low energy lamps served by chopped wave invertor

[odbob]

Is there an electronics wiz out there who can explain a phenomenon. I have a set up which includes P.Vs to battery to a chopped wave inverter, I cant measure the voltage off this inverter but the dim light output of any tungsten lamps served by it suggest that the voltage is somewhat lower than the mains voltage. However all of my low energy lamps seem not to be affected ie thier light out put is much the same as if on mains power. This is a very pleasing effect and I like to bring it into conversation when promoting alternatives, I would however feel happier if I knew the reason, is it to do with back emf or over correction of the power factor, what ever, it does not seem to upset the inverter.

[wyleu]

It would be interesting to (safely) put an oscilloscope across it to see what sort of thing you get to see.
Actually has any one got a gallery of invertor 'sine waves' for our delectation?

[Sigma Nova]

It just MIGHT be that the invertor is going into current limit because of the low cold resistance of the tungsten lamp. The resistance of a tungsten filament when cold is only a small fraction of its running temperature. That means that there is a large inrush of current when you switch on a tungsten lamp. That said, you say that the tungsten lamp does glow, but dimly. That implies that the resisitance is a lot higher than cold already. Another possibility is that the energy-saving light bulb is actually not producing as much light as you think. When a filament bulb is under-powered, the filament does not get so hot and teh colour spectrum of the emitted light goes redder. This is not the case with energy-saveing bulbs, which are essentially fluorescent lamps. The bulb generates ultra-violet light. This energises the phosphor coating on the inside surface of the bulb which then emits visible light. The spectrum of that light does not change when the power is reduced.

Both explanations are probably wrong.

[odbob]

Thanks Wyleu, I dont have an oscilloscope and if I did, douptfull I would know how to use it, maybe this would reveal what is truly happening though.
 Sigma Novas answer maybe covers what I need to know although I would imagine the current to these low energy lamps is bumped up slightly (on the basis, you get nothing for free) the light output certainly appears to be at the same level as if on mains.
 
Incidently the inverter is not undersized, I have 600 watt P.V. charging 25KW battery serving my lighting requirements approx 160 watt via this 600 watt inverter.

thanks to you both

[Peter.N.]

Could it be that the inverter in the low energy lamps is self regulating as in a TV i.e. (switch mode)?

Peter.N.