GE White Lucalox LU95/SP28/PG12 HPS
In the 2nd half of the 1980s there were concentrated efforts to develop low wattage HPS lamps with white light and high colour rendering, to replace halogen and incandescent lamps. The Japanese were the first to launch lamps whose colour temperature was increased to about 2500K with a CRI raised to the mid to high 80s, notably Iwasaki's SDX and Matushita's K-HICA-G series. The design was further refined with the invention of Philips' SDW lamps with modified arc tube seals to improve performance and reliability.

GE was relatively late to market, but the 1990 launch of its White Lucalox did not fail to impress. It achieved still higher CCT of 2800K, with CRI a little lower at 70+ to limit the efficacy drop that always accompanies white sodium lamps.

Whereas competitors achieved a whiter light by increasing the sodium vapour pressure, which complicates arc tube design and limits life, GE pioneered the novel concept of operating the discharge in pulsed mode. It requires a dedicated ballast co-developed with Tridonic, which delivers very high current pulses of about 15-20A and 50-100μs width at high frequency. This raises the plasma temperature so as to excite the normally weak blue and green sodium spectral lines, and thereby achieve a whiter light. A fairly standard arc tube construction is then possible, employing GE's typical external amalgam reservoir to improve colour stability from lamp-to-lamp and during ageing, and external heat shields to raise amalgam temperature. Incidentally, early lamps were plagued by a humming noise due to magnetostriction of the stainless steel 316 support frame under the high current pulses - this was later eliminated by changing the frame to a non-ferrous metal.
Manufacturer: General Electric Company U.S.A.
Lamp Power: 95 Watts
Lamp Current: 1.4 Amps 15-20A Pulsed @ 50-100μs
Lamp Voltage: 95 Volts
Cap Type: PG12 Polycarbonate
Bulb Type: T-32 T-10 in eighths/inch
Bulb Finish: Clear Lead borosilicate glass
Electrodes: Backwound Tungsten Ba2CaWO6 Emitter
Arc Length: 23mm 29/32 inches
Atmosphere: Inner: Na,Hg | Xe Outer: Hard Vacuum
Luminous Flux: 5,200 lm (@ 100 hrs) 4,160 lm (@ 5000 hrs)
Luminous Efficacy: 54.7 lm/W (@ 100 hrs)
Colour Temperature & CRI: CCT: 2800K CRI: Ra 70+
Chromaticity Co-ordinates: CCx: 0.446 CCy: 0.400
Rated Lifetime: 10,000 hours 50% survival & 60% flux
Warm-up & Re-strike Time: 3-4 minutes 1 minute
Burning Position: Universal
Overall Length: 149 mm 57/16 inches
Light Centre Length: 90 mm 31/2 inches
Factory: Cuyahoga, NELA Park Cleveland OH, U.S.A.
Date of Manufacture: December 1990 Date Code: M0G
Original Value: Unknown
 
References: 1) Lighting Design & Application, November 1990, p.11
2) GE Lamp Specification Bulletin 206-01042, White Lucalox Lamps, February 1990
3) General Electric USA Large Lamp Catalogue, Form 9200, 1990