LEDs

What are the advantages of using a remote phosphor process compared to using phosphor coated LEDs?

The remote phosphor process offers:

  • Longer lifespan, as it reduces temperatures and slows down the rate at which the phosphor layer degenerates.
  • Increased system efficiency with reduced operating temperature of the system.
  • Better color stability with longer life of phosphors.
  • Less glaring than phosphor coated LEDs
  • More consistent flux output and correlated color temperature for the products, since LEDs from various bins can be used to produce light with consistent characteristics using the remote phosphor process.

What terms describe the different forms of LEDs from (basic electronics to fully functional light fixtures) that are available in the market?

Here are the various terminologies for developmental stages of LED in chronological order:

  • LED Die – A small block of light emitting semi-conducting material on which functional LED circuitry is fabricated.
  • LED Package – This includes an LED die or more than one LED die with an optical element and mechanical, thermal and electrical interface.
  • LED Module – This includes and LED package or an LED die, possibly with an optical element connected to a circuit board, and with thermal, mechanical and electrical interface that are intended to be connected to the load side of the driver.
  • LED Engine – This is an LED module or array of packages with the associated control gear / LED driver. It is the nearest equivalent to the lamp in a conventional luminaire.

What does SMD mean?

SMD means surface mounted diode. This is a better technology than the first generation DIP LEDs. The SMD typeLEDs are mounted on an aluminum substrate and enveloped in an epoxy resin.

What are the advantages of SMD over DIP LEDs?

The advantages of SMD over DIP LEDs are:

  • Smaller size
  • More lumen output
  • Better heat dissipation
  • Lower lumen depreciation
  • Longer life

What are the various types of LED chip packages available in the market?

The basic types of chip LEDs are:

  • SMD (Surface mounted diode) is a standalone chip on a ceramic base that can be integrated into various packages for linear LED strips or downlights.
  • COB (chip on board) LED, which comes as a high powered chip in direct contact with a printed circuit board optimal thermal management.
  • MCOB (multiple chips on board) LEDs, which are multiple COB LEDs integrated to form a single chip. This technology is used in LED bulbs and tubes.
  • MCCOB (multiple chips and cups on board) packages, which are used for high bay fixtures and floodlights.

What are the typical types of LED modules available in the market?

LED modules may be available in the following forms:

  • Prefabricated chip on board which can be used for specific applications by luminaire manufacturers who design the heat sink and mounting conditions.
  • Chip on board with an optical lens or diffuser as a prefabricated piece with or without integrated heatsink. That can be used by luminaire manufacturers to integrate into luminaire.
  • Retrofit lamps to replace older (halogen) technology. This comes with an integrated heat sink and standard lamp base that can fitted directly into existing luminaires with a standard lamp holder.
  • Prefabricated luminaires with an integrated LED light source and heat sink complete with luminaire housing that is available as a sealed piece. The driver may be integral in the housing or may be remote.

What does “future-proofing” of LED products mean?

LED technology is constantly changing. Rapid innovation continues to improve the performance of LED on an almost daily basis. Future-proofing of LED modules allows luminaire manufacturers to switch from one generation to the next improved generation without major retooling or changes in luminaire design, offering backward compatibility with drivers.

What is binning?

LED chips are mass produced in millions and there are inevitably slight differences in color appearance and light output. Binning is way of sorting the chips so that all the LEDs from one particular bin look the same and have similar light output.

What is a light engine?

A light engine is the LED equivalent of a conventional lamp. It normally consists of a LED chip mounted on a circuit board that has electrical and mechanical fixings, meaning it is ready to be fixed in the luminaire. Note that the light engine may not consist of only one chip; it may be an array of 9 or 16, sometimes with a phosphor coating.

What makes LEDs more robust than other light sources?

LEDs have no gases, filaments and no moving parts to fatigue. They provide light through a one-step process that takes place within the diode. There is no glass to break or screwed contacts to loosen.

Why do LEDs have a higher initial cost than conventional light sources?

