Author Topic: Using 34 watt t 12 bulbs in ballast that uses 30 watt and 40 watt lamp  (Read 27750 times)
Ash
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Re: Using 34 watt t 12 bulbs in ballast that uses 30 watt and 40 watt lamp « Reply #15 on: August 03, 2012, 04:23:06 AM » Author: Ash
What about power factor ? You measure V and A on the output so get VA. This is not equal to W, as for example 105V * 430mA is 45W not 40W, but the lamp is 40W. The explanation is in the waveform which is not sine

The 34W lamps can have different waveform than the full power lamps which means that the W acn be different

As such the load on the ballast's primary may be what is really different, not on the secondary

Also how about testing it on a 40W-only ballast with the same lamps ? There may be some difefrence as well, as while the working point for F40 can be the same for both ballasts, the "curve" for different lamps can be different

From what you say, looks like the 30W lamp you tested is not really 30W but the same 34W labeled as 30W ?
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Medved
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Re: Using 34 watt t 12 bulbs in ballast that uses 30 watt and 40 watt lamp « Reply #16 on: August 15, 2012, 01:35:14 PM » Author: Medved
The voltage shape does not differ as much between lamp types, all discharges end up with about rectangular waveform, the only major differences are in the height of the reignition spike (after current zero cross). But as the reignition spike is very short in the time, it play's negligible role in the ballast current, neither do the small variations in the exact shape.
So if the F30 and F40 have the same voltage, they would run on the same ballast at the same wattage. The only difference is the filament, what is always designed for given operating current, so the F30 would have thinner wire than F34, so the F30 filament would run hotter, what usually mean the lamp would start easier (on ballast with high impedance heating, so mainly preheat). And the shorter length of the F30 play the role as well, on all ballasts...
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