Ballast Data

Tw:max working temperature

ΔT : temp rise

0.55 :power factor

Tw normally appears on the magnetic ballast.

It is the winding withstand temperature of the ballast. The life time of the ballast depends mainly on this temperature variation.

Other information has already share by BRAVO 88.

And this temperature value depends upon the ambient temperature of installation, delta T of the ballast, temperature rise of lamp, and method of installation of the fixture body.

FYI, the surface temperature of fluorescent lamps are designed to remain constant at about 40° C. This is required to obtain the maximum light output. It has nothing to do with the ballast temperature.

"This temperature value"

I mean this temp value as the overall temp rise of the ballast body, not the rated Tw of the ballast.

If I had to guess, Tw means working temperature. That is to say that under normal conditions, the outside temperature of the ballast in a well ventilated space where the surrounding temperature is 75° would be about 130° plus or minus a few degrees depending on the ventilation. This is quite common for a magnetic ballast which is the dinosaur of ballasts.

If you prevent air from circulating around the ballast, it will exceed 150° within 2 minutes. Within 2 hours, you will have significant smoke. If it has a thermo cut-off switch you will be spared the disaster that follows.

Other conditions can cause a malfunction resulting in overheating. That is why I included the disclamer about "under normal conditions"