LEDs are made of electronic components that need to be packaged together to offer long lasting efficient light sources to the end user. Apart from the LED chip itself which has sapphire and gallium in the semiconductor, the process of packaging with materials like ceramic, rare earth phosphors, silicone, solder and gold wire add to the overall cost. White LEDs require further tests for calibration and standardization.

What are the economic advantages of using LEDs over conventional light sources?

Although the initial cost of conventional light sources is less than LEDs, the operational and maintenance costs of LED are significantly lower. LEDs, having a longer life, reduce maintenance and lamp replacement cost. . Because LEDs need to be replaced less frequently, the owner spends less on new lamps and the labor needed to change them. LEDs also consume less energy; thus the overall cost of a LED system can be significantly lower than that of conventional lighting systems. Most applications with LEDs offer a payback period as low as three to four years.

What are the strategies in the development of LED technology that are helping to reduce the cost of LEDs in the future?

Some of the strategies for reducing the cost of LEDs in the future are:

• Reduction in the production process.
• Simplification and reduction in the number of components.
• Introduction of new materials.

What are the considerations that need to be taken into account when integrating LEDs into interior / architectural elements or furniture?

Here are some of the aspects that need to be taken into consideration: when

• Luminaire spacing and layout.
• Ways to prevent a view of the light source and minimize glare.
• Ventilation/cooling of LEDs
• Wiring access
• Access to LEDs in case of maintenance or replacement.
• Location of driver, if not integrated in luminaire.
• Switching / dimming capabilities, or control type and location.

What aspects need to be taken in consideration when replacing a light source with LEDs in a retrofit scenario?

• The lamp base / holder screw fixing position.
• The physical dimension of the LED lamp and how it fits into the existing housing.
• The electrical characteristics of LEDs compared to the existing system. (mains voltage, low voltage, control methods).
• The location and size of the light emitting surface in relation to the luminaire reflector and in comparison to the original light source.
• The light distribution, lumen output and other photometric properties like color temperature in comparison to the original light source.
• The heat generated by the LED during operation and the maximum operating temperature.

What are the types of LED units available for built-in wardrobes?

Lights built into wardrobes can be of the following types:

• Low voltage LED lights with a magnetic switch that comes in two components; one is fixed onto the wardrobe door and the other to the wardrobe itself. When the door is opened the contact is broken and power is sent to the light.
• PIR switches with an infra-red motion sensor that activates the light when the wardrobe is opened.

Can I use LEDs in a green house?

LEDs can produce concentrated beams of light at specific frequencies of light. While sunlight comprises the entire spectrum of light, LEDs can be designed to emit specific parts of the light spectrum that activate certain photoreceptors in the plant. For example, blue light promotes phototropism and cryptochromes which help germination and elongation of the plant, while red light stimulates phytochromes which help the plant to flower at the optimum time. Regulation of the spectrum of light based on the plants life cycle promotes faster growth, and a stronger plant than what would be produced under sunlight conditions.

Note that the light output of LEDs lessens at higher temperatures. You should make sure that the luminaire is suitable for the environmental conditions.

Is it true that LED lights do not attract insects?

Most insects are primarily attracted to Ultra-violet rays, which help them forage, navigate and select mates. For example, Indian moths are attracted to UV-365nm and green light-500nm. LEDs do not have UV content and hence do not attract many insects compared to conventional light sources.

How do LEDs keep food fresher than conventional light sources?

LEDs do not emit ultra-violet light and do not carry heat in the beam, unlike their conventional counterparts. This helps keep food fresher in refrigerators and cold stores.

What are the advantages of LED over neon in signage applications?

LEDs have the following advantages over neon:
• Power consumption: LEDs use much less power than neon to deliver the same light output.
• Versatility: LEDs offer a far wider a range of products and configuration of solutions than neon. Neon lights have limitations due the nature by which they produce light and the way they are fabricated.
• Heat dissipation: LEDs produce less heat than neon.
• Safety: Neon lights runs on high voltage and are unsafe when positioned in places where people can touch them.
• Neon lights use fragile glass tubes.
• Color range and effects: LEDs offer a wider palette of colour and color changing effects through digital control.
• Maintenance: LEDs need virtually no maintenance compared to neon.

What does one need to take into consideration when choosing a light source for art galleries and museums?

