Difference between revisions of "Philips SON"

*Requires external gear and appropriate wiring:

** Reactive inductive ballast (230V standard on Europe), rated as the lamp, different from mercury lamps

** Suitable ignitor

** May require power factor correction capacitor for balancing line load

Sodium vapour lamps are still widely used on street lighting as well as industrial, commercial and residential outdoor security applications. Most of these uses cases are already slowly transitioning to LED lamps that offer much better performance with lower energy consumption and easy servicing. There are still some specific uses that are specific to this technology such as greenhouse lighting but special LEDs are also  replacing them. Light appearance is golden yellow a bias towards greens and reds with very low ultraviolet emmission.  

Exterior lighting is a good application but most gardens and outside areas look rather dull. The lamp themselves do release some heat meaning that closed fixtures are not well suited if not specifically built for this purpose. A good high pressure sodium vapour fixture is flexible, being possible to repurpose it for mercury vapour or metall hallide lamps with some minimal rewiring and gear change, being a very popular and cheap option as sodium vapour fixtures have been manufactured in millions until recently and large stocks are still available worldwide. Modern lamp gears are more versatile as older ones, being able to operate all sodium vapour lamps of the specified wattage. Note that typical sodium lamp ballasts have three connections unsing the semi-parallel ignition scheme rather than the parallel ones as on metal hallide lamps.

Note: there are other bases such as, for instance, the British B22D or the American E26 and E39;

Generally, sodium vapour lamps were very durable and most modern products were released with even longer typical lifetimes. This is mainly due to the fact that the main market of streetlighting pressured producers to cot servicing costs which means that reliability improvements were mandatory. Unfortunately, due to the way that almost all lamps are designed, they age in a different way compared with other light sources. Sodium slowly permeates the ceramic arc tube meaning that the lamp voltage raises as the lamp ages, making it harder to remain in stable operation after startup. This creates the well known on-and-off lamp cylces that repeats every couple of minutes, accelerating as the lamps is close to demise. Eventually, the lamp does not start but this happens after a long cycling and gear stress that might span over months or even a whole year.

Compared with modern LED lamps, sodium lamps compare favourably but they have a much poorer light output and require careful wiring. In most cases operational cost is lower as less powerful LED luminaires can be used since all useful light is directed downwards compared with the ineffcient fixtures used on most sodium vapour lamps. Ballast and ignitors can survive tens of years if properly protected against direct rain or snow exposure. A complex circuitry means that lamp servicing is difficult and there are major risks due to improper wiring on servicing as large voltages may be present. 70, 100 and 150 watt lamps are very well built and they were highly popular.

The lamp technology was an improvement of previous lamps that were used in larger luminaires, the low pressure sodium types. Looking similar to fluorescent lamps, sodium lamps had a totally different operation. They output monochromatic lamps compared with a pleasant flourescent white light but they were very well suited for traffic as this light was very little affected by fog and contrast was perfect on roads. Very poor colour reproduction was a very important limitation in market adoption, and it was noticed that increasing sodium pressure broadened light spectra contributing reds and greens to the light output. Many years there was no stable arc tube material that was able to withstand high temperature and aggressive sodium.  

When a suitable ceramic arc tube was developed and manufactured the lamp's high performance was confirmed in applications. Early lamps were attempted to be released with no external additional gear but durability was very poor so ignitors were developed for this specific application. The wattage and voltage of sodium lamps was not compatible with mercury lamps so an operational compromise had to be used to allow operation with mercury vapour lamp gear. This was especially important many years ago as mercury lamp installations were dominant. There was also research that culminated in specialty, even higher pressure sodium lamps, that have improved colour reproduction and a pleasant whiter appearance but they were very costly, had a shorter life and efficiency. They were never popular due to fluorescent lamps being much cheaper and easier to use. These lamps can be easily noticed by seeing their rather thicker internal arc tubes or the higher colour temperatures in datasheets.

Later developments focused on releasing optimized ballasts and ignitors that followed slender and more efficient internal arc tubes. Efficiency was improved significantly, making 20 to 30 thousands our lifetimes a certainty, increasing servicing intervals, lowering early failures and making high pressure lamps a very reliable lighting system. Electronic gears were not popular due to high costs although they were entirely possible from a technological perspective and they offered simpler wiring along with higher system energy efficiency. Only ignitors made the switch to advanced electronics as they were products with frequent replacements. The last technological advancement was made by using Xenon and removing Mercury from the arc tube, improving lamp life and efficiency but requiring higher starting voltages and new ignitors. These lamps have a few degress lower colour temperatures expressed in Kelvin.

Overall, sodium high pressure lamps, as is the case of metal hallide lamps, differ very much in terms of performance, even for similar types. Using a datasheet is mandatory if the circuit diagram and lamp being used is not the one that was supplied with the fixture, making operation and servicing a higher skilled job than with previous mercury vapour lamps. Modularity was ensured by making whole fixtures easy to replace and restricting servicing, including cleaning, to offsite premises, avoiding electrocution and prolonged labour at height risks.

Most manufacturers have been releasing lamps for many decades. Lamps produced in the 70s and early 80s are probably not commonly found today. In the 90s and early 2000 Philips was manufacturing lamps in Holland and other countries, while in the last years they were doing the same thing in China. Quality was not severely affected as manufacturing quality was maintained and applications were demanding, used in wealthier as well as poorer countries. It should be noted that sodium vapour lamps were mass manufactured and considered mainstream products, meaning that quality and reliability had to be consistent.

Products manufactured by Philips were similar to General Electric and Osram, with a quality and consistency much above some East-European manufacturers in terms of colour rendering, light output and life. However, Philips was manufacturing lamps with shorter lifetimes than typical Osram ones, as the datasheets and installations performance shows. These differences are maintained even nowadays. Philips lamps, however, were much more popular and are easier to find.