With the advent of LED technology, more attention needs to be paid to how the luminaire is controlled. Toggling LEDs is easy, but dimming is a bit complicated. There are different ways of dimming (see below for different dimming types), and the type of LED driver needs to match the control system used. It also requires test drivers and dimmers, which, even though theoretically compatible, are not always the case in practice.
Different dimming types
- Switching power supply (non-dimming)
This is the driver type to choose if you do not need to dim the LED accessory. These drivers will work with traditional on/off light switches or lighting control systems.
- Power Dimming (Leading Edge)
This method of dimming is most commonly used in electronic low voltage transformers typically used for halogen lamps. Rarely used in LED accessories and often associated with LEDs. No control cables are required.
There are two types of built-in dimmers: rotary or push button.
Rotary, you can press the knob dimmer to turn the light on or off, turn the knob to choose the light intensity.
Push-button, works according to the same switching principle. However, to change the light intensity, you have to hold down the button. Some push-button dimmers alternate in operation (brightness increases on the first long press, dimming occurs on the second long press). Others press the dimmer to a specific percentage (brightness increases to a specific intensity when N% is reached, then dims again).
0-10V and 1-10V dimming
0-10V dimming driver sends a low DC voltage signal to a fluorescent ballast or LED driver. Lighting changes as voltage changes.
So at zero volts, the light will dim to 0% and turn off. At 10 volts, the system is running at 100% and the light will be fully on.
1-10V works similarly to 0-10v dimming, but the voltage is “absorbed” by the driver and only drops 10% before needing to physically shut down power to the circuit. This approach provides a very smooth dimming curve, which is especially useful for color-changing LEDs.
0-10V and 1-10V characteristics
a.Analog – Lighting changes in response to controlled changes in voltage.
b.Hardwiring – Each device requires its own wiring, which can make installation very tricky if the lighting control system is large and complex.
c.Unidirectional – Data only goes one way, from the dimming driver to the LED driver or fluorescent ballast. Because there is no signal coming back from the lights, there is no data to measure their performance, as there is with digital systems.
d.one 0-10V system can accommodate about 10 fixtures per controller.
DALI (Digital Addressable Lighting Interface)
DALI ballasts receive voltage over one pair of wires, while the other pair relays a digital signal from a controller device (such as a dimmer) to the light fixture.
In a DALI network, each ballast and relay switch is assigned a unique address to which commands can be sent. This allows the system to be controlled through web-based software installed on a PC.
Numeric — this means the system can dim the lights to a more precise brightness level.
Bi-directional — Bi-directional communication between DALI ballasts and luminaires means the system can diagnose problems and relay feedback and data to the user interface (i.e. PC software)
Open — as it is not proprietary technology, it is available from many different suppliers worldwide and can be used with equipment from other manufacturers.
The DALI protocol is useful if a luminaire needs to respond to multiple input devices such as wall switches and daylight sensors. Like 0-10V dimming, DALI requires a lighting control cable, but the cable can run between many accessories. In fact, a DALI network can accommodate up to 64 DALI ballasts. DALI allows lighting control to operate as a standalone system or be integrated into larger building management systems.
DMX is often used for color programmable accessories. DMX signals are generated by the lighting control system and require a dedicated cable between the controller and the driver. DMX is often used with professionally designed lighting control systems.
Understanding the different dimming types is critical to the success of any lighting project. As part of our lighting design service we can provide matching drivers and dimmers for lighting control systems, please contact us if you have any needs or questions.
For more information, please contact us.