Difference between revisions of "Philips HPL-N"

Nowadays, mercury vapour lamps are very well suited for outdoor lighting. As the number of available fixtures diminishes and only second-hand or used products are available, they may not be economically effective to purchase except when you can readily use them rather than collect them. Free standing lamps are quite capable on their own so if you need a compact light source that is highly durable and colour output is appreciated as is, then high pressure mercury vapour lamps are well suited. They are especially well suited for lighting in areas that are undergoing renewal work, workshops, gardens. Of special interest is renewals, since no modern LED lamp can output the same light spectra that dulls old painted areas and brightens newly painted ones.

These lamps are not well suited for frequent switching. They need a couple of minutes to reach maximum light output and they require a couple of minutes to restart after being turned off. The light colour and output changes from start-up to normal operation from a pink to white. A good lamp should have a strong pink light at startup, suggesting good internal coating performance. As the lamp ages, the coating degrades and light turns greenish.

The lamp requires a conventional or electro-magnetic gear of the same power output as the lamp, connected in series with a lamp. Connecting the lamp directly to mains damages it instantly as there is no current limitation. A power factor capacitor that has a specific value might be used to correct the power factor and current requirements on the circuit. The lamp itself is not influence by the presence or absence of this capacitor. When used sparingly in homes or some premises where not a lot of these lamps are located, power factor correction is not important but large industrial or commercial clients were required to maintain a specific power factor due to electricity distribution contracting.  

The best lamps in terms of useful lifetime, colour reproduction, light output, are the equivalent OSRAM HQL branded lamps, not Philips HPL-N lamps even if Philips lamps were very popular. Chinese branded lamps are much worse in all performance and quality metrics with a greener light output and poor reproduction of oranges and reds. Reflector lamps are generally less versatile than the classic one for most purposes but they do not require any fixtures in most instances.

Used lamp gears might work but old lamps are not as desirable. Rusted ballast may still operate but are a potential hazard while old, used lamps, may not have much useful life left and they may already exhibit some colour light emission issues. New old-stock lamps are the best choice, if available.

== History ==