Hello for all American and Canadian LG members:
In this picture I had reached conclusion that the terms HPF, NPF and LPF ballasts are all myths and BS. here I will tell why:
1. "HPF" is a term for a fluorescent ballast that incorporates a power factor correction capacitor inside their casing, thus making it high power factor.
2. "NPF" and "LPF" are two different terms for a fluorescent ballast that don't incorporates a PFC capacitor inside their casing thus have low power factor.
3. The only difference between "NPF" and "LPF" ballasts is the ballast current: The current of a "LPF ballast" is lower than that of a "NPF ballast", thus a "LPF ballast" underdrives lamps that a "NPF ballast" runs at full power.
In short: The power factor of a ballast can only be low or high, not "normal".
I hope that you have understood my things, since this is a popular myth even between lamp collectors and fans.

There is some confusion here between power factor and ballast factor

The power factor (for non harmonic loads) means the magnitude of a current component off-phase from the voltage. This current component does not deliver active power and has no effect on how the lamp works

The ballast factor means how much current the ballast actually provides to the lamp vs. the full lamp power. (In Europe for the most part all ballasts run the lamp at full power, so it's not as familiar concept as it is in the US where underpowered ballasts are more common). Also, this is only about the discharge current - The cathode heating is assumed to be either always correct (for RS) or absent (for IS) regardless of the ballast factor

Now there is a question, is there any correlation between the two ?

There seems to be, but this correlation is result of the demands on the market and not of any physical design constraints - nothing prevents the building of ballasts with whatever combinations of high/low power factors and high/low ballast factors

Traditionally high power factor is of concern to commercial installations only. Because you (as a system designer for example) feel its effects the most when it is not 4 luminaires in the garage, but 10's powered from one distribution board or 100's/1000's throughout a building. So this allready divides the market, to "professional" users wanting HPF and "home" users wanthing CHEAP, which implies LPF

The "professional" users also do some evaluation of light output (whether the full calculation with room cavity ratios, wall reflectivity, .... or at least some educated estimates) so they know what to demand from a lamp in terms of light output. They would tend to use the available lamp output to the fullest, so want high ballast factors

The "home" users choose pretty much everything by eyeballing (and failing that, by whatever the market pushes onto them) so this opens quite some opportunities for trolling them by pushing in lighting systems with reduced light output. I guess the interest to do something like that could come from the lighting manufacturers (save materials on ballasts, etc), green lobbyists (reduce power draw of lighting) and so on....

I guess the "Normal" power factor then came in as a marketing term, since "low power factor" sounds bad....



It reminds a little of the situation with ATX power supplies for PCs :

Most high end power supplies seem to show off how they are 80+ energy efficient and have high power factor, even though none of that actually matters to the home user (and the 2 parameters aren't physically related to each other either). Then when the users recommend power supply units to each other, they name the same things in the list of criteria for choosing a good power supply... Which technically makes little sense

However there is sense. It comes from the fact that there is indirect correlation between presence of those features vs. the power supply general build quality. A good reliable, true to rated power, etc unit will usually have a more advanced design that has power factor correction. and better component choice leading to better efficiency, while a bottom grade generic blowup box will have none of the optional features and undersized components that show up in the efficiency respectively

When I tried to see if I can observe any affects on lamp operation by removing the power factor correction capacitor from a HPF ballast, I have noticed that the lamp used on that ballast ran at the same arc voltage and current despite having the capacitor removed from the circuit. The only thing that I notice with removing a capacitor from a HPF ballast is that the line current goes up dramatically.

I think you have done it with a preheat ballast, since rapidstart ballasts, like CWA ballasts, requires the capacitor for lamp operation, as they uses it as the ballasting element.

I think you have done it with a preheat ballast, since rapidstart ballasts, like CWA ballasts, requires the capacitor for lamp operation, as they uses it as the ballasting element.

In my case, I actually tested that idea using North American 70w M98 pulse start metal halide ballasts that were actually used as preheat ballasts for F48T12 HO fluorescent tubes. Those ballasts had external power factor correction capacitors.