Re: Philips and Sylvania F32T8 having different power usage

I was going to ask if this was done under reference ballast conditions, but this latest post shows that the test was not. I wonder how muchg of this difference was natural variation?

Jeff Waymouth

ITSME.ULTIMATE wrote:

In article <bi6rt1hvqoutmnvvj7c6ns24ao7cv0l3e4@xxxxxxx>, xxx@lighting-
research.com says...

On Sun, 29 Jan 2006 20:35:40 -0800, ITSME.ULTIMATE
<itsme.ultimate@xxxxxxxxxxxxx> wrote:


Maybe the lamp specialists here could comment on my observation.


From a small number of samples, I noticed the F32T8 Philips lamps have a

higher arc voltage than electrically equivalent Sylvania lamps.

Just among the lamps I have around here, Philips lamps always cause a higher power draw (implying higher arc voltage considering the ballast is more or less a constant current source)

On a Sylvania/Motorola rapid start ballast a pair of Sylvania F32T8 32W makes the input power be around 60W.
Under the same conditions, a pair of Philips Alto F32T8 makes the input power around 64W, which I think is a fairly substantial difference when they're using F32T8 (30W) lamps to save power.

Ballast: QTP/2X32T8RSND120V
Lamp type 1: Philips F32T8/TL841 (green endcaps)
type 2: Sylvania FO32/841/ECO (Sylvania equivalent of environmentally friendly series)

Ambient: 20C ish, explosed lamp luminiaire
voltage: ~122v. Ballast is of auto-regulating type that maintains constant output.



Neither is of krypton filled "ES" type.

Different ballast/lamp makes a difference, but there's a trend of Philips lamps having a higher arc voltage than comparable Sylvania lamps

from my experience.

Is it just me or can you guys reproduce this trend too? What might cause them to have a different arc voltage? 

This is very strange. Both are rated for 32 watts, and the
rated power for both should be confirmed on the same
reference ballast. My experience is that there is usually
very little power variation between lamps when properly
measured.

Both are rated for either rapid start or instant start. The
Philips lamp is rated for 2950 initial lumens but the
Sylvania web site is not cooperating (or they will not let
me in because I don't remember my registration info right
now) so I can't get a comparative figure.

However, the only thing that should matter is that both of
these 4-foot T8 lamps are rated for the same power on the
same reference ballast. 

Considering the fact that the lamps have the same diameter
and length and both should use only argon and mercury, the
only factors that can change the voltage are the argon
pressure and the mercury vapor pressure. You can't change
the argon pressure but perhaps the factory messed up. Are
you sure that both lamps are fully warmed up? How long did
they burn before you made the voltage measurement?

Perhaps Jeff has an answer to this.


My testing procedures aren't standardized, but I believe it reflects on more of real world conditions.

Each set of lamps were warmed up for approximately 20 minutes. The lamps are not new. They all have about a thousand hours of use. Line voltage variation is a possibility, but as I said earlier, the ballast is a regulating constant power using a boost conveter topology. I have verified that varying the input voltage from 115 to 125 changes the voltage and current inversely proportionately, but input power remained the same(which I think is nice).

It would interseting if someone else here could compare Philips and Sylvania lamps the same way I did and post the result. 



.

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