SL*18 Compact Fluorescent with Integral Ballast

The Philips SL*18 lamp was the first successful one-piece self ballasted compact fluorescent to replace incandescent lamps. Offering energy savings of 75% and a five-fold longer lifetime it represented a sound investment, and became popular in commercial lighting applications.

The lamp consists of a 12mm fluorescent tube folded into three large U-bends to form four parallel sections, enclosing a wirewound magnetic ballast, and with a glowbottle starter and thermal fuse being integrated in the base. A prismatic glass jar refracts the light uniformly, and earned the SL its nickname as the jampot lamp - resembling the latter in both shape and weight! A crucial development that made this lamp feasible was the invention by Louis Vrenken of the rare earth phosphors having an aluminate host lattice, in place of the usual silicates or tungstates. These new materials slowed the rate of lumen depreciation, a degradation process that had always been very fast in tubes of such narrow diameter with traditional phosphors.

Compact fluorescent technology progressed a long way during the following four decades, but never achieved the low cost, convenience and simplicity of the incandescent lamp. Although the SL lamp featured here is technologically a great milestone, it is easy to see why it was slow to penetrate the market. Most notable is its great weight - owing to the conventional magnetic ballast inside, the mass of the lamp is more than half a kilogram and this was prone to make many table and standard lamps top heavy and unstable. The large dimensions precluded installation in some luminaires, the run-up time of three minutesproved unacceptable, and the light had a pronounced 50Hz flicker.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 18 Watts
Lamp Current: 0.180 Amps
Lamp Voltage: 220 Volts
Cap Type: E27s/27 Ni plated brass + vitrite
Bulb Type: T-72
Bulb Finish: Prismatic Moulded Soda-lime glass
Electrodes: Triple coiled tungsten Triple carbonate emitter
Atmosphere: Inner: Ar|Hg Amalgam Outer: Air
Luminous Flux: 900 lumens @ 100h hours
Luminous Efficacy: 50.0 lm/W @ 100h hours
Colour Temperature & CRI: CCT: 2700K CRI: Ra=80
Chromaticity Co-ordinates: CCx: 0.462 CCy: 0.412
Rated Lifetime: 5,000 hours to 70% survival
Warm-up & Re-strike time: 3 minutes Instant re-strike
Burning Position: Universal
Overall Length: 168 mm 65/8 inches
Light Centre Length:
Mass: 560 grams
Factory: Terneuzen The Netherlands
Date of Manufacture: March 1982 Date Code: C2
Original Value: GB £5.00 (1983)
References: 1) Philips Lamp Catalogue, 1982 UK.
2) Philips Technical Brochure PL3001, 1983 UK.