A NOTE ABOUT NODES Globally, there are two main types of standardised electro-mechanical interfaces to combine nodes with a luminaire: ANSI C136.41 (so called NEMA) and Zhaga book 18 (so called Zhaga-D4i). In both cases, a node can be plugged onto the corresponding receptacle of the luminaire during installation of the luminaire, or retrofitted at a later stage. Schréder luminaires can accommodate either or both. Both NEMA and Zhaga are open and futureproof and while we believe that Schréder EXEDRA is the most functionally and scalable complete CMS on the market, we also believe that customers can choose the solutions that best suit their city. The best way to choose between NEMA and Zhaga is to assess the specifications of the lighting infrastructure, what the objectives are and how the lighting infrastructure will be used. Both options bring potential shortcomings and benefits for future smart lighting control, and each ecosystem is open to provide flexibility and modularity to meet the different use cases of tomorrow’s cities. This is why Schréder supports and delivers compatibility with both the Zhaga-D4i and NEMA options.
NEMA
ZHAGA
NEMA stands for the National Electrical Manufacturers Association, an association created in the USA in 1926 which writes standards for electronic products. Any object can become connected to a system through a NEMA receptacle, including geolocalisation technology. Proper handling of the luminaire’s asset data during manufacturing is essential to ensure it is futureproof. With a NEMA node, the mains power passes through the node before it reaches the luminaire and its driver. A NEMA controller therefore includes surge protection, low voltage power supply, energy metering, and mains switching of the load, in addition to connectivity and luminaire control interface. If it is supplied connected-ready, it comes with a “shorting cap” which is removed and relaced by the node when it is connected. The NEMA interface supports several alternative protocols in terms of control interface and allows multiple potential uses as the controllers have two extra pins to connect other applications. It is therefore ideal for nodes with high demands (smarter sensing capabilities, higher bandwidth connectivity, etc.). It is a good choice for more complicated smart city features, or if multiple objects will be attached to the node.
The Zhaga Consortium was established in 2010 to set standards for the interfaces for components used in LED luminaires. The consortium is a membership programme of the IEEE Industry Standards and Technology Organisation. Zhaga’s specifications, which are called Books, address electrical, mechanical, optical, thermal and communication interfaces and enable component interoperability. Books mean that components are interoperable, easy to service and replace, and that an LED luminaire can be upgraded after installation when new technology is available. I With a Zhaga node, the mains supply reaches the luminaire first, and the driver provides a limited auxiliary 24V power supply to the node through the Zhaga receptable. As a result, the driver used in this architecture has more features than a conventional driver, such as enhanced surge protection, auxiliary power supply, energy metering and diagnostics, while the Zhaga-D4i based control device only provides the connectivity and the DALI control interface within the given power limit. While still truly interoperable, it is smaller and therefore less intrusive aesthetically. It can be a wise choice for luminaires where aesthetic appeal needs to be maximised.
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