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MELZ Medium Pressure Mercury ИГАР-2 500W |
The Soviet design has a number of differences vs Western lamps. Most notable is the unusually low luminous efficacy - this 500W rating delivering fewer lumens than the foreign 400W types. It is suspected that the reason may be due to a difference in the type of glass used for the arc tube. Foreign lamps employ high softening temperature aluminosilicate glasses, and over the years the glass was made progessively harder which permitted hotter operation - the resulting increase in mercury vapour pressure leading to increased efficacy. This Russian lamp is characterised by an unusually long discharge tube and quite low power density, which may have been required if it is made from a lower softening temperature glass, such as ordinary borosilicate.
The electrodes take the form of open coiled-coils, coated with an emissive oxide. The feedthroughs are unusually sleeved in small glass tubes. The emitter material appears to be different than on Western lamps. During run-up it is normal for tiny particles of emitter to become dislodged, and if these fall into the arc they become ionised. Most MA lamps show a pinkish colour flare when this happens, but this Soviet lamp produces an unusual deep violet colour flash, as illustrated in the third illuminated photograph.
| Manufacturer: | МЭЛЗ (MELZ Moscow Electric Lamp Plant) | |
| Lamp Power: | 500 Watts | |
| Lamp Current: | 4.4 Amps | |
| Lamp Voltage: | 125 Volts | |
| Cap Type: | E40s/45 | Galvanised Steel + Vitrite |
| Bulb Type: | T-41 | T-13 in eighths/inch |
| Bulb Finish: | Clear | Borosilicate hard glass |
| Electrodes: | CC-8 Open Coil | Emissive oxide coating |
| Arc Length: | 178 mm | 7.0 inches |
| Atmosphere: | Inner: Hg | Ar (1 atm) | Outer: Nitrogen |
| Luminous Flux: | 16,000 lm | @ 100 hrs |
| Luminous Efficacy: | 32.0 lm/W | @ 100 hrs |
| Colour Temperature & CRI: | CCT: 5400K | CRI: Ra 6 |
| Chromaticity Co-ordinates: | CCx: 0.337 | CCy: 0.421 |
| Lifetime: | 5000 hours | |
| Warm-up & Re-strike Time: | 6 minutes | 10 minutes |
| Burning Position: | Vertical ± 10° | |
| Overall Length: | 352 mm | 13⅞ inches |
| Light Centre Length: | 198 mm | 7¾ inches |
| Factory: | Moscow | USSR |
| Date of Manufacture: | February 1957 | Date Code II-57 |
| Original Value: | Unknown | |
