One thing that has perplexed me about the North American lighting community is that many North American collectors who own SOX low pressure sodium lamps and other types of low pressure sodium lamps often resort to using Fulham’s line of “Workhorse” instant start electronic fluorescent lamp ballasts to run their SOX low pressure sodium lamps and other types of low pressure sodium lamps after seeing other collectors running their lamps this way. The problem I often see is that many of these collectors do not measure the operating current of their lamps when they run them this way. I just see that many collectors just seem to “wing it” without taking any proper electrical measurements. Because of this, I wonder who initially came up with the idea of using Fulham Workhorse electronic fluorescent ballasts as a means of operating SOX low pressure sodium lamps and other types of low pressure sodium lamps in North America as a cheap alternative to the correct magnetic ballasts that were available at high prices.

It is not trivial to precisely measure lamp current at 30kHz by the way. Common multimeters will not work.

But resonant HF ballasts should have relatively flat load curves with output current not much dependent on load voltage, so this probably is the point.

 

These ballast can be modelled as a high OVC constant current source, similar to a high impedance leak transformer...