Signal Dimmers

An early implementation of signal dimming, broadcast a variable analog voltage to control light intensity. This ‘signal’ only allowed for one way communication, from the controller to the lamp driver. Since no signal came back from the driver, there was no data to measure performance, as with digital systems. With 0-10V or 1-10V analog operation, each broadcast lighting group requires its own wiring, making installation and diagnosis difficult in large systems. Although there are many installations still using 0/1-10V control, the trend for new installations is towards digital protocols such as DALI. DALI is a widely accepted industry standard that has significant benefits over analog methods such as 0/1-10V control.

1-10V control is more commonly used for lighting. It uses an analog DC voltage with the driver typically sinking the current. The lighting changes as the voltage is varied. At 1 Volt or less, lights dim to 0% and turn off. At 10 volts, lights are fully on at 100%. This method provides a smooth dimming curve that is especially useful for color changing LEDs.

DDBC, DBC, DMB, DDMC, DMC controllers and DGBM, DMD modules provide 1-10V control and automatically sink or source current depending on the connected driver. The DDBC1200 controller can provide 0-10V or 1-10V dimming in sinking and sourcing mode (loads must not use a mixture of sinking and sourcing drivers).

An analog circuit can typically accommodate around 10 luminaires per controller. The maximum number of drivers allowed on an analog output depends on controller specifications such as, box loading, channel loading and circuit characteristics. Check the controller/module specification sheet for detailed information.

0/1-10V control is polarity-sensitive. Positive and negative outputs from the controller must connect to the corresponding positive and negative inputs on the driver. The circuit will not work if wires are reversed. If the control signal is not connected or a wire is broken, affected drivers automatically go to either full brightness or a preconfigured system failure level to ensure adequate illumination.

DSI (Digital Serial Interface) was an early digital lighting control protocol developed by Tridonic, and was the precursor to DALI. DSI uses a single-byte broadcast messages with no addressing. DSI can dim drivers to 0%, so it does not require mains switching equipment to turn the lighting off, and its low bus voltage allows the use of relatively thin cables. However, the lack of addressing necessitates separate wiring for each lighting group, adding complexity to large installations.

DALI (Digital Addressable Lighting Interface) is a digital protocol and standard jointly developed and specified by several manufacturers to create a common platform for lighting control. Philips Dynalite produces a range of DALI controllers that seamlessly integrate DALI with DyNet and/or Ethernet communication. This enables great flexibility so installations can benefit from the best of both systems.

DALI controllers communicate directly with compatible DALI lighting drivers. DALI drivers are digital devices that offer several advantages over earlier protocols. They can:

DSI and 0/1-10V drivers are not separately addressable, and are controlled based on hardwired physical circuits. DALI provides greater flexibility and functionality with simpler wiring topology and easier installation.

DALI control gear may include LEDs, fluorescent HF drivers, low voltage transformers, emergency fixtures, exit signs, PE cells, sensors, motion detectors, wall switches and gateways to other protocols. Each lamp driver has a unique address with up to 64 DALI addresses on a single DALI bus, called a DALI universe. The DALI protocol does not allow for direct communication between different universes. Sites requiring more than 64 addresses are implemented by having multiple separate DALI universes linked together with controllers or gateways and a data backbone running another protocol, such as DyNet or with three-universe controllers such as the DDBC320-DALI pictured, or the DMD31X and DMD316FR-UL modules.

Developed in Europe, the DALI standard is known as IEC62386. The DALI standard encompasses the communications protocol and electrical interface for lighting control networks. Being digital, DALI can be used to create intelligent lighting management systems that provide increased energy savings, easier installation, maintenance, and control flexibility. Standard DALI control gear has the following specifications:

The DALI transport layer requires only two wires and a DALI power supply and is not polarity-dependent. DALI uses mains-rated, non-polarized cabling with free wiring topology (daisy chain, star, or combined). It is a single pair figure-eight cable or is typically combined with lighting supply cabling, only functionally isolated from mains (no safety isolation!).

The length of the DALI wires is limited to 300 m. To ensure reliable DALI communication, the voltage drop over the wires must be limited to 2 V. Therefore, it is advised to adapt the wire diameter as a function of the length according to the table below:

DALI drivers/transformers consume power to operate even when their fitting is off, approx. 0.5 to 2 watts per driver (up to 2% of operating power per luminaire).

DALI drivers can dim to 0% with mains power still applied. This can simplify mains wiring if there is no requirement to remove mains supply when the lights are turned off. However, the control electronics in each driver continue to draw energy even when the lamps are extinguished.

With some driver brands, this 'off state' power consumption can be high enough to become an energy management and wiring issue, particularly on large projects or sites with strict energy targets. Dynalite DALI controllers have inbuilt switching relays that automatically cut mains power to the drivers when all drivers in a universe are off.

When designing a control solution, take care to ensure that lighting circuit loads do not exceed the rated limits of the controller they are connected to. Each controller’s output capacity is clearly detailed in the published specification sheets.

DALI specifies dimming levels using an 8-bit arc power level message that provides 256 levels of brightness between 0% and 100%. The arc power level message is translated to the driver’s arc power via a logarithmic dimming curve. This curve gives larger increments in brightness at high dim levels and smaller increments at low dim levels.

This is an attempt to have a dimming curve that appears linear to the human eye. Sometimes issues arise when different fixtures are used together, such as DALI fluorescent drivers, DALI ELV (Extra Low Voltage) incandescent transformers and phase control dimmed fixtures. When different fixtures are operated together, it is often apparent to the eye that the dimming curves do not match, especially at lower levels, due to the lower end distribution of the DALI dimming curve. When implemented with DyNet, this can be addressed with custom dimming curves.

A DALI load controller communicates with the control gear (drivers) by means of its DALI interface. It can send messages to the drivers and receive messages from the drivers. The DALI Controller monitors and stores the settings and electrical characteristics of the DALI lighting system. DALI drivers can also be configured with parameters held in the memory of the driver itself.

Bi-directional information flow enables drivers to respond to control messages, configuration messages and status query messages.

DALI addresses are created using an enumeration process, where each driver in a universe is accessed and given a unique address by the controller. Each DALI driver can have three addresses:

The benefit of having an individual address and a group address is that a DALI driver can be controlled individually via its short address or as part of a group using the group address. For example, a room with three drivers can be changed from OFF to ON in the following two ways:

Depending on the controller capabilities, DALI controllers use one or more of the following methods to control the lighting:

All drivers/transformers on the same circuit respond together. No individual control or reporting is possible. Refer to Topic DALI: Broadcast and 1-10 V controllers.

Each independent lighting group requires individual wiring.

All drivers/transformers on the same circuit are individually addressable and allow for reporting. Keypads and sensors are connected to the DyNet network with commands forwarded to the DALI network by the controller. The drivers provide information on request by the controller. Refer to DALI Addressable Controllers.

DALI bus wiring to DALI enumerated drivers. A DALI universe has up to 64 unique addresses.

All drivers/transformers on the same circuit are individually addressable and allow for reporting. The controller can also respond to messages from DALI devices (keypads and sensors) on the DALI bus. DALI devices enable easier installation with less wiring.

DALI bus wiring to DALI enumerated drivers and DALI devices.

The model of controller determines the available control methods.

When implementing DALI, the built-in features of Philips Dynalite equipment provide the following benefits: