Philips Mastercolour CDM-TD 150W / 830

In the Autumn of 1994 Philips unveiled a radically new kind of light source, and announced the first successful design of metal halide lamp employing a ceramic arc tube. This 150W double ended product was one of the first to market.

Ceramics have several advantages over quartz as an arc tube material, most notably that they can better withstand the corrosive nature of the metal halide salts. Thus the arc tube wall temperature can be raised, bringing with it an increase in halide vapour pressures and a consequent gain in luminous efficacy. Colour rendering properties are also improved. Colour stability from lamp-to-lamp is enhanced in this high temperature state, and the greater consistency in shape of the ceramic tubes also minimises colour variations.

The lamp was made a commercial success by mastering a new seal technology. Niobium is the traditional seal in ceramic lamps, but it is attacked by halides and is unsuitable for a metal halide lamp. Thorn's earlier TSH 150W lamp employed halide-resistant cermet seals but the frit was only semi-resistant, and had to be kept so cold that full lamp performance could not be achieved. The Philips Protruding Plug concept is employed in this arc tube, a further development of the White SON lamp. The seals are made to niobium wires in narrow capillaries, some distance from the arctube to keep the temperature down, and so narrow that the halide remains in the hot arc tube body. The niobium is welded to a short molybdenum piece, the join being also frit sealed, making the seal fully halide resistant. To prevent cracking due to the different thermal expansion coefficient of moly, it takes the form of thin wire spiralled over a central rod which acts as a successful stress relief mechanism.
Manufacturer: Philips Lighting
Lamp Power: 147 Watts
Lamp Current: 1.80 Amps
Lamp Voltage: 96 Volts 3.5-5.0 kV ignition pulse
Cap: R7s-24
Bulb Finish: UV Block Quartz Alumina doped
Bulb Type: T-21
Overall Length: 135.4 mm
Light Centre Length: 57.1 mm
Electrodes: Tungsten single coil
Inner/Outer Atmosphere: Ar-Kr85|Dy-Ho-Tm-Tl-Na-Ix Outer: Hard Vacuum
Luminous Flux: 13,500 lm (@ 100 hrs) 10,800 lm (@ 2,000 hrs)
Luminous Efficacy: 90 lm / W (@ 100 hrs) 72 lm / W (@ 2,000 hrs)
Colour Temperature & CRI: CCT: 3000K CRI: 85
Chromaticity Co-ordinates: CCx: 0.435 CCy: 0.400
Burning Position: Horizontal
Rated Life: 6,000 hours to 50% survival
Warm Up / Re-strike Time 3 minutes 15 minutes
Factory: Turnhout Belgium
Date of Manufacture: October 1997
Original / Present Value: £64.15 (1995) £74.58 (2001)
References: 1) Philips Mastercolour CDM Product Information Booklet (Provisional, October 1995).
2) Philips UK Price List, 1995.