Philips 6096S Three Phase Lighthouse Lamp

The development of lamps for Lighthouses presents several challenges, many of which were solved in a particularly elegant fashion by Philips of The Netherlands.

The first challenge relates to the creation of a light source having a uniform luminous intensity distribution about its axis, such that the brightness of the lighthouse is consistent from all angles. The present solution employs standard grid-type filaments arranged into a single large cylindrical body. In case only one filament was used, the voltage gradient between its two ends would be too high and lead to flashover. To counteract this problem, three small filaments are employed, thus reducing voltage gradients to safe limits.

Since failure of a lighthouse lamp is hazardous to shipping, it is customary to provide one or two back-ups which can be swiftly brought into position, however there is always some time loss. By employing three filaments, the Philips design ensures that if one should fail, the remaining two continue to deliver 2/3 of the full luminous flux until replacement can be arranged. Since the arcing which often accompanies filament failure may lead to complete destruction of the lamp, three pairs of so-called "lightning conductors" are arranged above the filaments in the form of Jacob's Ladders. These ensure that any arcing is rapidly conducted upwards and quenched, thereby protecting the other filaments.

The resulting mount assembly is complex and requires a special six-wire stem having triple pinch-seals. The exhaust tube is sealed to the side of the stem tube in the so-called Jaeger fashion. The cap has four contacts enabling electrical connection of the filaments in Star configuration.
Manufacturer: NV Philips Gloeilampenfabrieken Type 6096S
Lamp Power: 3000 Watts
Lamp Voltage: 110 Volts
Lamp Current: 3x 9.09 Amperes
Cap Type: G25t-59 3-pin on 59mm collar
Bulb Type: GS-240 GS-75.5 in eighths/inch
Bulb Finish: Clear Soda-lime glass
Filament Type: 3C-13C 3-part Cylindrical
Atmosphere: Argon-Nitrogen Red phosphorus getter
Luminous Flux: 50,000 Lumens
Luminous Efficacy: 16.7 Lumens per Watt
Beam Intensity: N/A
Beam Distribution: N/A
Colour Temperature & CRI: CCT: 3000 Kelvin CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.452 CCy: 0.409
Rated Lifetime: 800 hours
Burning Position: Vertical cap down ± 30°
Overall Length: 428 mm 167/8 inches
Light Centre Length: 270 mm 105/8 inches
Factory: Emmasingel, Eindhoven The Netherlands
Date of Manufacture: November 1968 Date Code: L8
Original Value: Unknown
 
References: 1) Philips Lamp Catalogue, 1970, International Edition.