Lamps of the Future

These lamps compare with the most efficient, durable and long lasting lighting solutions available today, but are yet to get due recognition

Induction lamps are just like any other fluorescent lamp except that they do not use electrodes. In fluorescents, electrodes carry electric current to their inner cavity to excite the mercury ions present and generate UV rays, which after coming in contact with phosphor coating/fluorescent powder, produce visible light. Whereas in induction lamps there are no electrodes; rather, an electro-magnetic field is produced with the help of an induction coil (a wire wrapped around a metal core) and a radio frequency power supply. This field excites mercury particles present inside the lamp, producing UV rays that hit the phosphor coating to produce visible white light.
The induction lamp offers an amazing 60,000-1,00,000 hour life, making it virtually maintenance free. It offers crisp white light with 80+ CRI and a choice of 3K, 4K, 5K and 6K colour temperatures. The high CRI light makes the colours look more bright, vibrant and attractive. It produces up to 150 pupil lumens of light for each watt of energy, making it more energy efficient than any other light source. Just like with fluorescent lamps, the colour temperature of this lamp too can be varied by changing the composition of phosphors.
Induction lamps do not cause fading or damage to material, as the amount of UV light generated by an 80W induction lamp is roughly equivalent to that of a regular fluorescent lamp per 1000 lux. Since the damage factor to materials is rated at a low 0.3, they can be used in open luminaries without any front glass.
It offers high reliability and instant on and off. Plus, in the absence of electrodes, the problem of heating up and reacting with gases present in the lamp cavity is also eliminated, and gas pressure can be optimised to increase light intensity. This electrode-less lamp has proven its durability in high-vibration and windy installations such as bridges, tunnels and roadway applications.

Components
The induction lamp system is comprised of three components: generator, power coupler and lamp. The power coupler transfers energy from the HF generator to the discharge point inside the glass bulb using an antenna that contains the primary induction coil and its ferrite core. The power coupler also has a heat conducting rod with mounting flange, and the latter allows the system to be mechanically attached to the luminaire.
All three components are separately replaceable. End of life usually means that the generator must be replaced, and at that time it is usually recommended to replace the bulb, as phosphor degeneration at 1,00,000 hours lowers lumen output by up to 37%.

Types
Induction lamps can be distinguished only by the manner in which the electro- magnetic field is created. Many lamps use an external power device known as a ballast or a frequency generator with a power coupler, which converts AC to DC, and through the control circuitry, changes this current into the frequency required by the lamp.

Separate ballasted cavity induction lamps
In this type, the electro-magnetic field is created inside the lamp whose cavity houses an induction coil wound on the ferrite core, and is connected to an external ballast by coaxial cables. A copper conductor rod is connected to the lamp base to keep the coil and lamp cavity cool. This type of lamp resembles an incandescent bulb except that it requires a ballast.

Self ballasted cavity induction lamps
These lamps are single unit solutions. The induction coil wrapped around the ferrite core is present inside the lamp cavity and an RF generating ballast is also incorporated in it. These are the best alternatives to incandescent lamps and CFLs, as they do not require special fixtures.

External coil induction lamps
These are usually in the form of a 54mm diameter tube, and use closed ferrite cores and magnetic coils at the two ends of the tube. They are connected to an external ballast, whose life span also determines the lamps’ operating life. The operating principle of these lamps is very similar to that of a transformer, and they are more efficient and effective as compared to cavity lamps, as power deposition is distributed and not localised.

Application
Induction lamps are suited for applications where replacement and maintenance is cumbersome, hazardous and expensive. They provide the advantages of fluorescent lighting, but with the additional instant start and efficient operation even in extreme cold temperatures. This makes them a popular choice in warehouses, industrial buildings, cafeterias, gymnasiums, stadiums and highways. They are also suitable for signage, tunnels, bridges, roadways, outdoor areas and security fixtures, garages, public spaces, and freezer and cold storage lighting. They are being used in flood lights, street lights, bay lights, down lighters, high mast lights and focus lights.

In The Limelight
Unfortunately, the level of awareness and acceptance of induction lamps by designers and end-customers has made their utilisation very low. Few are aware of the technology that makes these lamps amongst the most efficient light sources commercially available today. Manufacturers too have found no reason to invest in R&D to further improve their quality, with little competition coming in. Suppliers and fixture manufacturers also have not been too aggressive in promoting this product because the extremely longer life of the induction lamp over HID and/or HPS means fewer replacements. Commercially, their high pricing and associated high frequency generators have made it difficult to market them.
However, the lighting industry is seeing renewed interest in these lamps. There are plans for a wider range of voltages forms and wattages so that their applications can be expanded into residential, off-grid, solar and larger/higher outdoor uses. Many importers and dealers are also becoming aggressive in promoting them in domestic lighting trade shows and through advertisements. No doubt, the revival of the induction lamp will give a boost to the industry, which is always on the look out for long lasting, energy-efficient, reliable and low-maintenance solutions.