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MEI/H Coolseal with Supercool Leads |
MEI lamps dissipate immense power in a small volume and the quartz-to-molybdenum seals at either end of the arc tube easily overheat, oxidise, and cause the lamp to fail by splitting the seals open. A great deal of energy is carried into the seals by the light pipe effect, in which radiation from the arc tube travels along the seals as though it was a large optical fibre. This energy is concentrated at the ends where it can cause overheating and premature failure.
Dr. Prest's invention was to etch the surface of the seals, thus destroying the light pipe effect and dissipating much of the radiant energy out the side of the lamp. The Coolseal principle was most effective in increasing lamp life, while also eliminating the need for cooling fins in the luminaire.
A further breakthrough came in 1984 when the Supercool principle was invented, also by GEC. To further reduce seal temperatures the usual metal end caps were dispensed with, and replaced with flexible leads, thus eliminating the heat build-up found in the old bases. Electrical connections were made at the end of heavy duty leads, thus displacing them to a lower temperature region away from the lamp. Ceramic baffle plates protect the connections from the radiant heat of the arc, and also serve as the lamp mounting. By suspending them between springs, as illustrated, the lamp was better protected from mechanical shocks in service.
| Manufacturer: | The General Electric Company of England PLC | |
| Lamp Power: | 2500 Watts | |
| Lamp Current: | 14.9 Amps (Magnetic) | 13.5 Amps (Electronic) |
| Lamp Voltage: | 190 Volts (Magnetic) | 180 Volts (Electronic) |
| Cap Type: | Supercool Leads | Female 8mm screw thread |
| Bulb Finish: | Clear Quartz | Sandblasted end seals |
| Bulb Type: | BTT-30 | BTT-14 in eighths/inch |
| Overall Length: | 303 mm | 11 15/16 inches |
| Light Centre Length: | N/A | N/A |
| Arc Length: | 25.0 mm | 0.98 inches |
| Electrodes: | Solid Tungsten | |
| Atmosphere: | Ar | (Dy,Ho,Tm)Ix, Hg | |
| Luminous Flux: | 240,000 lm | |
| Luminous Efficacy: | 96.0 lm/W | |
| Colour Temperature & CRI: | CCT:5600K | CRI:Ra 90-95 |
| Chromaticity Co-ordinates: | CCx:0.335 | CCx:0.335 |
| Burning Position: | Horizontal | |
| Rated Lifetime: | 500 hours | To 50% survival |
| Warm-up / Re-strike Time: | 2 minutes | Instantaneous |
| Factory: | Shaw, Oldham | England |
| Date of Manufacture: | June 1988 | Date Code VF2 |
| Original / Present Value: | £518.67 (1989) | £840.59 (2004) |
