| The topic of calculations oddly seems to be a polarizing one around here, with some people discouraging their use entirely, claiming that there is no accurate way to be able to do them at all, and they should be left only to the "professionals". I am pretty sure that is the opposite of what we want if we want anyone to be in this hobby. If you are one of those people, just know that your opinion has already been heard. Let's stay focused on the questions at hand, and not write discouraging comments.
What we have so far:
This is the equation I have been using so far for many calculations regarding lamps and ballast characteristics:
BallastImpedance=(LampPowerFactor*sqrt(OpenCircuitVoltage^2-LampVoltage^2))/LampCurrent
This is a true equation as far as I am aware, but only when all of the following requirements are met:
1. Ballast is a purely ohmic impedance (usably true for HX or chokes, completely false for CWA)
2. Lamp voltage does not change with current (false, but usable within a small threshold)
3. Lamp distortion power factor does not change with current (false, but usable within a small threshold)
Another inaccuracy of this calculation is my use of average power factor values. I have averaged the power factor values for many different lamps to get average values for each lighting technology, and use those for calculation. But wattage-to-wattage power factor changes exist, I find this is especially problematic with metal halide. This is easy to fix, just calculate it for each lamp (pretty easy), and that is what I will be doing from now on. This still doesn't fix the other issues though.
What we need:
1. Knowing the characteristics of CWA ballasts will be necessary if we want to be able to use them in our calculations. That would require making the resistance of the ballast into a function dependent on the load presented to the ballast.
2. We need to multiply the nominal lamp voltage by some function of lamp current, to make the voltage change based on current. This requires some knowledge of the thermal characteristics of discharge lamps, which is undoubtedly different for each lamp type.
3. We need to figure out how lamp distortion power factor changes with current. I really doubt there is a way to figure this out without just testing a bunch of lamps.
If anyone knows anything about how to help with this, I would love to hear it. I know just getting this far is decentle useful, but I would like to go further if possible.
Thank you all! I am curious to see how this goes down...
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