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Solarcolour Plug-In SON-I 310W |
Within two years GEC made a significant design departure from its competitors. A drawback of the original lamps was the difficulty upgrading existing mercury installations. Firstly, the failure of HPS lamps is caused by rising arc voltage over time, so to attain a reasonable life it must start with a lower voltage. To keep power ratings the same as mercury lamps, this requires higher current and new ballasts. Secondly, the control gear is made more complex by the requirement for a high voltage pulse to strike the arc. GEC recognised that if it could make its lamps work on existing mercury control gear it would have a greater market potential, and by doing just that it quickly grew to a dominant force in the HPS business.
GEC developed its lamps with a low arc voltage for long life, but accepted a compromise by allowing lamp power to drop to non-standard ratings when used on existing mercury ballasts. This 310W model was the first of the company's "Plug-In" series, designed for operation on 400W mercury ballasts tapped to 10V above the actual supply voltage. The ignition problem was solved with the development of the internal snap-starter - a bi-metal switch heated by a loop of nichrome wire, arranged in parallel with the arc, which creates an inductive pulse to strike the discharge.
Also of interest in this lamp are the early disc-type niobium seals of the arc tube. One end is blind, while the other contains sodium amalgam in the crimped-off exhaust tube.
| Manufacturer: | The General Electric Company of England PLC | |
| Lamp Power: | 310 Watts | |
| Lamp Current: | 3.2 Amps | 4.4A during starting |
| Lamp Voltage: | 110 +20-15 Volts | 1000V ignition |
| Cap Type: | E40s/45 | Ni plated brass + vitrite |
| Bulb Type: | TD-51 | TD-16 in eighths/inch |
| Bulb Finish: | Clear | Borosilicate glass |
| Electrodes: | Backwound Tungsten | BCT Emitter |
| Arc Length: | 90 mm | 31/2 inches |
| Atmosphere: | Inner: Na,Hg | Xe | Outer: Hard Vacuum |
| Luminous Flux: | 27,000 lm (@ 100 hrs) | 25,000 lm (average) |
| Luminous Efficacy: | 87.1 lm/W (@ 100 hrs) | |
| Colour Temperature & CRI: | CCT: 2100K | CRI: Ra 23 |
| Chromaticity Co-ordinates: | CCx: 0.526 | CCy: 0.418 |
| Rated Lifetime: | 6,000 hours | 80% survival, 90% lumens |
| Warm-up & Re-strike Time: | 5 minutes | 15 minutes |
| Burning Position: | Universal | |
| Overall Length: | 292 mm | 111/2 inches |
| Light Centre Length: | 175 mm | 67/8 inches |
| Factory: | Shaw, Oldham | England |
| Date of Manufacture: | October 1969 | Date Code AK10 |
| Original / Present Value: | AU $41.77 (1972) | GB £185 (2013) |
