Re: IceCap/Fulham

["Wayne Jones" <waj at mnsi_net>]

Scott wrote:

Home Depot stock varies widely from store to store (it ain't like
MacDonalds, which has the same group of burgers (for better or worse)
at thousands of locations.  But I assume you're referring to a high
frequency 4x32 ballast.  Rapid start or energy saving rapid start.

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All ballasts for 4 x 32 watt lamps are electronic high frequency. The
vast majority of them are instant start. Advance only lists one that
isn't and it is programmed start. I would avoid trying to use a rapid
start, programmed start or dimming ballast to try and run a non-standard
lamp. That way you do not have to worry about matching the filiment
current. This is most likely why all Fulham ballast are instant start as
it allows their ballasts to be used on a wide range of lamps.

Scott wrote:

> The same is likely true of a Workhorse 7 and some

Yes, with the right selection of ballast wires -- the 7 passes nearly
twice the juice of the 5 (220 watts max vs 128 watts max, including 3-
watts or so for the ballast itself).  If you check out Fulham's wiring
diagrams, you'l find that they don't simply say, each (red) wire is x
amount of watts and you can add them up by joining them.  Sometimes
that appears to be the case and sometimes not.  They actually suggest
different ballasts/wiring configurations for different brands of biax
bulbs rated for the same wattage.  Check out different combos of 36 or
55 watt bulbs.

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The average watts of the 4 x 32 ballast is about 112. It is lower
because the ballast factors for these ballast are always around .88. 32
watt lamps are actually about 30.5 watts so 4 x 30.5 x .88 = 107 + 5
watts (for the ballast losses) = 112. Since Fulham does not publish an
average watts rating for their ballast (not a suprise since it depends
on which lamp combination you are using) it is hard to compare the two
wattages. However, if a Workhorse 7 can run 2 96 watt lamps then the
average wattage is very likely no more than 2 x 96 x .94 = 180 + 8 watts
for ballast losses = 188 watts. An equivilent ballast should be one
intended for two F96HO lamps which is a 205 watt ballast. They are
normally instant start too. I am less sure that this ballast is the same
as a workhorse 7 as I am not positive of the current requirements of a
96 watt PC. I know for a fact though that people have used the 2 x F96HO
ballast to run 96 watt PCs.

The main problem is make sure that the ballast is sized so that it
supplies sufficient current and wattage to the lamp.  The voltage that
developes across the lamp is controlled by the length of the lamp,
longer lamps have higher voltages so they draw more power at the same
current. If the lamp is so long that it requires more power than the
ballast can supply then you have a problem. You also have a problem if
the current is too low. A 4 x32 ballast will not operate 4 F40 4' lamps.
This is because the current and wattage requirements of the F40 lamp are
too high. You can get around this by overdriving 2 F40s by using two
outputs per lamp at 265 mA. per output. With a .88 BF ballast the lamps
should end up being operated at 2 x 265 x .88 = 465 mA which is higher
but not far off their normal working range.

I have tested several lamps with this ballast and naturally 1-4 F17s
will work as well as 1-4 F32s. In addition 1 or 2 F20 T12s and F40 T12s
also overdrive quite nicely.

The Panasonic 55 watt lamps are used with the workhorse 7 but the Osram
lamps are used with the workhorse 5. This indicates the 2 brands of
lamps operate at different current levels and therefore must have
different gas fills. This is where it gets tricky. I still think that
the limitations of the workhorse 5 are also the limitations of a 4 x 32
ballast which means that they won't operate a 55 watt Panasonic lamp but
they will operate a 55 watt Osram lamp.

Anyway, that is my attempt at reverse engineering electronic ballasts. I
am sure it is way too simple but so far everything that I know fits with
that theory. If I am right then 2 55 watt Osram lamps will be driven at
465 mA which is just about their normal operating range.

Wayne