The street lights using LED made the "smart city", to consider these factors......

The "smart city" refers to the communication and integration of tangible assets into a cohesive network, providing safer and more livable, more energy-efficient environment for people living there.

In the smart city, providing real-time information to the administrator through the range of sensors and monitors. According to the design, the collected data can achieve many functions, such as weather and air quality monitoring, adjust the traffic signal to alleviate congestion, adjust the public transportation schedules to meet changing needs, and more rapid deployment of emergency personnel.

The United States has been in Kansas City two miles (about 3.2 kilometers) of the corridor to achieve a paradigm of the smart city concept. The sensor is integrated into the Kansas City outdoor street lighting, to generate traffic patterns, and even a real-time picture of open parking spaces.

Although the smart city facilities will vary across the United States and other regions of the world, but one thing in common is to use outdoor LED lamps as fixed point sensors "". This means that in addition to the appropriate lens and the light guide shell design output to where it is needed, while minimizing glare and light the sky. Here are some things to consider:

Energy monitoring and calculation - because the city administrator needs data to evaluate the overall performance of outdoor lighting system, and determine the method makes the system more efficient, so the lighting should ability includes data collection and transmission. The data includes the ambient light level, conduction time, energy consumption and the state (for example, fully open, dimming level), were collected and analyzed by the predetermined time interval is transmitted to the network center.

Light and color - outdoor street lighting integrated into the smart city network, the full realization of the potential of energy saving, so the lamp should be dimming through regulation and response to changing environmental conditions. For example, in order to minimize energy consumption, lighting should follow the preset schedule (Figure 1).

Figure 1. example LED lamp dimming schedule

In case of emergency, the administrator should have the ability to cancel the pre-set schedule, and can also be a warm white light (due to warm white small influence on the sky light residential general preference) into cold white, so as to provide better visual acuity for emergency personnel.

Figure 2. in case of emergency, cold white lights provide better visual acuity (source: United States Department of energy)

Overvoltage protection of lightning and switching impulse voltage and electrostatic discharge of outdoor products risk was significantly higher than that of the indoor use of products. The overvoltage protection in electronic equipment and external, can achieve remission.

The reliability of temperature and temperature fluctuations, humidity, dust and water, into the UV exposure and vibration are the reasons for performance degradation or failure of outdoor lighting. Although the use of LED package in the lamp is the most sensitive to high temperature, but the components of the system (such as driver, optical components and integrated sensor) effect may be affected by other environmental factors. Reliability and quality assurance plan comprehensively, including the robustness test, can help mitigate these risks.

The maintainability and scalability of GPS position, lighting state, sensor state, input voltage and current and the internal temperature is the type of information intelligent city outdoor lighting products can provide, for repair or upgrade components at least stop time. In order to facilitate the replacement or cleaning, maintenance / upgrade design is critical to the overall lighting system feasibility.

Interoperability - ANSI C137 lighting system interoperability committee will be defined as "a system or system component to the defined mode of transmission, reception, interpretation and / or response data and / or the ability to function". Interoperability is often confused with "compatibility". Compatibility refers to the equipment whether to abide by certain standards. In accordance with the same standard equipment should be defined in the standard function of interoperability. Confirm the lighting system components (e.g., lighting device, sensor, network hardware and software interoperability) will reduce the risk of obsolescence due to hardware and software.

Safety - the last to consider network security. The design of intelligent city seems to be the most clear in the roles and responsibilities of supplier and buyer, and therefore the most worrying. Although the safety factor itself is not a lamp design, but please remember, any device on the network may be vulnerable to hacker attacks. (compiled: LED James)

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