Difference between revisions of "Philips SON"

*Internal high pressure sodium discharge tube made out of quartz

*E27 base or E40 base (requires matching ballast)

*Luminous efficacy of 36 to 59 lumens/watt (highest on highest wattage lamps)

*Cool white colour designation (4200 to 3900K colour temperature)

** Suitable ignitor

[[Image:Philips HPL-N 250W.jpg|Philips HPL-N 250W]]

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 using the semi-parallel ignition scheme rather than the parallel ones as on metal hallide lamps.

| HPL-N 50W/542 E27 SG SLV || E27 || 50 W || 1800 lm || Cool White ||  4200 K || 49 || 16000 hours

| HPL-N 80W/542 E27 SG SLV || E27 || 80 W || 3700 lm || Cool White || 4200 K || 48 || 16000 hours

| HPL-N 125W/542 E27 HG SLV || E27 || 125 W || 6200 lm || Cool White || 4100 K || 46 || 16000 hours

| HPL-N 125W/542 E40 HG SLV || E40 || 125 W || 6200 lm || Cool White || 4100 K || 46 || 20000 hours

| HPL-N 250W/542 E40 HG CRP || E40 || 250 W || 12700 lm || Cool White || 4200 K || 45 || 16000 hours

| HPL-N 400W/542 E40 HG CRP || E40 || 400 W || 22000 lm || Cool White || 3900 K || 45 || 16000 hours

| HPL-N 700W/542 E40 HG CRP || E40 || 700 W || 38500 lm || Cool White || 3900 K || 45 || 12000 hours

| HPL-N 1000W/542 E40 HG CRP || E40 || 1000 W || 58500 lm || Cool White || 3900 K || 36 || 12000 hours

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 street lighting 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 inefficient 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.