I'm wondering, do they make semi resonant start fixtures for use on 120v, or is SRS just restricted to 240v land?
The 230V is bare minimum able to ignite only some lamps (T12 or the short ones), the 120V is way too low.
So the SRS is really possible only with the 230V supply.
On 120V you need some means to really boost the voltage, so either resonant, or a transformer.
The resonant concept means rather high capacitance, which would have to be connected parallel to the lamp. But the discharge nature does not like capacitances (capacitors tend to extinguish it, so it leads to relaxation oscillations with high current spikes, what will kill the lamp in short time), so such configuration is not usable with any discharge. So the capacitor would have to be separated from the discharge by some means of extra series inductance. But that means the capacitor voltage stress would become about 50% larger (so for 400V peak ignition voltage the capacitor rating would have to be at least 600V).
So practically the resonant concept is virtually reserved just for the high frequency, where the required capacitance is so small (2.2 to 15nF range), it charges or discharges sooner than the ionization level could change at all, so needs no extra current smoothing coil or so and even with 1kV rating it is still rather small and cheap component.
So for the mains frequency ballasts you end up with a transformer. And that is the base for the RS ballasts once so common in the US...
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