Philips HPI-T Plus 400W/745
Like the majority of other metal halide lamps, the original Philips HPI series was developed for operation on mercury lamp ballasts. However there were some exceptions existed, for instance the decision of both Osram and Thorn to develop their 250W lamps for use on sodium ballasts from the outset. Later Osram also redesigned its 400W lamps to operate on sodium ballasts, and a few other manufacturers followed. This created immense confusion, because many consumers were unaware that it was necessary to choose a lamp that matched the installed ballast. Moreover luminaires do not generally indicate what type of ballast is included, and lampmakers did not make it clear which ballast each lamp was designed for. As such, the performance of many metal halide installations began to be compromised.

Philips proposed a solution in 1999 with the launch of the HPI "Plus" range - the first lamps that claimed compatibility with both mercury and sodium ballasts. It was a clever marketing strategy that saw the company grow market share. In fact, very little was actually changed. When operating on mercury ballasts there is no difference vs standard HPI. On sodium gear, power and luminous flux are increased significantly - and lifetime is also greatly reduced vs competitor lamps designed for use on sodium ballasts, but Philips neglected to draw attention to that detail.

In the mid 2000's the HPI-T Plus arc tube was technically improved. The arc gap of the 400W model was reduced from 41.5mm to 30.5mm, and the tube diameter from 16mm to 13mm. This increase in power loading allowed the heat-reflective coating at the arc tube ends to be dispensed with, along with improved lumen maintenance.
Manufacturer: NV Philips Gloeilampenfabrieken
Lamp Power: 382 Watts
Lamp Current: 3.4 Amps
Lamp Voltage: 125 Volts 700V Ignition
Cap Type: E40s/45 Ni plated brass + vitrite
Bulb Type: T-46 T-16 in eighths/inch
Bulb Finish: Clear Borosilicate glass
Electrodes: Double Coil Tungsten Radioactive ThO2 emitter
Arc Length: 30.5mm 1.20 inches
Atmosphere: (Na,In,Tl)Ix, Hg | Ne-0.5%Ar Outer: Ne-40%N2
Luminous Flux: 32,000 lm (@ 100hrs)
Luminous Efficacy: 83.8 lm/W (@ 100hrs)
Colour Temperature & CRI: CCT: 4500K CRI: Ra 65
Chromaticity Co-ordinates: CCx: 0.361 CCy: 0.372
Rated Lifetime: 20,000 hours 50% survival & 60% flux
Warm-up & Re-strike time: 3 minutes 5 minutes
Burning Position: Horizontal ± 20°
Overall Length: 286 mm 111/4 inches
Light Centre Length: 180 mm 71/16 inches
Factory: Turnhout Belgium
Date of Manufacture: December 2012 Date Code: 2M
Original / Present Value: EUR 82.10 (2012)
 
References: 1) Philips Lampencatalogus & Prijspocket, Netherlands, 2012
2) Philips Presentation HPI-T Plus Lamps, 2001