Micrel KSZ8895 Specifications download pdf (Page 18)

TECHNICAL VIEW

www.futureelectronics.com

Improving comfort and cost savings with intelligent lighting

Growing interest in solid-state lighting is not only creating a need for

LEDs offering greater light output, reliability and quality, but is also

driving demands for cost-effective and interactive LED systems that

will deliver further reductions in energy consumption. In this article,

Future Lighting Solutions’ Regional Technical Manager Martin Schiel

and Technical Marketing Engineer Osama Mannan describe how an

intelligent lighting system that incorporates monitoring, control, and

a communication network can enable lighting designers to meet this

goal.

Intelligent Control

Many indoor and outdoor lighting applications, such as the office

downlights and municipal lighting, as well as display signs, parking

lights, architectural lights, garden lights and many other applications

are now making use of the unique advantages of LED technology.

These advantages include not only greater efficacy and quality

of light compared to conventional incandescent lamps, but also

the potential for various innovative methods of control. Whereas,

conventionally, light fixtures have been simply switched ON and OFF,

functionalities such as dimming, sensor interaction, and the ability

to control fixtures collectively or separately are quickly becoming

standard specifications. An intelligent lighting system is able to meet

such requirements.

One approach is to start from the basic semiconductor-IC level and

progressively build a solution that is tailored to the exact needs of the

application.

Another approach is to work with an off-the-shelf product, which

may come in the form of a black box that includes all necessary

components and is ready to be used instantly. This can be an

intelligent LED driver, a multi-functional remote control, or any device

that can be easily integrated with existing luminaires.

An intermediate option is to employ sub-systems that are not entirely

a finished product but are also flexible enough to provide the basis

for a customised control system.

Figure 1 shows an example of how a variety of intelligent control

components can be combined to manage light fixtures using several

methods. In this figure, a computer is connected to the Internet to

communicate with gateways enabling wireless control of multiple

fixtures in different locations. The computer can also be linked to the

wireless nodes through a wired or wireless connection to execute

control actions in each light fixture.

Communication

Data exchanges between intelligent control components and light

fixtures can take place using a variety of topologies. These topologies

define how the nodes in the intelligent lighting system are linked to

each other and how they communicate to deliver commands and

data.

Among the possible topologies, such as point-to-point, ring, star, tree,

or mesh topologies, the mesh is the most important topology for

lighting control. Its main advantage is that all nodes are equal peers.

In addition, the fact that all nodes are inter-connected to each other

provides high levels of flexibility and redundancy.

Regardless of the chosen implementation or topology, intelligent

lighting can be used with different communication methods. One

method is wireless communication. Many solution providers offer

systems that are easily integrated and can make use of wireless control

without having to manage the associated complexity. Alternatively,

Power-Line Communication (PLC) may be used to distribute control

signals and collect feedback from the light fixtures over the same

infrastructure that provides power to the fixtures.

A combination of wireless and PLC communications can be used to

configure a complete system capable of relaying commands and

information to the different nodes as required.

Features

Intelligent control offers a range of features depending on the need

and the capability of the lighting system. One key feature is dimming.

In addition to manual dimming, for example by adjusting a wall

dimmer or using a remote control, dimming signals can be sent

via a PC or the Internet using any of the communication methods

mentioned previously.

Moreover, the dimming signals can be generated automatically using

data from sensors such as motion detectors, ambient-light sensors,

light-output sensors, lightning detectors, or even temperature

sensors. Temperature sensing can be used to monitor thermal

conditions inside the fixture, allowing dimming to be used to protect

the LEDs and thereby enhance reliability.

Other potential intelligent-lighting features include monitoring of

energy consumption or failures within the lighting system.

From theory to practice

Since lighting contributes greatly to the overall energy consumption

of buildings such as factories, offices or homes, efficient lighting

systems can help to unlock significant energy savings. The following

example examines the performance of recessed downlights, one of

the most common applications in indoor lighting.

The comparison shows the power costs incurred by a conventional

Compact Fluorescent Lamp (CFL) downlight fixture, as in widespread

use today, an equivalent LED fixture using simple control, and an

intelligently controlled LED fixture. The intelligent lighting system

manages ON/OFF and dimming control according to the following

Fig. 1: Intelligent lighting-control components and methods

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Micrel KSZ8895 Specifications Page 18

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