It is important to compare the spectral power distribution of the light source (SPD), the Color Rendering Index (CRI), Correlated Color Temperature (CCT) and the Color Quality Scale (CQS) of the light source relative to the nature of exhibits / displays to be lit. The illumination level needed within the exhibition and the hours of operation also need to be considered. This is a specialist area, and proper set up of lighting reqiures the advice of a consultant such as the curator.

How can the color changing ability of LEDs be advantageous in retail and display environments?

In retail and display environments where the range of products change by the season, the colors can be changed to match the type of product on display. For example, electronic goods may require a cool white light while a warmer tone may be required for fabrics. When a fashion season has red as a theme, the store can utilize a color of light with more red in its spectrum to enhance and bring out the vibrancy of the display.

How can flexibility in changing color temperature offer more comfortable environments?

LEDs offer the capability of changing from warm white to cool white through digital control of the LEDs. This can be used in indoor or partly outdoor environments where the illumination level and color temperature can be adjusted to match the outdoor conditions (e.g. sunny, clear sky or overcast) depending on the feel required in the space.

What are the benefits of using LEDs in mining areas specifically?

Using LEDs in mining areas has the following benefits:

• Better focus on work area
• Safer enivronment due to low glare and LEDs being cool to touch
• No start-up time
• Being solid state the workplace is easier to make it explosion-proof and vibration-proof
• LED can be powered with AC or DC and has longer battery backup with option of charging battery with solar panels
• LED lights can be installed with satellite connection and can have integrated motion sensors and GPS, which offers remote access to live information about usage, location, and condition along with offer further security features.

Can LEDs help to improve performance in classrooms?

LEDs have the capability to offer “biologically optimised” solutions that simulate the color temperature of the sky. This have been proven to improve concentration and maintain alertness of students in classrooms. It has successfully dealt with a kind of morning tiredness in mostly observed in young people. One way of creating the  appropriate color temperature is by using a combination of independently controlled blue and white LEDs.

How can LEDs help combat jetlag in air travel between countries?

Use of tunable LEDs in aircrafts can help alter the circadian rhythms of the passengers. The time-controlled simulation of daylight, noon and dusk color temperatures with the LEDs in the aircraft can help passengers to gradually adapt to the time zone of the destination.

Why are LEDs advantageous in lighting underground caves?

Underground stalactites are damaged by the heat of halogen lamps. LEDs, with their long lifecycle also require much less maintenance than traditional light sources.

PV

Installation of distributed photovoltaic power generation system

Current common roof types are the following three: concrete roof, color steel roof tile roof structure.

What is solar pumping system?

The solar pumping system is composed of solar pumping inverter, 3 phase AC pump, and solar array. The solar array is composed of many solar cells panels in series and in parallel, and absorbs irradiation from Sunlight, and converts into electrical energy (DC). Inverter controls and regulates pumping operation system and converts DC voltage from PV modules to AC to drive the AC pump, with the function of MPPT and it regulates the output frequency according to irradiation in actual time to achieve the maximum power. The AC pump driven by a 3 phase induction motor, draws water from well or rivers and lakes, then water reserved on tank/ponds for irrigation systems or other applications. Based on the requirements and installation conditions, different types of pumps will be required.

The solar pumping system is widely used for sea water desalination system, desert controlling, daily life water supplying, agricultural irrigation, forest irrigation, waterscape, and water treatment project. The Solartech solar pumping system is dispensed with battery and that enhance the reliability of the system and reduce the bill invest.

I need a solar pumping system, what info I should offer for the suitable one?

Lift、Daily water requirement、installation site、the average sunshine hours of the installation site, usage of water etc.   

Why cubic meters/day not cubic meters/hour for measuring the solar pumping system.

solar pumping dedicated inverter is adopted to achieve MPPT (Maximum Power Point Tracking) to regulate the speed of the pump, and the water output changes while the sunshine radiation changes, so, cubic meters/day is the only standard measurement of the water output of a solar pumping system.

How long will the photovoltaic system serve?

The solar PV module is with 25 years of using life, and the output power will get lower as the time past.