be dimmed, and how do you do that?” one first has to determine if the driver is separate and accessible or if it is integrated with the LEDs. The driver is in the lamp base and the unit is sealed, so there is no possibility of connecting any dimming control wires. The LEDs and driver come as a single sealed item.Īn LED lamp. In LED lamps the driver is built-in and cannot be accessed. The driver is separate from the panel, so it is accessible for the connection of dimming control wires if required. This means that the driver is accessible to the installer so that, if the driver is the appropriate type, dimming control wires, in addition to the mains supply wires, can be connected to it.Īn LED panel with its driver. In commercial lighting fixtures, such as LED panels, downlights and spotlights, the driver is usually separate from the fixture. LEDs work at low voltages on direct current. Its main function is to run the LEDs at the correct voltage and current, converting the mains AC supply (typically 230V, 50Hz) to, usually 12 or 24V DC. So, to answer the question “Can these specific LEDs be dimmed?” it is necessary first to understand a little about LEDs and drivers.Īll LEDs need a driver, which is a piece of electronics. If it is practical or not to dim a particular LED lamp or lighting fixture will depend on the driver that is being used to control it. Yes, all LEDs can be dimmed, but it is not always simple. As a lamp or fixture is dimmed its lumen output decreases. The output of a lamp or lighting fixture is measured in lumens (lm) and is sometimes known as its “luminous flux”. What is Dimming? AN INTRODUCTION TO DIMMING LEDs / HOW TO DIM LEDS / LED DIMMINGĭimming means reducing the output of a lamp or lighting fixture.
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