Light+Building 2012 announced that Zayed University's sophisticated lighting solution in Abu Dhabi City ranked third among the DALI award winners. This cutting-edge project was achieved by Tridonic, a company specializing in innovative lighting concepts and lighting management systems. The DALI system jury was impressed by the optimized natural lighting and occupancy-sensing lighting control, the significant cost savings, and the ease of configuration. Tridonic designed this impressive concept using Beckhoff I/O components.
Abu Dhabi, the capital of the United Arab Emirates (UAE), is renowned as one of the world's most modern cities. The groundbreaking ceremony for Zayed University in Abu Dhabi, a prestigious project, took place in 2009. Construction was particularly tight because Zayed University was expected to open in October 2011. The 80-hectare site comprises 38 buildings, including an administration building, a library, and separate student facilities.
DALI technology for motion control and daylight-sensing lighting control
Tridonic, an international company headquartered in Dornbirn, Austria, was commissioned to implement the lighting system for Zayed University. Planning guidelines mandated the use of daylight and occupancy-sensing lighting control technology in all building areas. Mohammad Al Darwish, Tridonic's Middle East project manager in Dubai, said, "The sensible choice for lighting management on this project was the DALI protocol, which allows for precise location of each light through a central monitoring system, even in very large systems."
Approximately 42,000 DALI addresses need to be set.
Tridonic's winDM@net lighting management software is a perfect match for the Beckhoff technology platform. At Zayed University, approximately 150 BC9xx0 Ethernet bus terminal block controllers and 1,040 KL6811 DALI bus terminal blocks, along with a large number of digital and analog bus terminal blocks, are installed. The KL6811 is a DALI master terminal block module capable of connecting up to 64 DALI slaves. In addition, Tridonic provides approximately 4,700 DALI sensors for motion detection and approximately 2,450 DALI controller groups for automatic and manual dimming control. The lighting control system comprises a total of approximately 42,000 DALI addresses.
The lighting management software simplifies configuration and allows both normal and emergency lighting DALI loops to connect directly to an Ethernet TCP/IP network via the BX9xx0. This eliminates the need for additional loops, and the entire lighting system for 38 buildings can be easily monitored and controlled from a single PC. Each bus terminal module controller acts as a central modular gateway for communication between DALI and TCP/IP protocols. DALI sensors connect to the central PC control unit of the lighting management system via the KL6811 bus terminal module.
From a system topology perspective, Tridonic runs on a central PC; this central PC connects to the bus terminal module controllers via Ethernet TCP/IP and Modbus protocols. The protocols ensure that the bus terminal modules write DALI signals into Beckhoff's K-bus communication standard, and the data is then processed via Modbus for use by the central PC. The PC calculates the necessary control instructions based on the transmitted data. The Beckhoff bus terminal module controllers are adapted for Tridonic; for example, they operate using specific PLCs based on TwinCAT software. Data exchange within the central PC occurs via Beckhoff's TwinCAT ADS interface. The signal acquisition system implemented at Zayed University requires no special cables, as Mohammad Darwish reported: "This system has significantly reduced our material costs and installation time, making the Tridonic solution very cost-effective."
Improved energy efficiency and enhanced comfort
Constant light control allows artificial room lighting to interact with natural ambient light. To do this, an ambient light sensor measures the luminous intensity in the room, compares the measured intensity to a set brightness value, and adjusts the dimming until the intensity matches the set value. If multiple DALI sensors are used in the same lighting group, dimming continues until each sensor reaches its set brightness value. Dimming (Bright-Out/Bright-In) is based on the ambient light level: if the time it takes for the measured luminous intensity to exceed a defined threshold is longer than a specified delay, the DALI sensor turns off the lighting group. This also applies when no movement is detected in the room. If the measured luminous intensity is lower than the set brightness value, the lighting group is turned back on. DALI sensors can be used not only to determine the presence of people in an area but also to determine the size of moving objects. This avoids erroneous measurements caused by moving objects. The "constant light control" function ensures that the luminous intensity in the space remains constant, and variations (resulting from ambient light entering the space) are compensated for. The results include improved comfort, consistently high room illuminance, and, most importantly, energy savings.
