Letters
An option, not a necessity
With reference to the article within the Lighting Technology section of the IAEEL Mewsletter 1/92 entitled "60 000 hours of no maintenance ", I would like to clarify the point concerning replacement equipment needed at the end of the QL lamp system's operating life.Your article suggests that both the QL lamp and the luminaire it is housed in need to be replaced when the lamp system fails. This is, in fact, not the case. Only the failed component within the lamp system, either the HF electronic generator or the discharge vessel ("bulb"), needs to be replaced which helps minimize ongoing maintenance costs.
Of course, the ultra-long life of the QL lamp systems does provide luminaire designers with the possibility to fully integrate the lamp and luminaire; however, this is an option, not a necessity.
Factors such as operating hours and choice of luminaire materials will influence the decision. For example, in a streetlighting application burning typically 4 000 hours per year, a QL will have an operating life of some 14 years. Therefore the luminaire designer may decide to design a luminaire that also has an expected lifetime of 15 years.
Hoping to have been of assistance.
J.P.M. van Dijk
Ing., Product Mgr
QL lamp systems
Philips Lighting N.V.
Turnhout, Belgium