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Siemens MAT/V "Dual" Mercury Blended |
The filament performed the dual role of ballasting the discharge, and increasing the red ratio of emitted light. It was a popular light source in industrial installations before the development of phosphor-coated lamps, which increased the red ratio by a more efficient mechanism. In order to cause the arc tube to run-up suitably quickly, a higher current is required for the first few minutes. A normal inductive ballast will take care of this automatically, but a resistive tungsten filament is not suitable. At ignition, only half the filament is used and this permits higher current flow to warm up the arc tube quickly. After a few minutes, the closing of the contacts of a bi-metal switch near the lamp cap brings the rest of the filament into circuit, ensuring that both the arc and filament are then driven at a safe operating current. This specialised construction made MAT lamps very expensive, and before long they were totally superseded by cheaper MBT quartz mercury products.
MAT Mercury-blended lamps were manufactured solely by Siemens Bros. of Preston - however that company later became amalgamated into AEI and this very late design of MAT lamp was made at AEI's Leicester lamp works according to that factory's design, after all discharge lamp production had been centralised in Leicester.
| Manufacturer: | Associated Electrical Industries Ltd. | |
| Lamp Power: | 300 Watts | |
| Lamp Current: | 1.30 Amps | |
| Lamp Voltage: | 230 Volts | |
| Cap Type: | E40s/45 | Ni plated brass + vitrite |
| Bulb Finish: | Clear | Soda-lime glass |
| Bulb Type: | GS-85 | GS-27 in eighths/inch |
| Overall Length: | 285 ± 15 mm | 111/4 inches |
| Light Centre Length (Arc): | 160 mm | 61/4 inches |
| Light Centre Length (Coil): | 255 mm | 10 inches |
| Electrodes: | C-6 Open Coil | Thoria pellet emitter |
| Atmosphere: | Inner: Hg | Ar (1 atm) | Outer: Nitrogen |
| Luminous Flux: | 6,300 lm (@ 100hrs) | 5,400 lm (@ 2,000hrs) |
| Luminous Efficacy: | 21.0 lm/W (@ 100hrs) | |
| Colour Temperature & CRI: | CCT: | CRI: |
| Chromaticity Co-ordinates: | CCx: | CCy: |
| Burning Position: | Vertical cap up | |
| Rated Lifetime: | 3,000 hours | (to 50% survival) |
| Warm-up & Re-strike Time: | 5 minutes | 10 minutes |
| Factory: | Leicester | England |
| Date of Manufacture: | Circa 1955 | |
| Original & Present Value: | £3 0s 0d (1959) | £62.95 (2015) |