2.3.2. Measuring luminaires for T5 lamps
Before measuring the light output ratio of a luminaire, the T5 Extreme Temperature lamps should be in a stable condition. The following steps must be taken:
•To bring the lamps to a stable condition, operate the lamps for approximately 100 hours
•Wait for 12 hours with the lamps turned off
•Measure the top lumen output of the lamps in the photometer with a measurement time of approximately 15 minutes
•For measuring the total
2.4.Thermal luminaire design and ballast lifetime
The ballasts for T5 VHO and T5 HO have a T_case max of 194°F (90°C). To maximize the lifetime and to minimize the failure rate of the ballast, the ballast should be placed inside the luminaire at a point where the measured T_case is lowest.
The time after which 10% of the ballasts have failed is called
the constant failure rate. For a T5 VHO and HO ballast in normal operation, this constant failure rate is approximately 50,000 hours at a fixed specified case temperature (194°F). A temperature increase of approximately 18°F halves this lifetime (thus, 212°F gives 25,000 hrs), while approximately 18°F lower doubles this figure (176°F gives 100,000 hrs).
2.4.1.Thermal hints and tips
There is an increasing trend towards higher wattages and lumen outputs in fluorescent lighting, leading to higher internal temperatures of luminaires.
Every luminaire is different (difference in materials, dimensions, applications, requirements, etc) so there is not just one simple solution which helps to prevent overheating of the internal luminaire. These hints and tips provide some ideas on how to deal with heat management inside a luminaire.
In the case of T5 VHO, the minimum distance between the lamp and the reflector must be at least 10mm. Adapting existing T5 luminaires (<54W) for T5 VHO requires more adjustment than just changing the lamp holders and ballasts.
OEM Design Guide Philips T5 VHO and HO Extreme Temperature Lamps and Ballasts 5
