In this article, we will delve into the requirements established by the D4i standard for both drivers and control devices, as well as how it synergizes with the ZHAGA standard and how this is influencing optimization and design trends for the most modern street lighting luminaires.
LED DRIVERS
All D4i LED drivers must implement a DALI bus power supply, allowing sensors and/or control devices to be powered directly from the intra-luminaire DALI bus. The characteristics of this DALI bus power supply are defined in the DALI Part 250 specification (IEC 62386-250), which primarily includes the following requirements:
- Guaranteed DALI current: 50mA (minimum)
- The DALI bus source must be switchable (it must be able to be turned on/off), allowing its use in systems with multiple DALI bus sources. By default, it must be turned on.
- The terminals must be marked indicating their corresponding polarity (DA+/DA-)
On the other hand, D4i LED drivers can optionally a 24VDC auxiliary power supply (AUX) to power higher-consumption loads, such as a presence sensor or communication node, if the power supplied by the DALI bus source is insufficient. The characteristics of this auxiliary power supply (AUX) are defined in DALI Part 150 (IEC 62386-150), which mainly includes the following requirements:
- Rated power: 3W
- Peak power: 6W (2.2mS)
- Nominal output voltage: 24V (+/-10%)
- Maximum open circuit output voltage: 30V
- Maximum initialization time: 600ms (90% Vout)
As previously mentioned, the implementation of this DALI component is optional, so LED drivers can obtain D4i certification without needing to integrate a 24V auxiliary (AUX) power supply. On the other hand, we are certain that any D4i LED driver will always integrate a DALI bus power supply compliant with the requirements of DALI Part 250 (IEC 62386-250).
CONTROL DEVICES
The mandatory part that applies to control devices to obtain D4i certification is DALI Part 351, which classifies these devices into two different categories based on their power supply type:
- Bus-powered: Devices that are powered directly from the DALI bus itself.
- Externally powered: Devices that are powered via the AUX 24Vcc auxiliary power supply.
DALI part 351 also defines four classes of control devices (A, B, C and D) based on the type of integrated Application Controller (they can be Multi-Master or Single Master) and, as we can see in Figure 1, includes requirements on the maximum power/current consumption for each of these four classes.
Figure 1. D4i control device classes. Power supply types and maximum consumption requirements.
ZHAGA BOOK 18.
The Zhaga Consortium is a global organization comprised of manufacturers of luminaires, electronic components, and lighting technologies. Its main objective is to develop standardized technical specifications (known as Books) that ensure mechanical and electrical interoperability between the various components of an LED luminaire, such as modules, drivers, sensors, and communication nodes. This aims to facilitate component interchangeability, reduce integration costs, and enable more flexible, sustainable, and scalable designs.
One of these specifications developed by the Zhaga Consortium is Zhaga Book 18, which defines a standardized mechanical and electrical interface for integrating sensors and communication nodes into outdoor LED luminaires. It is based on the use of a 4-pin connector and its corresponding socket, typically mounted on the exterior of the luminaire, which allows for easy attachment and interchange of these devices.
Figure 2. Standardized mechanical and electrical interface in Zhaga Book 18
The combination of both standards (Zhaga Book 18 + D4i) results in a standard and interoperable solution for smart luminaires, increasingly adopted in public lighting and smart cities. EVOLUTION AND TRENDS After analyzing the power requirements of D4i drivers and control devices, a clear trend in modern smart luminaire design becomes apparent: the use of control nodes and sensors powered directly from the DALI bus, eliminating the need for auxiliary power supplies and significantly reducing the number of internal components. This evolution allows for cleaner and more efficient architectures, reducing space requirements, manufacturing costs, and energy consumption. In this context, solutions such as the CAS-ZHAGA-40-DA-LX control and communications node , designed and manufactured by Electrónica Olfer, for mounting on a Zhaga Book 18 socket and powered directly from the DALI bus, represent an ideal option for providing luminaires with wireless control and connectivity. The CAS-ZHAGA-40-DA-LX is a Casambi wireless communication node and a DALI master controller ( DALI-2 and D4i certified ). Its compact size helps maintain the original aesthetic of the luminaire design. Complementing this, the MRA-734SZ DALI-2 presence and light sensor , also powered directly from the DALI bus and compatible with the Zhaga Book 18 connector, offers great flexibility through its interchangeable lenses in a very compact format.
Figure 3. CAS-ZHAGA-40-DA-LX control node (left) and MRA-734SZ presence and light sensor (right).
Both devices can be used together in a dual-node architecture, installed in the same luminaire and powered by the integrated D4i driver. Furthermore, Olfer Electronics' communication nodes perform an automatic initial configuration of the DALI-2 sensors connected to the DALI bus, ensuring that communication between them (instance reporting) is successful and transparent to the user.
As we have detailed throughout this article, the combination of D4i devices and the Zhaga Book 18 interface has marked a turning point in the development of connected luminaires. This convergence enables more compact and efficient solutions, eliminating unnecessary components and facilitating the integration of sensors and communication nodes. By leveraging the direct power supply from the DALI bus provided by the D4i LED drivers, the costs and dimensions of the luminaires are optimized, paving the way for more streamlined and sustainable designs.
This synergy not only reduces costs and simplifies installation and maintenance, but also lays the foundation for an ecosystem prepared for the challenges of smart lighting in the urban and interurban environments of tomorrow.
